Journal of the Southeastern Association of Fish and Wildlife Agencies

This study was conducted to determine the effects of otter trawl tow length on variahility and catch rates, and to assess replicate sampling. Longer tows caught more individuals/minute, individuals/tow, and species/tow than the shorter tows. The total number of species caught per hour of sampling, however, were essentially equal for all tow lengths. No difference in precision hetween tow lengths were detected. The numher of replicates needed to detect changes within desirahle statistical limits were logistically impractical. We recommend that otter trawls he used strictly for qualitative purposes and conclude that a small number of replicated lO-minute tows would adequately descrihe hasic community structure.

During the 14 years after initial introduction, a viable striped bass (Morone saxatilis) sport fishery developed on Keystone Reservoir. Natural reproduction, first identified in 1970, continued through 1979 in tributary rivers. Selected endemic fish species showed no significant changes in standing crop estimates from cove rotenone studies 1971-73, 1976-79. Available prey-predator ratios (AP/P) showed a fluctuating availability of forage for small predators and ample prey for large predators.

The water level of West Point Reservoir is lowered 3 m from October to May for flood control purposes, exposing about 2,900 ha oflittoral zone. The effects of water level fluctuations on the benthic organisms inhabiting this zone were determined from samples taken at 2 bottom contours; the contour exposed during winter drawdown and the contour just below the winter drawdown that remained permanently inundated. During May and July, fewer organisms (P < 0.05) were collected from the contour exposed during drawdown than from the contour never exposed. By August there were no differences (P > 0.05) in the number of organisms inhabiting both contours, indicating that the community had recovered after about 4 months of inundation. Soil particle size analysis showed a smaller percentage (P < 0.05) of silt and clay and a larger percentage (P < 0.05) of sand in the contour exposed during winter drawdown than the contour that remained permanently inundated.

Arkansas has carried out an extensive program of chemical rehabilitation of lakes and reservoirs since 1953. In the 27-year period since the first renovation, over 220 major lakes and impoundments have been treated with 94,445 kg of 5 percent equivalent rotenone powder and 37,123 liters of 5 percent liquid rotenone. A total of 18,839 ha have been treated on these lakes. Chemical rehabilitation may be required every 3 to 5 years on some lakes in Arkansas. Gizzard shad (Dorosoma cepedianum) is usually the problem species but often sunfish, particularly Lepomis spp., and other species offish overpopulate, stunt and require thinning. Thirteen chemical renovations on 7 state lakes were evaluated. In II cases, desired goals were achieved. Generally, large gizzard shad populations can be significantly decreased by renovation with the black bass population often receiving the greatest benefit.

Juvenile gulf menhaden (Brevoortia patronus) data were extracted from otter trawl surveys conducted along the Louisiana coast since 1966. The relationships between various abundance indexes and commercial harvest of age-I fish were determined by correlation and linear regression analyses. Several indexes were significantly correlated at the 0.95 and 0.99 level with commercial harvest. The strongest indexes, involving frequency of occurrence of more than 25 or 50 gulf menhaden in samples, were used to predict commercial landings. Recommendations were made to continue monitoring the relationship between these abundance indexes and commercial harvest.

The age and growth of larval Atlantic croaker, Micropogonias undulatus, was determined from daily growth increments on their otoliths. Smaller and younger larvae were found offshore near probable spawning areas while larger and older larvae were found near shore and in the lower estuary. A Laird-Gompertz growth model, L(t) = 0.926 exp {2.876 [1-exp(-0.0428t)]}, described the growth of larvae to 62 days old. The agespecific growth rate, derived from this relationship, declined with fish age. Atlantic croaker spawned over a 5-month period from mid-September to late-February, with the majority probably spawning in October-November. Larvae were the same size, 9 to II mm SL, when they immigrated to the estuary in the period from late-October to mid-April, although mean age of fish entering in January and April (61 to 64 days) was almost twice that of fish entering earlier.

This study describes culture of Malaysian prawn (Macrobrachium rosenbergii) without feeding in brackish water ponds in Louisiana. Survival and average size increased with decreasing stocking densities. After 163 days, average production in kg/ha for stocking rates of 1.25/m2 , 2.5/m2 and 3.75/m2 was 159, 191 and 218, respectively. Orbit length-total length relationships were determined to be expressed by the linear equation: Orbit length = 1.498 + 0.736 (total length) with both sexes combined. Total length-weight measurements at harvest of both sexes resulted in the curvalinear equation Log Weight = -5.867 + 3.41O(Log Length). Measurements were in millimeters and grams.

Three marsh types (saline, brackish, and freshwater) in the Baratoria Basin were sampled with the Wegener Ring. Forty-four species were collected, representing 21 families. Overall species composition and within species abundance varied from saline to freshwater environments. Shannon-Weaver diversity and evenness diversity show a decreasing gradient from saline to freshwater marsh. Number of individuals collected had an opposite gradient. The order of sequence from highest to lowest for biomass was fresh, saline, and then brackish. The saline marsh had the highest species richness value, while freshwater marsh had a slightly higher value than the brackish marsh.

The long haul seine is a 1100-1450-m net about 3 m deep pulled by two 9.2 13.7- m boats for distances of up to 2 to 3 km. The fishery, unique to North Carolina, apparently started in the early 1900's. Since 1956, the number of haul crews has varied between 30 to 60 and there is no clear relationship between that number and the total annual catch. Since 1972 landings have tended to increase, with a record 1O,250t landed in 1979. Much of this increase can be attributed to croaker landings, which increased 45-fold from 1971 to 1979. Sixty-one long haul seine catches were sampled during April-October 1979 in Pamlico and Core Sounds and Neuse, Pamlico, and Pungo Rivers, North Carolina. A total of 53 species of fish, 4 species of invertebrates, and 2 species of turtles were observed in the catches. Together, spot, croaker, menhaden, and weakfish comprised 90 percent by number and 88 percent by weight of the samples.

Largemouth bass (Micropterus salmoides) are able to feed on relatively large prey. The relative size of prey, calculated as the ratio of prey length (or weight) to .predator length (or weight), changed only slightly witb increasing size of largemouth bass. Bluegills (Lepomis macrochirus), gizzard shad (Dorsoma cepedianum), and threadfin shad (D. petenense) were the most common fisbes consumed by largemouth bass in West Point Lake. Bluegills were more often eaten by small largemouth bass (3 to 15 cm TL), while shad were eaten by larger ones ( > 15 I'm TL). Regression equations for the sizes of bluegills and shad that largemouth hass consumed were calculated to p,"edict the average size of prey for different sizes oflargemouth bass. Largemouth bass could swallow bluegills at 0.4 times their length or shad at 0.5 times their length. The equations of Lawrence (1958) were corroborated by our study of size - selective predation in largemouth bass from West Point Lake.

Cross-sections cut from the articulating process (AP) of pectoral spines were used to determine age and back-calculate growth of 370 flathead catfish (Pylvdictis olivaris) from 2 Oklahoma reservoirs. The accuracy ofthis method was validated by the following: agreement between the number of annuli and known age of 16 fish; 1 new annulus formed in the pectoral spines of fish tagged in 1970 and recaptured in 1971; agreement between calculated length increments and known length increases of tagged fish; and agreement between assigned age and length frequencies of young fish. Pectoral AP sections were superior to dorsal AP sections for age determinations. Sole use of sections from the distal end of the basal recess of pectoral spines would have resulted in underestimation of age by 1 to 5 years in fish of 3 to 13 years of age.

Seasonal dynamics of metacercariae of Uvulifer ambloplitis (Hughes 1927), the black spot parasite of centrarchids, were monitored over a 12 month period for bluegill (Lepomis macrochirus) < 70 mm total length. Prevalence of infection ranged from 8 percent in April to 97 percent in September. Mean parasite density during September was 16 metacercariae per host although individual infections of over 100 per host were not uncommon. Prevalence and density of infection were greatest in bluegill 31 mm to 50 mm total length. Metacercariae were often localized in the caudal peduncle, gular plate, and isthmus of heavily infected fish. Analysis of variance indicated significant differences in weight and body condition (K) of heavily versus lightly infected individuals of the same length class (P < 0.05). Body condition was negatively correlated to parasite density (r = - 0.474, P < 0.01).

Israeli carp (Cyprinus carpio) eggs were cold-shocked after fertilization at various temperature regimes and durations. Nine months later their hlood was sampled for analysis. Stained erythrocyte nuclei were measured with an ocular micrometer to calculate mean relative areas. Polyploidy appeared to have heen induced in each coldshock group, hut no group appeared to consist entirely of polyploids. Gonadal examination showed no apparent differences hetween the control group and the cold-shocked groups.

Growth of striped bass Morone saxatilis fry on a diet of rotifers was studied in the laboratory and in the field. Although the rate of growth was slower when rotifers were the principal food than when other acceptable zooplankton were eaten, rotifers were judged to be acceptable as a starting diet. This was based upon the fact that survival was higher and more consistent from pond to pond than was the case when mixed zooplankton was the source of food initially. Trichlorfon as Masoten® was used in rearing ponds to reduce predaceous and competitive invertebrates and to favor development of the rotifer population.

During summer, 1976, limnological and fish population data were obtained from 56 flood prevention lakes of the Trinity River watershed. Fish samples obtained by gillnetting, electrofishing, and seining indicated that the principal fishes were largemouth bass Micropterus salmoides), bluegill (Lepomis macrochirus), black bullheads (Ictalurus melas), white crappie (Pomoxis annularis), green sunfish (Lepomis cyanellus), channel catfish (lctalarus punctatus), golden shiner (Notemigonus crysoleucas), and redear sunfish (Lepomis microlophus). Analysis of fish data was performed by simple and multiple correlation techniques in relation to physical, limnological, and biological variables. Variation in fish biomass, as indicated by gill net catch, was explained by a combination of biological and physical characteristics, whereas species composition was a more important factor in largemouth bass models.

The most noticeahle differences in the pre- and post-impoundment tailwater fish communities in Green and Barren rivers, Kentucky, were reduced biomass, loss of cyprinid species, increased game-fish numbers, and decreased rough-fish numbers. These differences were attributed to altered post-impoundment environmental conditions in the tailwater (lowered water temperatures and irregular flow patterns), and species recruitment through the dams. Carp, while not present before impoundment in the tailwater reaches, represented a prominent component of the community after damming.

Dispersion patterns of 578 tagged rainbow trout stocked into pool and riffle habitats of Big Stony Creek, Giles County, Virginia, were determined from voluntary tag returns and a creel census of fishermen during the 1979-80 trout fishing season. Twentytwo percent of the trout remained within the original 30 m stocking location; 45 percent of the trout moved downstream whilc 33 percent moved upstream. The median dispersion distance and direction for aU trout that moved beyond tbe initial release sites was 30 m downstream. The majority (75%) of the marked fish were caught within 400 m of the stocking location. There was no significant difference (P > 0.136) between the median distance moved of trout stocked into pools and those stocked into riffles. Three major physical factors (residence time, water temperatures, and stream flow rates) were found to strongly influence stocked trout dispersion.

Creel census data for 3 catchable trout fisheries in Virginia revealed that desirable attributes of the fisheries increased from a lightly-stocked stream to a lightlystocked lake to a heavily-stocked stream. Total effort, participation by non-local anglers, evenness of seasonal use, catch rate, and return rate all were higher for the heavilystocked stream than for the lightly-stocked stream. For the trout lake, total effort and participation by non-local anglers were similar to the heavily-stocked stream, but catch per effort, return rates of stocked fish, and seasonal distribution of effort were similar to the lightly-stocked stream. Most anglers at the lake fished from shore, so that a large portion of the potential fishing area was not utilized.

Two hundred and thirty Roanoke bass (Ambloplites cavifrons) were collected from the Tar and Eno rivers in Piedmont, North Carolina. Seven age groups (I to 7) were collected from the Tar River and 5 age groups (I to 5) were collected from the Eno River. Mean back-calculated total lengths were similar in both rivers. Five-year old fish from the Tar River averaged 246 mm and from the Eno River 243 mm. Roanoke bass were generally opportunistic feeders, hut larger individuals selectively fed on crayfish (Cambarus sp.) and fish. Feeding appeared to he concentrated in ve~etated riffle areas.

Age-growth analysis was performed on Anguilla rostrata from 2 study sites on the Cooper River, South Carolina. Length ranged from 98 to 834 mm and weight ranged from 1 to 1224 g. Examination of otoliths gave mean age of 5.1 years with a range of 0-15 years. Length-weight relationship was established as: log w = -6.56 + 3.34 log (L). Eels were sexed by morphological and histological examination of gonad tissue. Males comprised only 1.6 percent of the population from Pinopolis Dam and 1.3 percent from Wadboo Creek. Eels smaller than 210 mm could not be sexed.

Larval fish were collected in the Lower Mississippi River at Sunnyside Revetment on 27-28 June 1978 to investigate diel fluctuations in diversity and ahundance and to determine whethersamples collected for 1-2 hours and from opposite sides of the hoat can he considered replicate samples for a time period. Numher of taxa and density differed significantly (P < 0.01) hetween time periods of the diel cycle. Numher of taxa and density were greatest at dusk. Twelve taxa were collected only in dusk, night, and dawn samples. Aplodinotus grunniens, Carpiodes spp. and c1upeids accounted for 95 percent of the larvae collected. A. grunniens and Carpiodes spp. were more ahundant in dusk and night samples. Clupeids were more ahundant diurnally.

The 1978-79 survey of Arkansas' wild commercial fishery was compared to a previous 1977-78 survey. A tremendous increase in the commercial fishery industry has occurred since mid 1977. The 1978-79 commercial fishery harvest of 8,320,774 kg valued at $4,923,259 represents a probable all time high for the industry. Large increases in the number of licensed commercial fishermen and their gear were also documented for 1978-79. Catch per unit effort values were reported for the various gear types from each watershed.

Tilapia aurea and T. mossambica fry were stocked in a flowing system at varying stocking densities (5,10,20,30,40,50 and 60 fish/tank in 60 liters of water) in an intensive tank culture system. The fish were maintained for 1I5 days on commercial pelleted feed. In terms of length increase, weight gain, condition, total yield, and food conversion rates, T. aurea performed significantly better than T. mossambica at all stocking densities. The T. mossambica experienced much higher mortality and reduced growth due to an auto-immune reaction related to stocking density, which effectively limits the density at which this species can be stocked. Hypersensitivity reactions began when the biomass reached about 20g/liter with a turnover time of one-half hour, although further research is needed to completely quantify their crowding tolerance limits. T.

Ichthyoplankton communities of Galveston, Texas barrier island environments were characterized from 22 January through 27 August 1979. Beachfront and saltmarsh sites were sampled with a Renfro beam trawl to determine seasonal and diel trends in species composition and abundance of subadult fishes. Beach and saltmarsh constituted important temporary habitats for many ichthyoplankton species. Most larvae initially penetrated beach and tidal pass habitats but sought nutrient-rich saltmarsh environs. The beachfront yielded the highest number of taxa while the saltmarsh produced the greatest catch per effort. Peak ichthyoplankton abundances at both sites occurred during winter and early spring. Day and night sampling at the beach yielded similar catch statistics while peak yields at the saltmarsh consistently occurred during the day.

Artificial midwater structures constructed primarily with fiberglass panels and automobile tires were placed in an oligotrophic storage reservoir to determine the extent of fish association witb these structures. SCUBA observations were used to evaluate the effectiveness of the structures. Comparisons were made between these and previous structures used by Reeves et al. (1977). Six species of game fish were attracted; however, Alahama spotted bass (Micropterus punctulatus henshalli) and bluegill sunfish (Lepomis macrochirus) were the predominant species. Concentrations of harvestable spotted bass were noted throughout most of the summer months.