The Uncertain Influence of Spring Photoperiod on Spawning in the American Lobster, Homarus americanus

Abstract

The literature contains a report that induction of final vitellogenesis and time of spawning in American lobsters (Homarus americanus) is controlled by spring photoperiod. However, we could not corroborate this. Two experiments with American lobsters held throughout the winter in Canadian Atlantic seawater temperatures indicated no effect of spring photoperiod on time of spawning. In one experiment the onset of spring photophase was delayed by 2 mo. In the second experiment the photophase at the winter solstice (9 h 46 min) was gradually shortened over ensuing months to 5 h 30 min on 7 July. Neither of these treatments altered the time of spawning relative to control animals on a simulated natural photoperiod cycle. Spawning occurred at photoperiods of LD 6:18 and LD 15:9.