J.S. Stole; T. Gahn; V. Kasper
U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Northeast Fisheries Center, Sandy Hook Laboratory, Highlands, NJ
Steelhead trout (Salmo gairdneri) smolts were placed in flow through salt water tanks containing water pumped directly from Sandy Hook Bay. At the same time, fifty thousand of these fish were released as smolts into the Navesink River, an estuary feeding in& Sandy Hook Bay and the New York Bright. Our object was to maintain the fish and look at growth, survival, and disease prevalence under local conditions. During the first month fifty percent of moribund fish showed signs of gill disease due to myxo-bacteria although only in a small percentage was this determined to be the cause of death. Over a period of one week during the summer the fish were subjected to a period of extreme stress. NNP and PO4 levels were two to three times that of normal and temperatures reached 23°C. During this stress period 60% of the fish died some showing severe symptoms of disease. Furunculosis and myxo-bacteria were positively identified and Vibrio spp. was also strongly suspected.
Except during the period of extreme stress, the losses were few and we conclude that S. gairdneri are capable of surviving in the local environment in some cases through periods of extreme stress; the present survivors having been maintained for a period of one year and have increased their weight over 10-fold and have doubled in length.