Browsing by Author "Dr. James A. Rice, Committee Member"

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Effects of Fishing Practices, Gear Parameters and Gear Configurations on Target and Incidental Catch in the Southern Flounder (Paralichyths lethostigma) Gillnet Fishery of Pamlico Sound, North Carolina
(2002-06-26) Bianchi, Alan John; Dr. Lundie Spence, Committee Member; Dr. James A. Rice, Committee Member; Dr. BJ COPELAND, Committee Chair
In North Carolina, the southern flounder (Paralichyths lethostigma) fishery is one of the most valuable finfish fisheries in the state. A large portion of this fishery occurs during the fall (September 15 to December 15) in the southeastern area of Pamlico Sound, North Carolina, and is conducted with gillnets. The increase in the number of gillnets employed in this fishery has begun to raise concerns among fishery managers and conservationists. These concerns include the reputation that gillnets have for catching large amounts of bycatch, an increase in the number of stranded sea turtles in the area during the southern flounder fall gillnet season, the incidental take of seabirds during gillnet operations and the incidental capture of red drum in southern flounder gillnets. This study was conducted during the 2000 and 2001 fall southern flounder season to determine the impacts of gillnets on sea turtles, seabirds, red drum, other finfish and invertebrates in Pamlico Sound, North Carolina. The purpose of this study is to examine the catch-per-unit-effort (CPUE) of the target (southern flounder) and bycatch species that is occurring in the southern flounder gillnet fishery of southeastern Pamlico Sound, North Carolina. It is hypothesized that the CPUE of the target and bycatch species will differ between the two areas (deep and shallow), the halves of the fishing season, gear parameters, soak time and gear configurations. The objectives of this study are: 1) To characterize the bycatch composition and distribution that is occurring in the southern flounder gillnet fishery, 2) To test experimental gillnet configurations in an effort to reduce bycatch (emphasis on sea turtle bycatch) without reducing target catch in the deep area of the fishery, and 3) To suggest reasonable and prudent regulations for the fishery. The sea turtle bycatch was mostly composed of juveniles and subadults Kemp's ridley, green and loggerhead turtles. The majority of the finfish bycatch was composed of Atlantic menhaden and weakfish. Horseshoe crabs composed the majority of the invertebrate bycatch. Data analyzed from this study has determined that area was a significant factor affecting sea turtle and red drum bycatch. Other factors significantly affecting sea turtle bycatch included length and height of gillnet fished. Mesh size and length were significant factors in red drum and seabird bycatch. Effort was the only significant variable in the finfish analysis. Analysis of the southern flounder CPUE determined that twine size, length, height and soak time are all significant variables. Even though fishing season was not a significant factor in the analysis, the majority of observed sea turtle, seabird and red drum interactions occurred in the first half of the fishing season. Tie down configuration was an insignificant factor in the sea turtle, seabird and finfish CPUE analysis. However, it was a significant factor in the southern flounder CPUE analysis. Analysis of the experimental gear configurations determined that configuration was a significant variable. The low-profile configuration caught significantly less finfish and invertebrate bycatch than the control and double-lead line configurations. The low-profile configuration also caught significantly less southern flounder than the control. I suggest that the following regulations be implemented to reduce bycatch of all species in the fall southern flounder gillnet fishery of Pamlico Sound, NC. 1) Move the starting date of the fishery back to October 1. 2) Raise the minimum mesh size to 14.6 cm and lower the maximum mesh size to 16 cm. 3) Implement the use of the low profile configurations for the deep area of the fishery.
Live Fast and Die Young: On the Growth and Mortality of Largemouth Bass in Puerto Rico
(2003-02-21) Neal, Jason Wesley; Dr. E. Jacquelin Dietz, Committee Member; Dr. Thomas J. Kwak, Committee Member; Dr. James A. Rice, Committee Member; Dr. Richard L. Noble, Committee Chair
Largemouth bass (Micropterus salmoides) have been widely introduced into freshwater systems around the world. In Puerto Rico, this species presents a management challenge to natural resource agents who wish to promote it as a sportfish because growth and survival are unlike that observed in its native temperate regions. Juvenile growth is linear and rapid (≥1 mm/day), attributed in part to a continuous growing season near optimum temperature year-round. Upon maturation, growth rate slows to near 0 mm/day, and few fish surpassing age 3. This dissertation hypothesized that the slow growth of adult fish results from excessive energy allocation to reproduction. Largemouth bass in Puerto Rico reach sexual maturity in 1 year, spawn over a six-month period, and individual fish spawn multiple times. The diversion of energy from growth to reproduction causes growth rates to decline, and the risk of disease, parasites, predation, or other means of natural mortality increases. I used three approaches to address this hypothesis: (1) empirical assessment of population dynamics, (2) theoretical modeling of bioenergetics processes, and (3) direct experimentation to compare reproductive and non-reproductive largemouth bass. Adult mortality strongly coincided with the reproductive period (January-June), and limited mortality occurred thereafter. Fish condition varied seasonally and with size, and was generally lowest in November just before the reproductive period, making these fish more susceptible to spawning related mortality. Condition declined with increasing age, suggesting a cumulative effect with no recovery period. Overall, empirical data on largemouth bass population dynamics supported the reproductive energetics hypothesis. Bioenergetics simulation using a conservative mean daily ration of 2% body weight predicted that a non-reproductive, 500-g largemouth bass would grow to 1,140 g in six months (182 d), the maximum spawning season duration. The actual size from tagging studies was 740 g, yielding a 400-g discrepancy between observed and predicted weight. This discrepancy in observed and predicted growth was explained for females using a range of spawning frequency-magnitude combinations, and for males by accounting for lost consumption. To experimentally test the reproductive energetics hypothesis, techniques for artificially propagating largemouth bass and inducing triploidy are discussed. I validated erythrocyte cell length as a ploidy verification technique using known ploidy largemouth bass. Erythrocyte cell length 99% confidence intervals ranged 14.43-16.66 mm for triploids, and 10.23-13.62 mm for diploids. Erythrocyte length correctly distinguished 100% of known-status largemouth bass (n=22) using a sample of 100 erythrocytes per individual. Growth, condition, and reproductive development of diploid and triploid largemouth bass were compared through age 1 in Lucchetti Reservoir. Growth rates up to the size of maturity (275 mm) were similar for both groups, and maturity was not reached until midway into the spawning season, preventing extensive spawning of diploid bass, and resulting in growth rates similar to triploid bass. Diploid largemouth bass exhibited higher GSI values than triploids, and no triploid females had GSI values consistent with maturation, suggesting that the triploids do not invest significant energy into reproductive development. As a result of this study, more comprehensive management of largemouth bass is possible. I refined techniques to produce triploid largemouth bass, and demonstrated the reduced reproductive investment of these sterile fish. Further research using triploids is needed to determine the efficacy of triploidy as a management option, particularly to determine if accelerated adult growth rates are possible. Specific research needs and management recommendations are discussed along with ecological implications of this research.
Trout Population and Production Dynamics in North Carolina State Park Streams
(2010-03-29) Wallace, Benjamin Craig; Dr. Thomas J. Kwak, Committee Chair; Dr. James A. Rice, Committee Member; Dr. Kenneth H Pollock, Committee Member
ABSTRACT WALLACE, BENJAMIN CRAIG. Trout Population and Production Dynamics in North Carolina State Park Streams. (Under the direction of Thomas J. Kwak.) Stream trout (Salmonidae) fisheries provide popular recreational fishing opportunities in North Carolina and nationwide. These fisheries may be managed under historical practices with limited information available to evaluate or plan management alternatives. The use of dynamic rates of population functions can serve as a superior method to quantify trout populations and provide a scientific basis from which to guide management decisions. Three trout species, brook trout Salvelinus fontinalis, brown trout Salmo trutta, and rainbow trout Oncorhynchus mykiss, inhabit streams under a variety of management regulations and stocking regimes in Stone Mountain State Park, North Carolina. To investigate trout population and production dynamics in intensively utilized southern Appalachian Mountain streams, we studied six stream reaches to (1) intensively sample and quantify critical population parameters of stream trout in a State Park, (2) develop empirical estimates of stream trout production rate based on population parameters, (3) sample and quantify nongame fish assemblages associated with trout fisheries, (4) measure and quantify water quality and instream habitat characteristics associated with trout and nongame fish assemblages, and (5) present the results of this study in an applied context toward guiding management strategies for stream trout fisheries in North Carolina State Parks, as well as other coldwater streams across North America. Of the three unstocked streams sampled, brook trout were present in two and brown trout were present in all three. Wild trout are short-lived with a maximum age of two years among fish sampled in Stone Mountain State Park streams. Mean annual brook trout density in unstocked waters ranged from 195.09 to 234.13 fish/ha and that for brown trout was 169.87 to 2,038.69 fish/ha. Annual brook trout production ranged from 5.91 to 8.81 kg/ha and annual brown trout production ranged from 14.07 to 64.16 kg/ha in unstocked waters. Age-0 and age-1 fish contributed the most production in the unstocked waters. Allopatric brook trout were found in the uppermost headwaters of two unstocked streams. Brook trout, brown trout, and rainbow trout were present in all three sampled reaches of the East Prong Roaring River. Trout densities in delayed harvest managed waters fluctuated widely over time and could not be explained by the frequency and density of stocking alone. Few trout remained in the sampling reaches for long periods of time after stocking into delayed harvest waters. Trout density in hatchery supported waters declined rapidly after being opened to harvest. Nongame fish were collected in four of the six sampling reaches, and species richness ranged from 2 to 13. Nongame fish density was highest in a portion of the East Prong Roaring River where instream and riparian habitat rehabilitation previously occurred. Instream habitat, stream gradient, and overhead cover were similar within unstocked waters and within stocked waters but were different between the two stream groups. Stream temperatures in the East Prong Roaring River are marginally suitable for trout. Other water quality measurements were similar among all reaches that were studied. Salmonid production can be used to monitor success of stream trout populations and, in conjunction with the ecotrophic coefficient, guide management decisions in coldwater streams nationwide. P/B ratios developed from our empirical estimates of production can be used to estimate production in the future with reduced sampling effort. Based on our findings, management options for streams in Stone Mountain State Park are presented. My results, in addition to future research and monitoring, can improve understanding of trout population dynamics, native trout distribution, habitat modifications, and management effects.