Journal of the Southeastern Association of Fish and Wildlife Agencies

Radiotelemetry which employed temperature-sensitive transmitters was used to monitor spring movement and summer habitat selection of 19 adult striped bass (Marone saxatilis) in the Santee-Cooper reservoirs, South Carolina. Nine fish were followed for 63 days during the late spring and summer 1985. Of the 61 recorded locations, 9 were fish which had utilized a thermal refuge. Mean water column temperature (28.1 0 C) and average thermal selection (27.80 C) did not differ significantly in observations where fish did not use thermal refuges. Average water column temperature was 29.00 C when fish were observed using refuge sites. Refuge sites averaged 0.340 C cooler than the recorded bottom temperature. Ten fish were monitored during the late winter and spring 1986 and located on 74 occasions. Striped bass exhibited a spring migration out of the reservoirs and into upstream areas.

Fourteen radio-tagged adult hybrid striped bass (female Morone saxatilis x male M. chrysops) were tracked from February to November 1987 in Ross Barnett Reservoir, Mississippi. Radio-tagged hybrids moved into the Pearl River in early March and remained upstream until water temperatures exceeded 27° C and dissolved oxygen decreased below 4 mg/liter at which time all except 2 fish returned to the main lake. These 2 fish, remaining in a well-aerated refuge at a lowhead dam, died in July when water temperatures exceeded 30° C. The fish which returned to the main lake showed decreased movements and remained near mid-lake in 4 small areas in and adjacent to submerged oxbows and/or the Pearl River channel. Mean monthly dissolved oxygen was significantly higher in mid-lake than elsewhere. Adult hybrids avoided depths of 0-2 m. Concurrent radio telemetry studies of 5 largemouth bass (Micropterus salmoides) showed little overlap of habitat.

Densities of fingerling striped bass (Marone saxatilis) resulting from natural reproduction in the Santee-Cooper Reservoir were estimated. Estimates during July and August of 3 years were 3.9, 4.0, and 7.8 fingerlings per hectare, which are much lower than typical reservoir stocking rates. Estimates were derived using a combination of the Petersen method and relative abundance.

A defatted rice bran (DRB) product was evaluated as a potential ingredient in practical channel catfish (lctalurus punctatus) feeds by partial substitution of control feed ingredients. Fingerlings in aquaria were fed I of 4 feeds: 0 (control) - a standard commercial feed, 1 - DRB replaced regular rice bran, 2 - DRB replaced some com, soybean meal, and rice bran, 3 - DRB replaced some com, fish meal, and rice bran. There were no significant (P > 0.05) differences in survival or feed conversion among fish fed the 4 feeds, but fish fed feed 2 had a greater weight gain than fish fed feed 0 or feed 3. Feeds 0 and 2 were then each fed in 3 O.04-ha ponds stocked with fingerling catfish from June 1987 to November 1987. There were no significant differences (P > 0.05) in growth, survival, or feed conversion between fish fed either feed. Defatted rice bran appears to be an acceptable feedstuff for use in catfish feeds.

Two nursery trials were conducted in 0.I-ha ponds to examine effects of density on production of juvenile reciprocal cross hybrid striped bass (female Marone chrysops x male M. saxatilis). In 1986, 1.4-g hybrids were stocked at 5,000, 10,000 and 20,000 fishlha. In 1987, 1.7-g hybrids were stocked at 12,500, 25,000, and 37,500 fishlha. During the studies, the fish were fed a commercial trout feed (38% protein) several times per day. Aeration and water exchange were provided to maintain satisfactory oxygen levels. After approximately 280 days, fish were harvested. At harvest fish ranged from 165-195 g in mean size, except those stocked at 5,000/ha which were significantly smaller (mean size 116 g). Mean survival was similar in all treatments and ranged from 82%-99% (mean 90.4%). Harvest biomass was related to stocking density with the highest density yielding a significantly greater harvest biomass (5,984 kg/ha).

Inorganic fertilizers were tested in combination with organic fertilization to study enhancement of zooplankton communities in largemouth bass (Micropterus salmoides) rearing ponds in southeast Colorado. Under study conditions, additions of triple superphosphate produced the greatest number of zooplankton/liter, a combination of liquid ammonium nitrate and phosphoric acid produced the greatest growth, and the highest yields were found in ponds treated with phosphoric acid alone. Triple superphosphate was as effective as liquid inorganic fertilizers in maintaining sufficient numbers of zooplankton and was easier to apply. Fish were returned at the desired length of 50 mm, which was longer than in previous years in spite of an increased stocking rate. Although total zooplankton/liter was lower than in previous years at the hatchery, cladoceran populations were maintained with no significant declines.

Macrobenthos was sampled during the summer of 1984 in a series of experimental fishponds with water alkalinity artificially adjusted to different levels (2.0, 3.8,6.9,8.4, and 35.8 mg/liter of CaC03 equivalents). Chironomid midges, nematodes, and tubificid oligochaetes accounted for 67% of all benthic organisms recovered. No significant trends were apparent as to abundance or type of benthic organisms encountered in each treatment. The most numerous midge in the samples was the detritivore/herbivore Einfeldia. The smaller predator midge Procladius was the second most abundant. Chironomus was most common in ponds with deep, rich bottom muds. Tanytarsus was more common in ponds where many aquatic macrophytes had developed. Taxa diversity indices ranged from 1.88 to 2.82 and were not significantly different among treatments. Fish biomass increased with alkalinity but no significant correlation was found with benthos numbers.

Spotted seatrout (Cynoscion nebulosus) were collected from Matagorda Bay, Texas, from April 1984 through March 1986 and a gonosomatic index determined. Relative batch fecundity and ooycte maturation size were compared among females collected from April through October 1984, and randomly selected females were subjected to hormone-induced strip-spawning during June and July 1984. All females collected from April through August had yolked eggs and 4%-90% of fish collected in March, September, and October had yolked ova. No yolked ova were present in fish from November through February. Gonosomatic indices suggest greatest spawning activity occurred from April through May of each year. Median relative batch fecundity of females (N = 169) collected from April through October 1984 was 258 eggs/g body weight and was not significantly different from the median relative batch fecundity of 453 eggs/g body weight of hormone spawned fish (N = 16).

Differences in catch statistics (catch rates, length structure, and age structure) by gear and season were evaluated for white crappie (Pomoxis annularis) sampled with trap nets, electrofishing, and gill nets. Catch per man-hour of effort by trap nets was significantly higher than those of other gears tested in spring and fall. Variation in catch per man-hour was less for trapnet samples than for electrofishing or gillnet samples. Within-season variation in length distribution for trapnet samples was consistently less than within-season variation for the other gears tested. Gill nets sampled for the narrowest size range of crappie. Trap nets were the only gear that collected substantial numbers of age-O crappie in fall. Spring trap net and electrofishing samples caught a greater proportion of older Crappie than did the respective fall samples. Trap nets collected more fish and provided more precise data on white crappie populations than did the other gears tested.

Trap nets were evaluated as sampling gear for black crappie (Pomoxis nigromaculatus) in 4,900-ha Lake Wylie, North Carolina and South Carolina. Compared with a creel survey, cove sampling with rotenone, and spring electrofishing, trap nets were the most efficient and cost-effective gear used for capturing black crappie at Lake Wylie. Age and size structure of black crappie captured in trap nets were similar to that harvested by anglers during the same season. Trap net catch rates (number per net set) also appeared to reflect densities of black crappie in Lake Wylie. Biases were related to sampling season and to mesh sizes of the trap nets used. Catch rates of large (2:250 mm total length) black crappie in spring were significantly higher than those observed in fall, and catch rates of small (<250 mm total length) black crappie in fall were significantly higher than those observed in spring.

Growth rates for the 1980 year class of black crappie were determined from samples collected in the St. Johns River, Florida, 1981 through 1987. Actual mean lengths of groups of black crappie aged by otolith evaluation were compared to back calculated lengths from otoliths of black crappie collected each year. Differences in actual and back calculated lengths for black crappie collected were not significant (P > 0.05). Coefficient of determination values (r2) dropped rapidly as differential growth rates increased. Overall, back calculated lengths for age I and II black crappie increased as fish aged, exhibiting a reverse of Rosa Lee's phenomenon. The phenomenon was probably the result of size selective mortality. Black crappie collected between 1981 and 1986 indicated that the 1980 year class was larger than any other year class sampled. At actual age 6, the 1980 year class still comprised almost 8% of all black crappie collected.

Food habits, prey-size, and the occurrence of food in the stomachs were examined at various water temperatures among 1,152 Florida largemouth bass (Micropterus salmoidesfloridanus), northern largemouth bass (M. s. salmoides), and intergrade hybrids between the 2 subspecies in Aquilla Lake, Texas. Dietary composition, prey-size consumed, and the frequency of food items in the stomach were similar among the largemouth bass subspecies and their intergrade hybrid at temperatures between 80 and 31 0 C. A higher proportion of insects occurred in the diet of smaller (151-253 mm TL) largemouth bass compared to larger (≥254 mm TL) fish. When forage fish were consumed by largemouth bass, positive prey-size selection was evident. These size-dependent feeding differences conferred a foraging disadvantage to age-1 and younger resident-hatched Florida largemouth bass.

Two bluegill subspecies (common bluegill Lepomis macrochirus macrochirus and coppernose bluegill L. m. purpurescens) were subjected to cold tolerance tests in the laboratory. Juvenile and adult bluegills were exposed to water temperature decreases of 1°C/hour from acclimation temperatures of 20° and 30° C until loss of equilibrium. Response temperatures of both subspecies were similar; temperatures at which 50% oftest fish lost equilibrium were usually <1.0° C lower for common bluegill and overlapping occurred in fiducial limits. Bluegill acclimated to 20° C lost equilibrium at 0.6°-4.2° C; those acclimated to 30° C lost equilibrium at 6.4°-10.4° C. Adults were more resistant than juveniles to low temperatures when acclimated to 20° C but juveniles were more resistant at 30° C.

The spawning season and length at maturity were determined for female blue catfish in Kentucky Lake, Kentucky-Tennessee, where this species is commercially harvested. A gonosomatic index (GSI) was determined from 581 females of 3 length categories: 400-499 mm, 500-599 mm, 2:600 mm. The mean GSI for fish in the largest length category peaked at 3.72% during 1 May-15 May, when water temperature was 20.5° C, and rapidly dropped to 0.21% during 1 June-15 June. Spawning activity in 1986 peaked between 15 May and 15 June. Contributions to reproduction by fish <600 mm were clearly minimal. Population maturity of 241 females was described by the polynomial: Y = 444.88 + 5.88 X - 0.03)(2 (r2 = 0.988) where Y = fish length (mm) and X = percent mature. Females reached the 50% level of maturity at 661 mm and 100% were mature above 722 mm.

Diet composition was investigated in 3 channel catfish (lctalurus punctatus) populations in southeastern Louisiana, 2 of which were characterized by slow growth and reduced length at maturity. Multivariate analyses revealed that diets of catfish exhibiting slow growth were predominantly composed of marine prey. particularly engraulids, Corophium sp., and Penaeus sp., and were superior in quantity, diversity, and apparent nutritional value compared to diets of faster growing catfish from the Atchafalaya Basin. Slow growth and early maturity at reduced lengths did not appear to be forage-related, and may instead have reflected impacts of mesohaline conditions in coastal lakes.

Abundance and growth rates of flathead catfish (Pylodictis olivaris) from the Flint River, Georgia, were investigated during 1985 to gain basic information for future implementation of management strategies. Pectoral fins were disarticulated, sectioned at the articulating process, photographed, and enlarged for aging. The Schnabel and Schumacher-Eschmeyer multiple census population estimators produced similar results: there were 7,647 and 8,013 flathead catfish ≥ 305 rom in the 50-km section of river, respectively. Biomass estimates were 23.2 and 24.3 kglha. Growth was very fast for the earlier year classes (1976-1980), but had declined in recent years. Flathead catfish had become very abundant, and the reduced growth rate may be due to increased numbers, if growth is density dependent.

White catfish (lctalurus catus) and channel catfish (I. punctatus) from 3 Alabama Public Fishing Lakes were sampled from 1979-1982 to obtain information on age and growth. Growth rates were found to be relatively uniform between the 2 species. Average first year growth of white and channel catfish was 118 mm and 127 mm, respectively. Creel data collected during a 1-year study period indicated that channel catfish dominated the catch. Seventy-nine percent of the catfish harvested at Chambers County Lake, 95% at Dallas County Lake, and 96% at Monroe County Lake were channel catfish. Although white catfish are apparently self-sustaining in the 3 study lakes investigated, their low harvest rate does not justify purposeful introduction.

The growth and reproductive cycle of a landlocked population of blueback herring (Alosa aestivalis) were evaluated in Lake Theo, a North Texas reservoir. Scales were collected and length, weight, and gonad characteristics were recorded for individual herring. Herring reproduced each year of the study. Average size of Age I herring ranged from approximately 70 to 170 mm total length (TL). Average size of Age II herring was approximately 200 mm TL and maximum size was 237 mm TL. Scale annuli formation in immature fish began in April; spawning marks occurred on scales in late summer. Herring matured at Age I or II and lived 2-3 years. Size at sexual maturity was 175-200 mm TL. Fecundity ranged from approximately 30,000 to 60,000 eggs (> 0.2 mm diameter) for females 190 to 216 mm TL. Gonadosomatic indices suggested protracted spawning from April through July with a peak in May and June. Spawning temperatures ranged from 21° to 25°C; spawning ceased above 27°C.

Adult and larval blueback herring (Alosa aestivalis) were sampled in the Santee River, South Carolina, during 1983 and 1984 under different discharge regimes. Discharge and water temperature were less variable in 1984, when at least 2 distinct peaks in abundance of adult herring were observed compared to 1 major peak in 1983. Adult and larval herring were more abundant in 1984 than 1983. The major contributor to larval abundance in 1984 appeared to be the later-occurring peak in adult herring abundance. Abrupt changes in discharge and water temperature in 1983 appeared to adversely impact spawning adults resulting in reduced numbers of herring larvae.

Gizzard shad (Dorosoma cepedianum) were introduced into an 83-ha public fishing lake in central Missouri in an attempt to improve populations of high density, slow growing largemouth bass (Micropterus salmoides), white crappie (Pomoxis annularis), and bluegill (Lepomis macrochirus). A 380-mm length limit on largemouth bass was introduced at the same time. Growth rates of both bass and crappie increased. The annual catch of largemouth bass increased from 80 per hectare to 212 per hectare after gizzard shad were introduced, and that of white crappie from < 5 kg per hectare to 27 kg per hectare. The growth rate, population structure, and condition of bluegills improved somewhat.

Field and laboratory experiments were conducted to investigate possible competitive effects of the introduced species inland silversides (Menidia audens) and threadfin shad (Dorosoma petenense) on the native white crappie (Pomoxis annularis) population in Thunderbird Reservoir, Oklahoma. Field collections of zooplankton and stomach analyses were augmented by laboratory feeding experiments with the introduced planktivores and white crappie, alone and in combination. Field samples indicated that silversides, shad, and crappie, showed positive selectivity (Strauss' L) for Daphnia. Feeding studies in the laboratory corroborated this finding for all species tested individually. However, in feeding experiments, white crappie switched to an indiscriminant diet when in the presence of silversides or threadfin shad.

A study was conducted in Lake Benbrook and Squaw Creek reservoirs, Texas, to determine whether naturally occurring phytoplankton and crustacean zooplankton abundance in selected coves could be increased by fertilization. In each reservoir, I cove was fertilized once a week for 4 weeks using inorganic fertilizer (liquid 10-34-0, N-P- K, applied at I mg/liter PP,), 1 cove was fertilized with the same inorganic fertilizer plus organic fertilizer (cottonseed meal applied at 225 kg/ ha), and I cove received no fertilizer as a control. Nutrient and plankton levels in the coves were monitored before, during, and after fertilizer application. Nutrient levels increased imediately after application of fertilizer, but returned to pre-treatment levels within I week. Fertilized coves did not have higher phytoplankton or zooplankton densities than non-fertilized coves.

Angler surveys were conducted at 18 lakes in municipal parks during JuneDecember 1987. Anglers < 16 years old were the largest proportion of the participants. Of the anglers surveyed, 93% were residents of Lubbock. They averaged 6.9 fishing trips per month and fishing frequency differed among age groups and between summer and fall. Resident anglers travelled an average of 4.7 km to fish; distance travelled differed among age groups and between summer and fall. Anglers preferred to catch catfish (Ictalurus spp., 79% of anglers) and largemouth bass (Micropterus salmoides, 72%). Fishes most frequently fished for were catfish (31% of anglers), largemouth bass (11%), and sunfish (Lepomis spp., 10%; 49% of the anglers indicated they were fishing for "any fish." Exclusive of travel expenses, anglers spent an average of $5.78 per day to fish in Lubbock's lakes. Fifty-six percent of anglers had knowledge of fishing regulations.

Following 3 years of a 356 mm (14 inch) minimum length limit on black bass, a protective length range (slot) regulation was placed on Arbuckle Reservoir, Oklahoma. This slot length limit protected both largemouth and spotted bass in the 300-381 mm (12-15 inch) range. Bass density, as indicated by spring electrofishing catch-per-effort (C/f, increased over the duration of the study. Most noteworthy was the increase in density of largemouth bass>381 mm long. Proportional Stocking Density (PSD) also improved as an indication of changes in population structure. Initially, angler compliance was low (30% illegal harvest) but improved over the course of the study. Few spotted bass achieved a size greater than the slot and their proportion in the population relative to largemouth bass increased.

Freshwater drum (Aplodinotus grunniens) are a significant component of the fishery resource in the Jordan Dam tailwater (Coosa River, Ala.). Most of the exploitation of the freshwater drum is centered around a spring influx into the system which appeared to be primarily mature fish moving upstream to spawn. There was little evidence of reproduction by this species within the tailwater. Although condition factors were highly variable across the range of lengths sampled, growth rates for freshwater drum in the Jordan Dam tailwater exceeded those reported elsewhere in the United States. By age six, freshwater drum reached total lengths of approximately 400 mm. From April through July 1983, 28.2% of those anglers interviewed had harvested freshwater drum even though few had specifically targeted it. During this same period, 94.0% of the annual harvest of the freshwater drum was recorded.