Modelling infection of Baltic herring (Clupea harengus membras) by larval Anisakis simplex

Anisakis simplex larvae were counted in the body cavities of Baltic herring collected in the southern Baltic in 1992–1993, 1995–1996 and 1997. Mean infection intensity in infected fish was generally <10 in fish <30 cm in length but increased sharply to 20–50 in larger fish. Intensities recorded in 1997 were 30–40% higher than those documented in 1992–1993 and 1995–1996. Models relating infection intensity to fish length and weight were developed and used to estimate the asymptotic size of herring. The L estimates ranged from 32.8–34.0 cm, and the W varied from 335.4 to 356.0 g. Estimates of asymptotic length and weight from models of infection intensity were more stable and generally were more precise than those determined from length and weight-at-age data. 2001 International Council for the Exploration of the Sea