Frederic T. Barrows

Effect of Temperature on Growth and Survival of Bull Trout, with Application of an Improved Method for Determining Thermal Tolerance in Fishes

Abstract Elevated temperature is considered an important factor in the decline of the threatened bull trout Salvelinus confluentus, but the thermal requirements of this species have not been defined. We used the acclimated chronic exposure (ACE) method to assess the upper thermal limits and growth optima of bull trout fed daily to satiation over test temperatures ranging from 8°C to 28°C during 60-d trials. Survival of age-0 bull trout was at least 98% at 8, 10, 12, 14, 16, and 18°C, but 0% at 22, 24, 26, and 28°C after 60 d. The predicted ultimate upper incipient lethal temperature for these trout was 20.9°C. Peak growth, as estimated by regression analysis, occurred at 13.2°C (95% confidence interval, 10.9–15.4°C). Feed consumption declined significantly (P < 0.001) at temperatures greater than 16°C, and fish held at temperatures of 22°C and above did not feed. Feed, lipid, and protein efficiencies were similar at 8–18°C but declined significantly (P < 0.001) at 20°C. Our results corroborate field inves...

Chemical composition and protein digestibility of poultry by-product meals for salmonid diets

Abstract Poultry by-product meal (PBM) is a potential substitute for a portion of the fish meal typically used in salmonid feeds. The nutritional value of commercial PBM as a fish meal replacement will depend primarily upon the quality and quantity of protein in a particular PBM batch. The purposes of this study were to quantitate the chemical variability in samples of PBM obtained from several manufacturers in North America, and to determine the digestibility of PBM protein by salmonids using one in vivo and three in vitro methods. The range in dry weight proximate composition among PBM samples was 55–74% for protein, 10–19% for lipid, and 11–23% for ash. Of the three in vitro methods for predicting in vivo protein digestibility, a method using trout pyloric ceca enzymes was the most sensitive and was more closely correlated to in vivo results than the other in vitro methods examined. We found significant differences in chemical composition and protein digestibility of PBM samples obtained from different manufacturers, illustrating the range of protein quality in PBM products that fish feed manufacturers will encounter in the marketplace.

Temperature and competition between bull trout and brook trout : A test of the elevation refuge hypothesis

Abstract We tested the elevation refuge hypothesis that colder temperatures impart a competitive advantage to bull trout Salvelinus confluentus and thus account for increased biotic resistance to invasion and displacement by brook trout S. fontinalis in headwater streams. Growth, survival, and behavior were compared in allopatry and sympatry at temperatures of 8-20°C in the laboratory. In allopatry, age-0 bull trout and brook trout grew at similar rates at temperatures of 8.0-14.3°C, but brook trout grew significantly faster at higher temperatures. In sympatry, bull trout grew significantly less than brook trout at all test temperatures, with growth differences increasing linearly with increased temperature. Age-1 brook trout had significantly higher feeding and aggression rates than did similar-sized bull trout at 8°C and 16°C. The modeled growth of age-0 bull trout and brook trout based on tributary temperature data from a high-elevation site (mean summer temperature, 10°C) and a low-elevation site (14°...

Color and flavor analyses of fillets from farm-raised rainbow trout (Oncorhynchus mykiss) fed low-phosphorus feeds containing corn or wheat gluten

Abstract Rainbow trout were fed one of three diets for 12 weeks: a low phosphorus diet containing corn gluten, a low phosphorus diet containing wheat gluten, or a commercial control diet. Fillets were analyzed by a colorimeter and by sensory preference tests. Raw fillets from fish fed the corn gluten-based diet had the highest b* values (yellow color) and received significantly lower visual acceptance scores than fillets from the other dietary treatments. Dietary supplementation with 100 μg/g canthaxanthin increased the a* values (red color) and improved visual preference scores of raw fillets from the corn-gluten fed fish. Incorporation of either corn gluten or wheat gluten into the diet did not adversely affect flavor of the fillets.

Feeding Trials with Hatchery-Produced Gulf of Mexico Sturgeon Larvae

Abstract Survival and growth in larval Gulf of Mexico sturgeon Acipenser oxyrinchus desotoi fed live and formulated diets were evaluated. Live foods consisted of brine shrimp Artemia sp. and California blackworms Lumbriculus variegatus. Formulated diets consisted of commercially produced pellets and two experimentally formulated sturgeon starter diets (SS). Feeds were first offered at 5 d posthatch, 2 d before initiation of exogenous feeding. Significant differences (P 95%) and specific growth rate (12%; SGR, logarithmic growth per unit time). In contrast, commercially formulated feeds were poorly accepted at the onset of feeding, and their use resulted in nearly complete mortality (>99%) by 3 weeks. First-feeding larvae, however, displayed preference for an experimentally formulated sturgeon ...

Estimation of protein digestibility—II. In vitro assay of protein in salmonid feeds

Abstract The in vitro digestibility of protein in various salmonid feeds was determined by pH-stat using enzyme fractions from trout pyloric ceca. Data were compared with in vivo digestibility and growth of fish by linear regression analysis. Results indicated that there were good agreements between the degree of hydrolysis of most feed samples and growth of fish. The pH-stat method is not suited for feed samples that have been partially hydrolyzed during their preparation.

Evaluation of the Ability of Partially Autolyzed Yeast and Grobiotic-A to Improve Disease Resistance in Rainbow Trout

Abstract We evaluated the ability of partially autolyzed yeast and Grobiotic-A to improve immune response and disease resistance in rainbow trout Oncorhynchus mykiss. Experimental diets were prepared by adding partially autolyzed yeast or Grobiotic-A to a practical trout diet at the manufacturer-recommended level of 2%; the control was the same diet without supplementation. Rainbow trout (initial weight = approximately 14.3 g) were cultured in 145-L fiberglass tanks (50 fish/tank; 3 tanks/diet) in a freshwater flow-through system. Fish were hand-fed the diets to apparent satiation 3 times/d, 6 d/week for 9 weeks. At 3 and 9 weeks postweighing, fish were sampled to determine respiratory burst activity, plasma protein, total immunoglobulin and lysozyme, and tumor necrosis factor-alpha (TNF-α) expression. At the conclusion of the feeding trial (9 weeks), fish remaining after sampling were pooled by diet; one subsample was examined for the ability to respond humorally to infectious hematopoietic necrosis viru...

Report of the Plant Products in Aquafeed Strategic Planning Workshop: An Integrated, Interdisciplinary Research Roadmap for Increasing Utilization of Plant Feedstuffs in Diets for Carnivorous Fish

This article was downloaded by: [Bellis, Diane]On: 24 November 2008Access details: Access Details: [subscription number 905736162]Publisher Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,37-41 Mortimer Street, London W1T 3JH, UK

Effects of Surface Water Spray, Diet, and Phase Feeding on Swim Bladder Inflation, Survival, and Cost of Production of Intensively Reared Larval Walleyes

Abstract Three experiments were conducted to determine the effects of a surface water spray and diet on survival and swim bladder inflation of intensively reared larval walleyes. Survival and swim bladder inflation were determined at 30 d posthatch. In each experiment, 275-L cylindrical tanks were stocked with 20 fry/L. In experiment 1, a spray of water was applied to the surface of three tanks, and three additional tanks received no surface spray. BioKyowa FFK-B diet was fed to fish in all tanks. Survival of fish with the spray (11.8%) and without the spray (9.1%) was not significantly different, but the incidence of swim bladder inflation was higher with (98.4%) than without the spray (51.7%). In experiment 2, larval walleyes were fed one of three commercially available larval feeds—FFK-B, San Francisco Bay Brand EPAC, and Zeigler Larval AP200—and all tanks received a surface spray. Only the fish fed FFK-B had reasonable 30-d survival (33.1%) and swim bladder inflation rates (95.6%). In experiment 3, ph...

Survey of Swim Bladder Inflation in Walleyes Reared in Hatchery Production Ponds

Abstract We examined pond-reared fingerling walleyes (Stizostedion vitreum) for inflation of the swim bladder at harvest. We evaluated 120,064 fish from 15 facilities in nine states during 1989, 1990, and 1993. Samples of walleye were collected from 188 ponds, and only 3.5% (4,229) of the fish examined lacked an inflated swim bladder during the 3-year period. Walleyes with uninflated swim bladders were observed at each facility during one or more years. Of the 188 ponds, 53.7% (101) contained walleyes that lacked inflated swim bladders, and these fish (after freezing) were shorter and lighter in weight and had less body fat than walleyes with inflated swim bladders. There appeared to be no relationship between size of fish at pond harvest and the incidence of swim bladder inflation in any pond. Incidence of uninflated swim bladders reached 55% in one pond. Although only a small percentage of walleyes overall lacked an inflated swim bladder in this survey, we feel that walleye fingerlings should be sampled...