Parasitic fauna, diet and length-weight-age relationships of cod stocks off coastal Labrador within NAFO Divisions 2H and 2J

Abstract

Atlantic cod (Gadus morhua Linnaeus 1758) were sampled on coastal Labrador in August of 1985 at Makkovik (northern portion of NAFO (North Atlantic Fisheries Organization) division 2J) and at St. Lewis (southern portion of NAFO division 2J). A number of biological parameters were compared between the sample areas. These included length- weight-age relationships, diet, and parasitic fauna (nematodes, trematodes, acanthocephalans, and myxozoans). Cod from the two areas were significantly different from each other in prevalences and abundances of nematodes, an acanthocephalan, and a myxozoan. This indicated that separate sub-stocks of cod might exist within the all- encompassing Labrador - East Newfoundland cod stock complex. The present study was carried out in 1986 and 1987 with the same methodology but a larger scope. Sampling at St. Lewis was repeated in 1986 and 1987, sampling at Makkovik was repeated in 1986, three offshore sites parallel to these areas were sampled in February of 1986, and a sample was taken from the more northerly location of Nain (NAFO division 2H) in September of 1987. The results did not concur with the previous work. Prevalence and abundance levels of parasites examined were found to vary significantly with respect to both time and location. No consistently significant patterns were observed for any of the biological parameters examined. Based upon this result it was concluded that Atlantic cod which occur in NAFO divisions 2H and 2J cannot be distinguished in this way.