Journal of the Southeastern Association of Fish and Wildlife Agencies

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.

The relationship between the decline of macroinvertebrate standing crop and the loss of aquatic habitat due to box-cut access channel construction was assessed on Lake Tohopekaliga. Channelization of natural lake bottom had an adverse effect on benthic productivity by increasing both taxon richness and numbers of organisms routinely utilized by sportfish. For this study, channel substrate supported only 54% of the total standing crop of fish food organisms found in littoral substrate. Macroinvertebrates associated with vegetation were eliminated by the destruction of rooted macrophytes; approximately 420 fish food organisms were lost for every cubic meter of vegetated water column altered by channelization. It was estimated that an average standing crop of 840,000 fish food organisms would be lost due to the construction of a "standard" 200 X 10 X 2 m box-cut access channel.

Fish species diversity and abundance were examined over a 3 year period at 6 study sites within a single watershed in the Piedmont of South Carolina. The fish community was dominated by 3 cyprinid species, but included 22 species. Average Shannon-Weaver fish species diversity estimates ranged from 0.15 to 1.87, and were related to substrate diversity. Fish species diversity increased downstream, and decreased in relation to silt in the substrate and frequency of drying. Fish abundance increased downstream and with depth, but was also influenced by substrate characteristics known to influence distribution of aquatic insects.

Florida coastal waters contain more permitted artificial fishing reef sites (ca. 150) than any other state. Initiative stems primarily from local interests, including over 60 different private and public organizations. Florida's earliest reef was authorized in 1936 although 87% were proposed after 1962. Prevalent reef materials include some combination of concrete rubble, tires, automobiles and/ or vessels in 40% of Florida reefs, followed by vessels (25%), and automobile bodies and tires (13% each). Statewide resource agencies and educational organizations have fostered local reef building through financial assistance with construction, streamlined permitting procedures, information transfer via advisory services for siting and publications, and coordination of research, which has yet to address the economic impact of recreational reef fisheries.

The relationship between fish size and the activity of certain liver enzymes was assessed in age I rainbow trout (Salrna gairdneri) from 3 Virginia streams. Total length and body weight of the trout differed significantly among streams. Activity of glutamate dehydrogenase and aspartate aminotransferase also differed significantly among fish in the streams and both were negatively correlated with fish size. Differences in size and enzyme activity probably relate to differential caloric intake of fish in the 3 streams. Condition factor and alanine aminotransferase activity of the trout did not differ among streams.

Adult Florida (Micropterus salmoides floridanus) and northern (M. s. salmoides) largemouth bass were subjected in the laboratory to low water temperature regimes similar to those occurring on Texas hatcheries. Northern largemouth bass survived all temperature regimes experienced. Florida largemouth bass suffered mortality that increased as temperature decline rate (1, 2, and 4 C/ day) increased. They survived prolonged exposure (30 days) at 4 C well, but total mortality occurred at 3 and 2 C. Northern largemouth bass were more tolerant than Florida largemouth bass of rapid temperature decreases and low temperatures.

Agonistic behavior and social dominance relationships between similar-sized, wild, adult brook trout (Salvelinus fontinalis) and rainbow trout (Salmo gairdneri) were examined in a laboratory stream. Frequency of movements, aggressive encounters, and consumption of food items by trout when held as single specimens, intraspecific pairs, and interspecific pairs were compared. Rainbow trout were more mobile, aggressive, and successful foragers on drifting prey than brook trout; however, neither species appeared to possess a competitive advantage in establishing social dominance or displacing interspecific rivals. Brook trout were dominant in 9 of 14 interspecific matches. Female trout were dominant in 6 of 10 opposite-sex matches. Dominant trout, regardless of species or sex, exhibited significantly greater mobility, aggressiveness, and feeding success than subordinate trout.

Twenty largemouth bass (Micropterus salmoides) , 10 containing dummy radio transmitters and 10 control, were studied in hatchery ponds to determine the effects of implanted transmitters on swimming, feeding, spawning and catchability behavior. Eight additional bass were subjected to buoyancy compensation tests under laboratory conditions. Pond studies indicated no significant difference in swimming movement or catchability between transmitter and control bass. Both transmitter and control bass were observed feeding and spawning. All transmitters were encapsulated in a skin-like sac within the body cavity at study termination. Laboratory experiments indicated the negative buoyancy of the transmitters affected bass temporarily, and fin beats increased only during the time it took bass to adjust to the effect of the transmitter.

The spawning period and caloric density of body tissues during gonadal recrudescence were studied in a naturalized population of rainbow trout (Salmo gairdneri) from September 1979 to August 1980. As judged by gonosomatic indices and the percentage of spent females in semimonthly samples, the fish spawned from mid-February to early April, when water temperature and stream flow were both increasing. Decreases in calorific equivalents (cal mg-1 dry weight) of selected tissues during gonadal maturation in fall and winter were greatest in fat reserves along the alimentary tract.

Liberty Lake was stocked with fingerling largemouth bass (Mieropterus salmoides) at 448/ha in July, 1980. Monthly electrofishing samples collected for 1 year following stocking showed 76.4% of the 1980-year-class to have been stocked. A bimodal length distribution of stocked fish appeared in fall, 1980 and continued throughout the sampling period. Decreased survival of the stocked largemouth bass during the winter was noted. Most mortality occurred in the slower-growing fish. However, a decline in the number of fish from both length modes was evident.

Rainbow trout (Salmo gairdneri) were fed 38% protein experimental diets which contained either sunflower or soybean meal. Fish were reared in 2 sets of tanks under controlled and ambient water temperatures during January-April 1982. With controlled water temperature, fish fed the sunflower meal diet had a significantly higher final weight, average gains and food conversion ratio. Under ambient water temperature conditions, trout fed sunflower meal diet also had significantly higher final weight and average gain than trout fed soybean meal diets. A 35% protein sunflower meal adequately replaced a 49% protein soybean meal as a protein source in rainbow trout diets.

The fish fauna of Brumley Creek, Virginia, a third-order cold water stream in southwest Virginia, was sampled by electrofishing at 9 sites from headwaters to mouth. A total of 19 species were collected. Upstream sites had few species because of previous management activities. Downstream sites varied in species richness and composition as a function of several watershed characteristics. The differences in species composition among samples illustrates the problem that can occur if the fish fauna is described based on limited sampling, especially if the watershed is small and the management history is complex.

Black crappie (Pomoxis nigromaculatus) growth was reduced when hydrilla (Hydrilla verticillata) coverage exceeded 50% in Lake Baldwin, Florida, between 1977 and 1979. Black crappie did not reach harvestable size (>228 mm TL) until age 3 and 4 during periods of extensive hydrilla coverage and reduced threadfin shad (Dorosoma petenense) abundance. Following hydrilla removal and shad population reestablishment, harvestable size was obtained by age 2 and growth of older fish increased.