Spawning behavior dynamics at communal egg beds in the squid Doryteuthis (Loligo) pealeii

Abstract

Spring inshore spawning of the squid Doryteuthis pealeii was observed during 136 SCUBA dives over 3years, and focal behavioral sampling was used to analyze female mate choice and the multiple tactics that males use to achieve paired and extra-pair copulations. D. pealeii uses two mating positions, each with different placements and usage of sperm. Near Woods Hole, squids aggregated during the day, and then groups of squids descended to the substrate for reproduction on communal egg beds; the operational sex ratio in these mating arenas was 3.13 M:1 F. Four male mating tactics were observed: i. large males acted as paired consorts; ii. when unpaired, large males fought consorts or rarely attempted forced copulations with the paired female; iii. small males behaved as either surreptitious or iv. bold sneakers. In the absence of large males, small males acted as consorts. Paired consorts mated in the male-parallel position and then guarded the female until several egg capsules were laid. Consort males fought other males frequently, winning 90% of fights, and large size was important for winning. Consorts guarded mates, mated frequently, and had 89% mating success. Large lone males often fought consorts but achieved takeovers only 10% of the time and their mating success was 6%. Sneakers did not fight; they mated in the head-to-head position and were not usually challenged by consorts. Collectively, sneakers accounted for 45% of all successful matings due to frequent attempts; average success rate was 29%. Paired, receptive females mated every 14min, with either consorts or sneakers, and laid egg capsules every 5min. Results suggest that females exerted direct mate choice by rejecting 55% of all mating attempts; indirect mate choice was evident from multiple sperm sources available to each female and by previously demonstrated multiple paternity in egg cases. This short-lived species demonstrates conditional reproductive tactics with high flexibility.