Vulnerability of larval herring (Clupea harengus pallasi) to capture by the jellyfish Aequorea victoria

Abstract

Gut-content analysis of Aequorea victoria collected in Kulleet Bay, Vancouver Island, British Columbia, Canada, in 1983, showed that the jellyfish consumed herring (Clupea harengus pallasi) larvae, primarily yolksac [≦8mm notochord length (NL)] and post-yolksac larvae (≦12mm NL). Behavioral experiments with laboratory-reared larvae showed that the ability to escape after contact with a jellyfish tentacle increased dramatically from yolksac through pre-metamorphic larvae (up to 20 mm NL). Early yolksac larvae were captured in 91% of the contacts with a tentacle, but the largest larvae in only 13%. Unfed larvae were more vulnerable to jellyfish predation than fed larvae of the same age. Our results indicate that A. victoria is most important as a predator of herring larvae during a short period after the larvae hatch.