776 



Fishery Bulletin 88(4), 1990 



74" 



7.3" 



20 40 



kilometers 



72" 



Figure 1 



Middle Atlantic continental shelf with outlines of the ocean and 

 estuarine (bay) study areas where finfish were sampled during a trawl 

 survey of the New York Bight, June 1974-June 1975. 



16 



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J J A S O N D 

 1974 



J F M A M J 

 1975 



Figure 2 



Annual cycle of gonad-somatic indices for alewife Alosa pseudo- 

 harenyitx collected in the New York Bight, June 1974-June 1975, 

 including monthly means, ranges, 95% confidence intervals, and 

 number examined. In addition, percent ripe females per month is 

 given on the upper axis. 



Two study areas, ocean and estuarine, were desig- 

 nated (Fig. 1). The ocean area was delineated by an im- 

 aginary set of lines extending seaward from points on 

 Long Island, New York and New Jersey to the 28-m 

 isobath and from the 28-m isobath to the edge of the 

 continental shelf (366 m). This area corresponds to off- 

 shore strata 1-4 and inshore strata 6-17 of the North- 

 east Fisheries Center's resource trawl survey (Gross- 

 lein 1969). The estuarine study area included Sandy 

 Hook, Lower, and Raritan bays. 



Station locations in the ocean study area were 

 selected by stratified random sampling design (Gross- 

 lein 1969). Strata boundaries were determined by 

 depth as follows: 0-10, 11-19, 20-28, 29-55, 56-110, 

 111-183, and 184-366 m. A minimum of two stations 

 per stratum was selected randomly to be sampled dur- 

 ing each cruise. Inshore (0-28 m) and offshore (29-366 

 m) strata were sampled at rates of approximately one 

 station per 515 and 1030 km-, respectively. An aver- 

 age of 49 ocean stations was sampled per cruise. Ocean 

 stations were not sampled during December 1974 and 

 January 1975. 



The estuarine study area was divided into 103 poten- 

 tial sampling blocks. Except where interrupted by land, 

 each block measured 1' of latitude by 1' of longitude, 

 i.e., 1.8 km x 1.4 km (2.5 km-). A set of stations was 

 selected randomly from these blocks and retained 

 throughout the study. An average of 15 estuarine sta- 

 tions was sampled per cruise. Estuarine stations were 

 not sampled during December 1974. 



Fish collections were made with otter trawls towed 

 at approximately 6.5 km/hour for 15 and 30 minutes 



at estuarine and ocean stations, respectively. Estuarine 

 stations were sampled with a 9.1-m trawl and ocean 

 stations with a Yankee #36 trawl. All specimens of each 

 species, up to 35 individuals from each trawl station, 

 were selected and frozen for later laboratory analysis. 

 If the total catch of a species exceeded 35 individuals, 

 a size-stratified sample of 25 to 35 specimens was 

 frozen. At the laboratory each specimen was measured 

 from the snout to the extent of the middle caudal fin 

 ray (±1.0 mm), weighed (±0.1 g), sexed, and state of 

 maturity determined by macroscopic evaluation when 

 possible. Stage of ovarian development was determined 

 visually, and designated immature, developing, ripe, 

 or resting. Ovaries were weighed (±0.01 g) and GSI 

 calculated (ovarian weigh t/fish weight x 100). It should 

 be noted that only mature females were included in the 

 calculation of GSI. 



Temperature and depth observations were made at 

 all stations. Vertical temperature profiles were ob- 

 tained with expendable bathythermographs during 

 ocean cruises and with portable temperature probes 

 during estuarine cruises. Fathometers continually 

 recorded depth during each trawl tow. Detailed infor- 

 mation relative to survey design, methodology, species 

 distribution and abundance, and associated hydro- 

 graphic observations is given in Wilk et al. (1977). 



Results 



The majority (93%) of all ripe females collected during 

 the survey were caught in the ocean study area. Of the 



