SMITH: DISTRIBUTION OF SUMMER FLOUNDER 



We first caught eggs in mid-September. Most 

 of these were 9 to 19 km off western Long 

 Island where depths were 22 to 31 m (Figure 3). 

 Because this September cruise was cancelled 

 after sampling only the four northernmost 

 transects, the data do not show the full distribu- 

 tion of eggs within the area we normally 

 surveyed. Results of the following cruise, how- 

 ever, suggest that spawning in the first half 

 of September was limited to the area between 

 southern New England and New Jersey. 



All eggs caught in October were at stations 

 north of Chesapeake Bay, most of them off 

 New Jersey and Delaware. Stations 22 to 61 

 km offshore over depths of 20 to 48 m accounted 

 for 96% of the catch. No eggs were caught 

 south of Chesapeake Bay (Figure 4). 



In November, the area of spawning had 

 moved southward, for concentrations of eggs 

 were now 65 km east of Assateague Island, 

 Md., and 9 to 19 km off the outer banks of 

 North Carolina. Ten days elapsed from the 

 time we started sampling off Atlantic City 

 until we were able to sample the four northern 

 transects. During that period, spawning ap- 

 parently ended off New York and southern 

 New England, for we caught only one egg in 

 that sector (Figure 5). Considering the sub- 

 stantial number of larvae taken on the four 

 northern transects, it seems probable that the 

 distribution of eggs at the outset of the cioiise 

 in November extended further north than shown 

 in Figure 5, perhaps as far as Martha's Vine- 

 yard or beyond. 



By December (1965), spawning within most 

 of the survey area had ended, for we found 

 eggs only at stations in the southern portion 

 (Figure 6). The following cruise in late January 

 and early February proved even less productive. 

 We caught four eggs at the most southerly 

 station off Cape Lookout. Eggs were absent 

 from samples taken on cruises in April, May, 

 June, and August. 



VERTICAL DISTRIBUTION OF 

 EGGS 



Our sampling program was not designed 

 to study the vertical distribution of eggs and 

 larvae. The patterns of distribution, however, 



suggest that summer flounder eggs drift largely 

 within the shallow depths sampled by net no. 1. 

 At stations where both nets fished, net no. 1 

 caught 75% of the eggs and net no. 2 probably 

 caught some of the remaining 25% in the upper 

 levels during setting and retrieval. This ten- 

 dency of summer flounder eggs to float near 

 the surface was observed during a rearing 

 experiment set up to obtain early larval stages. 

 All artificially fertilized eggs floated in water 

 collected from just beneath the surface, or in 

 the least dense part of the water column, at 

 the site where gravid adults presumably would 

 have spawned soon thereafter. By floating near 

 or at the surface, the eggs were available to 

 our nets for only a part of the 30-min tow. 

 A short incubation period, 72 to 75 hr after 

 fertilization at an average water temperature 

 of 17.5 °C (Smith and Fahay, 1970), may also 

 affect the availability of eggs by limiting their 

 dispersion away from the spawning site. Thus, 

 the buoyancy of eggs and their relatively short 

 incubation period probably account for our nets 

 catching fewer eggs than larvae. 



THE SEASONAL DISTRIBUTION 

 OF LARVAE 



Judging from the changes in the number of 

 eggs in our samples, summer flounder spawned 

 north of Chesapeake Bay from September to 

 December and south of the Bay from November 

 to February. As expected, larvae were taken 

 at the same time as the eggs, and also over 

 a longer period. We caught larvae in the 

 northern half of the survey area from September 

 to February, and in the southern half from 

 November to May. 



Larvae as well as eggs of the 1966 brood 

 appeared first in our collections of mid-Sep- 

 tember, when we sampled only the four nor- 

 thernmost transects (Figure 3). The small 

 number and size of larvae collected then, the 

 more widespread distribution of eggs than 

 larvae, and the absence of both in June and 

 August all indicate that spawning had recently 

 started, probably during the first week of 

 September. The October cruise produced the 

 largest catch of summer flounder larvae of the 

 survey. All larvae were caught north of Chesa- 



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