Larval Anisakis simplex (Nematoda: Ascaridoidea) Infection in the Musculature of Atlantic Cod, Gadus morhua, from Newfoundland and Labrador

Abstract

Larvae of Anisakis simplex were found in the flesh of Atlantic cod, Gadus morhua, collected in 21 regions around Newfoundland and Labrador during 1985–87. Prevalence and abundance increased with cod size and varied geographically; cod off Labrador had the fewest larvae whereas those from the south coast of Newfoundland were the most heavily infected. Most larvae (~95%) occurred in flesh surrounding the body cavity (napes), with a significantly higher percentage of the nematodes (~58%) in the flesh on the left side. In 505 cod in which all tissues were examined, 85.6, 10.8, and 3.5% of the A. simplex resided in the body cavity and viscera, napes, and fillets, respectively. Cod surveyed tended to have more A. simplex in the musculature than those from other areas off eastern Canada, but are lightly infected compared with most other Atlantic cod stocks. The examination method (candling combined with slicing) recovered, on average, 42% of the A. simplex present in the flesh; consequently, infection statistics reported here are underestimates. Numbers of A. simplex in cod off Labrador and eastern Newfoundland are similar to those observed during 1947–53, but the abundance of A. simplex appears to have increased among cod from NAFO Subdivision 3Pn.

Occurrence of anisakid nematodes in Atlantic cod (Gadus morhua) and Greenland cod (Gadus ogac), West Greenland

“…Disregarding discrepancies that can be ascribed to variation in methodology, the nematode prevalence and intensity recorded here in Atlantic cod is generally in agreement with values observed also in waters off northern Canada and Norway (Brattey and Bishop 1992, Boily and Marcogliese 1995, Hemmingsen et al 2000. Regarding parasite prevalence there was a tendency of regional variation, in that Atlantic cod appeared to become more quickly infected in the Sisimiut area than in the Godthaab area.…”

“…Regarding parasite prevalence there was a tendency of regional variation, in that Atlantic cod appeared to become more quickly infected in the Sisimiut area than in the Godthaab area. Similar geographical variation has been observed off Canada, and may in part reflect the distribution of the phocid and cetacean definitive hosts (McClelland et al 1983, Brattey and Bishop 1992, Boily and Marcogliese 1995, McClelland 2002. However, it is difficult to quantify this difference and it is at present impossible to evaluate if the distribution of definitive hosts, which determines nematode composition in this area, influences parasite accumulation in the species studied here.…”

“…The present study is no exception as both nematode prevalence and intensity increased with the length of the cod. Because anisakid nematodes often are long-lived (several years) (Strømnes and Andersen 2002) and hence particularly prone to accumulate over time (Brattey and Bishop 1992;McClelland 2002), such relationship is to be expected. However, the relationship is clearly non-linear, showing a rapid increase in nematode prevalence as well as the rate of parasite accumulation in both species of cod around size class 2-4 (Figs 1 and 2, Table II).…”

Infection withPseudoterranova decipiens(Krabbe, 1878) larvae in cod (Gadus morhua) relative to proximity of seal colonies

“…MCCLELLAND (1980) found higher survival, fecundity and growth of sealworms in grey seals than in common seals, which indicate that grey seals are better final hosts than common seals. In areas with only common seals the seals are known to carry considerable amounts of sealworms, and therefore be an important source for P. decipiens infections, particulary in inshore cod stocks (SCOTT & FISHER 1958;MCCLELLAND 1990;BRATTEY & al. 1990).…”

A human case of gastric infection by Pseudoterranova decipiens larva

“…Considering these results, P. decipiens larvae seemed to be somewhat longer than those of Anisakis type I. Third stage larvae of P. decipiens are frequently found in the muscle of cod (Gadus morhua) in areas where seal are present (Brattey et al, 1990). However, there is still no report on the fish intermediate host of P. decipiens in Korea.…”