Anita M. Kelly

Cold Tolerance and Fatty Acid Composition of Striped Bass, White Bass, and Their Hybrids

Abstract Cold tolerance of striped bass Morone saxatilis, white bass M. chrysops, palmetto bass (female striped bass × male white bass), and sunshine bass (female white bass × male striped bass) were compared under controlled laboratory conditions. Two groups of each taxon were acclimated at 20°C in a recirculating-water system housed in an environmental chamber and were fed either a natural or prepared diet for 84 d. The fatty acid composition of the natural diet was 13% more unsaturated than that of the prepared diet. Fish fed the natural diet subsequently had unsaturated: Saturated fatty acid ratios 10-25% higher than fish fed the prepared diet. After being subjected to identical simulated cold fronts (10°C drop in surface water temperature, as if the fish were confined in cages or pens), all groups of fish fed the prepared diet suffered high mortality (50-90%) whereas there was zero mortality among the groups receiving the natural diet. White bass and sunshine bass fed the prepared diet had higher sur...

The Public Sector Role in the Establishment of Grass Carp in the United States

Abstract On 16 November 1963, the U. S. Fish and Wildlife Service Fish Farming Experimental Station at Stuttgart, Arkansas, became the first institution to import grass carp (Ctenopharyngodon idella) into the United States. This introduction was the result of at least seven years of effort to find an effective biological control for problematic aquatic weeds. The introduction was in keeping with a strong environmental and political mandate of that day to replace the broad use of chemicals with biological controls. For about 10 years, federal and state agencies and university systems strongly promoted introductions, spawning, and nationwide stocking of the grass carp. In 1966, the USFWS laboratory at Stuttgart, Arkansas, was apparently responsible for the first accidental release of grass carp to the environment. By 1972, grass carp were stocked in open water systems, documented in 16 states, and established in the Mississippi River system. All this occurred before the first private-sector commercial produ...

Are crustaceans linked to the ciguatera food chain

SynopsisAdult brine shrimp, Artemia spp., were used as an experimental organism to elucidate the role that crustacea may play in the transference of ciguatera toxins. Some ciguatera-implicated dinoflagellates were highly toxic to brine shrimp that had consumed them. Four clones of Gambierdiscus toxicus were fed in four trials at rates ranging from 2 to 480 cells per adult brine shrimp; the 24 h LD50 for the four clones were 2.8, 33.4, 41.1, and 104.5 cells per brine shrimp. Dinoflagellates Prorocentrum concavum and P. lima were also fed to adult brine shrimp, but minimal mortalities occurred at cell concentrations ranging up to 1000 cells per test animal. Tilapine cichlid (Oreochromis niloticus ×O. mossambicus) young fed brine shrimp containing G. toxicus cells displayed behavioral abnormalities ranging from spiral swimming to loss of equilibrium. The present data suggest that toxins accumulated by dinoflagellate-consuming crustaceans could produce toxicity in zooplanktivorous fish species, or to detritivores in cases where dinoflagellate consumption resulted in crustacean mortalities. Field studies of the ciguatera food chain should be expanded to include examination of crustacean diets to more fully define their role in toxin transfer.

MANIPULATION OF SPAWNING CYCLES OF CHANNEL CATFISH IN INDOOR WATER-RECIRCULATING SYSTEMS

Abstract Channel catfish Ictalurus punctatus were induced to spawn out of season by means of photothermal and hormonal manipulations in indoor water-recirculating systems. Groups of fish were maintained under the following temperature regimes: annual, cycles of 9 months in cool water (17 ± 2°C) followed by 3 months at spawning temperatures (25–28°C); compressed, 6 months in cool water, then 3 months at spawning temperatures; annual–compressed, 6 months at spawning temperatures, followed by alternating cycles of 6 months of cool temperatures and 3 months of spawning temperatures; and extended, 15 months at cool temperatures, then 3 months at spawning temperatures. At cool temperatures fish received light 8 h/d; at spawning temperatures they received light 14 h/d. Fish subjected to two successive compressed regimes consistently spawned at the outset and at two 8-month intervals thereafter. All fish in the other groups also spawned when water temperatures were increased to 25 ± 2°C. Injections of luteinizing...

Sunshine Bass Performance in Ponds, Cages, and Indoor Tanks

Abstract Performances of sunshine bass, the hybrid of female white bass Morone chrysops × male striped bass M. saxatilis, were compared between fish reared in round and rectangular cages in ponds, between fish reared in round and rectangular indoor tanks equipped with biofilters, and between fish reared in ponds without confinement and in rectangular cages in the same ponds. Fish weights at start were 100 ± 5 g, and trials lasted 108 d. Measurements were in terms of density equivalence for cage–cage and tank–tank comparisons and numerical equivalence for cage–pond comparisons. Survival was 100% in all culture units. Mean growth rates in round and rectangular units were similar (2.5 and 2.6 g/d in cages; 2.3 and 2.4 g/d in tanks). Fish grew better in open ponds (2.9 g/d) than in cages in the same ponds (1.4 g!d). Growth and survival of fish in all systems were comparable to reports for palmetto bass (striped bass female × white bass male) and for striped bass.

Effect of Carp Pituitary Extract and Luteinizing Hormone Releasing Analog Hormone on Reproductive Indices and Spawning of 3-Year-Old Channel Catfish

Abstract The efficacy of pituitary extract from common carp Cyprinus carpio (CPE) and luteinizing hormone releasing hormone analog (LHRHa) treatments in inducing spawning in channel catfish Ictalurus punctatus undergoing their first oogenesis just before the spawning season was evaluated in four commercial strains of channel catfish. Before the hormones were injected, the average oocyte size (1,624 μm) in May, the typical start of the spawning season, was smaller than that considered normal for mature oocytes (3,000 μm) in this species. Priming and resolving doses of CPE, LHRHa, or saline were administered in early May. Plasma estradiol (E2) and testosterone (T) levels were measured before the priming (0 h) and resolving (20 h) doses and 4 h later (24 h). Oocyte germinal vesicle migration and cathepsin B, D, and L activities were assessed at 0 and 24 h. At 20 h, estradiol levels were significantly higher in CPE- and LHRHa-treated fish. For LHRHa-treated fish, 20-h levels of T were also significantly highe...

Binding Affinities of Hepatic Nuclear Estrogen Receptors for Genistein in Channel Catfish

Abstract Soybean meal, the major protein source used in commercial feeds for channel catfish Ictalurus punctatus, contains natural phytoestrogens known as isoflavones, many of which have been found to be endocrine disruptors. This study investigated whether genistein (an isoflavone) in a soybean-based diet would increase plasma vitellogenin (Vtg) concentrations and whether it would compete with estradiol (E2) for binding sites on adult channel catfish hepatic estrogen receptors (ERs). Three-year-old channel catfish males and females were fed a casein-based diet (control) or a soybean-based diet. The genistein concentrations were 93.2 ng/g and 415,800 ng/g in the control and soybean diets, respectively. The binding specificity of the ERs was assessed by binding-affinity studies. In order of decreasing binding affinity, ethinylestradiol > E2 > genistein > testosterone, demonstrating that the hepatic ERs in channel catfish bind estrogens and genistein more than androgens. No significant differences in affini...

Apparent Control of Sexual Differentiation of Freshwater Prawn, Macrobrachium rosenbergii, Through Dietary Administration of Dopamine Hydrochloride

ABSTRACT Dopamine at concentrations of 0.15, 1.5, and 15.0 mg/kg was included in two different formulated diets that were fed to recently metamorphosed postlarvae of the freshwater prawn, Macrobrachium rosenbergii, for 60 days. Dopamine, in the form of dopamine hydrochlo-ride, was incorporated into the formulated diets by either solubilizing it in alcohol, followed by submersion of diet and evaporation, or inclusion in a lipid premix ingredient. The alcohol evaporation method at 0.15, 1.5, and 15.0 mg/kg significantly increased the percentage of individuals without external male characteristics. This research is the first reported use of dietary administration of dopamine to crustaceans, and the first documentation of the apparent dietary control of gonadal development and sex differentiation in crustaceans. Replication of results, a histological examination of a large sample of individuals, and continued monitoring of those individuals fed the dietary dopamine are needed to verify the apparent effect.

Menhaden Meal in Practical Diets for Channel Catfish Fry and Fingerlings Reared in Intensive Systems

Abstract Growth, survival, and proximate composition were evaluated in channel catfish Ictalurus punctatus fry and fingerlings fed one of three isocaloric practical diets (45% or 50% protein) containing 50, 65, or 75% meal from menhaden Brevoortia spp. in a recirculating aquaculture system. There were no significant differences in growth when the experimental diets were compared with each other or with a commercial salmonid starter diet (55% protein; fish meal type and content unknown). The proximate composition of whole fish fed the experimental diets included significantly higher moisture content and significantly lower fat content than that of fish fed the commercial diet. These results indicate the feasibility of reducing dietary protein to 45% (with menhaden meal comprising no more than 50% of total ingredients) for channel catfish fry and fingerlings that are reared intensively.

Efficacy of a Modified Opercular Hypophysectomy Technique in Tilapia as Determined by Serum Cortisol Levels

Abstract White tilapias, the hybrids of Nile tilapia Oreochromis niloticus × blue tilapia O. aureus, were rapidly hypophysectomized with a 2-mm, high-speed mototool cutter via an opercular approach. Two weeks post-hypophysectomy, serum cortisol levels were nondetectable in 98 of the surviving test fish. The remaining 6 test fish and the nonhypophysectomized and shamoperated control fish had blood cortisol levels of 62–125 ng/mL. Necropsy confirmed complete and partial or unsuccessful hypophysectomies with results congruent with serum cortisol levels. The use of cortisol radioimmunoassay eliminates the need for visual observation and confirmation of pituitary removal at necropsy.