YELLOWTAIL FLOUNDER OFF NEW ENGLAND 



231 



em New England stock or that the populations of 

 yellowtail were not uniformly distributed. That 

 both conditions exist is indicated by the irregular 

 tag returns from certain releases and by the differ- 

 ences in size, age, and sex composition at different 

 times in different statistical subareas (figs. 9 and 

 20, and appendix C) , 16 These phenomena prevent 

 the conventional determination of the effect of 

 fishing on the stock because we cannot satisfy the 

 assumption that the fishing is uniform on all parts 

 of the stock. 



The changes in availability also prevent any 

 clear determination of the recruitment resulting 

 from spawning. The assumption that larger re- 

 cruitment results from larger spawning stocks is 

 being challenged for many species as data become 

 available. Likewise, we doubt that large popu- 

 lations of spawning yellowtail produce more 

 young, because we have evidence that only one 

 slightly dominant year class ( 1941 ) was produced 

 during the years of large spawning populations 

 (1939 to 1942, and perhaps earlier). Probably, 

 natural conditions greatly affect the survival of 

 the young, because the collections of eggs and 

 larvae indicate that the young drift widely in 

 their pelagic stages at which time they must be 

 vulnerable to changing weather conditions, espe- 

 cially winds that may blow them far from suitable 

 bottom. 



Obviously, a great population of yellowtail ac- 

 cumulated through unknown but favorable cir- 

 cumstances and was ready for the fishery, which 

 sought it increasingly after 1938. The fish were 

 centered on a rather restricted kind of coarse red- 

 sand bottom and extended from there beyond the 

 scope of the fishery. We postulate that as the 

 fishery removed them from the favorite grounds 

 scattered groups or individuals moved in to be 

 caught and to make way for others. The new 

 groups of yellowtail became available as others 

 were caught at an estimated annual rate of 35 

 percent (the approximate annual equivalent of 

 an instantaneous rate of +0.30) over and above 

 any natural mortality. This process continued 



"Note especially in appendix C, p. 239, the usually, but not 

 always, greater size in subarea O compared with Q and S, the 

 great preponderance of 86 percent females (of small size) during 

 the third quarter 1943 in subarea Q, and the reversal of the size 

 of females in the large samples from subareas O and Q in the 

 fourth quarter of 1945 and the first quarter of 1946. The females 

 averaged 38.81 cm. in length in Q and 37.07 in O at first, and 

 then 37.46 in Q and 38.83 in O. 



until 1949, when there were no other yellowtail 

 to move in and parts of even their favorite 

 grounds were used by other species. Why the 

 stock, both on and beyond the fishing grounds, 

 was not replenished by young as the adults were 

 removed is unknown. It appears that the fishery 

 used up the accumulated stock during years when 

 few young survived. Further, the unchanging 

 growth rate indicates that the removals by the 

 fishery did not leave better living conditions for 

 the remaining fish. 



MANAGEMENT OF THE YELLOWTAIL 

 FLOUNDER 



We believe it is probable, although it cannot 

 be proved, that the major changes in the yellow- 

 tail flounder fishery were not caused by overfishing 

 although that may have hastened its decline. 

 Many of the documented facts about the yellow- 

 tail populations are not in accord with theoretical 

 changes caused by heavy fishing nor, with the 

 limited data available, can we develop a theory 

 that will, with a reasonable probability, associate 

 fishing with the decline. Therefore, we have no 

 answers to the fundamental questions of what 

 sizes and numbers of fish can be expected from 

 a given fishing effort or what measures would re- 

 sult in the greatest desired return from the fishery. 



A negative approach to the question of pro- 

 tective measures is warranted because only a few 

 practical measures have been devised to conserve 

 an ocean fishery of this kind. These measures are 

 all restrictive and should be adopted when they 

 probably will increase the catch or, as Graham 

 (1951) has suggested, fix the fishing level, 

 methods, or seasons, and give the fishermen peace. 

 Restriction for either of these reasons must be 

 considered in conjunction with all of the fishing 

 in the area, not merely for the yellowtail, which 

 after 1945 amounted to less than half of the land- 

 ings from the southern New England Banks. We 

 have little knowledge of these other fisheries, but 

 with what is available on them and the yellow- 

 tail we can eliminate most of the measures usually 

 employed from further consideration. 



A closed season on yellowtail appears to offer 

 no help except that which might accrue from re- 

 duction of the total catch (to be discussed later). 

 The period usually considered for closure is the 

 spawning season and with the yellowtail this has 



