OCCURRENCE OF A SWIM-UP SYNDROME IN LAKE-ONTARIO LAKE TROUT IN RELATION TO CONTAMINANTS AND CULTURAL-PRACTICES

Collections of lake trout eggs were made from Lake Ontario adults to e valuate the occurrence of a swim-up mortality syndrome and determine i ts relationship to cultural practices and egg contaminant burdens (PCB s, pesticides, dioxins, furans, polynuclear aromatic hydrocarbons, and trace metals). The syndrome, characterized by hyperexcitability, anor exia, loss of equilibrium, and eventual death, was observed in fry hat ched from eggs of 21 of 24 (87.5%) females. Mortality due to the syndr ome averaged 33.5% but was not correlated with fertilization rate, hat ching rate, or ally of six specific mortality types monitored in eggs and fry. Occurrence of the syndrome was not related to rearing tempera ture (i.e., 4 degrees C vs. 8 degrees C) or feeding (i.e., fed vs. unf ed). No significant correlations existed between any of the contaminan ts measured and either swim-up syndrome mortality or the sir mortality types monitored.