The bay anchovy is perhaps the most abundant 

 fish along the Atlantic Coast and is usually the 

 dominant ichthyoplankton species in estuaries 

 within its range (McHugh 1977; L^ak and Houde 

 1987). Its range extends from Cape Cod to Mex- 

 ico, with occurrences as far north as Maine 

 (Hildebrand 1943; Bigelow and Schroeder 1953). 

 They are commonly found inshore during the 

 warmer months and move offshore in the winter, 

 but are seldom found in water deeper than 25 m 

 (Grosslein and Azarovitz 1982). Hildebrand 

 (1943) believed that each section of the coast had 

 discrete anchovy populations and movements 

 were inshore and offshore. In LIS, spawning 

 takes place at depths of less than 20 m during 

 .lune through September (Richards 1959). Eggs 

 are pelagic and at 27°C hatch in about 24 hours 

 (Kuntz 1914). Since water temperatures in LIS 

 near Millstone rarely exceed 22°C, incubation 

 probably takes longer here. Development is rapid 

 and individuals may mature within 2.5 months of 

 hatching in Delaware Bay, and maximum life 

 span is probably not more than 2 or 3 years 

 (Stevenson 1958). 



Various anchovy life history stages were very 

 abundant in some programs, but rarely collected 

 in others. Their period of occurrence in each 

 program has been consistent among years 

 (NUSCO 1987b). Adults were primarily found 

 in impingement collections from May through 

 June, which corresponded to the spring inshore 

 spawning migration. The estimated numbers im- 

 pinged at Unit 2 have declined dramatically since 

 1984, particularly in 1986 and 1987 (Table 2). 

 This was probably related to the previously dis- 

 cussed overall decline in Unit 2 impingement for 

 all species. Adult anchovies were rare in the 

 demersal trawl program. Vouglitois et al. (1987) 

 reported large numbers of adults collected in 

 Bamegat Bay, NJ, but their data were from 

 semiballoon otter trawl collections as opposed to 

 our flat otter trawl, which may have accounted 

 for this difference. .luvenile anchovies, resulting 

 from the summer spawning were susceptible to 

 our trawling and were captured during August 

 through October, primarily at NB (Appendix III). 

 Even though anchovies ranked third in trawl 



catch, they were collected infrequently and in 

 large numbers with over 70% of them collected 

 in only 13 of the over 5,000 tows. This infrequent 

 collection of individuals greatly limited the use- 

 fulness of trawl data as an index of abundance. 



At EN, anchovy larvae ranked first among all 

 species and was the third most abundant egg 

 taxon (Table 4). Since over 50% of the eggs 

 collected annually occurred during a 2- to 3-week 

 period, spawning was during a short period of 

 time. The annual date of peak abundance, esti- 

 mated from the Gompertz function inflection 

 point, ranged from late June to mid- July (Table 

 10). The date of the larval peaks did not appear 



TABLE 10. Estimated date of peak of abundance anchovy 

 larvae at EN and NB and eggs at EN based on the inflection 

 point of the Gompertz function. 



to be related to the date of peak abundance for 

 eggs, but the dates for larvae at EN and NB were 

 similar. This similarity suggested that the factors 

 affecting the timing of maximum abundance were 

 probably the same throughout the Millstone area. 

 The causes of the later larval peaks in 1978 and 

 1986 were not known. Any potential impact of 

 the operation of MNPS on the anchovy popula- 

 tion would probably be due to entrainment with 

 annual estimates ranging from 16.0 to 807.7 mil- 

 lion for eggs and from 1.5 to 1,284 million for 

 larvae (Table 11). The estimated number of eggs 

 entrained increased in 1986 relative to the previous 

 year, because egg densities were low in 1985 and 

 the increased cooling water demands of Unit 3 in 

 1986. However, this increase was not apparent 



Fish Ecology Studies 



269 



