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Marine Ecology Progress Series

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MEPS 217:103-109 (2001)  -  doi:10.3354/meps217103

Bay anchovy Anchoa mitchilli in Narragansett Bay, Rhode Island. II. Spawning season, hatch-date distribution and young-of-the-year growth

Amy E. Lapolla*

Box 200, University of Rhode Island, Graduate School of Oceanography, South Ferry Road, Narragansett, Rhode Island 02882, USA

ABSTRACT: Seasonality becomes more pronounced with increasing latitude, so that at northern sites organisms must adapt to a shorter growing season and more extended and severe overwintering conditions. Narragansett Bay (Rhode Island, USA) lies near the northern extent of the range of the bay anchovy Anchoa mitchilli, an abundant member of this estuarine system during the summer months. The length of the spawning season, hatch-date frequency, and young-of-the-year (YOY) growth rates were evaluated for Narragansett Bay anchovies during the summer of 1997 by gonadosomatic indices (GSI) and otolith-increment analysis. GSI data indicated a shorter spawning season for this species in Narragansett Bay than at lower latitudes. Otolith-increment analysis data indicated that hatch-date-frequency was highest in July. Mean YOY growth rate (0.70 mm d-1) was much higher at this latitude than for conspecifics in Chesapeake Bay (0.47 mm d-1). One possible adaptation to a shorter growing season is an increased growth rate during favorable conditions.

KEY WORDS: Bay anchovy · Anchoa mitchilli · Spawning season · Countergradient variation · Otolith-increment analysis · YOY growth

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