Evelyn S. Sawyer

Survival and growth of vaccinated, medicated and untreated coho salmon (Oncorhynchus kisutch) exposed to Vibrio anguillarum☆

Abstract Vaccination and medication with terramycin resulted in increased survival of pen-reared coho salmon ( Oncorhynchus kisutch ) exposed to vibriosis in a Maine estuary. Mortality was significantly lower ( P

Growth of winter flounder (Pseudopleuronectes americanus) and smooth flounder (Liopsetta putnami) in heated and unheated water

Abstract 0-group and I-group winter ( Pseudopleuronectes americanus ) and smooth ( Liopsetta putnami ) flounder were reared at the Jackson Estuarine Laboratory, Durham, NH, U.S.A., between November 1975 and June 1976. Both species gained weight approximately three times more rapidly in heated than in unheated water. In unheated water the smallest winter flounder gained, on average, 116% of their body weight per month. Larger 0-group winter flounder increased body weight by 55% per month, while comparably sized female and male smooth flounder gained 52% and 28% per month, respectively. I-group female smooth flounder gained 9.5% and male smooth flounder 8.5% per month in heated water. In unheated water increases were 13%, 22%, and 14% per month for 0-group winter, female smooth, and male smooth flounder, respectively. I-group winter flounder in unheated water gained weight twice as rapidly (9.5% per month) as I-group female and male smooth flounder (4.0% and 4.5% per month, respectively). Fish were fed a moist diet at a level of 10% of their body weight per day. Conversions (dry weight of food/wet weight of fish) ranged from 1:1 for 0-group winter flounder in heated water to 27:1 for I-group smooth flounder in unheated water. Disease was a major cause of mortality. Vibrio anguillarum was confirmed as a pathogen; myxobacteria, and the protozoan parasites Kudoa sp. and Nosema sp. were associated with losses.

Sea ranching of pink (Oncorhynchus gorbuscha) and chum (O. keta) salmon in the western Atlantic

Abstract The purpose of this project was to establish commercially viable pink or chum salmon runs on the Maine coast. To obtain the best match of donor and recipient environment, we wanted to see if stocks from Japan, where latitude, climate, seawater conditions and ocean currents are similar to those of Maine, would produce better adult returns than North American stocks. Eyed eggs from Alaskan pink salmon ( Oncorhynchus gorbuscha ) and from chum salmon ( O. keta ) of both Japanese and North American origin were transplanted to Maine. Fry were reared in a hatchery and then in seawater cages for 2 weeks or more before release. Transplant of an odd-year strain of Alaskan pink salmon to Maine was successful in terms of number, size, and quality of returning fish. Eggs taken from these fish were not viable, probably due to high seawater temperature at the time fish were returning. No Asian pink salmon stocks were available for comparison. From 2 830 000 Japanese and 1 001 000 North American chum salmon released, only seven were recaptured. Tissue samples from four returning fish examined showed that all were Japanese in origin. Commercial ranching efforts were discontinued due to an Alaskan embargo on sale of pink salmon eggs and poor returns of chum salmon.