Studies on Ameliorating the Effects of an Acidic River on the Atlantic Salmon

Autor: Laurie Sperry, H.C. Freeman, G.B. Sangalang
Rok vydání: 2009
Předmět:
DOI: 10.1520/stp10293s
Popis: The decline in the Atlantic salmon populations in the poorly buffered rivers in southwestern Nova Scotia, Canada, has been coincident with increased acidic precipitation making mitigation a necessity. In our studies on mitigating the effects of acidic water, sexually maturing adult Atlantic salmon (Salmo salar) were held in the acidic Westfield River (pH 5.1 to 4.7) and the nearby less acidic Medway River (pH 5.7 to 5.2) as a control. Atlantic salmon fed a salt (sodium chloride)-enriched diet to compensate for blood salt losses that occur in acidic waters, had increased reproductive capacity. These fish had a larger percentage of spawners, a larger number of eggs per fish, increased fecundity (number of eggs per gram of fish), and a higher viability of fertilized eggs compared to fish that were fed a commercial trout diet. The female fish on the salt-enriched diet had higher peak levels of the female sex hormone, 17α,20β-dihydroxy-4-pregnen-3-one (17,20-dioHP), which was similar to levels in control fish. When the pH of the acidic river was elevated using limestone, the salmon lost less weight and had lower egg mortalities compared to the fish in the untreated acidic river water. All fish in the limestone-treated water, however, still did not perform as well as the control fish, and they were highly stressed as indicated by the increased production of corticosteroids by the head kidneys (adrenal homologues) in vitro.
Databáze: OpenAIRE