Search USGS⌕ Search

Geology topics

D. V. Rottiers

Publications and source records attributed to D. V. Rottiers.

At least 19 recordsLinked to original sources
USGS2006

Digestion of larval American shad by cyprinids

Cyprinids have pharyngeal teeth for grinding food before swallowing and a continuous gut with no discrete stomach. This digestive tract structure, as well as the feeding behavior traits shown by cyprinids, makes it difficult to identify and measure the amount of food consumed by these fishes. The relations among quantity of food in cyprinid gut, time after feeding and predator size were described by log-linear multiple regression. The number of intact American shad ( Alosa sapidissima (Wilson)) larvae eaten in laboratory experiments was estimated by extrapolating the regression for the amount of food in the gut over time for predators of various size. The numbers of larval American shad in guts of fish captured in the Juniata River, Pennsylvania, were not significantly different from those estimated with the equations derived from laboratory data. In view of their abundance in rivers and their potential digestion rate for larval fish, cyprinids can be expected to have a marked influence on reducing the numbers of larval American shad.

Ecology of Freshwater Fish↗
USGS1993

Elemental composition of a migratory and a land-locked strain of Atlantic salmon Salmo salar

1. The growth and elemental composition of an anadromous strain and a land-locked strain of Atlantic salmon ( Salmo salar ) were compared. 2. All fish were raised from the egg stage under identical conditions. 3. The land-locked strain was significantly higher in lipids than the anadromous strain throughout the study. 4. Results of exposure to seawater at 2-week intervals between days 431 and 512 of the study indicated that neither strain produced smolts. 5. Strains could not be separated by discriminant analysis into separate groups, based on concentrations of the six most abundant elements or all ten elements sampled during the expected period of smolting (days 440–550). 6. The laboratory fish differed significantly in composition from those collected in the Merrimack River. 7. The log e of the whole-body element content increased significantly with log e of wet body wt in both strains.

Comparative Biochemistry and Physiology, Part A: P↗
USGS1992

Effects of day length and cleaning regimen on the growth of yearling parr Atlantic salmon

Yearling Atlantic salmon ( Salmo salar ) were reared with 8 or 16 h of light each day in laboratory tanks that were cleaned daily or weekly, and growth was measured weekly for 10 weeks. Growth was greatest for fish on the 16‐h light and weekly cleaning routine. Reduced frequency of tank cleaning (weekly) significantly enhanced growth but accounted for only 8.5% of the partitioned variance, compared with 78.9% for increases in day length alone. Results of this study suggest that the increased growth observed at longer day lengths was primarily due to the stimulatory effects of increased amounts of light.

Progressive Fish-Culturist↗
USGS1992

Notes: Differences in stocks of American shad from the Columbia and Delaware rivers

American shad Alosa sapidissima from the Columbia River on the Pacific coast and the Delaware River on the Atlantic coast were reared from 3 June to 24 October 1986 in two adjacent hypalon‐lined ponds. Although fish from the Columbia River were introduced into ponds 29 d after those from the Delaware River, they grew significantly faster and attained a greater final weight. Fish from the Columbia River also had lower mortalities at all test salinities and temperatures than fish from the Delaware River. Electrophoresis revealed allelic differences between the two stocks at one locus (creatine kinase). We conclude that the two stocks of American shad are sufficiently different so that managers should not introduce them to different river systems without careful consideration.

Columbia River, Delaware River↗
USGS1991

Towable cage for studies of smoltification in Atlantic salmon

The floating towable cage described in this report was used successfully to hold and transport Atlantic salmon ( Salmo salar ) in estuarine waters. These rugged and versatile cages, constructed from readily available, inexpensive materials, were tied singly and in clusters to floating docks in fresh and brackish water, where they withstood strong currents, winds, floods, and tides for 2.5 months without visible damage.

Progressive Fish-Culturist↗
USGS1988

Lack of dietary effects on the timing of smoltification in Atlantic salmon

Six commercially available diets varying in lipid, protein, water, ash, and carbohydrate contents were fed to Atlantic salmon ( Salmo salar ) for 2 years to determine if diet affected smoltification. Each month, from March to September of the second year, sampled fish were exposed to 33‰ seawater for 24 h to determine smolt readiness, defined as the ability to maintain water and salt balance in a seawater challenge. Regardless of diet, Atlantic salmon were able to regulate plasma sodium and chloride ions (smoltify) only during early May. It is unlikely that hatchery managers could effectively use high‐energy diets to control the time of smoltification in Atlantic salmon.

Progressive Fish-Culturist↗
USGS1987

Support rack for portable water chillers

Construction and use of a polyvinyl chloride pipe rack that provides a safe, convenient, and versatile way of handling and storing portable 746‐W water chillers are described.

Progressive Fish-Culturist↗
USGS1986

Growth of tiger muskellunge fed different amounts of protein at three water temperatures

Growth rates of tiger muskellunge (muskellunge Esox masquinongy ♀ x northern pike E. lucius ♂) fed diets containing 35, 45, or 55% crude protein for 5 weeks at 17, 20, or 23°C were compared. Fish fed diets containing 45 or 55% protein grew faster at all temperatures than those fed 35% protein. Growth of tiger muskellunge fed a diet containing either 45 or 55% protein did not increase significantly at optimum growth temperatures (20 or 23°C). At 17°C, below the optimum temperature range, growth did increase when the percentage of protein in the diet was increased.

Progressive Fish-Culturist↗
USGS1985

Movement of underyearling walleyes in response to odor and visual cues

Underyearling walleyes, allowed to move freely in a Y‐shaped chamber into which various substances were added to one arm or another, were attracted to sodium chloride, sucrose, glutathione, vitamin B 12 , betaine, arginine, Daphnia slurries, some fish slurries, washings from live Daphnia and Artemia, and some commercial fish foods. They avoided cysteine, glycine, glycine‐betaine, Artemia slurries, some fish slurries, and fish mucus; and showed little reaction to valeric and caproic acid, and some commercial fish foods. Tests of visual response, in which beakers containing live food organisms were placed in the arms of the chamber, indicated that walleyes respond strongly to the movement of food organisms. Walleyes usually surrounded the beakers containing live food organisms and repeatedly struck the glass. They were attracted more strongly to Artemia than to Daphnia. Results indicate that odor plays an important role in movement of walleyes to food and that there is a potential for attracting intensively cultured walleyes to man‐made diets with odorants.

Progressive Fish-Culturist↗