Steves et a\ Settlement and nursery habitats for demersal fishes 



169 



Materials and methods 



Sample collection 



Ten sampling cruises were conducted between June 

 1996 and July 1997 on board an 85-foot commercial 

 fishing vessel, the Illusion. Summer and fall cruises 

 were conducted monthly, and winter and spring 

 cruises were conducted every other month (Table 1). 

 The 21 stations sampled during each cruise were 

 arranged in three transects (west, central, and east), 

 each with seven stations ranging in depth from about 

 20 meters to 90 meters ( Fig. 1 ). Stations on each tran- 

 sect were located according to bathymetrj' so that six 

 stations were distributed evenly across the range of 

 depths (one approximately every 15 m of depth). The 

 seventh station was placed to fill any large distance 

 between stations that was due to variability in the 

 slope. The distance from shore of stations at a par- 

 ticular depth varied between transects. 



Not all stations were sampled during every cruise 

 (Table 1). Owing to weather, only five stations were 

 sampled during cruise 6 (December 1996) and only 

 two of the three transects were sampled during the 

 February 1997 and April 1997 cruises. Because less 

 than 25^ of the stations were sampled during cruise 

 6, we did not include these data in some of the analy- 

 ses. However, cruises 7 and 8 were included because 

 of their broader range of coverage (between the two 

 cruises all three transects were covered at least once). 



Temperature and salinity data were collected after 

 trawling at each station by using an internally record- 

 ing conductivity-temperature-depth (CTD) probe 

 (Applied Microsystems Inc. model AMS-STD 12). 

 Care was taken to collect data from as close to the 

 bottom as possible without risking damage to the 

 CTD Because a backup CTD was unavailable and 

 the CTD used was not always reliable, gaps in the 

 physical data exist. Expendable bathythermograph 

 (XBT) data collected nearby in early August by the 

 MV Oleander as part of the NOAA Ship of Oppor- 

 tunity Program (SOOP) were substituted for miss- 

 ing temperature data for the central transect in that 

 month. 



Juvenile groundfishes were collected with a modi- 

 fied 2-m beam trawl with 4-mm stretch mesh net 

 ( and 5-cm stretch mesh outer net for chaffing), towed 

 at about 2-2.5 knots. The addition of a meter wheel 

 allowed us to measure the area swept as the dis- 

 tance trawled, multiplied by the width of the trawl 

 (as in Carney and Carey, 1980). At each station, 

 three 5-min tows were made; a fouled trawl was dis- 

 counted and another trawl was repeated. The mean 

 area swept during a 5-min tow was 698 m- ±35.1 m^ 

 (95% CI). 



41 5 



Figure 1 



Twenty-one stations ( numbers 1 on the continental shelf 

 of the New York Bight were sampled with a two-meter 

 beam trawl. 



Table 1 



Dates and sampling stations in the New York Bight for 

 each of the ten cruises in this study. For each of the three 

 transects, numbers indicate the stations sampled on a 

 given cruise (sample locations are depicted in Figure 1). 



' During the August cruise, no temperature or salinity data were 



collected. 

 - The center transect was supplemented by XBT data. 



A 2-m beam trawl is the recommended standard 

 trawl for juvenile groundfish research because its 

 fixed width allows for ready quantification of the 

 area trawled (Kuipers et al., 1992). Our trawl had 

 skids that were heavier than those on most stan- 



