Geology topics

Frederic T. Barrows

Publications and source records attributed to Frederic T. Barrows.

3 recordsLinked to original sources

USGS1999

The effect of dietary protein and lipid source on dorsal fin erosion rainbow trout, Oncorhynchus mykiss

A study was conducted to determine the effect of dietary protein and lipid source on dorsal fin erosion in rainbow trout. Seven diets were each fed to four replicate lots of 300 first-feeding fry cultured in 75 l aluminum troughs for 8 weeks. Two basal diets were manufactured with approximately equal nutrient content, one using krill and squid meals and the other anchovy meal as the primary protein-containing ingredients. The meals used to manufacture the diets were separated into two fractions: lipid (ether-extractable); and protein/ash (non-ether-extractable) using a large soxhlet. The fractions were then recombined to create two additional diets; one containing anchovy protein/ash with krill/squid lipid, the other krill/squid protein/ash with fish lipid. A fifth diet recombined krill/squid protein/ash with krill/squid lipid to evaluate effects of the extraction process. Two additional treatments included a diet with a portion of the krill meal replaced by poultry by-product meal, and the basal anchovy meal diet supplemented with sodium, magnesium, and copper. Fish consuming diets containing anchovy meal as the primary protein source gained more weight ( P <0.05) than fish consuming krill/squid meal-based diets. Dorsal fin index (DFI, measured as mean dorsal fin height×100/total fish length) was greater ( P <0.05) for fish consuming diets containing krill/squid meal protein/ash fraction (DFI=9.9%–10.0%) than for fish consuming diets containing anchovy meal protein/ash fraction (DFI=4.9%–5.3%), regardless of lipid source. Supplementation of the anchovy meal diet with sodium, magnesium, and copper improved ( P <0.05) DFI by approximately 20%, but not to the level supported by the krill/squid meal protein/ash fraction diets. The cost of the krill meal diet was reduced by inclusion of poultry by-product meal without affecting dorsal fin condition. These data indicate that the dietary agent contributing to dorsal fin erosion in rainbow trout is not present in the ether-extractable fraction of the diet, but rather in the protein or mineral fraction.

Aquaculture↗

USGS1997

The effect of diet on dorsal fin erosion in steelhead trout (Oncorhynchus mykiss)

A 2 × 2 factorial experiment of diet type (krill vs. fish meal) and steroid supplementation (0 vs. 30 μg 17α-methyltestosterone kg − ) was conducted to determine the effects on dorsal fin erosion in steelhead trout. Triplicate tanks of 250 fry were fed one of the four diets at a rate calculated to produce 115 g fish in 34 weeks. Fish were transferred to larger tanks when mean density index reached 0.40. Dorsal fin index (DFI, measured as mean dorsal fin height × 100/total fish length) was greater ( P < 0.001) among fish fed krill-based diets than for fish fed fish-based diets at weeks 12, 22, and 34 of the trial. Added testosterone decreased ( P = 0.04) DPI among fish fed the krill diet at week 12 but otherwise had no effect on fin condition. Addition of testosterone to either diet type decreased ( P = 0.02) critical thermal maximum, which is a measure of fish resistance to thermal stress. The results suggest that diet composition can influence the rate of dorsal fin erosion in steelhead trout through a metabolic, behavioral, or combined change.

Aquaculture↗

USGS1995

Metals-contaminated benthic invertebrates in the Clark Fork River, Montana: Effects on age-0 brown trout and rainbow trout

Benthic organisms in the upper Clark Fork River have recently been implicated as a dietary source of metals that may be a chronic problem for young-of-the-year rainbow trout ( Oncorhynchus mykiss ). In this present study, early life stage brown trout ( Salmo trutta ) and rainbow trout were exposed for 88&ensp;d to simulated Clark Fork River water and a diet of benthic invertebrates collected from the river. These exposures resulted in reduced growth and elevated levels of metals in the whole body of both species. Concentrations of As, Cd, Cu, and Pb increased in whole brown trout; in rainbow trout, As and Cd increased in whole fish, and As also increased in liver. Brown trout on the metals-contaminated diets exhibited constipation, gut impaction, increased cell membrane damage (lipid peroxidation), decreased digestive enzyme production (zymogen), and a sloughing of intestinal mucosal epithelial cells. Rainbow trout fed the contaminated diets exhibited constipation and reduced feeding activity. We believe that the reduced standing crop of trout in the Clark Fork River results partly from chronic effects of metals contamination in benthic invertebrates that are important as food for young-of-the-year fish.

Canadian Journal of Fisheries and Aquatic Sciences↗