Predation on the eggs of Norwegian spring-spawning herring at a spawning ground outside the westcoast of Norway in 1981

Abstract

Predation on the eggs of demersal spawners has been reported several times, and findings of haddock feeding on capelin or herring eggs is a well known phenomenon. A spawning ground where spawning has been detected through several years was selected as the study-area and investigations on the predation 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 was found to be the main predator on eggs in the area. The total amount of fertilized herring eggs being eaten in a period of 30 days was estimated to be about 10 000 metric tonnes. This is the spawning product of about 20 000 tonnes of herring.