James R. Jackson

Use of Telemetry Methods to Estimate Natural and Fishing Mortality of Striped Bass in Lake Gaston, North Carolina

Abstract Natural mortality can substantially affect fish population dynamics, but the rate is difficult to estimate because natural deaths are rarely observed and it is difficult to separate the effects of natural and fishing mortality on abundance. We developed a new telemetry approach for estimating natural and fishing mortality rates and applied it to the population of striped bass Morone saxatilis in Lake Gaston, North Carolina and Virginia. Our analyses were based on a sample size of 51 telemetered striped bass that were known to be alive and in Lake Gaston at least 1 month after capture and surgery. Relocations of live fish and fish that died of natural causes were used to estimate natural and fishing mortality rates and the probability of relocating telemetered fish. Fishing mortality rates varied seasonally, but few natural deaths were observed, so the best model incorporated a constant annual instantaneous natural mortality rate (M; ±SE) of 0.14 ± 0.02. With the uncertainty in model selection acc...

Current Status and Review of Freshwater Fish Aging Procedures Used by State and Provincial Fisheries Agencies with Recommendations for Future Directions

Abstract In 2006, the Fisheries Management Section of the American Fisheries Society formed the ad hoc Assessment of Fish Aging Techniques Committee to assess the current status of aging freshwater fish in North America. For seven species groups that included black bass ( Micropterus spp.), crappie/sunfish (Pomoxis spp./Lepomis spp.), catfish (Ictaluridae), morinids, percids, salmonids, and esocids, a survey of U.S. and Canadian fisheries agencies (N = 51 agencies responding) revealed that scales, otoliths, and spines were the most common structures used to age fish. Latitudinal clines existed for some of the structures that were examined, with scales typically used more in northern latitudes than otoliths. Many agencies conducted some validation of age estimation techniques and most assessed precision at least for some of the age samples collected. Providing personnel with training to age fish was common. Reasons for the structures used and the types of inferences and information generated from age data ...

Hatching Date Influence on Age-Specific Diet and Growth of Age-0 Largemouth Bass

Abstract Largemouth bass can hatch over a 70-d period, and among fish less than 90 d old, those hatched earlier can grow faster than those hatched later. Because faster growth of age-0 largemouth bass has been positively linked with fish consumption, it has been suggested that faster growth of largemouth bass hatched earlier was also due to higher fish consumption. We determined hatching-date-specific diets and growth of largemouth bass up to about 180 d old, collected in summer and fall 1987 in a North Carolina reservoir. Frequency of fish consumption for age-0 largemouth bass of all sizes tended to decrease as the growing season progressed. Largemouth bass that hatched earlier, however, were piscivorous at a younger age and maintained a higher level of piscivory late in the growing season than did fish that hatched later. Dietary differences that were hatching-date-dependent seemed to be due to seasonal decrease in prey fish availability. The growth advantage for fish hatched earlier was primarily expre...

Selectivity of Sampling Methods for Juvenile Largemouth Bass in Assessments of Recruitment Processes

Abstract Assessment of the recruitment processes of juvenile largemouth bass Micropterus salmoides has involved a variety of gears, and little consideration has been given to the biases that gear size selection may introduce. To determine the influence of collecting methods on the interpretation of cohort characteristics, we compared length distributions of juvenile largemouth bass collected with a 9-m bag seine, a hand-held electrofisher, and a traditional boom-mounted electrofisher. The hand-held electrofisher was effective for sampling all lengths of fish up to 200 mm total length and sampled smaller fish than the boom-mounted unit. Seining was effective for sampling fish shorter than 60 mm but, relative to the hand-held electrofisher, it consistently underrepresented the contribution of fish longer than 70 mm to the cohort. The boom-mounted electrofisher was effective at sampling fish longer than 150 mm, but, compared with the hand-held electrofisher, it underestimated the contribution of smaller fish...

Relationships between Annual Variations in Reservoir Conditions and Age-0 Largemouth Bass Year-Class Strength

Abstract Variable recruitment has been documented in populations of largemouth bass Micropterus salmoides throughout the species range. Shoreline electrofishing was used from 1988 to 1998 to assess the magnitude of variations in year-class strength of largemouth bass at the time cohort mean lengths reached 50 mm in Jordan Lake, North Carolina. Concurrent measures of adult stock characteristics, dynamics of larval and juvenile shad Dorosoma spp., lake elevation dynamics, and seasonal air temperatures were used to test published findings concerning factors that influence largemouth bass year-class strength. Catch rates of juvenile largemouth bass varied fourfold from 1988 to 1995. No significant relationships were observed between largemouth bass year-class size and spawning stock size, shad dynamics, or variations in lake elevations. However, late-winter and early spring air temperatures explained a significant amount of the observed variation in catch rates of age-0 largemouth bass. Abundance of yearling...

Reservoir Striped Bass Movements and Site Fidelity in Relation to Seasonal Patterns in Habitat Quality

Abstract Adult striped bass Morone saxatilis perform best when water temperatures are below 26°C and dissolved oxygen levels are above 2 mg/L and will begin to exhibit stress responses at higher temperatures or lower oxygen levels. In southern U.S. reservoirs, summer conditions may result in a reduction of suitable habitat for adult striped bass and therefore influence population dynamics and distribution. We tracked 51 adult striped bass that had been implanted with individually coded sonic transmitters for 2 years in Lake Gaston, Virginia−North Carolina, to determine the impact of habitat availability on seasonal trends in movement and distribution. Monthly movement rates of individual fish averaged 7,340 m (SE = 544 m) over the course of the study, and no significant differences in movement rates were detected among seasons or between sexes. Striped bass were relocated throughout the reservoir in all seasons despite evidence of spatial variability in the availability of suitable habitat during the summ...

Earliest References to Age Determination of Fishes and Their Early Application to the Study of Fisheries

Abstract Age data are routinely used in fish population studies today. While various works have touched upon aspects of the history of fish aging techniques, there does not appear to be a single source that attempts to summarize the earliest literature on age determination of fishes in a broad historical context. The Fisheries Management Section formed the ad hoc Assessment of Fish Aging Techniques Committee in 2006, with development of such a review as a goal. The earliest references to rings on the hard structures of fish by Leeuwenhoek and Hederstrom date to the seventeenth and eighteenth centuries. Scientific validation of annuli on the scales offish did not take place until the late 180Os, with the work of Hintze and Hoffbauer. The work of Reibisch on otoliths and Heincke with other hard structures quickly followed. These later studies on fish aging techniques came at a time when large-scale studies offish populations were gaining momentum. While the new aging methods were adopted rapidly by many fis...

Distribution of Age-0 Largemouth Bass in Relation to Shoreline Landscape Features

Abstract Relations between landscape features and the littoral distribution of young largemouth bass Micropterus salmoides were determined for 43 contiguous sections along the entire 8-km shoreline of an unvegetated embayment in B. E. Jordan Lake, North Carolina. Night shoreline electrofishing was conducted in July and October 1991–1992 and individual capture points of age-0 largemouth bass were recorded. Significant correlations among and between years in catch rate per section of shoreline indicated consistency in distribution. Habitat was characterized in 35 sections in July–August and 22 sections in October to quantify the relation between abundance and landscape components. Stepwise multiple regression indicated that distribution was strongly and positively related to landscape features, specifically bottom slope and gravel substrata. Correlations of catch rates with cover components were negative for July but positive for October. These data indicate that cover may be limiting late in the year, coin...

Comparison of Four Trawls for Sampling Juvenile Shad

Abstract A single-mesh neuston net, bimesh neuston net, paired frame trawls, and Tucker trawl were compared at three sites in Lake Texoma, Texas-Oklahoma, to determine their relative efficiency and precision in sampling juvenile threadfin shad Dorosoma petenense and gizzard shad D. cepedianum. The frame and Tucker trawls provided similar estimates of threadfin shad and gizzard shad densities that were significantly higher than those estimated for the two neuston nets. The bimesh neuston net provided significantly higher estimates of threadfin shad and gizzard shad density than the single-mesh neuston net. Correlation of density estimates of threadfin shad and gizzard shad among transects were highest for the frame and Tucker trawls, indicating that these gears provided the most similar trends in density estimates among transects. Similarly, the frame and Tucker trawls provided the most similar estimates of threadfin shad and gizzard shad size distributions. The Tucker trawl captured significantly higher p...

First-Year Cohort Dynamics and Overwinter Mortality of Juvenile Largemouth Bass

Abstract Relative year-class size of largemouth bass Micropterus salmoides following recruitment through the first winter can depend upon a variety of life history events. Shoreline electrofishing was used to assess juvenile largemouth bass cohort dynamics from school dispersal through the yearling stage in Jordan Lake, North Carolina, 1987–1995. Measures of environmental conditions and dynamics of juvenile shad Dorosoma spp. were collected concurrently to assess their potential effects on cohort dynamics of juvenile largemouth bass. Abundance of age-0 largemouth bass at the time cohort mean lengths reached 50 mm varied significantly among years, as did growth rates and mortality from July through October. No environmental or shad effects on largemouth bass growth or mortality were detected. Overwinter mortality rates did not vary among years, despite a 50-mm difference among years in largemouth bass mean lengths going into late fall, and little evidence was found to indicate significant size-selective ov...