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MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps13175

Long-term changes in the maturation and growth of Cape Cod/Gulf of Maine yellowtail flounder (Limanda ferruginea)

Gregory R. DeCelles*, Tiffany Vidal

*Corresponding author:

ABSTRACT: The objective of this study was to understand changes in the maturation and growth of Cape Cod/Gulf of Maine yellowtail flounder (Limanda ferruginea) by examining fisheries independent data from cohorts produced over a 38 year period (1976-2014). Yellowtail flounder in the Gulf of Maine have been harvested by commercial fisheries since the 1930’s, and the most recent stock assessment estimated that from 1985 to 2016 fishing mortality rates exceeded the fishing mortality reference point (F40%) in all but one year. Maturity ogives demonstrated that the length and age at 50% maturity declined for cohorts throughout the time period. Probabilistic Maturation Reaction Norms (PMRN), which describe the probability than an immature individual will become mature at a certain age and size class, demonstrated a shift towards maturation at younger ages and smaller sizes. For age-three female and male yellowtail flounder, the size at which the probability of becoming mature was 0.5 declined from 30.8 cm and 26.0 cm to 23.9 cm and 16.4 cm, respectively. Using von Bertalanffy growth curves, a decrease in asymptotic length (L) and an increase in the growth rate (K) was estimated for both sexes. Taken together, these life history changes are suggestive of fisheries-induced evolution. However, although the PMRN approach is designed to account for phenotypic plasticity associated with growth and survival, further work is needed to determine whether other factors (e.g., temperature and body condition) could be responsible for the changes in maturation observed in this study.