MEPS 557:177-187 (2016)  -  DOI: https://doi.org/10.3354/meps11854

ABSTRACT: In recent years, the abundance of American lobster Homarus americanus stocks has increased exponentially in coastal Maine, which is likely due to increased recruitment, enhanced growth rates, and decreased predation. This study analyzed the effects of lobster size (12-19.9, 20-29.9, and 30-39.9 mm carapace length, CL) and temperature on growth rates using an 18 yr mark-recapture study in coastal Maine during a period of considerable warming in the Gulf of Maine. Our results showed that the smallest size class of lobsters grew significantly faster than the 2 larger size classes. Peak molt incidence occurred in June and September for all size classes. Greater percent growth measurements were significantly more frequent in warm years for the 12-19.9 mm CL size class, and were also found to be significantly more frequent in the spring season during warm years for all size classes combined. In addition, time at 50% molt probability for the 20-29.9 mm CL and 30-39.9 mm CL size classes was significantly shorter in warm years. This study represents one of the first documentations of growth of small juvenile American lobsters (<20 mm CL) in the wild, and provides evidence of how juvenile growth varies between warm and cold years. Collectively, our findings have implications for how warming sea water temperatures may affect lobster stock productivity, and are of value to lobster stock assessment models and resource management efforts.

KEY WORDS: American lobster · Mark-recapture · Growth · Temperature · Molt probability · Gulf of Maine