Trematode Populations in the Atlantic Argentine, Argentina silus , and Their Use as Biological Indicators

• Published in: Journal of the Fisheries Research Board of Canada
• Main Author: Scott, J. S.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1969
• Subjects: General Medicine; Argentina; Argentine; Newfoundland
• Online Access: http://dx.doi.org/10.1139/f69-086; http://www.nrcresearchpress.com/doi/pdf/10.1139/f69-086

The trematode parasites Lecithophyllum botryophorum, Derogenes various, Hemiurus levinseni, and Lampritrema nipponicum were found in Argentina silus off Nova Scotia and Newfoundland. Changes in the length-frequency distribution in the population of L. botryophorum at different times of the year reflected changes in parasite recruitment and were used tentatively to estimate the life span of the parasite.Hemiurus levinseni had a high intensity and incidence in very young fish, decreasing to a low level in mature fish; L. botryophorum had the reciprocal relationship; and D. varicus was intermediate in incidence and had a low level of intensity in fish of all sizes. These results were related to the occurrence of the intermediate hosts of the parasites and to the movement of A. silus to deeper water as it increases in size. The intensity of infestation with L. botryophorum increased from south to north. Seasonal variation in recruitment, with a peak immediately after spawning, was reflected in the intensity of infestation, mean size, and percentage of immature specimens of L. botryophorum.The young A. silus are midwater plankton feeders and the mature fish change to a diet that incorporates a high proportion of the crustacean intermediate host of L. botryophorum, probably an amphipod. There is no parasitological evidence of separate populations of A. silus in the west Atlantic.