Distribution of Eggs by Depth and Vegetation Type in Pacific Herring (Clupea harengus pallasi) Spawnings in Southern British Columbia

Abstract

Pacific herring (Clupea harengus pallasi) spawn in southern British Columbia was surveyed by divers in 1976 and 1978. These surveys showed that the distribution of eggs is dependent on the type of vegetation on which the eggs are laid and on the slope of the beach. Most of the spawn on pure sea grass beds was deposited in the littoral zone. Spawn on mixtures of vegetation types was mostly sublittoral and the areal extent of these spawnings has been underestimated by surface surveys. To obtain a good estimate of egg deposition, diver surveys are required. Red algae were the major vegetation type for the study area, followed by sea grass, rockweed, kelp, and other brown algae. Eggs were deposited deeper as the beach slope became steeper. A small fraction of the total egg complement becomes exposed to air as a result of normal tidal cycles during the incubation period, and egg loss from predation and storms was estimated at 10%.Key words: Pacific herring, spawn, egg distribution, vegetation, depth, beach slope