MEPS 547:137-147 (2016)  -  DOI: https://doi.org/10.3354/meps11666

ABSTRACT: Extremely high recruitment events can have profound impacts on marine population dynamics. To demonstrate the complexities surrounding extremely high recruitment and its impact on population assessments, Atlantic sea scallop (Placopecten magellanicus) recruitment patterns from 2003 to 2014 were analyzed and the influence of these events on exploitable biomass and harvest numbers was examined. Since 2003, 2 extreme recruitment events have occurred within the scallop stock assessment area on Georges Bank and in the Mid-Atlantic. In 2003, about 12 billion (12 × 10⁹) recruits were present in the Mid-Atlantic, while the total scallop population was about 21 billion scallops. In 2014, about 31 billion recruits were present on Georges Bank, the largest recruit abundance ever recorded, while the total scallop population was about 39 billion scallops. A similar event was also observed outside of the traditional stock assessment area in the Gulf of Maine during 2009. These events dramatically improved the status of the resource. They were not correlated to increases in spawning stock biomass in prior years, suggesting scallop populations do not grow at a constant rate. This growth pattern may be explained based upon scallop fecundity, heterogeneity in scallop distribution, and the importance of early life-history factors. This scenario is not exclusive to scallops and suggests a mismatch between marine population ecology and fisheries management. This mismatch might be rectified through better recognition of ecological and environmental factors, but the complexities surrounding recruitment, exemplified by extremely high recruitment events, suggest a continued need for adaptable management based upon empirical data.

KEY WORDS: Placopecten magellanicus · Population dynamics · Benthic imaging