Settlement, growth, and movement of silver hake Merluccius bilinearis in nursery habitat on the New York Bight continental shelf

Abstract

Silver hake Merluccius bilinearis from the New York Bight were examined for the quality and quantity of their offshore settlement and nursery habitats. Juveniles were collected during 10 cruises between June 1996 and July 1997 using a 2 m beam trawl. Settlement began in July 1996 and peaked in September and October 1996 on the outer shelf (47 to 95 m; 8 to 10°C). Otolith analysis of fish collected during peak settlement was used to calculate the mean age and length at settlement, 34.5 d and 15 mm, and pre- and post-settlement growth rates, 0.35 and 0.51 mm d-1, respectively. Back calculated settlement dates suggest that peak settlement is tied to the lunar cycle. Post-settlement growth rates along a temperature gradient (8 to 12°C) indicate that silver hake in areas of cooler bottom temperatures (~9°C) were not only larger and more abundant, but also faster growing. Movements of early juveniles imply that settlement habitat is more specific than juvenile nursery habitat. Overall, the outer portion (60 to 95 m) of the continental shelf serves as important nursery habitat for silver hake.