Journal of the Southeastern Association of Fish and Wildlife Agencies

Epistylis infestations occurred on 16 of 32 fish species collected from Mountain Island Lake and Lake Norman, North Carolina, during 1974 and 1975. Percichythids, centrarchids, and ictalurids were the fishes most commonly infested, while infestations were rare on clupeids, cyprinids, and percids. Epistylis was generally more prevalent on fishes during fall (September through November). Percichthyids, followed by centrarchids, had the highest intensity of infestation. Intensity of infestation increased with surface area and length of percichthyids, but not with that of centrarchids. Although the attachment site varied among fish species, Epistylis infestations were restricted primarily to the bony parts. The prevalence of Epistylis on fishes did not correlate with the abundance of Epistylis in the plankton.

Weekly samples of river shrimp (Macrobrachium ohione) were collected from the commercial bait fishery located at Port Allen, Louisiana. Mean size was 30.6 ± 0.2 mm (total length) (n = 7,058); the mode was 27 mm (n = 851); and the range was 17-92 mm. Mean size declined from approximately 39 mm in early March (when fishing began) to approximately 28 mm in mid-August (when fishing ended). The mean size of ovigerous females was 66.1 ± 1.7 mm (n = 88); and the range was 27-92 mm. Bopyrid parasitization is discussed. A comparison is made with data collected from the same area in the early 1930's prior to extensive industrialization.

A sonar fish counter installed at the Pinopolis Dam navigation lock near Moncks Corner, South Carolina in 1975 was used during the last 3 springs to enumerate blueback herring (Alosa aestivalis Mitchill) passing into the Santee-Cooper Lakes. Construction of the biomass fish counter was based on the design of salmon smolt counters used successfully in Alaska. Characteristics of fish movement and schooling patterns were determined and their relationship to accurate counting of herring was evaluated. Initial tests to prove the accuracy of counts were not successful. However, other population indices indicated that trends were accurately assessed.

Sustained voluntary swimming speeds of 5 species of juvenile estuarine fish were determined in a laboratory circular flume, 2.5 m in mean circumference. Successful tests depended on the fish's ability to avoid downstream displacement through positive rheotaxis. The following swimming speeds, in body lengths (BLjsec, were measured: 3 to 6 em Atlantic menhaden (Brcvoortia tyrannus), the species of primary interest, swam 5 (at 13 C) to 11 (at 30 C) BLjsec; striped mullet (Mugil cephalus), 3 em, swam 8 (at 15 C) to 12 (at 25 C) BLjsec; pinfish (Lagodon rhomboides), 4 em, swam 11 BLjsec (27 C); spot (Leiostomus xanthurus), 4 em, swam 6 BLjsec (25 C); Atlantic croaker (Micropogon undulatus), 7 em, swam 5 BLjsec (30 C). An evaluation of the apparatus and implications of the data for predicting impingement of juveniles on power plant intake screens are included.

Techniques have been developed for spawning adult southern flounder. (Paralichthys lethostigma), spotted seatrout (Lynoscion nebulosus), and red drum (Setaenops ocellata) and rearing their larvae for freshwater acclimation and introduction into heated freshwater reservoirs in Texas. Egg production, percentage egg fertilization, percentage hatch, percentage return of larvae stocked into laboratory aquaria and hatchery ponds, and potential for fingerling survival in fresh water were compared for the 3 species. Red drum was found to be the most suitable for culture and introduction into fresh water. A diagram and estimated construction cost of a laboratory facility for holding and spawning marine fishes is presented.

Prey selection by sauger (Stizostedion canadense) was monitored from November 1976 through April 1977 in the portion of Watts Bar Reservoir, Tennessee, near the Kingston Steam Plant. Threadfin shad (Dorsoma petenense) provided the entire forage base for sauger until the population of threadfin was almost completely eliminated by low temperatures in December and January. Some sauger switched to alternate prey, but food consumption was greatly reduced in February-March as > 75% of stomachs were empty. Food consumption of sauger smaller than 30 em was restricted earlier in the year by the lack of threadfin less than 8.0 em. Digestive rate studies in the laboratory indicated digestion continued at a reduced, but effective, rate at temperatures < 10 C.

Scales from blue tilapia (Tilapia aurea) captured in gillnets indicated that annulus formation occurred primarily in March and April in 1973 and 1974, but in April and May 1975,. Average back-calculated total lengths of males were 197 and 258 mm at Age I and II and for females 183 and 248 mm. Total population of blue tilapia in December 1974 was estimated as 4,856,963. Of this total 3,120,810 were Age 0 and 1,591,823 were Age I. Biomass of the tilapia population was estimated to be 799,978 kg or 2,640 kg/ha. Survival of blue tilapia from Age I to II was calculated to be 7%. From these estimates the potential yield of harvestable blue tilapia would be 1,629,501 fish weighing 521,153 kg.

Copper sulfate was evaluated as a potential control for parasitic fungal infestations on largemouth bass (Micropterus salmoides) and striped bass (Morone saxatilis). Treatments were planned to reduce the incidence of free-swimming zoospores of the fungi. Largemouth bass fingerlings (15-20 cm T.L.) were stocked in 0.04 ha ponds and given multiple treatments of copper sulfate at 0.5; 1.0 or 2.0 ppm or Dimethylamine salt of 2,4-Dichlorophenoxy (acetic acid) at 2.0 ppm. Chemical treatments were made on the day before stocking and at regular' intervals thereafter for 6 treatments. Survival rates of largemouth bass treated with copper sulfate were 96, 91.7 and 100'70 at concentrations of 0,5,; 1.0 and 2.0 ppm respectively; only 10.7% of the controls survived. No significant difference of survival rate between control and 2,4-D treated fish was noted. Striped bass adults were treated with multiple copper sulfate treaments a 1.0 ppm after being captured in gill nets.

The need to suspend newly hatched striped bass (Marone saxatilis) larvae until swim-up prompted comparison of holding techniques. Fingerling returns were tabulated over a 3 yr period from fry held in aquaria vs. returns from fry held in Saran cages in rearing ponds. Mean production for a 3 yr period from ponds stocked with fry held in cages was better overall than other methods. The success of holding cages resulted in a substantial saving in manpower as constant care of fry was not needed. The cage holding method is only I of many facets of striped bass rearing and is only a contributing factor to high production, not a critical factor such as the quantity and quality of food available. This technique would apply to those situations where unsuitable temperature, turbidity or limited facilities make the tank or aquaria method impractical.

A simple recurrence model is developed for the prediction of DDT flux through Atlantic menhaden (Brevoortia tyrannus). The DDT body burden in young-of-the-year menhaden at any time is equal to the body burden on the previous day plus the DDT accumulated on the current day minus the DDT turnover. Accumulation of DDT is simulated and compared with field observations. Estimations of DDT ingestion, assimilation, turnover, and egestion are made on both per fish and population bases. It is estimated that emigrating juvenile menhaden export 20 g DDT year -, from the Newport River estuary in North Carolina.

In the Dixon Springs area of the Cumberland River, Tennessee, larval Lepomis spp. began feeding upon crustacean zooplankton, especially Bosmina longirostris, when the fish attained lengths of 6.7 mm in 1975 and 8.8 mm in 1974. Cladooerans remained the dominant food item throughout the larval stage. The fish food selection diversified [to include other taxa.] larva reached approximately n.5 mm. At greater lengths, Lepomis spp larvae and postlarvae begin to rely more on chironomid larvae.

Laboratory spawning and larval rearing studies were conducted with red drum (Scianenops ocellata) and southern flounder (Paralichthys lethostigma) from 1974 through 1977. Adult fish were placed in 29.92 kl spawning tanks equipped with biological filters and subjected to photoperiods and temperatures regulated to simulate seasonal variations. Red drum spawned 52 times producing 6.0 X 107 eggs. Southern flounder spawned 13 times producing 1.2 X 105 eggs. Eggs were collected and incubated, and larvae were reared to fingerling size. This paper describes techniques used to produce fingerling red drum and southern flounder.

The effects of Masoten, an organophosphate parasiticide, on phytoplankton and zooplankton in earthen ponds were studied. In 2 separate trials, 3 ponds (0.04 hal received a single application of Masoten at a rate of 0.25 mg/l (active ingredient) and 3 ponds served as untreated controls. Net plankton samples were collected at pretreatment, and 5, 24 and 48 hI's following treatment. Toxic effects were based on quantitative.qualitative plankton analyses. Phytoplankton and rotifers were unaffected by treatment. The copepod Diaptomus sp. and nauplii were also unaffected. However, variability in response of copepods and nauplii to Masoten can be anticipated. Cladocerans were the most sensitive to Masoten; losses are to be expected when the compound is employed for control purposes. Information regarding residues and decomposition of Masoten is presented.

Jocassee Reservoir (3,063 ha) is the upper pool for a 61O·MW pumped storage hydroelectric plant in northwestern South Carolina. Trout (200-225 mm long) have been stocked annually since 1972. The volume of trout habitat during summer has decreased annually from 1973 to 1976, and is associated with increases in the temperature and volume of water pumped from the lower reservoir. The top of the thermocline during September was lowered from about 9 m in 1973 to nearly 19 m in 1976, and trout habitat was reduced by about 65%. On the basis of a regression presented, we predict that trout habitat will be reduced to nil when plant operation reaches 63% of capacity (perhaps by 1981).

This study was conducted to determine if water temperature increases during the walleye (Stizostedion vitreum vitreum) spawning period reduced egg hatch rate and if water temperature manipulation during egg fertilization would increase hatch rate. Walleye eggs were subjected, before and during fertilization, to 1 of 3 treatments involving water temperatures above and below 12 C. Water temperatures above 12 C were found to reduce hatch rates. Stripping and fertilizing eggs collected from reservoir water temperatures above 12 C into water chilled to 7.2 C significantly increased hatch rates. Use of this technique could improve walleye culture and management operations in some southern regions.

This study investigated possible factors inhibiting spawning of largemouth bass (Micropterus salmoides) in Victor Braunig Lake, a 547 ha power plant cooling reservoir in Bexar County, TX. Data on water quality, fish communities, pesticide and heavy metal concentrations and largemouth bass blood components and sexual development were analyzed from Braunig Lake and Calaveras Lake, a similar power plant lake nearby. All factors were similar between the 2 lakes. Largemouth bass from Braunig Lake began spawning 2 days after being moved to hatchery ponds. Largemouth bass from Calaveras Lake which had a normally reproducing popUlation failed to spawn in pens in Braunig Lake. Braunig Lake largemouth bass had no chronic abnormalities that would inhibit spawning. Fertilized largemouth bass eggs collected from a private lake hatched in Braunig Lake water and healthy fry were produced. Largemouth bass fry collected from the same lake also survived and healthy fingerlings were produced.

Midwater artificial structures were placed in a freshwater reservioir to determine if fish would associate with these structures. SCUBA observations were used to evaluate the effectiveness of the structures. Alabama spotted bass (Micropterus punctulatus henshalli) and bluegill sunfish (Lepomis macrochirus) were attracted to structures suspended over water depths up to 33 m and as far as 250 m from the shoreline. Behavioral observations of fish on structures and the development and subsequent association of spotted bass fry spawned on a structure are discussed.

Channel catfish (Ictalurus punctatus) were stocked at rates of 250, 500, 1,000 and 2,000 fry /208 1 drum, and reared to fingerling size. No significant differences occurred in rate of gain from days 0-33, but gains ranged from 0.22 g/day at the 250 stocking rate to 0.08 g/day at the 2,000 stocking rate from days 0-70. The highest average total biomass of 10,095 g was reached at the 2,000 stocking rate. Flow rate was maintained at a constant 0.32 I/sec in all drums. Food conversion from days 17-70 ranged from 1.42 at the 250 stocking rate to 2.67 at the 2,000 stocking rate. Water quality was monitored to evaluate the effect on growth. Oxygen concentration became a critical limiting factor as total biomass increased. Growth rates were best at the lower stocking rates in which the oxygen concentrations were higher.

Supplemental stocking of fingerling and intermediate size largemouth bass (Mieropterus salmoides) did not provide substantial control of forage fish populations; however, stocking fingerling bass may have improved year class strength in those years they were stocked. Although loss of stocked intermediate-size bass over the spillway was negligible, those fish were vulnerable to angling. A measured rate of fishing (F = 0.08) was exerted on a population of bass estimated at 22.3 harvestable bass/ha weighing 34 kg/ha.

The quantity, quality, and timing of freshwater inflows to the San Antonio bay system are recognized as major factors in fishery production. A methodology has been developed using commercial fishery statistics and gaged inflow records to analyze the fishery dynamics and its relation to freshwater inflows from the contributing river basins. Statistical correlation analysis and assessment of "best" versus "worst" years of production were employed to evaluate the effects of year to year fluctuations in freshwater inflows. Although somewhat rudimentary, the results of the analyses are clear enough to be of practical value for future water resources planning and management. an inflow regime, with a monthly distribution of 1.48 x 10' total annual ha-m of freshwater, is presented that could meet the minimum sustaining requirements of the estuary's fisheries.

The tailwater fisheries of Lake of the Ozarks and Pomme de Terre Lake were measured by a part-time roving creel survey from 1965 through 1974. Catch rates of fishes were compared with temperature, conductivity and dissolved oxygen, but no significant correlations were found. However, high positive correlations existed at Lake of the Ozarks tailwater between annual average catch rates and the annual average discharge of water, and also between preceding mean monthly discharges and following monthly catch rates. There was also a high positive correlation between estimated number of fishes caught in this tailwater and the number of days per year that the flood gates were open. At Pomme de Terre tailwater, there was a high positive correlation between discharge and catch rate for monthly, seasonal, and annual periods.

Channel catfish (Ictalurus punctatus), were reared in 1.0 m' cages suspended in the intake canal of a cooling reservoir. Effects of density were tested by stocking cages in replicates of 4 at densities ranging from 500 to 900 fish in increments of 25 individuals. There was a significant increase in net production and variation in length and a signifi· cant decrease in feed efficiency, mean fish weight, and percentage of harvestable-size fish as stocking density increased. Survival was not affected by number of fish per cage.

Quantitative samples of fish were obtained from warm-water streams with detonating cord. Preliminary results indicate this explosive is an effective tool for fish sampling in streams. Numbers of fish collected per kilometer of stream ranged seasonally from 200 to 473.

The relationships of abundance of brown shrimp (Penaeus azteeus Ives) and white shrimp (P. setiferus L.) to spring and fall river flow into San Antonio Bay, Texas were studied. Standing crop indices determined from trawl sampling and bay commercial landings were poorly correlated; only those indices obtained from trawl samples were deemed valid. Brown shrimp abundance showed no detectable relationship to changes in freshwater inflow; white shrimp abundance, however, showed a significant positive correlation with May-June inflow and with the previous year's September-October inflow.

Length at maturity computed for female flathead catfish (Pylodietus olivaris) from marshes of southwest Louisiana was 589 mm. Empirical data showed males approach maturity in the 390-439 mm size range. The length-weight regression for flathead catfish was best described by: Log W = -8.9640 + 3.3732 Log L, where W = weight in kg and L = length in mm, r = 0.97. The computed total length-collarbone length conversion equation for flathead catfish was Y = 10.3428 + 0.7251, where Y = total collarbone length in mm and X = total body length in mm, r = 0.99. Dressout-live weight relationship for flathead catfish was Y = 0.3308 + 0.7123 X, where Y = cleaned ( headed and eviscerated) weight in kg and X = live weight in kg, r = 0.70. Computed length at maturity for blue catfish (letalurus fureatus) was 481 mm.