Microchemical Signatures in Juvenile Winter Flounder Otoliths Provide Identification of Natal Nurseries

Variation of otolith microchemical signatures between natal nurseries from young-of-the-year (age 0) Winter Flounder Pseudopleuronectes americanus were evaluated. Fish were collected in summer 2012 from 12 nursery areas from New Jersey to New Hampshire, spanning >500 km. Nursery specific microchemical signatures were developed using element : Ca ratios, which were determined with solution-based inductively coupled plasma-mass spectrometry on the whole otolith. Age-0 flounder microchemical signatures showed significant nursery-specific differences and varied on a small spatial scale (about 12 km) based on elemental (Li, Na, Mg, Mn, Sr, Cd, and Ba) ratios. Via quadratic discriminant function analysis, fish were classified back to natal nursery areas with 73% average cross-validation classification accuracies. Based on this preliminary study, otolith microchemistry has the potential to be an effective tool to assess the connectivity between the inshore nursery areas and the offshore adult populations of Winter Flounder; however, further baseline studies are needed. In particular, between-year and within-year variation in the otolith elemental concentrations must be quantified. These elemental analyses need to be linked to specific management needs to be useful to fisheries managers; for Winter Flounder, the ability to rank estuaries by the yield of recruits may help solve estuary-specific anthropogenic challenges.