Abstract
Christopher F. Batsavage. LIFE HISTORY ASPECTS OF THE HICKORY SHAD
{ALOSA MEDIOCRIS) IN THE ALBEMARLE SOUND/ROANOKE RIVER
WATERSHED, NORTH CAROLINA. (Under the direction of Roger A. Rulifson).
Department of Biology, East Carolina University, December 1997.
The hickory shad (Alosa mediocris), which supports commercial and recreational
fisheries in the Roanoke River and Albemarle Sound, North Carolina, is an anadromous
species closely related to the American shad (A. sapidissima). The Albemarle Sound
population has exhibited a surge in numbers since 1989, but the cause is unexplained.
Little is known about the life history of this species, which now supports a fast-growing
sport fishery on the Roanoke River near Weldon, NC, and increased commercial catches
in Albemarle Sound. The goal of this study was to characterize key life history aspects of
hickory shad in the Albemarle Sound/Roanoke River watershed including the age, size,
and sex compositions of the population, the sexual maturity schedule (age to maturity),
potential fecundity of adults, and identification of the nursery grounds. Fish examined in
this study were captured in 1996 from the Albemarle Sound and Roanoke River. The sex
ratio (males:females) of adult fish sampled from Albemarle Sound and the Roanoke River
at Weldon was statistically similar (0.73:1 and 0.76:1, respectively). A 57% agreement
was found between aging fish with scales and otoliths; scales overestimated younger-aged
fish and underestimated older-aged fish. Most males were age 3 and most females were
age 4; few fish were older than age 4 and the maximum age was 7. Males were generally
smaller than females; overlapping lengths and weights at age make estimates of size at
age difficult. Some fish were mature by age 2, and essentially all were mature at age 3.
Fecundity estimates ranged from 80,290 to 478,944 eggs with most fish spawning two or
three times before leaving the population (from harvest or natural mortality). Reduced
visceral fat of fish in the Roanoke River indicated use of stored lipid reserves during
migration. Juvenile hickory shad apparently do not utilize Albemarle Sound as a nursery
ground in the same manner as American shad and river herring, but they may use coastal
ocean waters. A short life span and low fecundity makes this population vulnerable to
overharvest.
LIFE HISTORY ASPECTS OF THE HICKORY SHAD {ALOSA MEDIOCRIS) IN THE
ALBEMARLE SOUND/ROANOKE RIVER WATERSHED, NORTH CAROLINA
A Thesis
Presented to
The Faculty of the Department of Biology
East Carolina University
In Partial Fulfillment
of the Requirements for the Degree
Master of Science in Biology
by
Christopher F. Batsavage
December 1997
LIFE HISTORY ASPECTS OF THE HICKORY SHAD {ALOSA MEDIOCRIS) IN THE
ALBEMALRE SOUND/ROANOKE RIVER WATERSHED, NORTH CAROLINA
by
Christopher F. Batsavage
APPROVED BY:
1 1
DIRECTOR OF THESIS
Rogé A. Rulifson, Ph.I
Acknowledgments
I am very grateful to Dr. Roger A. Rulifson for his endless guidance, support, and
suggestions. I would also like to thank my committee members. Dr. Charles S. Manooch,
III, Dr. Ronald J. Klauda, and Dr. Charles A. Singhas for their constructive comments
and suggestions. I thank the NCDMF, especially Harrel Johnson, Steve Trowell, Sara
Winslow, and field technicians of the Elizabeth City office, for their assistance in fish
collection and for suggestions and advice that helped me carry out this study. I also thank
the NMFS sampling crew, headed by Dr. David S. Peters, and the RRNWR sampling
crew, headed by Jerry Holloman, for letting me examine adult hickory shad collected
from the Refuge. My thanks to Pete Komegay of the NCWRC for estimating the
recreational harvest of hickory shad on the Roanoke River for 1996. I am grateful to the
anglers at Weldon, North Carolina who were interested in my study and allowed me to
sample their catches. A special thanks goes out to the ECU undergraduate students that
helped in the laboratory and in the field, especially Marcy Hutchinson, Corey Pressley,
Tanya Eatmon, Crystal Small, and Chris Williams. A special thanks also goes to Dr.
Manooch and Jennifer Potts of NMFS for the use of their laboratory for otolith back
calculations and for their helpful advice and suggestions regarding this study and report.
And a special thanks goes to my family for their patience and support. Funding for this
project was provided, in part, by the North Carolina Marine Fisheries Commission
Fishery Resource Grant Program, Project No. M6057 to Dr. R. A. Rulifson.
Table of Contents
List of Figures v
List of Tables vii
Introduction 1
Materials and Methods 9
Adult Collection 9
Scale and Otolith Aging 9
Spawning History 10
Mortality Estimates 11
Scale and Otolith Back Calculations 13
Fecundity 14
Mesentery Fat and Gut Content Analysis 15
Juvenile Nursery Grounds 15
Results 22
Adult Sex Ratios 22
Adult Size Distributions 24
Age Analysis 32
Spawning History 43
Mortality Estimates 43
Scale and Otolith Back Calculations 47
Reproductive Analysis 57
Mesentery Fat and Gut Content Analysis 65
Nursery Grounds 65
River Flow and Year Class Abundance 77
Discussion 81
Adult Sex Compositions of the Catch 81
Scale Age/Otolith Age Agreement 82
Age to Maturity 83
Table of Contents (continued)
Fecundity 83
Fork Length at Age 86
Scale and Otolith Back Calculations 87
Spawning Habitat 89
Juvenile Distributions 90
Comparison of Hickory Shad to Alabama Shad 90
River Flow and Year Class Abundance 91
Conclusions 92
Management Recommendations 92
Research Recommendations 93
Literature Cited 95
List of Figures
1. Illustration of a hickory shad and an American shad 2
2. Map of the Roanoke River watershed, NC showing the sampling sites for
the independent gill net survey in the Roanoke River National Wildlife Refuge
(RRNWR) and for the recreational sport fishery in Weldon, NC 7
3. Map of Albemarle Sound and its tributaries showing the seine and trawl
sampling sites for the juvenile hickory shad survey 8
4. Map of Albemarle Sound and its tributaries showing the sampling sites for
the juvenile striped bass and the juvenile alosid seine surveys conducted by
the North Carolina Division of Marine Fisheries (NCDMF) 18
5. Length frequencies of adult hickory shad into 10 mm size classes, by sex 25
6. Percent frequencies of adult hickory shad into 10 mm size classes, by sex 26
7. Log-transformed body weight (g) to log-transformed fork length (mm)
relationship of adult male hickory shad 27
8. Log-transformed body weight (g) to log-transformed fork length (mm)
relationship of adult female hickory shad 28
9. Log-transformed somatic weight (g) to log-transformed fork length (mm)
relationship of adult male hickory shad 29
10. Log-transformed somatic weight (g) to log-transformed fork length (mm)
relationship of adult female hickory shad 30
11. Total length (mm) to fork length (mm) relationship for adult hickory shad 31
12. Age comparison analysis between scales and otoliths 33
13. Age class distributions of male and female hickory shad 35
14. Age class to fork length (mm) relationship for male hickory shad 37
15. Age class to body weight (g) relationship for male hickory shad 38
16. Age class to fork length (mm) relationship for female hickory shad 40
17. Age class to body weight (g) relationship for female hickory shad 41
18. Otolith radius (mm) (16x) to fork length (mm) relationship for male
hickory shad 48
19. Otolith radius (mm) (16x) to fork length (mm) relationship for female
hickory shad 49
20. Otolith radius (mm) (16x) to fork length (mm) relationship for both sexes
of hickory shad 50
21. Scale radius (mm) (24x) to fork length (mm) relationship for virgin male
hickory shad 52
22. Scale radius (mm) (24x) to fork length (mm) relationship for virgin female
hickory shad 53
23. Potential fecundity to fork length (mm) relationship for female hickory shad 59
24. Potential fecundity to somatic weight (g) relationship for female hickory shad 60
25. Potential fecundity to age class relationship for female hickory shad 61
vi
List of Figures (continued)
26. Potential fecundity to gonadosomatic index (GSI) relationship for female
hickory shad 62
27. River flow patterns in the Roanoke River downstream of Roanoke Rapids dam
during the hickory shad spawning season (February-April), 1989-1992 79
28. River flow patterns in the Roanoke River downstream of Roanoke Rapids dam
during the hickory shad spawning season (February-April), 1993-1996 80
List of Tables
1. Description of beach seine and trawl sites in the Albemarle Sound and selected
tributaries for the juvenile hickory shad survey 19
2. Two-way and three-way comparisons of Chi-square analyses of the male to
female ratios for Albemarle Sound, RRNWR, and Weldon, NC 23
3. Scale and otolith age class distributions of Albemarle Sound/Roanoke River
hickory shad by sex, 1996 34
4. Observed mean values of fork length (mm), body weight (g), and somatic weight
at age of male hickory shad collected from the Roanoke River near Weldon, the
Roanoke River National Wildlife Refuge, and Albemarle Sound during
spring 1996 36
5. Observed mean values of fork length (mm), body weight (g), somatic weight (g),
and potential fecundity at age of male hickory shad collected from the Roanoke
River near Weldon, the Roanoke River National Wildlife Refuge, and Albemarle
Sound during spring 1996 39
6. Observed mean values of fork length (mm), body weight (g), and somatic
weight (g) at age of hickory shad sexes combined collected from the Roanoke
River near Weldon, the Roanoke River National Wildlife Refuge, and
Albemarle Sound during spring 1996 42
7. Number of spawning marks for male hickory shad from the Albemarle
Sound/Roanoke River watershed, 1996, by age class 44
8. Number of spawning marks for female hickory shad from the Albemarle
Sound/Roanoke River watershed, 1996, by age class 45
9. Age at maturity (percent) of male, female, and combined sex hickory shad in the
Albemarle Sound/Roanoke River watershed, 1996 46
10. Results of linear regressions describing the relationships among fork length
(FL, mm), scale radius, and otolith radius for male and female hickory shad 51
11. Comparison of mean fork lengths at age from observed data and back calculated
data for males and females, and from the von Bertalanffy growth equation data
for both sexes combined 54
12. Calculated fork length at age for adult hickory shad (sexes combined) 56
13. Mean and range (in parenthesis) of GSI values for ages 3 and 4 female
hickory shad from Albemarle Sound, RRNWR, and Weldon, by month 58
14. Potential fecundity of female hickory shad calculated gravimetrically and
estimated from regressions developed for age class, fork length (FL, mm),
body weight (g), and somatic weight (g) 64
15. Results of linear regressions describing the relationship between somatic
weight (g) and mesentery fat weight (g) for male and female hickory shad
from Albemarle Sound and the Roanoke River 66
viii
List of Tables (continued)
16. Species composition from the juvenile hickory shad survey seine and trawl
samples in the Albemarle Sound and selected tributaries, 1996 68
17. Catch per unit effort for the four juvenile Alosa species by region in beach
seines in the Albemarle Sound and selected tributaries 70
18. Species abundance for each sample week of the NCDMF juvenile striped bass
survey 71
19. Juvenile hickory shad collected during the NCDMF juvenile striped bass and
juvenile alosid seine surveys 73
20. Fish species associated with juvenile hickory shad 74
21. Water quality parameters for the 16 seine stations in the Albemarle Sound and
selected tributaries for the period May to October 1996 75
22. A comparison of life history aspects of American shad, hickory shad, alewife,
and blueback herring 84
23. A comparison of fork length at age from this study to previous hickory shad
studies 88
Introduction
The hickory shad {Alosa mediocris) is one of four anadromous Alosa species
native to North Carolina. It ranges from Cape Cod, Massachusetts to the Saint John's
River, Florida (Robins et al. 1986), although there does not appear to be any spawning
populations north of Maryland (Richkus and DiNardo 1984). Hickory shad is
intermediate in size between the larger American shad (A. sapidissima) and the smaller
alewife (A. pseudoharengus) and blueback herring (A. aestivalis). The largest hickory
shad reported was 60 cm total length (TL) (Robins et al. 1986 ); however, adults are
typically 30-45 cm fork length (FL) and weigh 0.5-1.0 kg (Figure 1).
The hickory shad has a low commercial value when compared to American shad,
alewife, and blueback herring (the latter two marketed together as river herring) (Marshall
1977). Typically it is a bycatch species in the American shad gill net fishery in
Albemarle Sound and the Atlantic Ocean. It also is caught in pound nets, haul seines,
drift gill nets used for river herring, and in the offshore winter trawl fishery for striped
bass {Morone saxatilis) (Street et al. 1975). The mesh sizes (102-140 mm) used in the
gill net fishery only catch the larger hickory shad. The females are marketed together
with American shad, while the males are often sold as crab bait (Richkus and DiNardo
1984). Hickory shad along the southern part of the range has a higher commercial value
in the winter before the other alosid species commence their spawning migrations
(Bigelow et al. 1963; Godwin 1968; Richkus and DiNardo 1984).
2
Figure 1. Illustration of a hickory shad (top) and an American shad (bottom) (from
Manooch 1984).
 
3
The statewide commercial catch of hickory shad has been increasing over the past
several years, from 26,170 kg in 1994, and 30,699 kg in 1995 to 85,399 kg in 1996
(North Carolina Division of Marine Fisheries (NCDMF) 1997a) even in spite of a 1994
moratorium on the sale of commericial fishing licenses in North Carolina (North Carolina
Moratorium Steering Committee 1996). In 1995 the northern coastal district, which
includes Albemarle Sound and its tributaries, contributed the largest proportion (81.5%)
of the statewide commercial catch with 25,028 kg. These increases in the commercial
catch reflect a noticeable growth in the hickory shad population in the Albemarle Sound
region, and the rest of North Carolina. Consequently, the stock status of hickory shad is
classified as “stressed recovering” by NCDMF (NCDMF 1997b).
A sport fishery for hickory shad, which is rich in tradition, has thrived for many
years on the Neuse River, North Carolina (Hawkins 1980; Manooch 1984). This sport
fishery has expanded in recent years in the coastal rivers of northeastern North Carolina
during the spawning migration in late winter and early spring. In the northern district,
fishing typically is centered near the hypothesized spawning locations on the Roanoke
River near Weldon, North Carolina and on the Cashie River near Windsor, North
Carolina (Pete Komegay, North Carolina Wildlife Resources Commission (NCWRC),
personal communication). Hickory shad are caught on a variety of baitfish-imitating lures
such as small spoons, shad darts, spinners and jigs (Manooch 1984). They are relatively
easy to catch and exhibit a sporting fight when hooked, which are two attributes that
make them popular with anglers. Also, since they ascend rivers in the Albemarle Sound
region before the other alosids, striped bass, and white perch {Morone americana), they
offer the first major fishing opportunity of the year for many anglers in eastern North
Carolina.
4
The increase in the North Carolina hickory shad population, suggested by
increasing recreational and commercial catches, has resulted in a much improved sport
fishery. It is common for anglers to harvest 50-100 fish in a day. The recreational
harvest of hickory shad in the Roanoke River for 1996 was an estimated 58,621 fish (P.
Komegay, NCWRC, personal communication). In contrast, a creel survey conducted by
the NCWRC in 1968 estimated only 143 hickory shad harvested by sport anglers in the
Roanoke River and another 2,377 fish caught by special devices such as gill nets and dip
nets (Baker 1968). Hickory shad was declared a gamefish species in inland waters of
North Carolina in July 1996; however, there are no size or creel limits at the present time.
Little is known about life history aspects of hickory shad. The most
comprehensive studies on hickory shad were done in the 1950s on the Patuxent River,
Maryland (Mansueti 1962), the late 1960s on the Neuse River, North Carolina (Pate
1972) and the Altamaha River, Georgia (Street 1970). Life history aspects examined
included egg and larvae development, fecundity, time and duration of spawning,
spawning habitats, nursery areas, food habits, and age and growth. The importance of
hickory shad and other Alosa species to the Native Americans up to the present was
reviewed by Heath (1997).
The status of hickory shad spawning populations is unknown in many states. It is
assumed that hickory shad return to natal streams to spawn, but this aspect has not been
documented. A 1992 survey of east coast fisheries agencies indicated that the current
status of hickory shad spawning populations was unknown in 50% of the rivers; North
Carolina agencies could not offer any responses to this portion of the survey because
hickory shad information for North Carolina was lacking (Rulifson 1994).
Understanding key life history aspects as well as the status of individual
populations are critical to the management of the species in this state. Currently, the
5
Atlantic States Marine Fisheries Commission (ASMFC) is updating its interstate fishery
management plan for shad and river herring (ASMFC 1995). Information on life history
aspects of hickory shad was identified as a priority for future research by the ASMFC
(Richkus and DiNardo 1984 ). Key life history aspects include: population structure (age,
size, and sex distributions), the sexual maturity schedule (age to maturity), fecundity,
spawning habitats, and nursery grounds.
The goal of this study was to characterize key life history aspects of hickory shad
in the Albemarle Sound/Roanoke River watershed because of the increased commercial
and recreational harvest in this system. Objectives to accomplish the goal were: 1) to
describe the age, size, and sex composition of prespawning adults in the spring staging
areas of Albemarle Sound; 2) to describe the age, size, and sex composition of hickory
shad during the spawning migration near the (hypothesized) spawning sites in the
Roanoke River; 3) to identify possible nursery grounds; and 4) to determine relative
abundance of juveniles at selected sites.
The Roanoke River flows in a northwest to southeast direction and enters
Albemarle Sound at its western end. The headwaters are located in the Appalachian
Mountains of southwest Virginia. It flows 220.5 km from the last dam at Roanoke
Rapids Reservoir to Albemarle Sound (Figure 2) (Street et al. 1975; Rulifson and
Manooch 1990). Much of the channel is greater than 4 m with holes in excess of 15 m in
depth (Street et al. 1975). The coastal plain portion of the watershed below the last dam
has an extensive floodplain consisting of hardwood forest, backwater swamps, oxbow
lakes, and small creeks (Zincone and Rulifson 1991) which are connected to the river by
natural and anthropogenic openings in the natural river levee.
Most of the river is freshwater with the lower part of the river subject to both wind
and lunar tides. However, the section of river between Plymouth, North Carolina and
6
Albemarle Sound occasionally becomes slightly brackish as a result of salt wedges from
the sound (Zincone and Rulifson 1992). The natural river flow has been altered by
several reservoirs located upstream. A flow regime for the lower Roanoke River from 1
April to 30 June was established by the Roanoke River Water Flow Committee to ensure
favorable conditions during the striped bass spawning migration (Rulifson and Manooch
1991). The hydroelectric dams on the Roanoke River are undergoing relicensing through
the Federal Energy Regulatory Commission (FERC) with fish passage and lower river
habitat utilization by anadromous fish as research priorities (Virginia Power and Foster
Wheeler Environmental Corporation 1996).
Albemarle Sound is an extensive estuary in northeast North Carolina measuring
88.5 km long (west to east) and 4.8 to 22.5 km wide (north to south) (Figure 3) (Street et
al. 1975). The Roanoke, Cashie, and Chowan rivers are tributaries of Albemarle Sound
that have spawning populations of hickory shad (Street et al. 1975). Its central basin
ranges from 5.5 to 7.6 m deep. The shoreline consists mostly of cypress swamps and
small sand beaches. It is essentially freshwater through the western and central portions
and brackish in the eastern sound. Closest access of Albemarle Sound to the Atlantic
Ocean is at Oregon Inlet, which is located between Bodie Island and Harteras Island.
Albemarle Sound is not significantly influenced by lunar tides; instead, wind tides
prevail.
7
Figure 2. Map of the Roanoke River watershed. North Carolina showing the sampling
sites for the independent gill net survey in the Roanoke River National Wildlife
Refuge (RRNWR) and for the sport fishery in Weldon, North Carolina.
 
8
Figure 3. Map of Albemarle Sound and its tributaries showing the seine (circles) and
trawl (triangles) sampling sites for the juvenile hickory shad survey.
 
9
Materials and Methods
Adult Collection
Specimens of adult hickory shad were collected by the NCDMF independent gill
net survey in Albemarle Sound and its tributaries from 20 February to 1 May 1996; the
Roanoke River National Wildlife Refuge (RRNWR) independent gill net survey, which
was conducted by National Marine Fisheries Service (NMFS) and RRNWR personnel
from 30 March to 17 April 1996; and from the sport fishery on the Roanoke River at
Weldon from 16 March to 17 April 1996 (Figure 2). The NCDMF study used single
mesh gill nets 9.15 m long with mesh sizes from 64 to 102 mm stretch mesh (Winslow
1989). The RRNWR independent gill net survey employed single mesh gill nets ranging
from 3.6 m long x 1.5 m deep to 12.2 m long x 2.3 m deep; gill net mesh sizes ranged
from 63 mm to 76 mm stretch mesh (Settle et al. 1996). Fish from the Weldon sport
fishery were examined fresh at the access points, while gill-netted hickory shad were
received frozen and examined at East Carolina University (ECU). Data recorded
included fork length (mm), total length (mm), body depth (mm), body weight (g), and
gonad weight (g). Ovaries of all females were preserved in 10% buffered formalin for
fecundity estimates, and the viscera of all specimens were also preserved in 10% buffered
formalin for mesentery fat and gut content analysis. Chi square analyses were performed
to test for significant differences in adult sex compositions between the three collection
sites (Albemarle Sound, RRNWR, and Roanoke River at Weldon, North Carolina).
Regression analyses were performed for log-transformed fork length to weight, and for
total length to fork length.
Scale and Otolith Aging
Ten to 20 scales were removed with a scalpel from the left side of the fish above
the lateral line and below the dorsal fin, and were stored in scale envelopes. Scales were
10
soaked in soapy water for at least six hours to remove dirt, mucous, and residual pigment.
They were dried and individually viewed under a dissecting scope to determine which
scales were suitable for aging. These scales were mounted between two microscope
slides and read using a microfiche reader equipped with a 24x lens.
Otoliths were removed by using a hacksaw to make a diagonal cut behind the eye,
which bisected the brain cavity. The labyrinth with the otoliths attached was removed
with a pair of forceps. Excess tissue was removed from the otoliths by rubbing them
between the thumb and forefinger. Otoliths were stored dry in 20-ml scintillation vials.
Whole otoliths were aged by placing each in a watch glass containing distilled water and
viewed under a dissecting scope at 30x magnification. The otoliths were not sectioned
before aging because the short life span of the fish and the thin nature of the otoliths
allowed the rings to be visible on the external portion of the structure (Charles Manooch
and Jennifer Potts, NMFS, Beaufort Laboratory, personal communication).
Both scales and otoliths were aged independently three times. Age analyses used
those scales and otoliths whose ages agreed on two readings; samples that had no age
agreement were not used for age analyses. Scale aging techniques followed criteria used
by Gating (1953), Judy (1961), Street and Adams (1969), and Pate (1972). Otolith aging
techniques followed criteria used by Komegay (1977) and Libby (1985). Fish that had
both scale and otolith ages were used to analyze the percent agreement between these
ages. Regression analyses were performed to determine the relationships of age to fork
length and age to weight for both sexes.
Spawning History
Spawning history for both sexes was determined by counting the number of
spawning marks on the scales. These marks are formed by the erosion of the scale
margin from lack of feeding during the spawning migration and are counted as annuli.
11
Spawning marks are thicker and more visible than the winter annuli formed before fish
are sexually mature. Presence or absence of these marks on scales indicates the
percentage of the population spawning for the first time.
Mortality Estimates
Total instantaneous mortality estimates of fish within the River were obtained by
taking the age and sex composition of fish collected from the Roanoke River at Weldon,
and then applying it to the NCWRC recreational harvest estimate in the Roanoke River.
This procedure was necessary because the creel survey used to obtain the harvest estimate
did not record the age or sex of the fish (P. Komegay, NCWRC, personal
communication). This provided a sufficient number of males and females in each age
class to estimate mortality from a catch curve (Van Den Avyle 1993).
Total instantaneous mortality (Z) was estimated for ages where recruitment was
greater than 95% complete (Males; ages 3-5; Females; ages 4-6; Sexes combined; ages 3-
6) to eliminate age classes not fully recruited to the population. Total instantaneous
mortality was calculated by estimating the slope of the line from a catch curve from a
single season. The equation is as follows:
log„(Nt) = logn(No)-Z(t)
where Nt = number alive at time t.
No = number alive initally (at time to),
Z = instantaneous mortality rate, and
t = time elapsed since to (Van Den Avyle 1993).
12
Annual total mortality (A) was estimated by taking the inverse natural log of -Z and
subtracting it from one:
A = 1 - e'^ (Ricker 1975).
Natural mortality (M) was estimated by using von Bertalanffy parameters (Lc
and K) and mean water temperature (T, °C) for the spawning habitat (Pauly 1979 as
discussed in Manooch et al. 1997). The equation is as follows:
logioM = 0.0066 - 0.279 logioL,» + 0.6543 logioK + 0.4634 logioT.
The mean water temperature of 20 °C used in this equation was estimated by combining
the mean of the spawning temperature range for hickory shad found in Table 22 and the
mean of the water temperature range of Albemarle Sound in Table 21. Fishing mortality
(F) can be estimated by F = Z - M.
Annual rates of fishing and natural mortality were calculated for a Type 2 fishery,
in which fishing and natural mortality operate together (Ricker 1975). Annual fishing
mortality (u) was calculated with the following equation:
u = FA/Z,
where, F = instantaneous fishing mortality rate,
A = annual total mortality rate, and
Z = instantaneous total mortality rate.
Annual natural mortality (v) was calculated with the following equation:
v = MA/Z
where, M = instantaneous natural mortality rate.
13
A = annual total mortality rate, and
Z = instantaneous total mortality rate (Ricker 1975).
Scale and Otolith Back Calculations
Scales and otoliths used for back calculations were those in which the ages were
the same. For each fish, the largest scale with legible annuli was selected for taking
measurements of the scale image projected on the screen of a microfiche reader. Scale
measurements were taken diagonally from the focus to the anterior margin. Otoliths from
75 fish were measured in order to determine the otolith radius to fork length relationship.
All specimens < 250 mm FL and > 350 mm FL were examined (otoliths from eight fish >
350 mm FL were unreadable). The dominant length classes, 250 to 300 mm FL and 300
to 350 mm FL, were subsampled to minimize the bias associated with dominant size
classes affecting the linear regression calculations. Otolith images were measured using a
video screen connected to a dissecting scope magnified at 16x. Otolith annuli were
measured vertically from the nucleus to the ventral margin with a millimeter ruler.
Fork length back calculations were estimated from the von Bertalanffy growth
equation (Cailliet et al. 1986). The mean back calculated fork lengths at age (sexes
combined) for otolith-measured fish were used to calculate this equation. The von
Bertalanffy equation is expressed as:
L = U(1 -
where L = predicted length at time t.
Loe = maximum length predicted by the equation,
e = base of the natural log.
14
t = time,
to = the size at which the fish would have been age 0, and
K = the growth coefficient (instantaneous rate).
Back calculations were also computed by the direct proportion method (DeVries and Frie
1996) using the following equation:
U = [Si /Se] U
where Li = back calculated length of the fish when the ith increment was formed,
Lc = fork length (mm) at capture.
Sc = radius of otolith at capture, and
Si = radius of the otolith at the ith increment.
Fecundity
A subsample of ovaries was examined for fecundity estimates. The formalin was
decanted from the specimen bag and the whole ovaries were blotted with a paper towel,
then weighed to the nearest 0.01 g. Three subsamples, each weighing at least 0.50 g,
were taken from each ovary: one from the anterior region, one from the medial region,
and one from the posterior region. Eggs were counted in each subsample and
extrapolated to estimate the number of eggs/g. The mean number of eggs/g from the
three subsamples was multiplied by the ovary weight to estimate the number of eggs in
that ovary. The sum of the two ovaries provided the estimate of potential fecundity. The
gonadosomatic index (GSI) was estimated for these fish by dividing the gonad weight by
the body weight and multiplying the quotient by 100. Monthly differences in mean GSI
by age were analyzed. Paired t-tests were used to detect significant differences in weight
and potential fecundity between left and right ovaries. An analysis of variance (ANOVA)
was used to see if signicant differences in the number of mean eggs/g occurred between
anterior, median, and posterior sections of the ovaries. Regression analyses between
15
potential fecundity and fork length, somatic weight, age and GSI were used to see which
variable was the best predictor of potential fecundity.
Mesentery Fat and Gut Content Analysis
The few literature references indicate that other hickory shad populations do not
feed during the spring spawning migration (White and Curtis 1969; Curtis 1970; Perkins
and Dahlberg 1971; Pate 1972). However, hickory shad in the Roanoke River have been
observed with full stomachs (unpublished data, Manooch, personal communication;
Batsavage, present study), and they commonly strike at baitfish-imitating lures. I
hypothesized that hickory shad feed in the ocean waters before the spawning migration,
and they use mesentery fat as an energy source during the migration instead of feeding, so
mesentery fat content of the body cavity and stomach contents were examined to confirm
if significant feeding occurs in this watershed. Mesentery fat was removed from the
viscera and weighed to the nearest 0.01 g. Food items removed from the stomach and
intestine were identified to the lowest practical taxon, enumerated, and weighed to the
nearest 0.01 g. T-tests were used to test for significant differences in mesentery fat
between males and females and between fish collected in Albemarle Sound and fish
collected in the Roanoke River.
Nursery Grounds
The juvenile hickory shad survey began after the conclusion of the adult spawning
season. It was conducted twice a month during daylight hours from May to October 1996
in the Albemarle Sound and selected tributaries (Figure 3). Two gear types were used: a
semi-balloon trawl (i.e., Hassler trawl) with a 5.5 m headrope, and a 18.2 m x 1.8 m
beach seine with 6.35 mm ace mesh that contained a 1.8 m x 1.8 m tailbag (Rulifson et al.
1993). The trawl was towed behind a 6.7 m fiberglass boat equipped with a 150 hp
outboard motor. Two 5 min tows at 1200 rpm were made at each site. The seine was
16
deployed in the water approximately 1 m in depth parallel to the shoreline and then pulled
into shore. The distance pulled through the water varied with each site because of
differences in water depth; however, all samples at a single site were collected in the
same manner. Therefore, each seine haul was considered one unit of effort. Air
temperature (®C), water temperature (°C), dissolved oxygen (mg/L), conductivity (mS),
secchi visibility (cm), wind direction and velocity (miles/hour), weather conditions, and
time of day were recorded at each site. Dissolved oxygen (DO) was measured with a
YSIxm Model 52B DO meter. Conductivity was measured with a total dissolved solids
(TDS) tester. Samples were preserved in 10% buffered formalin and returned to ECU
for enumeration to lowest practical taxon.
The Albemarle Sound sampling locations (Figure 3) and their abbreviations are
listed in Table 1. Seine sites SAP and SOV were established on 14 May. Seine sites
CPN, CWC, MCR, BAT, NPL, and WOM were established on 27 May . Trawl sites
BUB, ALR, CHR, and seine sites SCR, ALR, and DIS, were established on 10 June.
Seine sites 32N, ESP, EBP, CSM, and, CSR were established on 22 July. Trawl sites
EBP, EOP, ESP, SAP, and SOV were established on 22 August. Unfavorable weather
conditions sometimes prevented sampling of certain sites on every sampling trip.
Logistical problems involving boat availability and unfavorable weather precluded us
from sampling trawl sites on a regular basis.
Seine sites were divided into five regions: northwest (BAT, CPN, CWC, MCR),
north-central (EBP, ESP, SAP, 32N), southwest (NPL, WOM), south-central (SCR,
SOV), and southeast (ALR, CSM, CSR, DIS). There were no seine sites in the northeast
section of Albemarle Sound. Species composition and catch per unit effort (CPUE) for
the four juvenile Alosa were examined and calculated for each region.
17
At the same time, the NCDMF conducted a juvenile alosid survey and a juvenile
striped bass survey in Albemarle Sound. Both surveys employed a seine with the same
dimensions as the juvenile hickory shad survey (Steve Trowell, NCDMF, Elizabeth City,
personal communication; Winslow 1989). The juvenile striped bass survey was
conducted in the western sound with nine sites sampled weekly from 4 June to 8 July
1996 (Figure 4). The juvenile alosid survey was conducted from June to October 1996
with 23 sites located throughout Albemarle Sound (Figure 4). Eleven of these sites were
sampled monthly, and 12 of the sites were sampled once in September.
18
Figure 4. Map of Albemarle Sound and its tributaries showing the sampling sites for the
juvenile striped bass (circles) and juvenile alosid (triangles) surveys conducted
by the North Carolina Division of Marine Fisheries (NCDMF).
U
Sound
19
Table 1. Description of beach seine and trawl sampling sites in Albemarle Sound and
selected tributaries for the juvenile hickory shad survey.
Code Site name Coordinates Description
Juvenile Hickory Shad Seine Survey (HSS)
North shore
MCR Mouth of Chowan 36.00° N, 76.41°W west shore of Chowan River
River mouth, north shore western
Albemarle Sound
CPN Chowan River, 36.02° N, 76.42° W west shore of Chowan River
between the pound nets south of Rt. 17 bridge north
shore of western Albemarle
Sound
CWC Chowan River, west 36.01° N, 76.42° W west shore south of Rt. 17
shore cliffs bridge at base of bluffed
shoreline north shore of
western Albemarle Sound
BAT Batchelor Bay 35.58° N, 76.42° W western Albemarle Sound
between Cashie River Mouth
and Black Walnut Point
32N Rt. 32 Bridge, North 36.00° N, 76.30° W central Albemarle Sound
Shore north shore just west
of Rt. 32 bridge
SAP Sandy Point Beach 36.00° N, 76.30° W central Albemarle Sound,
north shore just east of Rt. 32
bridge
ESP East of Sandy Point 36.00° N, 76.29° W central Albemarle Sound
north shore, east of Sandy
Point
EBP East of Bluff Point 36.01° N, 76.27° W central AlbemarleSound
north shore, east of Bluff
Point
20
Table l,cont.
Code Site name Coordinates Description
South Shore
WOM West of Mackey's 35.56°N, 76.36°W western AlbemarleSound,
Creek south shore west of NC
power lines
NPL Near Powerlines 35.56° N, 76.36° W western Albemarle Sound,
south shore, next to old barge
SOV Soundview 35.57° N, 76.29° W western Albemarle Sound,
south shore just east of Rt. 32
bridge
SCR Scuppemong River 35.56° N, 76.18° W eastern shore of Scuppemong
River, south shore of central
Albemarle Sound
ALR Alligator River 35.53° N, 75.58° W east shore of Alligator River
between Rt. 64 bridge and
NCWRC boat ramp, south
shore of eastern Albemarle
Sound
DIS Durant Island 35.57° N, 75.56°W eastern Albemarle Sound
east of Alligator River mouth
CSM Croatan Sound at 35.55° N, 75.43° W west shore of Croatan Sound
Mann's Harbor north of Rt. 64 bridge,
eastern Albemarle Sound
CSR Croatan Sound on 35.55° N, 75.43° W east shore of Croatan Sound
Roanoke Island north of Rt. 64 bridge,
eastern Albemarle Sound
Juvenile Hickory Shad Trawl Survev tHTSI
ALR Alligator River 35.54° N, 75.57° W western shore of Alligator
River, south shore of eastern
Albemarle Sound
Table 1, cont.
Code Site name Coordinates Description
BUB Bull Bay 35.56° N, 76.20° W central Albemarle Sound,
south shore at Colonial
Beach
CHR Chowan River 36.00° N, 76.41° W west shore of Chowan River
between Rt. 17 bridge and
Salmon Creek mouth, north
shore of western Albemarle
Sound
EBP East of Bluff Point 36.01° N, 76.27° W central Albemarle Sound
north shore, east of Bluff
Point
EOP East of Powerlines 35.56° N, 76.33° W western Alb. Sound south
shore east of NC power
lines
ESP East of Sandy Point 36.00° N, 76.29° W central Albemarle Sound
north shore, east of Sandy
Point
SAP Sandy Point Beach 36.00° N, 76.30° W central Albemarle Sound,
north shore just east of Rt. 32
bridge
SOV Soundview 35.57° N, 76.29° W western Albemarle Sound,
south shore just east of
Rt. 32 bridge
22
Results
Results of this study are divided into the following components: adult sex ratios,
adult size distributions, age analysis, mortality, age back calculations, fecundity analysis,
and the juvenile nursery ground survey. Since adult hickory shad came from three
sources (NCDMF independent gill net survey in Albemarle Sound, RRNWR independent
gill net survey, and the recreational sport fishery at Weldon, NC), portions of the results
analyze these three groups individually.
Adult Sex Ratios
Of the 643 adult hickory shad examined, the majority (83%) were from
Albemarle Sound and the Roanoke River at Weldon, which were similar in the
maleifemale ratios. A total of 266 specimens were from the Albemarle Sound area, 111
from the Roanoke River National Wildlife Refuge (RRNWR), and 266 from the Roanoke
River at Weldon. A two-way chi-square analysis indicated that the male;female ratios for
Albemarle Sound (0.73:1) and the Roanoke River at Weldon (0.76:1) were statistically
similar (X^ = 0.064, n = 532, df = 1, P> 0.05) (Table 2). The independent gill net survey
in the RRNWR had a male to female ratio of 4.29:1 (Table 2), a value significantly
different from Albemarle Sound and Weldon, NC (X^ = 54.28, n = 643, df = 2, P< 0.(X)1).
However, interpretation of this three-way comparison should be made with caution
because of the small gill net mesh sizes used in the refuge survey, which likely selected
for the smaller male fish.
23
Table 2. Chi square analysis of male to female ratios for Albemarle Sound, RRNWR, and
Weldon, NC. O = observed E = expected.
Total Male to female
Location Male Female examined ratio
Two-way comparison
Albemarle Sound 0= 112 0= 154 266 0.73:1
E= 113.50 E = 152.50
Weldon, NC 0= 115 0= 151 266 0.76:1
E= 113.50 E= 152.50
Total (observed) 227 305
N = 532 X^= 0.064 P>0.05
Three-way comparison
Albemarle Sound 0= 112 0= 154 266 0.73:1
E= 131.14 E= 134.86
Weldon, NC 0= 115 0= 151 266 0.76:1
E= 131.14 E= 134.86
RRNWR 0 = 90 0 = 21 111 4.29:1
E = 54.72 E = 56.28
'
A ^
Total (examined) 317 326
N = 643 = 54.28 P< 0.001
24
Adult Size Distributions
Most males were between 270-330 mm FL, while most females were 290-360
mm long (Figure 5). Male hickory shad ranged from 257 mm to 376 mm FL, and
female hickory shad ranged from 280 mm to 402 mm FL. Dominant sizes of males
(47.3%) were in the 280 mm and 290 mm size classes, while females (41.5%) were in the
330 mm and 340 mm size classes (Figure 6).
Log transformed body weight (Logn BWT) plotted against log transformed fork
length (Logn FL) indicated that body weight generally increased with fork length for both
males (r^ = 0.78, Figure 7) and females (r^ = 0.73, Figure 8). The equations for these
relationships were:
Males: Logn BWT (g) = 3.09 (Logn FL (mm)) -11.75, and
Females: Logn BWT (g) = 2.94 (Logn FL (mm)) -10.78.
Since variations in gonad weight of both sexes varied considerably, these data
were analyzed using log-transformed somatic weight (Logn SWT) (total body weight -
gonad weight); results showed a similar trend (males: r^= 0.81; females: r^= 0.76)
(Figures 9 and 10). The equations for these relationships were:
Males: Logn SWT (g) = 3.01 (Logn FL (mm)) -11.34, and
Females: Logn SWT (g) = 2.77 (Logn FL (mm)) -9.96.
Total length plotted against fork length showed a strong relationship (r^= 0.98,
Figure 11). The equation for this relationship was:
TL (mm) =1.15 (FL (mm)) + 4.06.
25
Figure 5. Length frequencies of adult hickory shad into 10 mm size classes, by sex.
Males: black bars. Females: white bars.
90
80
70
60
50
40
30
20
10
0 Il
250 o O o o O O O
O O O O O O O
«o 00 O O 1— CM CO UO O OO O
CM CM CM CM cO cO CO CO CO CO CO CO CO CO 400
10 mm size classes
26
Figure 6. Percent frequencies of adult hickory shad into 10 mm size classes, by sex.
Males: black bars. Females: white bars.
30
25
20
15
10
5
0 —rn n 1-1
o O O O O O O O O O O O O o O O
lO •O oo O O 1 CM CO lO O 00 o O
CM CM CM CM CM CO CO CO CO CO CO CO CO CO CO
10 mm size classes
27
Figure 7. Log-transformed body weight (g) to log-transformed fork length (mm)
relationship for adult male hickory shad.
6.80 -1
Males
6.60 - y = 3.09x-11.75
i^= 0.78, n = 316
6.40 -
(wgeigh)t 6.20 ?b 6.00 -LoQdyn
5.80 -
5.60 -
?
5.40 -
?
5.20 -
5.00 - — —1— 1 1 1— —I
5.50 5.60 5.70 5.80 5.90 6.00
Logn fork length (mm)
28
Figure 8. Log-transformed body weight (g) to log-transformed fork length (mm)
relationship for adult female hickory shad.
 
29
Figure 9. Log-transformed somatic weight (g) to log-transformed fork length (mm)
relationship for adult male hickory shad.
6.60 n Males
y = 3.01x-11.34 ? ?
6.40 ? i^ = 0.81, n = 316 ? ?
(LswogoemiQgahtic)tn
?
5.20 -
5.00 H 1 1 1 1 1 1 1 1— —I
5.50 5.55 5.60 5.65 5.70 5.75 5.80 5.85 5.90 5.95
Logn fork length (mm)
30
Figure 10. Log-transformed somatic weight (g) to log-transformed fork length (mm)
relationship for adult female hickory shad.
6.80 1 ? ?
Females
6.60 -
y = 2.77X - 9.96 ?
?
1^ = 0.76, n = 324
6.40
6.20
(g) 6.00 -LwsooemiQgahtict 5.80 - ? ? ??n 5.60 -
5.40 -
5.20 -
5.00
5.60 5.70 5.80 5.90 6.00
Logn fork length (mm)
31
Figure 11. Total length (mm) to fork length (mm) relationship for adult hickory shad.
475
y = 1.15X + 4.06
? ??
= 0.98, n = 342 ?
450
425
400
375
350
325 *
300
275 I T"" " I I
300 325 350 375 400 425
Fork length (mm)
32
Age Analysis
Age comparison analysis between scales and otoliths of 480 fish showed 57%
agreement, with scales overestimating younger-aged fish and underestimating older-aged
fish (Figure 12). The scale age never deviated more than + 2 years from the otolith ages;
most scale ages deviated + 1 year (Figure 12). For example, 61% of otolith age 3 fish
were correctly assigned using scales (149 of 242), but 34% were mis-assigned by one year
(scale age 2 or 4), and 4% were mis-assigned by two years (scale age 5). There was no
agreement between age 2 scales and otoliths, and age 4 scales and otoliths had 61%
agreement. Only 26% of age 5 scales and otoliths agreed. Otolith age data were used in
all further age analysis because otoliths are considered to be more reliable than scales for
aging (DeVries and Frie 1996).
Most (90%) of the 509 hickory shad examined were ages 3 and 4; the majority of
males (66%) was age 3 and most females (55%) were age 4 (Table 3; Figure 13). The
number of fish ages 2 through 4 (483) was considerably more than the number of fish
ages 5 through 7 (26).
Mean fork length and body weight for both sexes generally increased with age,
but size ranges and weights at age for males (Table 4, Figures 14-15), females (Table 5,
Figures 16-17), and combined sexes (Table 6) show a large degree of overlap. Females
were larger at age than males. However, the overlap of size ranges at age for both sexes
causes difficulty in estimating the age using fork length measurements.
33
Figure 12. Age comparison analysis between scales and otoliths.
1 1
o 2 3 4 5 6 7
Otolith age
34
Table 3. Scale and otolith age class distributions of Albemarle Sound/Roanoke River hickory shad by sex,
1996.
Scale Male Female
Age class Number Percent Number Percent
2 9 3.0 3 1.0
3 171 57.8 90 29.1
4 98 33.1 161 52.1
5 16 5.4 49 15.9
6 2 0.7 4 1.3
7 0 0.0 2 0.6
Total 296 100.0 309 100.0
Otolith
Age class
2 16 6.0 8 3.3
3 177 66.2 80 33.1
4 69 25.8 135 55.8
5 4 1.5 18 7.4
6 1 0.4 1 0.4
7 0 0.0 2 0.8
Total 267 100.0 242 100.0
35
Figure 13. Age class distributions of male (black bars) and female (white bars) hickory
shad.
? Male
? Female
2 3
class
36
Table 4. Observed mean values of fork length (mm), body weight (g), and somatic weight (g) at age of
male hickory shad collected from the Roanoke River near Weldon, North Carolina, the Roanoke River
National Wildlife Refuge, and Albemarle Sound during spring 1996. SD = standard deviation.
Fork length (mm) Body weight (g) Somatic weight (g)
Age n Mean + SD Range Mean + SD Range Mean ± SD Range
2 16 293 ±9.3 278-314 330±41.7 273-411 310±35.8 256-388
3 177 288+ 12.9 257-328 319±54.1 210-548 300 ±57.8 197-525
4 69 319± 11.9 283-354 451 ±70.2 316-698 422 ±59.8 297-640
5 4 332+ 16.4 318-355 452 ±65.2 403-542 430 ±69.6 385-532
6 1 376 651 638
37
Figure 14. Age class to fork length (mm) relationship for male hickory shad.
 
38
Figure 15. Age class to body weight (g) relationship for male hickory shad.
 
Table 5. Observed mean values of fork length (mm), body weight (g), somatic weight (g) and potential fecundity at age of female hickory shad collected
from the Roanoke River near Weldon, North Carolina, the Roanoke River National Wildlife Refuge, and Albemarle Sound during spring 1996. SD =
standard deviation.
Fork length (mm) Body weight (g) Somatic weight (g) Potential fecundity
Age n Mean + SD Range Mean ± SD Range Mean ± SD Range n Mean ± SD Range
2 8 304 ±7.0 292-313 391 ±27.3 358-446 343 ± 15.8 325-379 1 85,803
3 80 313 ± 18.4 280-360 440 ± 85.4 291-839 390±71.1 280-612 14 137,523 ±33,573 80,290-230,645
4 135 339 ±15.3 296-390 591 ± 101.1 359-839 505 ± 83.2 318-705 19 223,576 ± 6,067 113,661-334,126
5 16 343 ± 18.8 320-397 639 ± 113.9 447-908 542 ± 84.6 417-710 3 294,798 ± 156,362 179,505-472,769
6 1 402 1,031 871 1 478,944
7 2 397 ±4.2 394-400 946 ± 192.0 810-1,082 779 ± 145.4 676-881 2 350,918 ±92,205 285,719-416,116
CO
CD
40
Figure 16. Age class to fork length (mm) relationship for female hickory shad.
Females ? ?
y = 0.02X - 3.43
1^ = 0.42, n = 242 ?
5 - ? ? ? ? ??
(O
w 4 - «M«N
CO
O
2 - ??? >
1 -
0 I 1 1 1 r- —I I 1
250 275 300 325 350 375 400 425 450
Fork Length (mm)
41
Figure 17. Age class to body weight (g) relationship for female hickory shad.
7 n Females
y = 0.004X + 1.68
6 =- 0.43, n = 242
5 - ? ? «•» ? ?? ?
(/) 4 ???
_ca
Ü
0)
O) Q ? ? ???
<
2 - 4» ?
1 -
0 “I
300 400 500 600 700 800 900 1000 1100
Body weight (g)
42
Table 6. Observed mean values of fork length (mm), body weight (g), and somatic weight (g) at age of
hickory shad sexes combined collected from the Roanoke River near Weldon, North Carolina, the Roanoke
River National Wildlife Refuge, and Albemarle Sound during spring 1996. SD = standard deviation.
*= females only.
Fork length (mm) Body weight (g) Somatic weight (g)
Age n Mean + SD Range Mean + SD Range Mean ± SD Range
2 24 297 ± 10.0 278-314 352 + 47.5 273-446 322 ± 33.7 256-388
3 257 296+ 18.8 257-360 343 + 88.1 210-707 329 ± 69.5 197-612
4 204 332+ 17.1 283-390 543 ±112.8 316-839 477 ± 85.2 297-705
5 20 341 + 18.6 318-397 605 ± 128.9 403-908 522 ±91.9 385-710
6 2 389 ±18.4 376-402 841 ±268.7 651-1,031 755 ± 164.4 638-871
7* 2 397 +4.2 394-400 946 ± 192.3 810-1,082 779 ± 145.4 676-882
43
Spawning History
Essentially all males and females were sexually mature by age 3, and all were
mature by age 5 (Table 7). Some individuals of both sexes were mature by age 2. Virgin
fish comprised nearly half of the male population compared to about one-fourth of the
female population. An additional 45.5% of the males spawned only once before, and
7.7% had spawned previously two or more times. No males exhibited more than three
spawning marks (Table 8). Only 24.9% of the females examined (233) were virgin fish
(Table 9). A total of 45.5% of the females had spawned once before with few showing
evidence of spawning more than twice. One age 7 female had four spawning marks.
Mortality Estimates
Total mortality (Z) for males was 1.43 (ages 3-5), 1.76 for females (ages 4-6), and
1.40 for both sexes combined. Natural mortality (M) for both sexes was 0.29, and fishing
mortality (F) was approximately 1.11. Annual total mortality for males and females
combined was 0.75; the annual rate of total mortality was calculated for the sexes
combined because the natural and fishing mortality rates are also based on both sexes
together. The annual natural mortality rate was 0.16 while the annual rate of fishing
mortality was 0.59. Annual mortality rates for hickory shad for previous Albemarle
Sound studies ranged from 0.40 to 0.65; however, annual mortality was calculated by the
Robson and Chapman method which computes survival from a catch curve from a single
season (Street et al. 1975; Johnson et al. 1978). Fishing mortality rates for hickory shad
in the Altamaha River, Georgia were about 0.30 for females and 0.13 for males (Godwin
1968; Richkus and DiNardo 1984). By comparison, fishing mortality rates for American
44
Table 7. Age at maturity percent of male and female hickory shad in the Albemarle Sound/Roanoke
River watershed, 1996. Numbers of fish mature by each age in parenthesis.
Otolith age
n 2 3 4 5
Male 233 36.1 97.9 99.6 100.0
(84) (228) (232) (233)
Female 213 38.5 93.9 98.6 100.0
(82) (200) (210) (213)
Sexes combined 446 37.2 96.0 99.1 100.0
(166) (428) (442) (446)
45
Table 8. Number of spawning marks for male hickory shad from the Albemarle Sound/Roanoke River
watershed, 1996, by age class.
Spawning marks
Otolith
age 0 1 2 3 4 Total
2 12 12
3 92 56 148
4 4 50 14 68
5 1 0 1 2 4
6 0 0 0 1 1
Total 109 106 15 3 233
Percent 46.8 45.5 6.4 1.3
of total
population
46
Table 9. Number of spawning marks for female hickory shad from the Albemarle Sound/Roanoke
River watershed, 1996, by age class.
Spawning marks
Otolith
age 0 1 2 3 4 Total
2 7 7
3 38 24 62
4 6 69 48 123
5 2 4 9 3 18
6 0 0 0 1 1
7 0 0 1 0 1 2
Total 53 97 58 4 1 213
Percent 24.9 45.5 27.2 1.9 0.5
of total
population
47
shad in the natal streams when the stocks were stable were estimate at less than 0.40; this
rate assumes a constant non-natal stream fishing mortality rate of 0.15 (ASMFC 1985).
Scale and Otolith Back Calculations
A strong relationship was established between otolith radius and fork length
(males: r^= 0.95; females: r^= 0.92; sexes combined: r^= 0.93) (Figures 18-20) but not
between scale radius and fork length (males: r^= 0.15; females: r^= 0.26) (Table 10). A
second regression analysis was performed on just virgin fish to minimize any variation in
scale radius caused by spawning mark erosion, but this relationship also was weak
(males: r^= 0.08; females: r^= 0.10) (Figures 21-22). The regression equations for the
otolith radius to fork length relationship were:
Males: FL = 8.3 (Otolith radius (16x)) -62.3,
Females: FL = 7.3 (Otolith radius (16x)) -31.2, and
Sexes combined: FL = 7.3 (Otolith radius (16x)) -29.2.
The von Bertalanffy growth equation was Lt = 460 (1 - e *^^^).
Mean back calculated fork lengths using the proportional method for male hickory shad
ages 2 through 4 were less than the observed mean fork lengths, while the mean back
calculated fork length for age 5 males was greater than the observed mean fork length
(Table 11). Mean back calculated fork lengths using the proportional method for female
hickory shad ages 2, 3, and 7 were less than the observed mean fork lengths, while the
mean back calculated fork lengths for age 4 and 5 females was greater than the observed
mean fork length (Tablet 1). The predicted fork lengths from the von Bertalanffy growth
48
Figure 18. Otolith radius (mm) (16x) to fork length (mm) relationship for male hickory
shad.
50
Males
45
y = 8.3x - 62.4
40 ^ = 0.95, n = 24
35
30
25
20
15
10
5
0 I ' I I I r" —I 1
50 100 150 200 250 300 350 400
Fork length (mm)
49
Figure 19. Otolith radius (mm) (16x) to fork length (mm) relationship for female hickory
shad.
60
Females
?
55 y = 7.3x-31.2
i^=0.92, n = 51
50
45
40
35
30
25
?
20 ??
15
10
5
0 1 1 1 1 1— —I 1
50 100 150 200 250 300 350 400
Fork length (mm)
50
Figure 20. Otolith radius (mm) (16x) to fork length (mm) relationship for both sexes of
hickory shad.
65
60 Sexes combined
y = 7.3x - 29.2
55 r^=0.93, n = 75
50
45
40
35
30
25
20
15
10
5
0 T 1 1 1 1 1 1 1 1
50 100 150 200 250 300 350 400 450
Fork length (mm)
51
Table 10. Results of linear regressions describing the relationships among fork length (FL, mm), scale
radius, and otolith radius for male and female hickory shad.
Independent Dependent SE of
variable variable n Intercept Slope slope r'
FL (all males) Scale radius 128 199.4 19.0 4.0 0.15
FL (all females) Scale radius 147 202.1 23.3 3.3 0.26
FL (virgin males) Scale radius 108 254.6 0.3 0.1 0.08
FL (virgin females) Scale radius 53 261.0 0.4 0.2 0.10
FL (males) Otolith radius 24 -62.4 8.3 0.4 0.95
FL (females) Otolith radius 51 -31.2 7.3 0.3 0.92
FI (sexes combined) Otolith radius 75 -29.2 7.3 0.2 0.93
52
Figure 21. Scale radius (mm) (24x) to fork length (mm) relationship for virgin male
hickory shad.
160 n Males
150 y = 0.27X + 254.6-
r^= 0.08, n = 108
140 H
?
«? ?
4 ?
^30 ??
E ??? ?
E ? ? ? ?
w120 ? ??? ?
? ?
? ? ? ?
'T3 «?
2 ? ?
Olio ? 4^
CO ? ^ ??r
Ü ? ?
CO ? ? ? ?
100 H ?
90 -
80 1 —I
275 300 325 350
Fork length (mm)
53
Figure 22. Scale radius (mm) (24x) to fork length (mm) relationship for virgin female
hickory shad.
160 n
Females
150 -
y = 0.37x + 261.0
X i^ = 0.10, n = 53.140 -
X ? ? ?
(N ? ? ?
?? ;
|130
? ?? ?
w ? ? ?
? ?
«120- ? ?
0) ? ?
CO
Ü
CO 110 -
?
?
100 ?
90 I —1“ “T 1 1 1
275 300 325 350 375 400 425 450
Fork length (mm)
Table 11. Comparison of mean fork lengths at ages from observed data and back calculated data for males and females, and from von
Bertalanffy growth equation data for sexes combined.
Males Females Sexes combined
Mean FL Mean FL Mean FL Mean FL Mean FL
Age (observed) (back calculated) (observed) (back calculated) (von Bertalanffy)
1 206 212 215
2 293 247 304 263 268
3 288 287 313 306 309
4 319 293 339 345 341
5 332 355 343 363 366
6 376 402 402 386
7 397 394 402
oi
55
while the predicted fork lengths for age 5 to 7 fish were greater than the observed fork
lengths; the predicted fork lengths for age 3 and 4 fish fell between the mean observed
fork lengths for males and females (Table 11).
Back calculated fork lengths for ages 1-2 decreased in older fish (Table 12). Age
2 hickory shad had back calculated fork lengths of 226 mm at age 1 and 304 mm at age 2
while age 7 fish had back calculated fork lengths of 197 mm at age 1 and 243 mm at age
2. These differences in fork lengths at age provide some evidence for Lee’s phenomenon,
which states that larger fish in a year class often have a higher mortality rate than smaller
individuals (Cailliet et al. 1986).
56
Table 12. Calculated fork length at age for adult hickory shad (sexes combined).
Back calculated fork lengths at age
Age N Mean FL at capture 1 2 3 4 5 6 7
3 304 + 4.5 226 304
22 299 ± 27.4 209 255 299
37 341 +24.7 209 242 299 341
5 363 + 19.4 214 268 309 339 363
1 402 231 277 310 356 376 402
7 1 394 197 243 282 315 341 368 394
57
Reproductive Analysis
Seasonal pattern in the GSI was not related to age, but mean GSI for age 3 and 4
hickory shad from Albemarle Sound, RRNWR, and Weldon increased from February to
March before decreasing in April (Table 13). Prespawn females caught in Albemarle
Sound during February had the lowest mean GSI of any month (age 3 = 8.93; age 4 =
10.98). Water temperatures in the Sound during this month were approximately 6-7°C.
Spawning temperatures on the Roanoke River at Weldon from 16 March to 17 April 1996
ranged from 8°C to 12°C. Mean GSI decreased from March to April as more postspawn
females were captured from the three locations (Table 13). GSI increases as the oocytes
mature prior to spawning but sharply decreases after the fish spawns and the ovarian
tissue is resorbed.
Potential fecundity estimates for 47 prespawn females ranged from 80,290 eggs to
478,944 eggs; fecundity generally increased with fork length, body weight, and age
(Table 5). Several post spawn hickory shad still had some eggs in the spent ovaries,
suggesting that not all eggs are spawned during the season. Potential fecundity increased
with fork length (Figure 23) and somatic weight (Figure 24). Somatic weight was used
instead of total weight because larger, heavier ovaries will naturally have more eggs and
would therefore influence the relationship. Potential fecundity generally increased with
age (Figure 25) and GSI (Figure 26), however, some variation existed. These variations
were likely the result of the overlapping ranges of fork lengths found at each age class
and the variations in fecundity at a given GSI.
Table 13. Mean and range (in parenthesis) of GSI values for ages 3 and 4 female hickory shad from Albemcirle Sound, RRNWR, and Weldon by month.
Age 3 Age 4
Albemarle Sound RRNWR Weldon Albemarle Sound RRNWR Weldon
Month n=27 n= 14 n= 36 n= 76 n= 2 n= 57
February 8.93 ± 6.39 10.98 ±3.39
(4.41-13.41) (7.97-16.65)
March 12.11 ±2.73 13.45+4.25 14.89 ±2.67 16.49 ±3.62
(7.87-15.75) (5.36-18.91) (4.45-21.49) (8.47-20.61)
April 8.96 ± 3.72 11.40 + 4.12 13.39 + 4.36 11.13+4.10 7.61 ±3.93 14.11+4.38
(2.99-13.56) (3.69-19.58) (5.53-21.77) (4.4.32-15.27) (4.82-10.39) (5.06-24.33)
ui
00
59
Figure 23. Potential fecundity to fork length (mm) relationship for female hickory shad.
fPeocteunntidality
60
Figure 24. Potential fecundity to somatic weight (g) relationship for female hickory shad.
fPeocteunntidality
300 800
61
Figure 25. Potential fecundity to age class relationship for female hickory shad.
500000 1
450000 - y = 68,235.2x - 56,304.6
400000 i^=0.52, n = 47^ -
c 350000 -
?
0 300000 -
« 250000 - i ?
I #200000 - ?
£ 150000 - I
100000 -
50000 - T
0 1 2 3 4 5 6 7
Age class
62
Figure 26. Potential fecundity to gonadosomatic index (GSI) relationship for female
hickory shad.
500000 -I y = 16,690x-59,174.7
450000 i^=0.53, n = 47-
?
400000 -
350000 -
?
fecundity 300000 ? ? ? ??Potential 250000 - \* ** *? ?200000 -
?
?
150000 - ? i
?
?
>
100000 -
? ?
50000 -
5 7 9 11 13 15 17 19 21 23 25 27 29 31
GSI
63
Fecundity estimates derived from the regression equations for fecundity as a
function of age class, fork length, body weight, and somatic weight at each age were
compared to the mean gravimetric fecundity estimates for each age. Age was the closest
predictor of fecundity for age 2 and age 5 fish, body weight was the closest predictor of
fecundity for age 3 fish, and fork length was the closest predictor of fecundity for age 4
fish (Table 14). Fork length, body weight, and somatic weight equations overestimated
fecundity for age 6 and 7 females within 10% of the gravimetric estimate, while age
overestimated fecundity for age 6 and 7 females by 17%.
The mean number of eggs per gram of ovarian weight ranged from over 1,500
eggs/g to under 4,000 eggs/g. The anterior portion of both ovaries tended to have a
higher number of eggs/g than the posterior region; this relationship was significant for the
left ovary (n= 47; F= 4.68; P = 0.011) but not the right ovary (n= 47; F= 1.21; P = 0.303).
The left ovary was significantly greater in weight and mean fecundity compared to
the right ovary. Mean left ovary weight was 51.53 g, while the mean right ovary weight
was 44.03 g. A paired t-test found these means to be significantly different (n= 47; t=
4.48; P < 0.0001). Mean fecundity of the left ovary was 111,037 eggs, while the right
ovary contained an average of 93,630 eggs. These means also were significantly different
(n= 47; t= 4.71; P< 0.0001).
64
Table 14. Potential fecundity of female hickory shad calculated gravimetrically and estimated from
regressions developed for age class, fork length (FL, mm), body weight (g), and somatic weight (g).
Fecundity Fecundity Fecundity Fecundity
Gravimetric estimated estimated estimated estimated
Age n fecundity by age by FL by body wt. by somatic wt.
1 85,803 80,165 135,215 111,663 118,814
14 137,523 148,400 158,756 135,791 147,376
19 223,576 216,635 226,764 210,143 217,262
3 294,798 284,870 237,227 314,635 239,746
1 478,944 353,105 391,533 426,799 439,680
7 2 350,918 421,340 378,475 384,945 383,771
65
Mesentery Fat and Gut Content Analysis
Reduced mesentery fat of Roanoke Riyer fish indicated use of stored lipid
reseryes as fish migrated from Albemarle Sound upstream. Mesentery fat weight was
significantly greater in both sexes from Albemarle Sound than from both sexes from the
Roanoke Riyer (males: t= -3.05, P= 0.005; females: t= -4.54, P< 0.0001). Mesentery fat
for Roanoke Riyer males was significantly less than Roanoke Riyer females (t= -2.14, P=
0.03). There was no significant difference in mesentery fat for males and females from
Albemarle Sound (t= -1.57, P= 0.12), suggesting that both sexes fed extensiyely in ocean
waters prior to entering Albemarle Sound for the spawning migration. The relationship
between somatic weight and mesentery fat for both sexes was linear but weak (Table 15).
Of the 212 stomachs examined for gut analysis, 26% (n = 62) of the fish from
Albemarle Sound and 28% (n = 110) of the fish from the Roanoke Riyer contained
identifiable items. Fiye of the six items (83%) present in the stomachs were found in
both Albemarle Sound and Roanoke Riyer fish. These items were fish (family
Clupeidae), parasites, seeds, wood, and plastic. Insects were found only in the stomachs
of Roanoke Riyer fish.
Nursery Grounds
A total of 47 finfish species, including all four Alosa species, was collected from
the 16 seine sites (130 samples) and 8 trawl sites (11 samples). Thirteen species were
found in both seine and trawl samples; no alosids were found in trawls. Eyery species
collected in trawls also was found in seines. Many of the species caught were in the
juyenile stage. In the seine samples, the top 10 species in order of abundance were
66
Table 15. Results of linear regressions describing the relationship between somatic weight (g) and
mesentery fat weight (g) for male and female hickory shad from Albemarle Sound (A.S.) and the Roanoke
River (R.R.).
Independent Dependent SE of
variable variable n Intercept Slope slope r'
Somatic weight Mesentery 34 270.3 111.0 48.9 0.14
(R.R. males) fat weight
Somatic weight Mesentery 64 371.2 90.0 31.2 0.12
(R.R. females) fat weight
Somatic weight Mesentery 28 362.5 32.6 18.0 0.11
(A.S. males) fat weight
Somatic weight Mesentery 46 451.6 43.2 27.4 0.13
(A.S. females) fat weight
67
Atlantic menhaden (Brevoortia tyrannus) (11,758), blueback herring (6,140), white perch
(5,443), spottail shiner {Notropis hudsonius) (1,157), striped bass (1,033), eastern silvery
minnow (Hybognathus regius) (662), yellow perch {Perea flavescens) (588), inland
silverside (Menidia beryllina) (523), bay anchovy {Anchoa mitchilli) (384), and alewife
(232) (Table 16). The frequency of occurence in seine samples, by species, was white
perch (64% of all samples), striped bass (64%), inland silverside (48%), spottail shiner
(34%), yellow perch (33%), alewife (32%), spot {Leistomous xanthurus) (29%),
blueback herring (24%), Atlantic menhaden (18%), sunfish species {Lepomis spp.)
(18%), and Atlantic needlefish {Strongylura marina) (18%) (Table 16).
Blueback herring was the most abundant juvenile alosid found in Albemarle
Sound seine samples (6,140), followed by alewife (232), American shad (38), and hickory
shad (10) (Table 17). Juvenile alosids were found in all five regions; alewife was the
only one found in every region (Table 17). Blueback herring abundance was the highest
in the southwest region while alewife abundance was highest in the south-central region.
Most of the 38 juvenile American shad and 10 juvenile hickory shad were collected in the
north-central region. CWC, CPN, EBP, SAP, and ALR were the only sites where hickory
shad were collected. No conclusions should be made about the distribution of either
species in the Albemarle Sound area since such small numbers were collected.
The NCDMF juvenile striped bass survey collected a total of 35 hickory shad for a
catch per unit effort (CPUE) of 0.6 (Tablel8), while the NCDMF juvenile alosid survey
collected only 22 hickory shad for a CPUE of 0.32 (Steve Trowell, NCDMF, personal
communication). Hickory shad were collected at three NCDMF sites during the month of
Table 16. Species compositions from the juvenile hickory shad survey seine and trawl samples in the Albemarle Sound and selected tributaries, 1996.
Seine samples (n = 130) Trawl samples (n = 11)
Percent Percent Percent Percent
presence Total of total presence Total of total
Scientific name Common name in samples catch catch in samples catch catch
Brevoortia tyrannus Atlantic menhaden 18 11,758 40.2 0 0 0.0
Alosa aestivalis Blueback herring 24 6,140 21.0 0 0 0.0
Morone americana White perch 64 5,443 18.6 73 113 10.9
Notropis hudsonius Spottail shiner 34 1,157 4.0 9 11 1.1
Morone saxatilis Striped bass 64 1,033 3.5 100 378 36.5
Hybognathus regius Eastern silvery minnow 15 662 2.3 0 0 0.0
Perea flavescens Yellow perch 33 558 2.0 18 11 1.1
Menidia beryllina Inland silverside 48 523 1.8 9 1 0.1
Anchoa mitchilli Bay anchovy 17 384 1.1 27 163 15.7
Alosa pseudoharengus Alewife 32 232 0.8 0 0 0.0
Leiostomus xanthurus Spot 29 222 0.8 73 279 26.9
Strongylura marina Atlantic needlefish 18 169 0.6 0 0 0.0
Bairdiella chrysoura Silver perch 8 143 0.5 0 0 0.0
Dorosoma cepedianum Gizzard shad 14 130 0.4 0 0 0.0
Lepomis spp. Sunfish species 18 100 0.3 9 2 0.2
Micropogonius undulatus Atlantic croaker 17 98 0.3 36 58 5.6
Menidia menidia Atlantic silverside 9 63 0.2 0 0 0.0
Fundulus spp. Killifish species 14 60 0.2 0 0 0.0
Notomegonus crysoleucas Golden shiner 6 56 0.2 0 0 0.0
Ameiurus catus White catfish 8 49 0.2 0 0 0.0
Micropterus salmoides Largemouth bass 12 40 0.1 0 0 0.0
Alosa sapidissima American shad 13 38 0.1 0 0 0.0
Anchoa hepsetus Striped anchovy 5 23 0.1 0 0 0.0
Ictalurus punctatus Channel catfish 3 23 0.1 9 4 0.4
Ethostoma olmstedi Tesselated darter 5 21 0.1 0 0 0.0
Mugil cephalus Striped mullet 7 14 <0.1 0 0 0.0
Lagodon rhomboïdes Pinfish 4 12 <0.1 0 0 0.0
Trachinolus carolinus Florida pompano 2 12 <0.1 0 0 0.0
Alosa mediaeris Hickory shad 5 10 <0.1 0 0 0.0
Table 16, continued.
Seine samples (n = 130) Trawl samples (n == 11)
Percent Percent Percent Percent
presence Total of total presence Total of total
Scientific name Common name in samples catch catch in samples catch catch
Anguilla rostrata American eel 5 10 <0.1 0 0 0.0
Ameiurus natalis Yellow bullhead 5 8 <0.1 0 0 0.0
Cynoscion nebulosas Spotted seatrout 2 6 <0.1 0 0 0.0
Trinectes maculatus Hogchoker 3 6 <0.1 27 11 1.1
Moxostoma erythrurum Golden redhorse 2 5 <0.1 0 0 0.0
Dorosoma pretense Threadfm shad 3 4 <0.1 0 0 0.0
Paralichthys dentatus Summer flounder 3 4 <0.1 18 4 0.4
Syngathus spp. Pipefish species 3 4 <0.1 0 0 0.0
Ameiurus spp. Bullhead species 1 2 <0.1 0 0 0.0
Caranx hippos Crevalle Jack 1 2 <0.1 0 0 0.0
Pomatomus saltatrix Bluefish 1 1 <0.1 0 0 0.0
Pomoxis nigromaculatus Black crappie 2 2 <0.1 0 0 0.0
Archosargus probatocephalus Sheepshead 1 1 <0.1 0 0 0.0
Cyprinus carpió Common carp 1 1 <0.1 9 1 0.1
Elops Ladyfish 1 1 <0.1 0 0 0.0sauras
Opsanus tau Oyster toadfish 1 1 <0.1 0 0 0.0
Orthopristis chrysoptera Pigfish 1 1 <0.1 0 0 0.0
Raja 0 0 0.0spp. Skate species 1 1 <0.1
Q
(O
70
Table 17. Catch per unit effort (CPUE) of the four juvenile Alosa species by region in beach seines in
Albemarle Sound and selected tributaries. Number of samples in parenthesis.
CPUE by region
Species Northwest North-central Southwest South-central Southeast
(n= 39)(n=27)(n= 15)(n^ 20) (n= 26)
Hickory shad 0.1 0.2 0 0 0.1
(n= 10)
American shad 0.2 1.0 0.1 0.1 0
(n= 38)
Alewife 1.1 3.1 0.7 4.0 0.5
(n= 232)
Blueback herring 1.8 19.2 366.9 2.4 0
(n= 6,140)
Table 18. Species abundance for each sample week of the NCDMF juvenile striped bass survey (Unpublished data, NCDMF, Elizabeth City, NC).
Species
Date Striped bass White perch Blueback herring Alewife Hickory shad American shad
960604 332 133 45 0 5 29
960613 277 898 100 147 10 27
960618 440 904 0 42 3 0
960625 266 880 61 19 10 0
960703 227 2,620 2 92 3 0
960708 643 8,350 186 54 4 0
Total 2,135 13,785 394 354 35 56
CPUE 39.5 255.3 7.3 6.6 0.6 1.0
72
August in the juvenile alosid survey (Table 19). The small number of hickory shad
collected precluded any detailed analysis of distribution patterns in Albemarle Sound.
Twenty different species were present at least once in the seven seine samples that
contained juvenile hickory shad, but alewife was the only species present in all seven
samples (Table 20). American shad and blueback herring were present with hickory shad
in one sample each, while white perch and striped bass, the species most commonly
found in seine samples, were present in five of the seven seine samples.
Water temperatures among juvenile hickory shad sites were similar with a range
from 22.6 °C to 28.0 °C, but other water quality parameters showed significant
differences among sites (Table 21). Mean conductivity was highest in sites located in the
eastern sound with CSR having the highest mean conductivity (8.3 mS). BAT, which is
located in the western sound near the mouths of the Roanoke and Cashie Rivers, and
WOM, which is on the south shore of western Albemarle Sound, had the lowest mean
conductivity (0.1 mS). Mean dissolved oxygen values at most of the sites ranged from
6.6 mg/L to 7.6 mg/L. SCR, which is located on the east shore of the Scuppemong River,
had the lowest mean DO (4.7 mg/L), and CPN, located near the mouth of the Chowan
River on the west shore, had the highest mean DO (8.0 mg/L) among the sites. Mean
secchi visibility values were lowest in sites located in the eastern sound with CSR
(Croatan Sound at Roanoke Island) having the lowest mean secchi visibility (33.6 cm).
Table 19. Juvenile hickory shad collected during the NCDMF juvenile striped bass and juvenile alosid seine surveys (Unpublished data, NCDMF,
Elizabeth City, NC).
Date Survey Area N Mean TL (mm) Min TL (mm) Max TL (mm)
960604 Striped bass Edenton Bay 2 35.0 ±2.8 33.0 37.0
960604 Striped bass Avoca Farm 3 29.3 ±5.9 25.0 36.0
960613 Striped bass US 17 Bridge 1 35.0
960613 Striped bass W. of Mackeys 3 31.7±3.2 28.0 34.0
960613 Striped bass Old Bayliner Plant 4 37.3 ±13.5 28.0 53.0
960613 Striped bass Edenton Bay 2 34.5 ±2.1 33.0 36.0
960618 Striped bass Cape Colony 3 55.3 ±4.5 51.0 60.0
960625 Striped bass Old Bayliner Plant 2 61.0±2.8 59.0 63.0
960625 Striped bass Batchelor Bay 8 56.9 ±5.2 47.0 64.0
960703 Striped bass US 17 Bridge 3 53.7 ±6.7 48.0 61.0
970708 Striped bass Cape Colony 4 54.0 ±0.8 53.0 55.0
970813 Alosid Sandy Point 12 70.5 64.0 80.0
970813 Alosid Arrowhead Beach 8 58.6 54.0 68.0
970815 Alosid Colonial Beach 2 72.0 54.0 73.0
Table 20. Fish species associated with juvenile hickory shad.
Total catch in samples Number present in
Scientific name Common name with hickory shad in samples with hickory shad
Alosa pseudoharengus Alewife 28 7
Menidia beryllina Inland silverside 30 5
Morona saxatilis Striped bass 64 5
Morona amaricana White perch 71 5
Strongylura marina Atlantic needlefish 5 3
Bravoortia tyrannus Atlantic menhaden 1,158 3
Lapomis spp. Sunfish species 2 2
Notomigonus crysolaucas Golden shiner 15 2
Perea flavescens Yellow perch 26 2
Leiostomous xanthurus Spot 28 2
Notropis hudsonius Spottail shiner 39 2
Ethostoma olmstedi Tessellated darter 1 1
Fundulus spp. Killifish species 1 1
Mugil cephalus Striped mullet 1 1
Pomoxis nigromaculatus Black crappie 1 1
Alosa sapidissima American shad 2 1
Hybognathus regius Eastern silvery minnow 7 1
Anchoa mitchilli Bay anchovy 11 1
Alosa aestivalis Blueback herring 38 1
Table 21. Water quality parameters for the 16 seine sites in Albemarle Sound and selected tributaries for the period May to October 1996. SD=
standard deviation.
Water temperature (°C) Dissolved oxygen (mg/L) Secchi visibility (cm) Conductivity (mS)
Site n mean + SD range mean ± SD range mean ± SD range mean ± SD range
Northwest
BAT 10 26.4 + 4.6 18.0-31.0 7.1 ± 1.7 4.0-9.8 70.0 ±15.8 45.0-90.0 0.1 0.1-0.1
CPN 9 25.9 ±3.9 18.0-29.0 8.0 ± 1.3 5.6-10.0 60.6 ±21.3 30.0-85.0 0.3±0.4 0.1-1.2
CWC 10 26.2 + 3.6 21.0-30.0 7.6 ± 1.0 5.8-8.7 68.0±21.1 30.0-90.0 0.3 ±0.5 0.0-1.4
MCR 10 26.0 ±4.2 18.0-31.0 7.1 ± 1.2 4.7-8.6 77.0±21.8 40.0-100.0 0.4 ±0.6 0.1-1.8
North-central
EBP 5 24.1 ±5.1 16.0-28.0 7.5 ±0.7 6.9-8.6 63.8 ±25.0 30.0-90.0 1.0 ± 1.0 0.2-2.8
ESP 6 22.6 ±5.5 15.0-27.5 7.2 ± 1.3 5.9-9.6 60.8 ± 25.0 20.0-90.0 1.0 ±0.9 0.2-2.6
SAP 11 25.4 ±4.3 18.0-30.5 7.6 ±1.3 5.4-9.8 75.0 ±20.4 40.0-100.0 0.5 ±0.7 0.1-2.6
32N 6 24.8 ±3.4 19.0-28.0 7.3 ±0.6 6.7-8.4 83.3 ± 16.3 60.0-100.0 0.8 ± 1.1 0.1-2.8
Southwest
NPL 10 22.7 ±5.8 12.0-30.0 6.6 ±2.1 3.2-9.3 58.5 ±27.5 10.0-90.0 0.3 ±0.5 0.1-1.8
WOM 7 25.7 ±4.3 15.0-31.0 6.8±2.1 3.1-8.5 67.9 ± 18.2 40.0-95.0 0.1 ±0.1 0.1-0.3
Table 21, continued
Water temperature (“C) Dissolved oxygen (mg/L) Secchi visibility (cm) Conductivity (mS)
Site n mean + SD range mean + SD range mean + SD range mean + SD range
South-central
SCR 8 28.0+2.6 24.0-31.0 4.7+2.3 1.5-8.0 59.4+ 26.1 15.0-90.0 1.2±0.6 0.2-1.9
SOV 12 25.0 + 4.9 15.0-31.0 7.5 ± 1.2 5.2-8.6 59.2 + 25.1 15.0-90.0 0.3 ± 0.4 0.1-1.6
Southeast
ALR 7 25.0 + 3.9 17.0-25.0 7.0 ± 1.0 5.8-8.8 46.4+19.7 30.0-85.0 4.3+ 0.3 3.9-4.9
CSM 5 26.3 ± 2.9 23.5-29.5 6.6 ±0.8 5.7-7.8 34.0 ± 12.9 15.0-50.0 6.7+ 2.3 4.3-10.4
CSR 7 24.0 + 4.1 18.0-29.5 6.9+ 1.5 4.0-8.2 33.6± 13.1 20.0-50.0 8.3 ±2.0 5.0-10.9
DIS 7 25.0 + 3.6 18.0-29.0 7.4+ 0.9 6.4-8.6 47.1 + 10.7 35.0-60.0 4.5 ±0.3 4.2-5.2
77
River Flow and Year Class Abundance
It is not clear why the abundance of hickory shad has increased since the 1980s in
the Albemarle Sound/Roanoke River watershed, so patterns of river discharge (flow)
downstream of Roanoke Rapids Dam during the spawning migration (February through
April) were visually examined for possible correlations of year class abundance with river
flow from 1989 to 1996 (Figure 27-28).
Hickory shad in 1996 first appeared in the Roanoke River at Weldon in February
and were abundant from mid-March through mid-April. The entire month of February
had steady flows > 35,000 cubic feet per second (cfs), which was associated with snow
melt from winter storms in the upper watershed (Figure 28). The first half of March had
significant fluctuations in flow, but the latter part of March experienced steadier flows
between 25,000 and 35,000 cfs. A sudden drop in flow occurred at the end of March
before returning to steady flows between 20,000 and 30,000 cfs in April.
The age 3 hickory shad were bom in 1993 during a relatively steady river flow >
20,000 cfs during March and a flow > 30,000 cfs during April as a result of a winter
storm in mid-March (Figure 28). The age 4 hickory shad were bom in 1992 during
significant fluctuations in river flow from 2,000 to 20,000 cfs for Febmary and March, a
relatively steady flow around 9,000 cfs for the first three weeks of April, and a sudden
increase in flow to about 20,000 cfs on 23 April (Figure 27). The spring seasons from
1989 to 1991 had fluctuations in flow from Febmary through April with periods of steady
flows around 20,000 cfs (Figure 27), while 1994 had a stable river flow around 20,000 cfs
from mid-Febmary to early April (Figure 28). An average discharge of 8,500 cfs in the
spring mimics the preimpoundment river flow that would inundate the floodplain
(Rulifson and Manooch 1991), which is the spawning habitat utilized by hickory shad
(Street 1970; Pate 1972; Settle 1996).
79
Figure 27. River flow patterns in the Roanoke River downstream of Roanoke Rapids
dam during the hickory shad spawning season (February-April), 1989-1992.
D(1isc0hxa0rg0e )
80
Figure 28. River flow patterns in the Roanoke River downstream of Roanoke Rapids
dam during the hickory shad spawning season (February-April), 1993-1996.
1(D0iscx0har0ge)
81
Discussion
Adult Sex Compositions of the Catch
The male to female ratios from Albemarle Sound (0.73:1) and the Roanoke River
at Weldon (0.76:1) do not indicate a significant sex selective harvest of female hickory
shad in 1996. This can be an important indicator of harvest practices since in some
fisheries, females are targeted by the fishery (e.g., hickory shad, American shad, sturgeon
{Ascipenser spp.)) (Rulifson et al. 1982). In earlier investigations, the sex ratios of
hickory shad and American shad were difficult to ascertain because the gill net mesh sizes
selected for the larger fish, in this case, the females (Street et al. 1975; Winslow 1989,
1990). Pound net gear is non-selective; sex ratios for alewife and blueback herring for
many studies are considered to be unbiased (Winslow 1989; Klauda et al. 1991b). In
some cases males are more abundant than females, likely related to a greater proportion
of males reaching maturity at an earlier age, and the differential arrival of males and
females on the spawning grounds. Such is the case of alewife and blueback herring in the
Chesapeake Bay (Klauda et al. 1991b). Pate (1972) found the male to female ratio of
hickory shad sampled by a non-selective haul seine in the Neuse River, NC to be 4:1.
This ratio could have been the result of a large proportion of virgin males recruited to the
spawning population (47.3% of the males were age 2).
The present study, however, found the male to female ratio of hickory shad from
Albemarle Sound in 1996 to be 0.73:1, which contrasts the findings of Pate (1972). We
believe that the ratio was a good representation of the sex composition for the Albemarle
population because the fishery-independent gill net survey which collected these fish
82
employed several gill net mesh sizes to minimize size and sex-selective biases (Table 2).
A similar sex ratio was obtained by sampling catches of sport fishermen at Weldon
during 1996 (0.76:1), indicating that females in both locations did slightly out number the
males. The small gill net mesh sizes used in the RRNWR independent gill net fishery in
1996 appeared to select for males and small females, which may explain why the male to
female ratio was significantly different than the ratios from Albemarle Sound and Weldon
(4.29:1) (Table 2).
Scale Age/Otolith Age Agreement
The 57% agreement between scale and otolith ages for this study is the same
agreement level Komegay (1977) found with alewife from Albemarle Sound; however,
the agreement level he found with blueback herring was approximately 68%. The alewife
scale ages never deviated more than + two years from the otolith age, but two blueback
herring scale ages deviated + three years from the otolith age (Komegay 1977).
Scale ages differing by one or two years from the otolith age is a relatively large
deviation for a fish with a longevity of only seven years. Likewise, the 57% agreement
level between scales and otoliths is low. Alosa scales are commonly regenerated,
spawning marks sometimes obscure annuli near the scale margin, the first annulus is
sometimes confused with the freshwater zone (a false annulus formed when juvenile
Alosa first enter the marine environment), and the first annulus is not always visible on
the scale (Gating 1953; Judy 1961; Komegay 1977). In addition hickory shad scales are
considered the most difficult A/oia scales to age (Richkus and DiNardo 1984).
Therefore, otoliths should be used whenever possible for aging hickory shad.
83
Age to Maturity
The short life span of hickory shad, combined with an early age to maturity and an
anadromous migration pattern, suggests that most fish in the population could be
subjected to recreational and commercial harvest in inland waters for only one or two
seasons before being removed by exploitation or natural mortality. Approximately 37%
of both sexes of hickory shad are sexually mature as early as age 2; 96% of the population
is mature by age 3, and 100% of the population is mature by age 5 (Table 9). One or two
spawning marks on the scales are common; three or more are rare.
Based on age to maturity and spawning patterns, hickory shad and American shad
are exploited similarly in the Albemarle Sound region, but the amount of exploitation on
these species differs south of Cape Hatteras. American shad in Albemarle Sound usually
reach sexual maturity by age 3 to 4 for males and age 4 to 5 for females; both sexes
spawn up to three times (Winslow 1989, 1990). American shad show a latitudinal
gradient between semelparity and iteroparity through the species range (Leggett and
Carscadden 1978). Populations south of Cape Hatteras seldom spawn more than once,
while populations in New York and Connecticut spawn up to five times (Table 22).
Hickory shad appear to be iteroparous south of Cape Hatteras as indicated by repeat
spawners in the Neuse River, North Carolina (Pate 1972; Hawkins 1980) and in the
Altamaha River, Georgia (Street 1970).
Fecundity
Since hickory shad spawn only one to three times with a relatively low fecundity
(80,000 to 475,000 in Albemarle Sound), the population could decline from
Table 22. A comparison of life history aspects of American shad, hickory shad, alewife, and blueback herring.
Life history
aspect American shad Hickory shad Alewife Blueback herring
Distribution Nova Scotia to Massachusetts to Nova Scotia to Nova Scotia to
Florida “ Florida ^ South Carolina‘S Florida*"
Size (TL, mm) up to 750 mm, up to 600 mm, up to 400 mm, up to 400 mm,
usually 500 mm '* usually 300-400 mm"* usually 200-300 mm '* usually 200-300 mm '*
Juvenile habitat tidal freshwater poorly documented, tidal freshwater estuaries tidal freshwater
estuaries estuaries migrate to saltwater estuaries, migrate to saltwater migrate to SW in fall,
saltwater in fall *" migrate to ocean in fall, some some overwinter in
ocean in summer *"’' overwinter in estuary *" estuary *"
Juvenile growth 80-110 mm in fall *" 119-189 mm in fall ' 75-110 mm in fall “ 50-70 mm in fall “
(TL, mm)
Mean size at M" F*" M“ F“ F“ F“
age (FL, mm): 1 192.6 209.2
2 306.0 321.9 295.6 315.0
3 380.8 404.2 321.2 337.1 233.0 235.4 247.5
4 414.0 435.0 341.1 350.7 239.5 248.2 240.0 246.2
5 440.0 463.8 360.0 376.6 251.0 265.8 248.9 257.7
6 448.1 478.0 381.6 402.5 261.2 270.3 258.9 267.3
7 464.8 499.6 372.7 411.0 263.5 274.5 253.5 273.8
8 482.8 511.3 397.0 411.0 266.0 286.5 262.0 276.5
Longevity up to age 11-12 *" up to age 7-8 *" up to age 9-10 “ up to age 9 “
Age to maturity males; age 3-5 males; age 2-3 males: age 2-4 combined: age13-6*"
females: 4-6 ‘i,bage females: f )age 2-4 females: age 3-5 '
a b
Fecundity 100,000-600,000 43,000-730,000 100,000-467,000 120,000-440,000 “
h
higher in southern latitudes “’*" 80,000-475,000 CX5
Table 22, continued
American shad. Hickory shad Alewife Blueback herring
Spawning season ApriP mid March- mid May ® mid March- early May ® mid March-
Albemarle Sound mid March- late April early May®
Spawning 12-20 9.5-22 “C “ 10-18 "C^ 13-26 “C“
temperatures
Spawning duration ~ 1 month ^ 2-2.5 months ® ~2 months ® ~ 2 months ®
Spawning habitat main channel “ swamps, small creeks, swamps, small creeks, swamps, small creeks,
ponds, main channel ^ ponds ** ponds, ricefields “
Spawning frequency once, S of Cape Hatteras mostly 1-3 times ^ up to 5-6 times ‘ up to 4-5 times
1-2 times in North Carolina mostly 1-2 times,
1-4 times in Maryland up to 4 times ’’
and Virginia
up to 5 times in New York
and Connecticut
Ocean migration long distance— American unknown—hickory shad shorter distance—alewives long distance—mixed
range shad from all states and have been found off Long found in Bay of Fundy during stocks in Bay of Fundy
provinces found in Bay Island, NY and New England summer are mostly regional from as far away as
of Fundy during summer ‘ during summer ^ or local in origin ‘ North Carolina ’
a. Rulifson et al. 1982 b. Klauda et al. 1991 c. Richkus and DiNardo 1984 d. Robins et al. 1986 e. Street 1970 f. Pâte 1972
g. Street et al. 1975 h. Batsavage present study i. Melvin et al. 1986 j. Bigelow et al. 1963 k. Schaefer 1967
1. Rulifson et al. 1987
00
Ü1
86
overharvest. Other commercially-important, long-lived iteroparous fish such as striped
bass can produce from 1,000,000 to 5,000,000 eggs in a single spawning season (Olsen
and Rulifson 1992). American shad fecundity is slightly greater than hickory shad with
higher fecundity estimates seen in the semelparous, southern populations (Table 22).
Because large female hickory shad make up the greatest proportion of hickory shad
bycatch in the American shad gill net fishery, and since potential fecundity increases with
fork length (Figure 23), the most fecund females are subject to more commercial
exploitation than smaller individuals (Richkus and DiNardo 1984).
Fork Length at Age
Difficulty in determining age from fork length compounds the effectiveness of
size limit regulations (Tables 4-6). Size limit regulations also are inappropriate because
they are used to protect size classes having the greatest potential for rapid growth before
harvest (i.e., to prevent growth overfishing) (Richkus and DiNardo 1984). The period of
rapid growth for both species appears to be during the immature life stage and would not
be exploited by commercial and recreational fisheries targeting the spawning population.
Size limits for hickory shad would only have an impact in terms of mortality by sex since
the males are smaller than females of equal age (Richkus and DiNardo 1984). Creel
limits and commercial quotas would be better management strategies because they would
allocate the harvest among commercial and recreational fishers while limiting the total
harvest. Since hickory shad are a short lived species with only a few year classes
exploited, unrestricted harvest could result in stock overfishing instead of growth
overfishing. So instead of a decrease in the potential biomass by harvesting fish too early
87
in the growth period, stock overharvesting may become evident in subsequent precipitous
declines of the spawning stock (Richkus and DiNardo 1984).
Mean fork lengths at age of both sexes from age 3 on are smaller than those
reported from earlier investigations (Table 23). This could be a function of capture
methods in which the hickory shad were collected in large gill net mesh sizes set for
American shad (Street et al. 1975; Hawkins 1980). However, Pate (1972) examined
hickory shad captured in a non-selective haul seine. It is possible that the larger
individuals in each age class are being harvested disproportionately to the smaller fish
(i.e., Lee’s phenomenon), the evidence for this which is depicted in Table 23.
Scale and Otolith Back Calculations
The weak scale radius to fork length relationship occurred because two age classes
dominated the sample and because of the large overlap in size ranges for each age class.
Also, between-scale variations in scale radius on the same fish made choosing a
representative scale difficult. Since the majority of total growth for hickory shad is
reached by age 2, no age 0 or age 1 fish would have a considerable effect on back
calculations and the von Bertalanffy growth curve (Pate 1972). A better otolith radius to
fork length relationship occurred because otoliths have less size variation than scales,
otoliths were available from age 0 fish, and a subsample of the dominant size classes
were taken to reduce the influence these size classes had on the relationship.
88
Table 23. A comparison of fork lengths at age from this study to previous hickory shad studies.
Age class
Study Sex 1 2 3 4 5 6 7 8
Batsavage (1997) M 293 288 318 332 376
F 304 313 339 343 402 397
Pate (1972) M 294 332 346 356 357 369
F 311 354 376 395 409 379 420
Street et al. (1975) M 289 325 350 371 360 365
F 341 341 355 387 384 390
Hawkins (1980) M 295 318 342 353 374 384 397
F 302 337 350 373 393 413 410
89
Spawning Habitat
Although this study did not survey spawning habitat of hickory shad in the
Roanoke River, both ripe and spent adults were collected from tributaries of the Roanoke
River in the RRNWR. Spawning activity of hickory shad in the Neuse River, North
Carolina and the Altamaha River, GA was confined to flooded bottomlands and
tributaries away from the mainstem of the river (Street 1970; Pate 1972). Mansueti
(1962) found hickory shad spawning in the mainstem of the Patuxent River, Maryland,
upstream of American shad spawning sites. Hickory shad have been found to spawn in
both the mainstem and tributaries of rivers in Virginia (Klauda et al. 1991a). This study
collected hickory shad running ripe from the mainstem of the Roanoke River near
Weldon, North Carolina, but no spent fish were collected.
The historic range of anadromous Alosa spawning migrations on the Roanoke
River before the dam blocked further migration at Roanoke Rapids, North Carolina was
near Salem, Virginia (Hightower et al. 1996). However, only American shad, alewife,
and blueback herring were documented as spawning in the Piedmont region of the
Roanoke River. It is possible that hickory shad also utilized the Piedmont stretches of the
river since they are commonly misidentified as American shad (Richkus and DiNardo
1984). However, because hickory shad are found to utilize flooded swamps and
tributaries on the Coastal Plain as spawning habitat, and because of the lack of evidence
that hickory shad ever migrated into the Piedmont region of the Roanoke River, it is
difficult to conclude that fish passages installed on the hydroelectric dams of the Roanoke
River would provide more spawning habitat for hickory shad.
90
Juvenile Distributions
Development of state and interstate fishery management plans for hickory shad
are difficult without knowledge of nursery grounds and migration patterns of the young-
of-year, and the habitats and migration patterns of adults at times other than during the
spawning migration (Richkus and DiNardo 1984). Hickory shad have a seasonally early
and prolonged spawning period that occurs before the other Alosa species in the
Albemarle Sound region, which puts the juveniles into the system before the other young-
of-year anadromous species (Table 22). Based on the large adult population in the
Albemarle Sound region, there should be good young-of-year recruitment during some
years, which this study and the NCDMF surveys failed to document in 1996.
I believe that the majority of juvenile hickory shad do not use Albemarle Sound
as a nursery ground during the same time period as the other juvenile Alosa. The
majority of juvenile hickory shad may have migrated to the ocean before the survey was
completely underway. Street (1970) found juvenile hickory shad in nearshore ocean
waters off the coast of Georgia. This scenario may explain why hickory shad exhibit high
growth in the first year compared to other juvenile Alosa that utilize estuaries during the
first year of life (Table 22).
Comparison of Hickory Shad to Alabama Shad
Although many life history aspects of hickory shad differ from the other
anadromous Alosa on the East Coast of the U.S., it has some similarities to the Alabama
shad {Alosa alabamae), a Gulf Coast anadromous alosid. Alabama shad is a short lived
species with a longevity of only four to six years (Pattillo et al. 1997). They mature early
in life with some males mature by age 1 and both sexes mature by age 2. Juvenile
Alabama shad, like the juvenile hickory shad, are fast growing with some as large as 140
mm FL (Mills 1972, cited in Rulifson et al. 1982). However, juvenile Alabama shad tend
to stay in freshwater longer than juvenile hickory shad with young of year Alabama shad
collected as late as November in natal rivers (Mills 1972, cited in Rulifson et al. 1982).
River Flow and Year Class Abundance
Higher river flows in the late winter and early spring contribute to the initiation of
the spawning migrations of anadromous fish. Additionally, steady river flows > 20,000
cfs inundate the floodplain by water from the main channel overtopping natural levees,
passing through openings in the levees, and back flooding through creek mouths
(Rulifson and Manooch 1991), which could potentially increase the amount of spawning
habitat for hickory shad, alewife, and blueback herring. Higher river flows also could
reduce catchability of adults, which would allow more fish to spawn. It is not clear if a
particular flow regime is more favorable for year class abundance. Variations in year
class abundance are more pronounced in short-lived species and for species with brief
spawning periods, or for those that spawn in variable, unpredictable environments (Van
Den Avyle 1993). Other studies have found age 3 and 4 hickory shad to be the dominant
age classes as well (Street et al. 1975; Johnson et al. 1978; Hawkins 1980) so this might
be a normal characteristic for hickory shad populations. But since hickory shad are short-
lived and spawn in unpredictable habitats, river flow patterns and/or other environmental
factors may have a large effect on year class abundance.
92
Conclusions
Based on the results of my study and review of the hickory shad literature, the
following conclusions can be made:
1. The male to female ratios from Albemarle Sound (0.73: 1) and Weldon (0.76.1) do
not indicate a significant sex selective harvest of female hickory shad in 1996.
2. The short life span, combined with a young age to maturity, results in individuals
subjected to one or two seasons of commercial and recreational harvest before they
leave the population (from exploitation or from natural mortality).
3. The low fecundity combined with repeat spawning only one or two times makes
hickory shad and other anadromous Alosa susceptible to overharvest; harvest of the
larger, more fecund females by the American shad gill net fishery could increase the
likelihood of population decline.
4. Overlapping fork lengths at age, and size differences between males and females at
age, make size limit regulations inappropriate.
5. Juvenile hickory shad do not appear to utilize Albemarle Sound as a nursery ground
like the other three Alosa species.
Management Recommendations
Based on the conclusions listed above, the following management
recommendations are offered:
1. Impose a creel limit of hickory shad and American shad in aggregate on anglers
fishing near the spawning grounds. Many anglers cannot distinguish American shad
from hickory shad, so identical regulations for both species would minimize
93
2.Mcongonumrodfuifsyion by anglers. A daily creel limit would allow anglers to harvest a reasonableber of fish and at the same time reduce potential for overharvest on the spawningunds.seasonal limits on the American shad gill net fishery to prevent the excessive
bycatch of female hickory shad. Since hickory shad commences its spawning
migration before American shad, the opening of the American shad gill net fishery
could be delayed to allow hickory shad to enter the rivers to spawn before they
become susceptible to commercial harvest.
Research Recommendations
Based on the life history aspects of hickory shad that are not yet understood,
the following areas of research are recommended:
1. Initiate a tagging study to characterize the ocean migration patterns, to estimate the
population size of spawning stocks, to estimate the exploitation rate, and to quantify
the sources of exploitation for hickory shad.
2. Characterize the primary nursery grounds of juvenile hickory through the species
range by sampling the estuaries earlier in the spring and by sampling nearshore ocean
waters from late spring to fall.
3. Characterize the spawning habitats and the locations of these habitats for hickory shad
in the Roanoke River.
4. Expand results of the mesentery fat and gut analysis study by examining fish in the
ocean prior to spawning, in the prespawing staging areas of the esturaries and near the
spawning grounds just prior to spawning. The analysis should examine both
94
mesentery and intramuscular fat along with gut analysis to determine what the
primary energy source for hickory shad is during the spawning migration and if the
energy source changes during the migration.
95
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