Journal of the Southeastern Association of Fish and Wildlife Agencies

Food habits of hybrid bass (Morone saxatilis x Morone chrysops) were studied in Clarks Hill Reservoir from 1 July 1980 to 30 June 1981. Stomachs from 820 hybrid bass ranging from 221 mm to 736 mm total length and 0.13 kg to 4.21 kg were examined. Overall, threadfin shad was the predominant food item of hybrid bass (62% frequency of occurrence). Data indicated hybrid bass were fully utilizing the threadfin shad. Hybrid bass did not shift to gizzard shad despite the apparent winter depletion of threadfin shad. Analysis by season and by size group indicated that insect larvae and non-shad fishes were of periodic importance and occurred in the diets at levels higher than previously reported.

Biotelemetry studies of 13 striped bass (Morone saxatilis) x white bass (M. chrysops) hybrids in the Escambia River, Florida demonstrated positive affinity of the hybrids for saline waters. Average salinity at relocation sites ranged from 0.5 to 4.1 ppt at the surface and from 3.6 to 21.8 ppt on the bottom. Movements of hybrids in the river system appear to be strongly influenced by seasonal fluctuations in river discharge. Hybrids usually inhabited the lower, tidal delta of the river during periods of low and normal discharge and moved into the bay during times of high flow. No evidence of significant upstream emigration was observed. Two hybrids emigrated from the Escambia River estuary into adjacent river systems. Maximum movement recorded was 88 km.

Fingerling Morone hybrids were stocked into Lake Apopka, Florida, in an attempt to create a sportfishery in the hypereutrophic lake. The lake was stocked with 635,000 original hybrids (8 fish/ha) in May, 1980 and 315,000 original hybrids (4 fish/ha) in May, 1981. Growth during their first year (age 0) was not rapid for either year class, however, by 23 months the mean total length of the 1980 year class was comparable to that of other hybrids in Florida and the southeast. Analysis of stomach contents indicated extensive use of shad (Dorosoma spp.), although grass shrimp (Palaemonidae) comprised a large part of the stomach contents of hybrids 292 mm total length and smaller. Enthusiastically accepted by anglers, a successful but localized put-grow-and-take sportfishery was created.

The effects of sunlight intensity on survival of Morone saxatilis X Morone chrysops hybrid fry were examined through studies performed in replicated aquaria and hatchery rearing ponds. The aquaria and ponds were exposed to direct sunlight and 2 types of sunlight reduction (overhead shading and decreased water clarity). Direct sunlight reduced fry survival in the aquaria and pond experiments. In aquaria, variations in overhead shade and water clarity significantly affected fry survival, and decreased water clarity was more effective than an increase in overhead shade in increasing survival. In ponds, overhead shading was more effective than water clarity in increasing fry-to-fingerling survival.

The scale method and length-frequency analysis were not adequate for accurately aging and measuring growth rate of black crappie (Pomoxis nigromaculatus) collected in Florida. Black crappie otoliths (sagittae) showed clearly recognizable: bands in whole view, suggesting possible use of otoliths to age black crappie. Otoliths satisfied necessary criteria for validating aging structures: growth was proportional to black crappie growth, annuli formed in the spring, and back-calculated lengths agreed with lengths for age-classes estimated from length-frequency analysis. We consider otoliths useful for accurately aging black crappie in Florida.

A food habit study was conducted for the redbreast sunfish (Lepomis auritus) and the longear sunfish (Lepomis megalotis) occurring in small streams of the Coastal Plains and Piedmont Plateau physiographic provinces near Auburn, Alabama. Fish stomach analyses revealed that redbreast and longear are primarily insectivores. The bulk of the diet of both species in small streams was composed of aquatic and terrestrial insects. Crustaceans were also consumed by both species regularly. Ingestion of a wide variety of other organisms suggests opportunistic feeding in both species. Based on 24-hour sampling results, both species had the greatest food item diversity during daylight hours and the least after dark. Redbreast was the more active feeder. Significant overlap in food habits between the 2 species was evident using the Schoener Index to food overlap.

A total of 791 young-of-year white bass (Morone chrysops) from 2 East Tennessee reservoirs were examined to determine food habits and growth. An effort was made to determine when they switched from an insectivorous to a piscivorous diet. White bass in Cherokee Reservoir consumed primarily insects (Chironomidae) during their first year and in Norris Reservoir, primarily zooplankton (Cladocera). When they began consuming fish, young-of-year white bass in Cherokee Reservoir were between 2.5 and 5.0 cm in length while white bass in Norris Reservoir were between 5.0 and 7.5 cm. Numbers of fish consumed by white bass were analyzed as a percentage of numbers of all foods consumed, and as a percentage of foods occurring in the guts of all fish in the study. White bass grew larger (18.4 cm) in Norris than in Cherokee (14.0 cm) during their first year, although mean ,condition factors were similar in both reservoirs (Norris 0.67 to 1.1, Cherokee 0.86 to 1.21).

Diel occurrence and feeding of alewives (Alosa pseudoharengus) in shoreline areas of Claytor Lake, Virginia was investigated concurrent with food habits of resident juvenile bluegill (Lepomis macrochirus) , pumpkinseed (L. gibbosus), and yeHow perch (Perca flavescens); and the composition and abundance of the littoral zooplankton community. Schools of alewives entered coves at sunset and fed intensively through the night, departing soon after sunrise. Alewives and juvenile fish consumed the same 16 items, but to different degrees. Alewives fed primarily on zooplankton in the water column, whereas the juvenile fish ate mostly epibenthic forms with which they were associated In the aquatic macrophyte/brush habitat. Alewife stomachs contained 9 to 30 times the volume and number of items as did those of juvenile fish. The hIgh foraging efficiency of alewives in large schools may result in trophic competition with littoral zooplanktivores despite partial resource partitioning.

Releases of large volumes of water from low-level release ports during generation of peaking hydropower at Hartwell Dam, Georgia-South Carolina, resulted in large daily flow fluctuations and altered water quality in a section of the Savannah River. Flows ranged from a minimum of 3 m3/sec during nongeneration to 665 m3/sec during generation. Thermal stratification in Hartwell Reservoir generally resulted in low water temperatures (≤20 C) throughout the 14-km study area and low dissolved oxygen concentrations <3 mg/I) in the 2-km section of the river immediately below the dam. Distribution of fish species was similar at all sampling locations, but abundance generally increased downstream. Major factors affecting fish abundance below Hartwell Dam appeared to be recruitment of fish from the reservoir, a reduction in habitat diversity just below the dam, water temperatures suitable for sunfish spawning, and stocking of rainbow and brown trout (Salmo gairdneri and S. trutta).

Tests were performed to determine the acute toxicity of simazine, a herbicide commonly used in pond aquaculture, to the cIadoceran Daphnia pulex and to 3- and 7-day old larval striped bass (Morone saxatilis). The 48-hour LC50 for 3-day-old striped bass was r8 mglIiter in hard water (220 mg/liter as CaC03 ) and r6 mglIiter in soft water (120 mglIiter as CaC03 ); corresponding estimates for 7-day-old larvae exceeded roo mg/liter. The estimated 48-hour LC50 for D. pulex exceeded 50 mg/liter in both hard and soft water. These estimates were considerably higher than recommended pond application rates of simazine, but abnormal behavioral responses of both test organisms to sublethal concentrations suggested that long-term exposure could be harmful. Inasmuch as 7-day-old larvae were far less sensitive than 3-day-old larvae, the timing of simazine applications in relation to age of fish could have pronounced effects on survival of striped bass in ponds.

The effects of supplemental feeding on the winter growth of male bluegill (Lepomis machrochirus) x female green sunfish (L. cyanellus) F1 hybrids were investigated in northeast Mississippi. Four 0.04 ha ponds were each stocked at the rate of 2471 fish per ha. Fish in 2 ponds were fed daily while the other fish subsisted only on natural food. Mter 90 days at water temperatures below 15 C, fed fish were significantly (P <0.05) heavier. but not longer than non-fed fish. Coefficients of Condition (K) for fed fish showed a significant (P < 0.05) increase through the winter and were significantly higher than K for non-fed fish, which showed no significant change in K through the winter.

Fingerling channel catfish (lctalurus punctatus) fed a 25% crude protein practical feed grew as well as or better than fingerlings fed a 35% crude protein practical feed in both Mississippi and Arkansas ponds during 2 consecutive winters. Fingerlings in Texas grew better on the 35% protein feed, although poor survival may have affected the results. The 35% protein feed provided no growth advantage to adult fish in Mississippi. Both feeds had equivalent energy to essential amino acid ratios and both contained 12% fish meal. There were minimal differences in feed conversion ratios and survival of fish fed the 2 feeds in Mississippi and Arkansas.

Tilapia aurea fingerlings were fed semipurified diets differing only in the degree of saturation in the lipid component (soybean oil). Growth improved significantly as degree of unsaturation in dietary lipid increased. All fish became depleted in high (> 18 carbon atom) molecular weight polyunsaturated fatty acids during the course of the study. This may indicate that desaturation and elongation of such dietary fatty acids as linoleic and linolenic acid either did not occur or was so slow that such fatty acids as 20:5n-3, 22:5n-3 and 22:6n-3 were metabolized before appearing in the depot lipids of the fish.

Two populations of channel catfish (lctalurus punctatus) with different histories of domestication-Marion (Alabama) and Kansas-were grown in earthen ponds at 7,500/ha. The largest 10% of each population were selected when population mean weights were 500 g. The reproductive performance of these selects was compared to that of brood from random control populations. Data were analyzed for each strain then pooled and re-analyzed. No differences were found in spawning day, spawning rate, hatchability of eggs and survival of sac fry. Fecundity (eggs deposited) was increased (P < 0.05) in the pooled select brood fish. Fingerling output was also higher for selects (P < 0.05) in the Marion and pooled populations, but lower (P < 0.05) in the Kansas select population. Fecundity, sac fry survival, and fry survival had the largest effects on fingerling output.

Blue catfish (lctalurus furcatus) , channel catfish (I. punctatus) , white catfish (I. catus) , and their hybrids channel x blue, blue x channel, channel x white, and white x blue were produced and grown to an average total length of 150 mm and weight of 30 g in earthen ponds. Blue catfish (P < 0.0 I) and white catfish (P < 0.02) were more uniform in length than channel catfish. The channel x blue hybrid was more uniform in length than its reciprocal blue x channel hybrid and channel catfish (P <0.02). Uniformity of channel x white and white x blue hybrids was not different from that of channel catfish (P > 0.05). Paternal predominance for length uniformity found in reciprocal channel-blue hybrids was not found in hybrids involving white catfish. Skewness in length distribution were zero or slightly negative, indicating catfish fingerling populations were normally distributed. More competitive environments increased skewness (P < 0.05).

A finely-pulverized agricultural limestone was much more effective than a coarse agricultural limestone in elevating the total alkalinity of ponds and of laboratory mud-water systems. The relative abilities of different particle-size classes of agricultural limestone to raise total alkalinity were determined. A method for correcting pond lime requirements for the neutralizing value and fineness of agricultural limestone was proposed.

Mark-recapture techniques were used to estimate the abundance of harvestable size paddlefish (Polyodon spathula) in Norris Reservoir, Tennessee, during spring 1980. Results indicated a harvestable population of 8,772 fish with a 95% confidence interval of 4,557 to 18,467. A comparative study using gill nets of various bar mesh sizes showed that gill nets with 17.8-cm bar mesh or larger were more efficient for collecting harvestable paddlefish while having less adverse impact on sport fish species than did nets with smaller mesh sizes.

A survey was made of incidental catch in the Louisiana gulf menhaden (Brevoortia patronus) purse seine fishery. Samples were taken in 1980 and 198 I at plants located at Empire, Dulac, and Cameron. Overall the bycatch comprised 2.68% by number and 2.35% by weight of the catches sampled. The most abundant species were Atlantic croaker (Micropogonias undulatus), seatrout (Cynoscion spp.), threadfin shad (Dorosoma petenense) , Atlantic bumper (Chloroscombrus chrysurus), hardhead catfish (Arius felis), and spot (Leiostomus xanthurus). Differences in species composition and abundance of bycatch among plants were found. The effects of the gulf menhaden fishery on other fisheries was considered insignificant.

A creel census was conducted on Albemarle Sound and its tributaries from February 1, 1977 through January 31, 1980 to estimate the total annual sport fishing pressure and harvest of major sport fish species, particularly striped bass (Morone saxatilis). Total sport fishing effort was in excess of 400,000 party-hours per year, and largemouth bass (Micropterus salmoides), was the species for which the greatest amount of specific effort was exerted. The harvest of striped bass and most other species declined drastically during the study. The relative harvests of the sport and commercial fisheries operating on the Albemarle Sound-Roanoke River striped bass population are compared and possible causes of the decline in harvest are discussed.

The Texas Parks and Wildlife Department mailed 2 different survey questionnaires to 5,000 randomly selected households to estimate the number of residents fishing and the ways they fished in Texas from 1 September 1978 through 31 August 1979. The questionnaires in this survey were identical except one sub-group (1000) asked household members questions regarding their possession of a valid fishing license. Differences in responses to these 2 questionnaires were used to assess response biases. Estimates of total license sales (a known statistic) from survey data showed a strong positive bias (license sales were overestimated by 62% ). The mean number of fishermen per household was significantly greater (P < 0.05) in the group which was not asked about the possession of fishing licenses. Return rates and responses to questions regarding all other fishing activities were identical for the different survey questionnaires.

Roving creel surveys were conducted on 2 Southeastern reservoirs from March 1980 to February 1981. Two creel clerks performed the field work. Evaluation of creel clerk performance descriptors (number of missing questionnaire entries and interview length) documented a clerk break-in period. Variation in fishing effort affected clerk data gathering efficiency (percent of fishermen sampled). Clerks differed in administering a modified Likert response format on 12 of 17 attitudinal questions posed to fishermen. Clerks did not differ in their sampling of fishermen types or total number of fish observed at each reservoir. These data indicate that effective structuring of creel surveys must address interview methodology as well as traditional design considerations.

Blue Tilapia (Tilapia aurea) were introduced to Florida in 1961. Subsequently they have become established throughout the central part of the state. Tilapia were first collected from Lake Tohopekaliga in 1976. Since that time a considerable expansion in both numbers and biomass has been documented. The juvenile tilapia population has increased by a rate of approximately 500% per year from 1979 to 1981. Blocknet samples taken in the fall of 1981 indicated that young of the year and adults of this species conservatively comprised 0.5% by number and 16% by weight of littoral zone fish populations. Experimental gill nets of 127-, 152- and 178-mm stretch mesh have proven effective in sampling limnetic tilapia populations.

Low water levels, sustained high temperatures, and potential increases in predatory pressure appear to have adversely affected the largemouth bass (Micropterus salmoides) population of Lake Elmdale, Arkansas. An estimated population of 3,916 bass were present in 1981 compared to previous estimates of 11,770 in 1977 and 8,937 in 1979. Size overlap between 2- and 3-year-old bass is indicative of differential states of sexual maturity and associated reproductive activity during the harsh drought conditions.

Hydrilla (Hydrilla verticillata) encroachment in Lake Parker and Lake Hunter was directly proportional to production of invertebrates, forage fish species and juvenile largemouth bass (Micropterus salmoides). Survival of young of the year largemouth bass was positively correlated with the presence of hydrilla. Improvements in the sportfish standing crop on both lakes indicated a reversal from hypereutrophic to a mesotrophicl eutrophic fishery. Water quality data revealed a possible trend of stabilization andlor improvement of nutrient levels with hydrilla encroachment.

Giant bulrush (Scirpus californicus) proved to be an excellent aquatic plant for transplanting into lakes. Bulrush has a desirable growth pattern and acts as a natural congregating area for freshwater sportfish. Growth densities allow good angler utilization. Consistent survival and rapid growth response after transplanting was documented in all study lakes.