COLVOCORESSES and MUSICK: CONTINENTAL SHELF DEMERSAL FISHES 



TABLE 1. — Hydrographic and average catch parameters by site group for Spring NMFS Groundfish Survey cruises, Middle 

 Atlantic Bight, 1968-76. The 1968-72 cruises used a #36 Yankee trawl, the 1973-76 cruises a #41 Yankee trawl. Numbers 

 in parentheses are retransformed values. 



I 



II 



IV 



Site group 



1968-72 



1973-76 



1968-72 



1973-76 



1968-72 



1973-76 



1968-72 



1973-76 



No. of stations 

 Abundance 



log (x + 1) 

 Biomass (kg) 



log(x * 1) 

 No. of species 



Depth (m) 



Temperature 

 ( C C) 



x 



SD 



x 



SD 



x 



SD 



range 



x 



SD 



range 



x 



SD 



237 



2.19(154) 

 040 

 1.70(50) 

 0.40 

 10.1 

 28 



18-101 



50.0 



17.3 



2-9 



46 



1.5 



188 



2.47(296) 

 045 



1.97(95) 

 036 

 12.4 

 3.0 



18-90 



46.5 



15.4 



3-11 

 6.0 



1.5 



92 



2.40(252) 



0.54 



1.79(62) 



0.54 



97 



29 

 24-329 

 117.9 

 46.8 



4-14 

 100 



2.1 



90 



2.62(416) 

 0.40 



2.14(138) 

 0.43 



12.1 

 2.5 



29-152 

 78.9 

 21 9 



7-16 



9.6 



2.0 



138 



2.17(149) 

 068 



1.58(38) 

 0.59 



8.1 



29 



18-349 



84.1 



542 



5-13 



8.9 



22 



53 



2.35(224) 

 0.67 



1 92(84) 

 0.51 



88 

 3.3 



27-152 



75.2 

 332 



5-14 

 10.2 



2.1 



110 



2.16(144) 

 054 

 1.56(37) 

 0.57 



9.1 

 3.3 



66-379 

 222 1 

 78.3 



5-16 

 10 1 



2.0 



112 



2.36(230) 

 0.51 



1.65(45) 

 0.46 



13.1 



4.3 



53-341 

 194.0 

 72.1 



5-15 

 11.4 

 16 



Delaware Bay. This group was generally con- 

 tained behind a strong thermal gradient and ex- 



20 - 



U 



rr is 



z> 



< 

 or 



UJ 



a. 'o 



UJ 



100 



200 



300 



400 



DEPTH (m) 



FIGURE 5. — Temperature-depth envelopes for pooled spring site 

 groups. Middle Atlantic Bight area, 1968-76. To avoid distortions 

 introduced by misclassified stations, points falling over two 

 standard deviations from either mean were excluded. 



hibited the warmest bottom temperatures in the 

 study area. These groups were assigned to site 

 group I for the pooled analyses (Fig. 6, Table 2). 

 Extending northward from these groups along the 

 inner shelf was a second, colder site group which 

 tended to be constricted toward shore between 

 northern Long Island and Cape Cod (group II). 

 During 1973 and 1974, when thermal stratifica- 

 tion was weaker and inshore water temperatures 

 in the north were higher, there was no distinct 

 break between northern and southern inshore sta- 

 tion groups (groups I and II), but instead there 

 were two station groups with members in both 

 northern and southern inshore and mid-shelf 

 waters. One group from each of these years was 

 assignable to each of the two major pooled groups 

 based on faunal similarity; but such assignment, 

 of course, led to the geographical overlap between 

 groups I and II seen off Long Island and 

 Chesapeake Bay in Figure 6. 



One or two site groups each year occurred on the 

 northern mid-shelf primarily between 35 and 90 

 m, in the region of the coolest shelf waters (group 



TABLE 2. — Hydrographic and average catch parameters by site group for Fall NMFS 

 Groundfish Survey cruises, Middle Atlantic Bight, 1967-75. All cruises used a #36 

 Yankee trawl. Numbers in parentheses are retransformed values. 



303 



