SCHWARTZ AND PORTER: FISHES. MACKOINVERTEHRATES OFF NORTH CAROLINA 



- 34'30' 



34*00' 



FIGURE 3. — Twenty-two sediment sample stations. Dominant 

 grain size is indicated by station. Broken lines enclose the com- 

 mercial area, an area fished by the calico scallop fishery. 



the food items to species was possible in most 

 cases. 



Scallops 



Scallops were sampled from two areas — one 

 general and one specific. The general area, here- 

 after referred to as the commercial area, included 

 wherever the scallop fishery was operating (Fig- 

 ures 1-4). Scallop tissue samples from this area 

 were taken, when possible, once a week; shell 

 length measurements and other appropriate scal- 

 lop data were taken more frequently. Tissue, 

 gonad and/or spawning condition data will be cov- 

 ered in a paper by Porter and Schwartz (in prep.). 



The specific area, hereafter referred to as the 

 experimental area, was an area just northwest of 

 the commercial area. This area was sampled 

 monthly by the Beveridge and was marked from 

 June to September 1972 by a large red buoy; this 

 buoy further served to support the Braincon cur- 

 rent meter (Figure 3). The seabed interval be- 

 tween this area and the commercial area to the 

 south contained no scallops, which suggested that 

 this area was a small separate bed. Only briefly 

 during the latter part of the commercial scallop 



season was the experimental area worked by the 

 1972 fishery. 



Sea Stars 



Data were accumulated on seasonal distribu- 

 tion of the sea stars present on the scallop beds, 

 their size, and relative abundance. Sea star size is 

 here defined as the radius of a sea star through its 

 longest arm. 



About 20 Astropecten articulatus and about 20 

 Luidia clathrata were examined weekly, when 

 available, for stomach contents. Luidia alternata, 

 Goniaster americanus, and Echinaster brasiliensis 

 stomachs were also examined, when available. 

 Stomach analysis examinations which also de- 

 lineated associated organisms were similar to 

 those of Porter (1972b) and will be reported on 

 elsewhere. 



Associated Macroinvertebrates 



Unculled bushels of scallops, as caught by the 

 trawlers, were examined periodically by the field 

 investigator to note other associated organisms, 

 amount of shell material, and signs of dead or 

 dying scallops. Counts were made of each or- 

 ganism and the amount, of dead shell or trash. A 

 log was also kept of all macroinvertebrate species 

 seen during each cruise. 



ENVIRONMENTAL OBSERVATIONS 



Bottom water temperatures exhibited a natural 

 progression from about 12°C in February to a high 

 near 26°C in September. These were within the 

 range 9.9°-33°C noted by Waller ( 1969). Vernberg 

 and Vernberg ( 1970), in laboratory experiments of 

 North Carolina calico scallops, found none sur- 

 vived after 48 h exposure to water of 10°C. 



Bottom salinities throughout the bed, as evi- 

 denced during the shifting seasonal fishing effort 

 (Figure 4), remained fairly constant at 35%o (range 

 31-37%o, Figure 5). This agreed with observations 

 of others for scallop grounds elsewhere (Anderson 

 et al. 1961; Hulings 1961; Grassle 1967; Pequeg- 

 nat and Pequegnat 3 ). 



Kirby-Smith (1970) and Allen and Costello 

 (1972) suggested that upwelling in the vicinity of 



3 Pequegnat, W. E., and L. H. Pequegnat. 1968. Ecological 

 aspects of marine fouling in the northeastern Gulf of Mexico. 

 Texas A&M Univ. Dep. Oceanogr. Proj. 286-F, Ref. 68-22T, 80 p. 



431 



