176 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



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 HAMPSHIRE 



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NAUTICAL MILES 

 10 20 30 AQ SO 



Figure 3. — Locations where tagged yellowtail were released. The data in the circle are the experiment number (from 



table 4), the date released, and the number released. 



In discussing these groups of yellowtail we 

 shall use the word "population" to mean an 

 assemblage of yellowtail in a small area at a defi- 

 nite time. The time specification is important 

 because it appears that different populations are 

 found in an area at different times. We shall use 

 the word "stock" to specify larger groups of yel- 

 lowtail consisting of several intermingling popu- 

 lations all of which can be fished by a single fleet 

 of vessels. 



Between February 27, 1942, and August 31, 

 1949, a total of 2,597 yellowtail was tagged and 

 released (table 4, tig. 3) on all of the major United 

 States fishing grounds. Recaptured through De- 

 cember 1952 were 377, or 14.5 percent, 



A tag consisting of two cellulose-nitrate disks 

 joined by a pure nickel pin was placed on each 

 fish selected for tagging. This tag had been suc- 

 cessfully used with winter flounders (Perlmutter 



1946), which are very similar to the yellowtail in 

 body shape and habits. The disk was ^ inch in 

 diameter and bore a serial number and instruction 

 to the finder regarding return of the tag. The 

 tag was attached by pushing the pin through the 

 muscular part of the fish's body about V/2 inches 

 behind the head and % inch from the base of the 

 dorsal fin. The pin was looped over with pliers 

 leaving about y s inch for growth between the 

 disks and the body of the fish. 



The finder was paid $1 for return of the tag, 

 but this was not always enough to stimulate a 

 busy fisherman to send in the tag. In the early 

 part of the program a considerable proportion of 

 the returns came from filleters and other han- 

 dlers. By increasing our personal contact with 

 the fishermen, however, we obtained more tags 

 from them, as well as more complete information 

 concerning the recapture. 



