CHAPTER 11. PART 1 



Table 11.1-1 — Dales, vessels, affiliations, and types of gear aseil to collect clams and scallops before, during, and after the 1976 oxygen depletion 



event 



Dale 



Vessel 



Affiliation 



Type of gear 



NOAA 



NOAA 



NOAA 



State of N.J. 



Commercial 



NOAA 



NOAA 



Commercial 



Commercial 



Commercial 



Commercial 



Commercial 



NOAA 



Commercial 



Commercial 



NOAA 



NOAA 



NOAA 



scallop dredge 



clam dredge 

 otter trawl 

 clam dredge 

 otter trawl 

 otter trawl 

 otter trawl 

 clam dredge 

 clam dredge 

 otter trawl 

 clam dredge 

 clam dredge 

 otter trawl 

 otter trawl 

 clam dredge 

 scallop dredge 

 otter trawl 



clam dredae 



New Jersey. Evidence of mortality in surf clams was re- 

 corded at 12 stations, ocean quahogs at 9 stations, and sea 

 scallops at 1 station. 



Surf Clam Mortality 



Mortalities in surf clams had been determined before 

 the anoxic event. During an April b to May 13, 1976, 

 resource assessment survey, 217 clam stations were sam- 

 pled in the Middle Atlantic Bight, and included 82 stations 

 at 11. (J to 85.3 m off New Jersey (Northeast Fisheries 

 Center 1967a). Only 5.0 percent of the clams off New 

 Jersey had recently died. 



Surveys in the affected area off New Jersey on August 

 6-8, September 9-14, and October 7-8, sampled a total 

 of 25, 31, and 11 stations, respectively (Northeast Fish- 

 eries Center 1977a). The stations were about 18.5 km 

 apart. The entire area was not surveyed during October, 

 because the weather was inclement. 



During the August 6-8, 1976, cruise, mortalities from 

 4.5 to 34.3 percent were observed at 11 stations. The 

 average mortality value for 25 stations was 7.5 percent, 

 compared with 5.0 percent for the April-May 1976 cruise. 

 Data were separated into three depth ranges: 0-18 m 

 (shallow), 19 to 37 m (middepth), and 38 to 54 m (deep). 

 Middepth stations had the highest mortalities. During the 

 September 9-14, 1976, cruise, the overall mortality for 

 the area surveyed was 53.4 percent. Again mortality was 

 highest at middepths. During the October 7-8, 1976, 



cruise, the clam mortality for the entire area surveyed was 

 92.1 percent. At several stations mortality was 100 per- 

 cent. Mortalities averaged 97.4 and 98.2 percent at the 

 shallow and middepth ranges, respectively. High mortality 

 at the deep stations was observed for the first time, show- 

 ing that the clam kill had progressed offshore. 



Ocean Quahog Mortality 



In the New Jersey study area, ocean quahogs were sam- 

 pled only from the shoreward margin of the quahog pop- 

 ulation; most quahogs are in the outer half of the conti- 

 nental shelf. During the August 6-8 cruise, mortalities 

 were low (0.8%). By the September 9-14 cruise, quahog 

 mortality in the area surveyed had increased to 13.3 per- 

 cent. During the October 7-8 cruise, the quahog mortality 

 was 9.2 percent. 



Sea Scallop Mortality 



Sea scallops were assessed before the anoxia event. 

 During August 7-16, 1975, 99 scallop stations sampled in 

 the Middle Atlantic Bight (Northeast Fisheries Center 

 1975), and 27 stations were sampled off New Jersey. In- 

 substantial mortality was observed. 



In October and November 1976, two surveys were made 

 to assess the effects of the anoxic conditions on the sea 

 scallop resource (Northeast Fisheries Center 1977a). Dur- 

 ing the October 6-15 survey, 17 stations were sampled on 

 the inner half of the continental shelf off New Jersey. The 



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