Staudinger Piedation by four fish predators on two squid species on the Northwest Atlantic continental shelf 607 



68-30 



i_ 



New York 



New Jersey 





Atlantic 

 Ocean 



e ® 



Figure 1 



Map of fishery-independent sampling locations. Circles (•) are locations sampled during the National Marine 

 Fisheries Service annual bottom-trawl survey cruise, triangles (A) are locations sampled by the New Jersey 

 Department of Environmental Protection, squares (■) are locations sampled during a Sea Grant sponsored 

 cruise transecting the continental shelf along Block Island Sound Canyon. 



To obtain an index of relative abundance, final mass 

 values were divided by the number of tows made during 

 each time of day, year, and seasonal period. 



For Equations 1 and 2, values for P and R were es- 

 timated from longfin squid collected regionally during 

 the winter, spring, and fall. Mantle lengths (mm) and 

 the corresponding body weights (g) of individual squid 

 measured in Hunsicker (2004) were used to calculate 

 the percent distribution of biomass in each of the two 

 size classes during each seasonal period. These esti- 

 mated proportions were then used to partition the total 

 catches reported at each NMFS station into prerecruit 

 and recruit biomass. For each seasonal and diurnal 

 period, catches were averaged between years and used 

 to contrast relative concentrations of longfin squid in 

 the demersal environment. Gear biases may affect the 

 catchability of prerecruits more than recruits; therefore 

 relative catch rates were compared among seasons only 

 within each size class. 



Sampling 



Bluefish, goosefish, silver hake, and summer flounder 

 were collected from continental shelf waters off the 

 coasts of New York, New Jersey, Connecticut, Rhode 

 Island, and Massachusetts from February 2002 to July 

 2003. Samples were obtained from two main sources: 

 from fish landed by commercial fishing boats and from 

 scientific survey cruises. Fishery-independent collections 

 were made in conjunction with bottom trawl surveys 

 conducted bimonthly by the New Jersey Department 

 of Environmental Protection (NJDEP) and seasonally 

 (except summer) by the National Marine Fisheries 

 Service, Northeast Fisheries Science Center (NMFS- 

 NEFSC) (Fig. 1). Samples were also collected aboard the 

 RV Sea Wo// (Sea Grant) during an independent survey 

 that transected the continental shelf along the Block 

 Island Sound Canyon (Fig. 1). The proportion of samples 

 collected from fishery-independent sources is shown in 



