Interaction of Temperature and Photoperiod in the Regulation of Spawning by American lobsters (Homarus americanus)

Abstract

Various studies have yielded conflicting information on the role of photoperiod in the regulation of spawning by the American lobster (Homarus americanus). Some have indicated a requirement for short days followed by long days, while others have suggested that there is no photoperiod requirement. To resolve the question of photoperiod control, we exposed mature female lobsters to various combinations of temperature and photoperiod for 1 yr starting in December and found that there was no requirement for spring photoperiod under local winter seawater temperature (0–5 °C, but when winter seawater temperature was maintained at 10–17 °C, spawning came under the influence of spring photoperiod. It therefore appears that vitellogenesis and spawning of nearshore lobster populations are normally regulated by seasonal seawater temperature but that photoperiod can assume a regulatory role if the winter seawater temperature remains abnormally high.