USGS Science⌕ Search
Home/Archive/USGS

USGS · 1000095

Decline of mercury in young fishes from western Lake Erie between 1970-71 and 1974

Wolf-Dieter N. Busch
View original source ↗Export metadata ↓

Abstract

Concentrations of total mercury were determined for samples of age 0-II whole fish of six species collected from western Lake Erie in 1970-71 and five species collected in 1974. Within years, average total mercury concentrations increased with age and size in all species. The concentrations were significantly lower (37 to 86%) in 1974 than in 1970-71. Methylmercury concentrations and the proportion of methylmercury to total mercury increased with age and size of fish in samples of four species collected in 1970-71.

Explore related subjects

Progressive Fish-CulturistArticle

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Wolf-Dieter N. Busch. 1983. Decline of mercury in young fishes from western Lake Erie between 1970-71 and 1974. https://doi.org/10.1577/1548-8659(1983)45%5B202%3Adomiyf%5D2.0.co%3B2

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2000

Effects of rearing density and raceway conformation on growth, food conversion, and survival of juvenile spring chinook salmon

Four brood years of juvenile spring chinook salmon Oncorhynchus tshawytscha were reared in conventional and baffled raceways at various rearing densities and loads at Willamette Hatchery, Oregon. A period of rapid linear growth occurred from August to November, but there was little or no growth from November to March when the fish were released. Both fall and winter growth rates were inversely related to rearing density. Final weight and length were also inversely related to rearing density. No significant relationship between load and any growth variable was observed. Fish reared at lower densities in conventional raceways tended to develop bimodal length distributions in winter and early spring. Fish reared in conventional raceways showed significantly larger growth rates and final lengths and weights than those reared in baffled raceways. Food conversions and average delivery times for feed were significantly greater in baffled than in conventional raceways. No significant relationships were observed between either rearing density or load and condition factor, food conversion, or mortality. Mortality was not significantly different between the two raceway types. When fish were transported to seawater for further rearing, there were no significant relationships between mortality in seawater and rearing density or load, but fish reared in baffled raceways had significantly higher mortality than those reared in conventional raceways.

Progressive Fish-Culturist↗
USGS1998

Effects of routine handling and tagging procedures on physiological stress responses in juvenile chinook salmon

Juvenile chinook salmon Oncorhynchus tshawytscha were subjected to handling and tagging protocols typical of normal hatchery operations and monitored for their physiological response to stress. Treatments included coded‐wire‐tagging, counting, ventral fin clipping, adipose fin clipping, and a procedure simulating a pond split. Treatment fish were also subjected to a standardized stress challenge (1 h confinement) to evaluate their ability to deal with disturbances subsequent to a handling or tagging procedure. Circulating levels of cortisol and glucose were used as indicators of stress. Each of the treatments elicited very similar responses among treatment groups. Cortisol increased from resting levels of about 20 ng/mL to about 90 ng/mL by 1 h poststress and returned to near resting levels by 8 h poststress. Glucose levels increased from 50 mg/dL to about 80 mg/dL by 1 h poststress and remained elevated for much of the experiment. The cortisol and glucose responses to the confinement stress did not differ over time or among treatments. However, the confinement stress results do suggest a small but significant cumulative response, indicating small residual effects of the original handling protocols. No deaths were noted among treatment groups.

Progressive Fish-Culturist↗
USGS1998

Control of furunculosis and enteric redmouth disease in sea-run Atlantic salmon broodstock in the Connecticut and Merrimack Rivers

Adult sea‐run Atlantic salmon Salmo salar captured and transported to Richard Cronin National Salmon Station (Sunderland, Massachusetts), Nashua National Fish Hatchery (Nashua, New Hampshire), and Whittemore State Fish Hatchery (Waterford, Connecticut) during 1986–1992 were treated with oxolinic acid and a bacterin. The bacterin was developed against furunculosis and enteric redmouth disease. Among the 2,552 fish that were treated since 1986, 362 died and 65 (18%) of those fish had furunculosis. Among 206 untreated fish that were maintained as controls, 109 died and 63 (57.8%) had furunculosis. The reduction in mortality could not be attributed to either vaccine or antibiotic alone without further study. A 3‐year study was designed to investigate if adult Atlantic salmon, undergoing the stress of migration, handling, and spawning, could mount a protective humoral immune response. Although the salmon were able to produce an agglutinin response, evidence was not found for production of a protective humoral response by these vaccinated Atlantic salmon.

Progressive Fish-Culturist↗