Comparison of Some Life History Characteristics of Pacific Herring (Clupea pallasi) from the Canadian Pacific Ocean and Beaufort Sea

We compared several growth and reproductive characteristics of Pacific herring (Clupea pallasi) from the Canadian Pacific Ocean and Beaufort Sea using data for 2310 fish gillnetted in the northern Strait of Georgia or near Tuktoyaktuk, N.W.T., over the 1985 spawning season. Weight-at-age was similar but Beaufort Sea fish were longer-at-age. Total weight-at-length was significantly greater for Strait of Georgia herring because their size-specific ripe ovary weights were 2.1 times greater. We attributed differences in growth and surplus energy allocation to adult instantaneous mortality rates being 1.8 times higher for Strait of Georgia herring. Size-specific ripe egg weight was 30% smaller in Beaufort Sea herring presumably because warmer sea temperatures over the larval period resulted in a higher mortality rate. Weight-specific fecundity was 1.5 times greater in Strait of Georgia fish. Ovarian growth rates near spawning were lower in Beaufort Sea herring because they mature in colder water.

Egg Weight, Fecundity, and Gonad Weight Variability among Northwest Atlantic Herring (Clupea harengus) Populations

Egg weight varies among northwest Atlantic herring (Clupea harengus) populations that spawn in different seasons (n = 12), but the range in weights is less than half of that known for northeast Atlantic populations. Egg weights were similar for both spring (May–June)- and autumn (August–October)-spawning herring (1.06 ×) and most dissimilar between spring- and summer (July)-spawning herring (1.21 ×). Mean population egg weights were not correlated with temperature either at spawning or for the last 2 mo of the egg development period. The product of egg weight and fecundity (standardized to length) differed between spring- and autumn-spawning herring of the southern Gulf of St. Lawrence. Spring-spawners, particularly smaller fish [Formula: see text], have lower ripe ovary weights than do autumn-spawning herring. Differences between spawning seasons in the relative allocation of storage energy to gonad and metabolism, a process mediated by the duration of the gonad maturation period, are the likely basis for the observed patterns.