11-74 



quent (monthly) sampling intervals, it appears qualitatively as though 

 there has been a shift in the principal importance of New Haven Harbor 

 regarding anchovy reproduction from nursery area to spawning area. 



Ichthyoplankton data from other power plant locations (LILCO, 



1974; NUSCO, 1977) indicate June and July to be the months of peak egg 



3 

 production. In 1976 peak densities ranged from a low of 2 eggs per m , 



3 

 at Glenwood to a high of 19 m at Millstone; in New Haven Harbor the 



3 

 1976 peak value was 22 eggs per m . The larvae, which were very scarce 



3 

 in 1976 (approximately 0.001 per m ), were far more common at other Long 



Island Sound power plants; their densities ranged from a peak of 4400 



3 3 



per m at Port Jefferson, to 14 per m at Glenwood. Because peak larval 



abundance at Glenwood was greater than egg abundance, this might be 



construed as evidence to support the hypothesis that prime spawning and 



nursery areas may be spatially distinct for this species . 



Atlantio Mackerel (Soombev soombrus) 



According to Bigelow and Schroeder (1953) the Atlantic mack- 

 erel is one of the swiftest swimming species of open ocean fish. It is 

 popular both as a commercial and sport fish. Mackerel are planktivor- 

 ous, feeding on copepods, euphausid shrimp, and other large planktonic 

 Crustacea (Bigelow and Schroeder, 1953) . In winter, mackerel move out 

 into deeper waters of the continental shelf, and return inshore in 

 spring. 



Mackerel are so constantly on the move that sampling methods 

 used in the New Haven Harbor study would not be expected to catch a 

 quantitative sample. The most effective commercial methods of catching 

 this species are the purse seine, and gill nets (Bigelow and Schroeder, 

 1953) . In the New Haven Harbor study, gill nets were by far the most 

 successful (Figure 11-28) , with no catch by beach seine. The greatest 

 catch occurred in May 1975 when 122 fish (37 to 50 cm long) were recov- 

 ered from gill nets at Station 19 (Figure 11-29) . Only the outermost 



(Text continued on page 11-78) 



