Predation on the eggs of Norwegian spring-spawning herring (Clupea harengus L.) on a spawning ground on the west coast of Norway

Predation on the eggs of demersal spawners has been reported several times, and evidence of haddock (Melanogrammus aeglefinus) feeding on capelin (Mallotus villosus) or herring eggs is a well-known phenomenon. A spawning ground where herring spawning has been observed over several years was selected as the study area, and investigations on the predation of eggs were carried out in three steps: (a) stomach sampling; (b) controlled experiments to find the rate of gastric emptying of herring eggs; and (c) bioacoustic surveys to study the distribution and abundance of predators. Haddock were found to be the main predator on eggs in the area. The total number of fertilized herring eggs being eaten in a period of 50 days was estimated to be about 2·7 × 1012, which was about 4% of the total egg production of the herring stock spawning in this area.