206 



NOAA Technical Report NMFS 140 



Geographic Distribution 



Starfishes had a moderately broad areal distribution in 

 the study area (Fig. 226). They occurred in an espe- 

 cially large proportion of the samples from offshore 

 Southern New England and the southern part of 

 Georges Bank but were noticeably absent or sparse in 

 the central Gulf of Maine, central Georges Bank, off 

 Newjersey and along most of the continental rise. 



Asteroid density was generally low throughout the 

 New England region, averaging only 1 to 19/m 2 . The 

 slightly higher densities of 10 to 19/m 2 occurred only 

 in the coastal and near-coastal zones. Biomass of star- 

 fishes was relatively high compared with their numeri- 

 cal abundance, and although they averaged less than 10 

 g/m- over most of their range, there was a substantial 

 number of localities where the average biomass was 

 between 10 and 105 g/m 2 . The rather high biomass ( 10 

 to 50 g/m L ) along the outer margin of the continental 

 shelf off Southern New England corresponds to the 

 distribution of sand in that area (see Fig. 7). 



Differences in starfish density among the six stan- 

 dard geographic areas was moderate — extremes of mean 

 density were 0.2 and 2.5/m 2 (Table 6; Fig. 227). Densi- 

 ties of starfishes were generallv higher in the continen- 

 tal shelf areas than they were on the continental slope. 

 Indications of a north-south trend were revealed by a 

 low density in the Nova Scotian shelf area, intermediate 

 values in the Gulf of Maine and Georges Bank region, 

 and relatively high density in Southern New England. 



Biomass distribution was similar to density. There 

 were only two geographic areas in which the biomass 

 was unusually small (0.02 and 0.05 g/m 2 ), the two slope 

 areas (Table 8; Fig. 227). Relatively high biomasses ( 1.0 

 to 4.5 g/m L ) occurred in the continental shelf areas. 



Disparity in the average size of starfishes from the 

 different areas was substantial. For example, in the 

 Nova Scotia area the average weight of individuals speci- 

 mens was 1 g, whereas in the slope areas, they averaged 

 only 0.1 g each. 



The frequency of occurrence of starfishes was low (6 

 to 19%) in all geographic areas (Table 10). 



Bathymetric Distribution 



Asteroids occurred at depths ranging from 13 to 2,329 

 m, and at a mean depth of 184 m. They occurred in 

 substantially higher densities (1.8 to 2.5/m 2 ) at depths 

 between 25 and 200 m than at other depths (Table 1 1; 

 Fig. 228). In very shallow water (less than 25 m) and in 

 depths beyond the continental shelf their density was 

 0.1 to 0.7/m 2 . Densities were generally lowest in the 

 deepest water. The maximum density of 167/m 2 was 

 encountered at a depth of 49 m. 



Starfish biomass varied considerably from one depth 

 i lass (o another, but the distributional pattern was simi- 

 lar to that described above for density (Table 13; Fig. 



228). The average biomass on the continental shelf was 

 3 to 4 g/m 2 (except in the 25-49 m depth class where 

 the biomass was unusually small). In depths below 200 

 m, the biomass averaged 0.04 g or less per square meter 

 but was slightly higher on the lower continental slope 

 and continental rise than on the middle and upper 

 continental slope. 



The proportions of samples in the various depth 

 classes that contained starfishes ranged from 5 to 20% 

 (Table 15). Their frequency of occurrence was slightly 

 higher between 50 and 200 m than at other depths. 



Relation to Bottom Sediments 



Starfishes were taken in all sediment types except shell, 

 and there were marked differences in quantity between 

 samples from fine-texture sediments compared yvith 

 those from coarse sediments (Table 16; Fig. 229). Earg- 

 est quantities were from fine-grain sediments. 



Average density in the coarse substrates (till and 

 gravel) was 0.2 and 0.8/m 2 , respectively'. In the finer 

 substrates (sand, sand-silt, and silt-clay) asteroids aver- 

 aged 1.3 to 1.8/m 2 . 



Asteroid biomass was 0.5 g or less per square meter in 

 the coarse sediments and 2.0 to 3.6 g/m 2 in the fine- 

 grain sediments. 



Starfishes occurred in a markedly higher proportion 

 (14 to 16%) of samples from sediments composed of 

 fine particles than of samples composed of gravel and 

 till (Sand 9%) (Table 20). 



Relation to Bottom Temperature 



Asteroids were found in moderate to low amounts in all 

 temperature range classes (Table 21; Fig. 230), but they 

 were more abundant where the temperature range yvas 

 moderate rather than extreme. 



Average densities (0.4 to 0.9/m 2 ) of starfishes in the 

 extreme temperature range classes (0°-3.0° and 16°- 

 23.9°C) were considerably below those found in the mid- 

 ranges (4°-15.9°C) where values of 1.2 to 2.7/m 2 oc- 

 curred. In terms of total faunal density, asteroids pro- 

 vided only 0.2%) or less of the total number of specimens 

 in each of the six temperature range classes (Table 22). 



The average biomass of starfishes in the intermediate 

 temperature range classes was quite stable, varying only' from 

 2.8 to 3.6 g/m ; the two extreme classes, however, yielded 

 only 0.1 to 0.5 g/m 2 , respectively (Table 23; Fig. 230). Star- 

 fishes in the various temperature range classes represented 

 from 0.1 to 4% of the total faunal biomass (Table 24). 



The proportion of samples that contained asteroids 

 was lowest (6-4%) in the two extreme temperature 

 range classes and the highest (21%) in the 8°-11.9°C 

 temperature range class (Table 25). 



Relation to Sediment Organic Carbon 



Asteroids yvere present in only four of the eight organic 



