On survival of the larvae of marine parasitic nematode <i>Anisakis simplex</i> sensu lato (Rudolphi, 1809) in the fresh waters

Abstract

Survival of the larvae of marine parasitic nematode Anisakis simplex sensu lato (Rudolphi, 1809) in the fresh waters was monitored. In total, 37 live larvae of A. simplex s.l. were sampled from charr Salvelinus malma caught in the lower reaches of the Kamchatka River. The larvae were kept in the freshwater refreshed everyday, without food, their viability was examined daily at 9 a.m. All larvae were still alive in the 4th day (100 %); 2.7 % were alive after 9 days in freshwater, but all of them were died after 10 days. Dependence of the number of dead larvae on the time of their exposition in the freshwater is well approximated by von Bertalanffy equation (R2 = 0.996). Besides, viability of A. simplex s.l. larvae in the bodies of dead sockeye spawners was examined at the spawning grounds in Lake Azabachye: the larvae were alive in the body cavity of fish that died at least 3–5 days ago and remained alive at least 3 days more being placed in the freshwater. The larvae of marine nematode A. simplex s.l. are able to enter to the fresh waters with migratory fish. Following to our results, they can survive there for several days. So, measures for disinfecting against A. simplex s.l. are recommended for the freshwater fish caught in the water bodies connected with the marine environment.

Keywords

• freshwater fish
• salmon
• natural experiment
• lake azabachye
• kamchatka