11-78 



gill net stations (13 and 19) have taken more than 3 fish at any one 

 time. Mackerel catches in New Haven Harbor have occurred exclusively 

 from May through July. 



The extremely low impingement rate for this species is also 

 indicative of its swimming strength and low abundance in the harbor. Only 

 one individual has ever been recovered from the New Haven Harbor Station 

 traveling screens (22 June 1977) . Similar impingement rates have been 

 reported at other Long Island Sound power plants (NUSCO, 1977; LILCO, 

 1977; CLP, 1977) . 



"Mackerel . . . shed their eggs wherever their wandering habits 

 have chanced to lead them when the sexual products ripen" (Bigelow and 

 Schroeder,, 1953). A 0.85 kg female mackerel is capable of producing up 

 to 546,000 eggs (Bigelow and Schroeder, 1953). Bigelow and Schroeder 

 (1953) also stated that "...mackerel vary so widely in abundance over 

 periods of years that the precise localities of greatest egg production 

 may be expected to vary from year to year depending on local concentra- 

 tions of fish." Such descriptions of mackerel life-history are consis- 

 tent with the history of mackerel egg abundance in New Haven Harbor. In 



1975, the average density during May, the peak month, was 13.30 eggs per 



3 

 m . This contrasts sharply with peak densities recorded for 1976 (0.95 



3 3 



per m ) and 1977 (1.50 per m ). In 1976, peak mackerel-egg densities 



3 

 ranged from 3.60 to 17.50 per m in the vicinity of other Long Island 



Sound power plants. It is also evident from Long Island Sound ichthyo- 



plankton data that mackerel eggs may be expected to occur in substantial 



quantities in this region from May through June (NYOSL, 1974; NUSCO, 



1977). 



In contrast to the observed egg densities , mackerel larvae 



appear to be rather sparsely distributed in inshore waters . In New 



3 

 Haven Harbor, the maxim^am density encountered was 0.001 larva per m (in 



May 1975) . Among the 1976 Long Island Sound ichthyoplankton surveys 



reviewed, the highest larval density reported (for Millstone, in June) 



was 0.01 per m (NUSCO, 1977). 



