ABSTRACT
Recently, high incidences of intersex fish (males with testicular oocytes) were reported in some rivers in the southeastern U.S. To date, a systematic evaluation of the extent, severity, and causes of intersex fish has not been completed... more
Recently, high incidences of intersex fish (males with testicular oocytes) were reported in some rivers in the southeastern U.S. To date, a systematic evaluation of the extent, severity, and causes of intersex fish has not been completed in Georgia. Our objectives were to (1) assess intersex condition in black bass collected from rivers and impoundments across Georgia, and (2) determine estrogenic potency (a measure of the estrogens and estrogen-like substances) of surface waters where fish were collected. Fish (n=15-35) and water samples were collected from sites near municipal wastewater effluent discharges in each of four rivers and from a river that does not receive major wastewater effluent discharges. Fish and water were also sampled from 12 impoundments without major wastewater inputs to determine if a natural ‘background’ rate of intersex could be established for fish from relatively unpolluted water bodies. Gonads from all male fish were examined and the incidence and sever...
Tripletail (Lobotes surinamensis, Lobotidae) are a medium-sized, deep-bodied fish that occur in tropical and subtropical waters worldwide, including the coast of Georgia, USA. Typically these fish are found associated with submerged,... more
Tripletail (Lobotes surinamensis, Lobotidae) are a medium-sized, deep-bodied fish that occur in tropical and subtropical waters worldwide, including the coast of Georgia, USA. Typically these fish are found associated with submerged, emergent, or floating structure; but in the murky Atlantic Ocean off the Jekyll Island, Georgia coast, they float along the surface in large numbers from May through July. This aggregation is the target of an expanding recreational fishery and popularity of this sportfish is increasing across the southeast USA. Increasing popularity with anglers and the lack of basic life history data suggest the need for basic biological information for fisheries managers. Our primary goal was to increase the life history information of tripletail, specifically reproductive, age, and growth data, while evaluating non-lethal sampling techniques. A total of 226 tripletail were sampled primarily by hook-and-line methods from the Jekyll Island aggregation during March thro...
Fisheries biologists manage waterbodies similarly, but fish communities within these waterbodies can differ across locations. This disparity in fish condition can create uncertainty as to appropriate management strategies for a particular... more
Fisheries biologists manage waterbodies similarly, but fish communities within these waterbodies can differ across locations. This disparity in fish condition can create uncertainty as to appropriate management strategies for a particular waterbody. To examine how fish communities differ across waterbodies and how to successfully manage these differences, we conducted an investigation into the influence of multi-scale factors on fish condition. We sampled fish via electrofishing in 26 impoundments throughout Georgia, USA, and we calculated relative weight and proportional stock density for sportfish species. We used empirical sampling and geographic information systems to obtain measurements for multi-scale factors including mean depth, land cover, and climate for each impoundment. We used information theory, with hierarchical linear regression to evaluate the relationship between multi-scale factors and structural indices. We found fish condition was predicted by both lake- and lan...
ABSTRACT In coastal South Carolina, many wetlands are impounded and managed as migratory waterfowl habitat. Impoundment effects on fish production and habitat quality largely are unknown. We used the size-frequency method to estimate... more
ABSTRACT In coastal South Carolina, many wetlands are impounded and managed as migratory waterfowl habitat. Impoundment effects on fish production and habitat quality largely are unknown. We used the size-frequency method to estimate summer production of fish guilds in three impoundments along the Combahee River, South Carolina. We predicted that guild-specific production would vary with impoundment salinity, which ranged from 3 to 21 practical salinity units. We expected that marine species that use the estuary as nursery habitat would have greatest production in the impoundment with the highest salinity regime, and that species that inhabit the upper reaches of the estuary would have greatest production in the impoundment with the lowest salinity regime. Finally, we expected that estuarine species would be highly productive in all study impoundments, because these species can reproduce within these structures. We found that guild-specific productivity varied both among years and among impoundments, generally following salinity gradients, though to a lesser extent than expected. Our guild-specific estimates of fish productivity fell on the low end of the range of previously published estuarine fish production estimates. Additionally, we observed large mortality events in the study impoundments each summer. The results of our study indicate that during the summer, the study impoundments provided poor-quality fish habitat to all guilds.
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Age and growth information is used to understand populations' life history and ecology and monitor their trends. Such information is useful for evaluating the success of establishment of introduced populations. Prior studies have... more
Age and growth information is used to understand populations' life history and ecology and monitor their trends. Such information is useful for evaluating the success of establishment of introduced populations. Prior studies have validated age determination methods for ...
... CLASSIFICATION OF A WETLAND AREA ALONG THE UPPER MISSISSIPPI RIVER WITH AERIAL VIDEOGRAPHY Cecil A. Jennings US Fish and Wildlife Service National Fisheries Research Center PO Box 818 La Crosse, WI 54602 ...
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... 199619. Jennings, CA, Shelton, JL, Freeman, BF and Looney, GL 1996. ... Drift of larval fish in the upper Colorado River.. Journal of Freshwater Ecology , 3: 567–577. [Taylor & Francis Online], [Web of Science ®], [CSA] View all... more
... 199619. Jennings, CA, Shelton, JL, Freeman, BF and Looney, GL 1996. ... Drift of larval fish in the upper Colorado River.. Journal of Freshwater Ecology , 3: 567–577. [Taylor & Francis Online], [Web of Science ®], [CSA] View all references; Harvey 198715. Harvey, BC 1987. ...
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... a & Cecil A. Jennings a pages 327-336. ... Copeia , 1994: 174–183. [CrossRef] View all references). Studies of fish distribution in lentic areas of large rivers have found a direct association of centrarchids (Dewey et al. 19972.... more
... a & Cecil A. Jennings a pages 327-336. ... Copeia , 1994: 174–183. [CrossRef] View all references). Studies of fish distribution in lentic areas of large rivers have found a direct association of centrarchids (Dewey et al. 19972. Dewey, MR, Richardson, WB and Zigler, SJ 1997. ...
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Surface push nets have been employed in the Savannah River estuary (SRE) to monitor striped bass Morone saxatilis spawning activity since the 1960s, but most intensively since the mid-1980s. These methods provide relative... more
Surface push nets have been employed in the Savannah River estuary (SRE) to monitor striped bass Morone saxatilis spawning activity since the 1960s, but most intensively since the mid-1980s. These methods provide relative catch-per-unit-effort data for comparing ...
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Page 1. - NOTE - Spawnlng Activity of Paddiet ish (Polyodon spathula) In the Lower Black Rlver, Wisconsin ABSTRACT We present Indi rect evidence of successful paddleflsh (Polyodon spcthulr reproduction In 1989 and 1991 ...
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ABSTRACT
Research Interests: Zoology, Demography, Reproduction, Sex, Biology, and 6 moreEcology, Fish Biology, Sex ratio, Fisheries Sciences, Spawning, and Fecundity
I used replicated 37.8 1 aquaria in a factorial design (four densities of zebra mussel, Dreissena polymorpha; two hydrologic regimes) to determine if the survival or growth of juvenile fathead minnows (Pimephales promelas) was affected by... more
I used replicated 37.8 1 aquaria in a factorial design (four densities of zebra mussel, Dreissena polymorpha; two hydrologic regimes) to determine if the survival or growth of juvenile fathead minnows (Pimephales promelas) was affected by the density of zebra mussel or by the retention time of the test system. None of the fathead minnows died during the 30-d experiment. However, growth of fathead minnows was lower (P0.05). These laboratory results suggest that juvenile fish survival will not be affected by low to moderate densities of mussels (0–3000 m-2) but fish growth might be adversely affected at moderate densities of mussels (e.g., 3000 m-2).
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... Page 3. shrimp, Litopenaeus setiferus (Linnaeus), during the spring and autumn, and brown shrimp, Farfantepena-eus aztecus (Ives), during the summer months. Partic-ipation in the study was voluntary on the part of boat captains and,... more
... Page 3. shrimp, Litopenaeus setiferus (Linnaeus), during the spring and autumn, and brown shrimp, Farfantepena-eus aztecus (Ives), during the summer months. Partic-ipation in the study was voluntary on the part of boat captains and, therefore, not random. ...
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Declines in striped bass (Morone saxatilis) populations have been well documented over the past 30 years. During the 1980s, Savannah River striped bass also suffered a population decline, when catch per unit effort (CPUE; #/hr) of large... more
Declines in striped bass (Morone saxatilis) populations have been well documented over the past 30 years. During the 1980s, Savannah River striped bass also suffered a population decline, when catch per unit effort (CPUE; #/hr) of large adults declined by 97% and egg production declined by 96%. Loss of freshwater spawning habitat through harbor modifications was identified as the primary
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Research Interests: Zoology, Water quality, Ecology, Discriminant Analysis, Habitat, and 11 moreEstuaries, Environmental Variables, Fisheries Sciences, Canonical Correlation Analysis, Dissolved Oxygen, Water Quality, Essential Fish Habitat, Prey Availability, Environmental biology of fishes, Habitat Association, and Total Variation
ABSTRACT
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1. Robust redhorse Moxostoma robustum is an imperiled, potadromous fish in the southeastern USA. Initial recovery efforts have focused on supplementing existing populations and establishing refugial populations through extensive stocking... more
1. Robust redhorse Moxostoma robustum is an imperiled, potadromous fish in the southeastern USA. Initial recovery efforts have focused on supplementing existing populations and establishing refugial populations through extensive stocking programmes. However, assessment of the success of these programmes has not yet been conducted, and there are few reports evaluating the effectiveness of such programmes with other potadromous species. 2. Radio telemetry was employed to assess the effectiveness of a stocking programme aimed at addressing whether stocked individuals would remain in an area free of introduced predators and ascertaining the ability of stocked fish to integrate into a resident population. 3. Hatchery-reared robust redhorse were captured from refugial populations established in other river systems and were transferred to the Ocmulgee River, Georgia where a population of hatchery-reared individuals and an unknown number of wild fish reside. 4. These transferred robust redhorse exhibited an exploratory phase for the first 3 months before adopting behaviour patterns, including spawning migrations, that were consistent with those reported for wild fish in other systems. However, some individuals seemed unable to locate suitable spawning habitat. 5. Approximately half of the radio-tagged fish remained within the area free of introduced predators. 6. At least some radio-tagged robust redhorse fully integrated into the resident population as evidenced by their presence in spawning aggregations with resident individuals. 7. The effectiveness of a stocking programme is dependent upon the ability of stocked individuals to integrate into an existing population or replicate the behaviour and functionality of a resident population. Evaluations of stocking programmes should incorporate assessments of behaviour in addition to surveys to estimate abundance and survivorship and genetic assessments of augmentation of effective population sizes.
Flows in the lower Savannah River have been considerably altered since the construction of Strom Thurmond Dam in 1954. The effects of this flow alteration on fish have received little attention until recent years. We are collaborating... more
Flows in the lower Savannah River have been considerably altered since the construction of Strom Thurmond Dam in 1954. The effects of this flow alteration on fish have received little attention until recent years. We are collaborating with The Nature Conservancy and the Army Corps of Engineers to develop flow alternatives below Strom Thurmond Dam by evaluating relations between flow
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Tricaine (MS-222) is the most widely used anesthetic for fishes, but induction and recovery times are rather long. Studies on salmonids have shown that electroanesthesia is a good alternative to MS-222 for short term (<1 min)... more
Tricaine (MS-222) is the most widely used anesthetic for fishes, but induction and recovery times are rather long. Studies on salmonids have shown that electroanesthesia is a good alternative to MS-222 for short term (<1 min) immobilization. However, data on longer-duration (3–5-min) immobilization needed for surgical procedures are lacking. We analyzed induction and recovery times for 20 adult (52–81-cm) striped
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We estimated the growth and mortality of larval sunfish Lepomis spp. in backwater habitats of the upper Mississippi River with an otolith-based method and a length-based method. Fish were sampled with plankton nets at one station in... more
We estimated the growth and mortality of larval sunfish Lepomis spp. in backwater habitats of the upper Mississippi River with an otolith-based method and a length-based method. Fish were sampled with plankton nets at one station in Navigation Pools 8 and 14 in 1989 and at two stations in Pool 8 in 1990. For both methods, growth was modeled with an exponential equation, and instantaneous mortality was estimated by regressing the natural logarithm of fish catch for each 1-mm size-group against the estimated age of the group, which was derived from the growth equations. At two of the stations, the otolith-based method provided more precise estimates of sunfish growth than the length-based method. We were able to compare length-based and otolith-based estimates of sunfish mortality only at the two stations where we caught the largest numbers of sunfish. Estimates of mortality were similar for both methods in Pool 14, where catches were higher, but the length-based method gave significantly higher estimates in Pool 8, where the catches were lower. The otolith-based method required more laboratory analysis, but provided better estimates of the growth and mortality than the length-based method when catches were low. However, the length-based method was more cost-effective for estimating growth and mortality when catches were large.
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... a , Bruce Vondracek b & Cecil A. Jennings c pages 546-556. ... Individual paddlefish exhibit long-distance, directional movement to and from select sites within river systems (Combs 19829. Combs, DL 1982. Angler exploitation of... more
... a , Bruce Vondracek b & Cecil A. Jennings c pages 546-556. ... Individual paddlefish exhibit long-distance, directional movement to and from select sites within river systems (Combs 19829. Combs, DL 1982. Angler exploitation of paddlefish in the Neosho River, Oklahoma. ...