Spawning Habitat, Continental Shelf Area and Herring Production in the North Pacific Ocean

Abstract

Abundance of Pacific herring (Clupea harengus pallasi) populations may be limited by (1) the available area of summer feeding habitat, mainly on coastal shelf waters with depths of 200 m or less, and (2) the area of suitable spawning habitat. Shelf areas may serve as summer feeding areas that account for most of the production of herring biomass. In offshore waters, adult herring rarely are found in waters exceeding 200 m depth and herring schools often are seen close (< 5 m) to the bottom. Throughout the N Pacific, the largest herring populations occur in association with large continental shelf areas. Spawning and nursery habitat consists of shallow, near-shore areas protected from the open sea. The relative proportion of shelf and near-shore habitat varies among areas and populations. The Sea of Okhotsk has a broad shelf area, but maximal herring production often may not be realized because of limited available near-shore habitat suitable for spawning and rearing of the larval and juvenile stages. In contrast, in British Columbia there is a relative abundance of near-shore spawn and nursery habitat and a relative scarcity of suitable shelf areas.