Geology topics

R. W. Soderberg

Publications and source records attributed to R. W. Soderberg.

5 recordsLinked to original sources

USGS1995

Influence of tank design and hydraulic loading on the behavior, growth, and metabolism of rainbow trout (Oncorhynchus mykiss)

Subadult rainbow trout ( Oncorhynchus mykiss ) stocked at 48 kg/m 3 (3 lb/ft 3 ) were subjected to treatments of tank design (rectangular plug flow, circular, and cylindrical cross flow) and water exchange rate (1·5 and 2·5 exchanges/h) to determine their effects on fish behavior, growth, and metabolism. Ambient light levels and current velocities were also measured in each of three tank sectors (upstream, middle, and downstream) to determine their relative contributions to behavioral effects. Tank design significantly affected fish orientation to current, contact time with tank surfaces, and frequency of agonistic encounters, though aggression levels were relatively low overall. Gradients in fish distribution by sector were greatest in plug-flow tanks. Effects were either modified or eliminated by increasing the water exchange rate from 1·5 to 2·5/h. Multiple-regression analysis showed the following hieararchy of independent-variable effects on fish distribution: tank type > exchange rate > aggression level > current velocity > light level. Significant effects of tank design were also observed on fish growth in terms of biomass gain (cross flow > plug flow > circular). These results were matched in metabolic studies, where both oxygen consumption and ammonia excretion were highest in circular and lowest in cross-flow tanks. Reduction (cross-flow compared with circular tanks) in oxygen consumption averaged 13·6%, ammonia excretion 17·5%. These results were also modified by an increase in water exchange rate. Tank-design effects on fish metabolism and growth may be mediated, at least partly, through changes in fish behavior.

Aquacultural Engineering↗

USGS1993

Growth, survival and food conversion of Atlantic salmon reared at four different densities with common water quality

Our objective was to determine the maximum effective rearing density for Atlantic salmon ( Salmo salar ) at 17.5°C, a temperature typically used in hatcheries to accelerate growth. We reared 5.8‐g (mean weight) parr for 80 d to final rearing densities of 14–55 kg/m 2 (rearing unit bottom area) or 80–310 kg/m 3 (rearing unit volume). Weight gain was slightly depressed in fish at a final rearing density of 26 kg/m 2 (146 kg/m 3 ), but mortality, food conversion, and gain in length were not affected. At densities greater than 26 kg/m 2 , fish growth was slower and food conversion was higher, but mortality was unaffected. Atlantic salmon may be reared at 17.5°C to densities of at least 14 kg/m 2 (80 kg/m 3 ) without adverse effects on growth and health, but final rearing densities should not exceed 26 kg/m 2 .

Progressive Fish-Culturist↗

USGS1992

Effects of sodium and calcium on acute toxicity of un-ionized ammonia to Atlantic salmon and lake trout

Acute, static 6-hour toxicity tests were conducted on two sizes each of lake trout and Atlantic salmon in the presence of three levels each of NaCl and CaCl 2 . Calcium did not protect smolts from NH 3 toxicity but had no effect on the tolerance of Atlantic salmon fry to NH 3 . Both cations increased the tolerance of 8-g lake trout fingerlings to NH 3 , but neither significantly affected the toxicity of NH 3 to 0.9-g lake trout fry. These results suggest that the mitigating effects of solution cations of NH 3 toxicity may be related to species, size, and life stage.

Journal of Applied Aquaculture↗

USGS1987

Effects of rearing density on growth, survival, and fin condition of Atlantic salmon

Parr of Atlantic salmon (Salmo salar) were reared to final densities of 0.53‐4.29 lb/ft 2 of rearing container bottom area under conditions of constant temperature, water quality, and diet. Growth and survival were not affected by density. After 171 d, the condition of pectoral and dorsal fins had not changed from that initially recorded and did not differ among treatments. We conclude that rearing density alone does not affect growth, survival, or fin condition of Atlantic salmon reared at densities likely to occur at production hatcheries.

Progressive Fish-Culturist↗

USGS1987

Growth and survival of fingerling lake trout reared at four densities

Fingerling lake trout (Salvelinus namaycush) were reared at density indexes (fish density, in pounds per cubic foot, divided by fish length in inches) of 0.25, 0.50, 1.0, and 2.0. Final lengths, weights, condition factors, and mortality rates did not differ among the treatments. We conclude that fingerling lake trout may be successfully reared at a density index of at least 2.0 if water requirements for respiration and waste dilution are met. Our results indicate that fish length may be less important in determining allowable fish densities than was previously suspected.

Progressive Fish-Culturist↗