First observations of ‘sneaker mating’ in the California market squid, Doryteuthis opalescens, (Cephalopoda: Myopsida)

Abstract

Commercial harvest of the California market squid, Doryteuthis opalescens, formerly Loligo opalescens, has caused this species to become the largest fishery in the state in the last dozen years, in terms of both tonnage and economic value. All harvest occurs on spawning aggregations. Mating behaviour of Doryteuthis opalescens squid was observed on the egg beds in Monterey, CA during daytime, in La Jolla, CA during the night, and in the laboratory. Small males appeared to insert spermatophores into the mantles of females that were being held in a mating embrace by larger males on several occasions. These ‘sneaker mating’ interactions took 1–15 seconds. After egg deposition females jetted rapidly to disengage themselves from males, and then swam up into the water column. In Monterey, mating groups involved 10–20 individuals and had a sex ratio of one to two males for each female. No larger schools of squid were detected in the vicinity. Monterey observations occurred during a period of decreasing commercial landings and decreasing observations of egg beds on a spawning ground that had been productive since 1863.