Larvae from the Nematode Contracaecum sp. were found in the body cavity of 62% of 53 Northern Anchovies collected from the San Francisco Bay during the months of April, June, July, August, September, and October of 1981. The fish were collected from two sites in the southern part of the Bay, between the Dumbarton and San Mateo Bridges. Parasite larvae were removed from the fish, stained with acetocarmine and identified to genera. The effect that fish size, water temperature, salinity, cyanide (CN), and dissolved oxygen (D.O.) levels in the water had on the frequency of parasitism in the anchovy was examined for statistical significance by means of a chi squared analysis. The parasite frequency increased as water temperature and fish size increased. The parasite frequency was highest when the salinity was 28-29 ppt and when the CN and D.O. levels were at the lowest concentrations. These situations occurred during the months of July and August, indicating a possible seasonal relationship between Contracaecum sp. infections in the anchovy and a changing aquatic environment.
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