222 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Table 43. — Yellowtail larvae taken April 12-24, 1929 



(Roman numerals indicate the localities (see fig. 25); numbers in parentheses 

 indicate stations established during the mackerel studies, 1925-32 (see 

 Sette 1943)] 



Table 45. — Vertical distribution of yellowtail larvae (off 

 Fire Island) at station A 20498, May 17-18, 1929 



Station and depth of tow 



Montauk Point: 

 Station I (20456): 



Surface 



Deep 



Station III (20454): Deep _.. 



Shinnecock: 



Station I (20448): 



Surface 



Deep 



New York: 



Station I (20447): 



Surface 



Deep 



Station II (20446): 



Surface 



Deep 



Atlantic City: 



Station I (20439): 



Surface 



Deep 



Cape May: Station II (20438): Deep. 

 Hog Island: 



Station I (20424): Surface 



Station II (20432): Deep 



Currituck: Station II (20428): Surface 



Number 

 of larvae 



Length 

 (mm.) 



3.5 

 5.0 



6.0 



3.5 

 3.5 



3.5 

 2.5-4.0 



4.0 

 3.5 



3.0 

 2-3 

 4.0 



4.0 

 4.0 

 4.0 



Table 44. — Yellowtail larvae taken May 10-18, 1929 



Roman numerals indicate the localities (see fig. 25); numbers in parentheses 

 indicate stations established during the mackerel studies 1925-32 (see 

 Sette 1943)] 



that some of the larvae were escaping the net dur- 

 ing the daylight hours. This is borne out in that 

 the larvae averaged slightly larger (4.3 mm.) dur- 

 ing the midnight tows than during the morning 

 (3.6 mm.), noon (3.9), or evening (3.8) tows. 



Horizontal distribution of larvae in 1932. — Sev- 

 eral factors prevented obtaining as comjjlete in- 

 formation on the yellowtail during the cruises of 

 the mackerel investigations in 1932 as in 1929. Be- 

 tween the 1929 and 1932 cruises, much was learned, 

 about the distribution of the mackerel eggs and 

 larvae and better methods of quantitatively sam- 

 pling them were developed. Some stations at the 

 southern end of the series where mackerel eggs 

 and larvae had not been taken in 1929 were 

 dropped, and the 1932 cruises were delayed until 

 May 1 so as to cover the mackerel spawning sea- 

 son more effectively. The method of towing was 

 changed from horizontal to oblique, and the use 

 of two nets, one at a lower level and the other at 

 the upper level, was introduced. Compensation 

 was made for variations in the amount of water 

 strained by the addition of flowmeters to the nets 

 which made it possible to convert the catch to the 

 standard basis of numbers of larvae or eggs per 

 17.07 cubic meters of water strained per meter of 

 depth fished. Finally, with the emphasis on 

 mackerel, the large numbers of yellowtail eggs 

 taken could not be counted ; consequently, we have 

 available counts only of the larvae taken on the 

 1932 cruises. These were divided into two sizes: 

 large, those more than 5 mm. in length ; and small, 

 those from about 2.5 to 5 mm. Details of the 

 methods of towing and counting may be found 

 in Sette (1943). Complete counts of yellowtail 

 larvae are given in appendix E, page 256. 



The small larvae were found in considerable 

 numbers on every cruise (fig. 27). On cruise 1 

 (May 2 to 6) the center of their distribution was 

 from southern New Jersey to Virginia, but this 

 changed abruptly during the following week, and 

 on cruise 2 (May 9 to 16) two principal centers of 

 distribution were found — off southern Massachu- 

 setts and off northern New Jersey. These centers 



