Mass Abundances of Abnormal Pacific Herring Larvae at a Spawning Ground in British Columbia

Abstract

Abnormalities including contortion of the body and reduction of the jaws and pectoral fins occurred among 2–25% of the yolk-sac Pacific herring larvae Clupea harengus pallasi collected in 1985 from Kulleet Bay, a spawning area on Vancouver Island, British Columbia. An additional 4–68% of the post-yolk-sac larvae had underdeveloped lower jaws. Abnormal larvae were distinguished from healthy larvae through discriminant analysis of morphometric characters. The high frequency of larval abnormalities in 1985 may have been related to unseasonably sunny, warm weather during the 14-d incubation of the eggs, which resulted in stress to eggs exposed to sun and warm air during especially low midday tides. Underdeveloped jaws affected feeding by postyolk-sac larvae, as evidenced by lack of food in the guts and by shallow body depths characteristic of starvation.