OCCURRENCE OF SILVER HAKE, MERLUCCIUS BILINEARIS, 



EGGS AND LARVAE ALONG THE MIDDLE ATLANTIC 



CONTINENTAL SHELF DURING 1966 



Michael P. Fahay^ 



ABSTRACT 



During an ichthyoplankton survey over the continental shelf between Martha's Vineyard, Mass. 

 and Cape Lookout, N.C., from December 1965 to December 1966, 3,241 eggs and 11,032 larvae 

 of the silver hake, Merluccius bilinearis, were collected. Eggs were collected from May until 

 November, with a peak in June. Most of the eggs {7T7c) were collected south of Martha's 

 Vineyard, Mass. The southernmost occurrence of eggs was off North Carolina in November. Larvae 

 were collected from May until December, with a peak in September. Larvae were most abundant 

 on the shelf between Hudson Canyon and Martha's Vineyard. The evidence suggests that most 

 of the eggs and larvae collected on the survey had been spawned near the northeastern edge of the 

 survey area and drifted southwesterly. There is also evidence of a size-related, diel, vertical migration 

 by the postlarvae. 



In December 1965, the Sandy Hook Marine 

 Laboratory began a 1-yr ichthyoplankton survey 

 of the continental shelf between Martha's Vine- 

 yard, Mass. and Cape Lookout, N.C. The survey 

 was designed to delimit the spawning times and 

 locations of marine game fishes, define dispersal 

 patterns of larvae, and form the first phase in a 

 study to determine what species depend on an 

 estuarine environment during some phase of their 

 early life history. We placed emphasis on no one 

 species and began the survey with no preconceived 

 notions on either the geographical extent or the 

 seasonality of spawning of any species. This report 

 on the eggs and larvae of silver hake, Merluccius 

 bilinearis (Mitchill), represents one of a series 

 resulting from that survey. 



The silver hake is an important sport and 

 commercial species widely distributed over the 

 continental shelf of eastern North America 

 from the Gulf of St. Lawrence (McKenzie and 

 Scott, 1956) southward to South Carolina, with 

 centers of abundance between Nova Scotia and 

 New York (Bigelow and Schroeder, 1953). Silver 

 hake are found in both shoal and deep water 

 within a wide temperature range, usually over 

 bottoms of sand or sand-silt mixtures (Fritz, 1965). 

 When winter cooling occurs on the shelf, silver 



'Middle Atlantic Coastal Fisheries Center, Sandy Hook 

 Laboratory, National Marine Fisheries Service, NOAA, High- 

 lands, NJ 07732. 



hake migrate to warmer waters on the conti- 

 nental edge and slope. 



Silver hake in the western North Atlantic con- 

 sist of two morphologically separable and non- 

 mingling populations (Conover, Fritz, and Vieira, 

 1961) roughly separated by the 41°30'N meridian 

 (Nichy, 1969). Hence, the Gulf of Maine and 

 northern edge of Georges Bank contain one 

 population, while the southern slopes of Georges 

 Bank and continental shelf south and west of 

 Cape Cod contain the other. This report concerns 

 the eggs and larvae produced by the latter 

 population. 



Spawning in the Gulf of Maine extends from 

 June to October, with a peak in July and August 

 (Bigelow and Schroeder, 1953). Kuntz and Rad- 

 cliffe (1917) described the embryological and lar- 

 val development of silver hake and suggested 

 that "the spawning period for this species is a 

 protracted one and not all the eggs mature at 

 one time." Sauskan and Serebryakov (1968), in a 

 study of the gonads of silver hake from Georges 

 Bank and the Nova Scotian shelf, showed: 1) 

 larger females mature and spawn earlier than 

 smaller ones; 2) vitellogenesis is asynchronous, 

 and individual fish spawn in three portions within 

 a season; 3) the initial spawning of an individual 

 female accounts for half the total seasonal pro- 

 duction of oocytes. 



Silver hake eggs and larvae have been collected 

 from Halifax, Nova Scotia to Cape May, N.J. 

 (Bigelow and Schroeder, 1953). Eggs and larvae 



Manuscript accepted December 1973. 

 FISHERY BULLETIN: VOL. 72, NO. 3, 1974. 



813 



