The effects of Lernaeocera branchialis on the Merlangius merlangus population in the Medway Estuary

Whiting entering estuarine waters during autumn are largely free from the copepod Lernaeocera branchialis (L.). Infection soon follows and, between 1973 and 1975, an average 40.4% whiting were infected. The parasite's effects on fish weight over this period are assessed and, in a separate study, its effects on the host's lipid biochemistry determined. Mature adults of L. branchialis caused a significant reduction in body weight. Liver lipid content was also lower in these individuals, by more than 50%. Phospholipid levels were lower but cholesterol readings were greater in infected fish. Fatty acid composition of liver lipids appeared unaffected.