GROWTH OF BLUEFIN TUNA 



43 



saiiic iiH'thoil ill coiijunctiuii with counts of 

 vertebral rings in studying tlic growth of western 

 Pacific tunas, as did Partio (1955) for northeastern 

 Pacific albacore. Westnian and Gilbert (1941) 

 and Westnian and Neville (1942) used the method 

 in conjunction with scale studies for bluefin tuna 

 taken off Long Island, X.Y. 



We have based our size-frequency study on 

 lengths rather than on weights, as we believe 

 tluit, for fish of a given age, lengths are subject 

 to smaller and more regular variations. Because 

 we lack sufficient data on the large sizes, we have 



Table 3. — Length frequencies of bluejin tuna from iO.H 

 to 56.5 inches long taken off Long Island ' in 1941 ii^d 

 off Kew England - in 1950-57 from late June to mid- 

 October 



' Westman and Xeville's (1942) sample consisting of 1,129 fish, was meas- 

 ured at Frecport, L.I., (N.Y.). 



' A tew fish caught off Nova Scotia, Long Island (N.Y.), and .Vew Jersev 

 arc included. Most of this sample was taken in the vicinity of Cape Cod', 

 but many of the fish were from the offshore waters, mostiv in the vicinity 

 of Georges Dank. Frank Kilcv measured 1,8'Jl fish at I'rovincelown (\I:iss.") 

 in 1953-54. We are indchted to Lewis R. Day of the Fisheries Hoard of 

 Canada for measuring 5 fisti in Nova Scotia in ly.TO, Jean .McClean Wight of 

 nest Hartford (Conn.) for measuring 5 fish in Nova .-^cotia in l'J.54. Capt. 

 Charles A. Mayo. .Ir.. of I'rovlncetown (Mass.) for measuring ,57 fish there 

 in 19.W, and Dr. Kobert II. Oibbs, Jr., recently of the Wooiis Hole Occano- 

 ?r,''l'"''' '"'•"""""• '">■ mciisuring 69 fish In the Cape Cod area in 19.W and 

 > . ' •. ., '' remainder of the sample was measured by the authors and Donald 



' Includes 102 fish measured June 28-30, 1953. 

 551440 O — 60 2 



not attempted to analyze lengths greater than 

 56.5 inches. 



From various sources, we have compiled length 

 measurements of 4,990 bluefin tuna less than 

 56.5 inches long. With the exception of the 1941 

 sample which was measured on JjOng Island by 

 Westman and Neville (1942), and several fish less 

 tiian 20 inches long which were from more south- 

 erly waters, most of these were taken in the New 

 England area from 1950 to 1957. With the excep- 

 tion of a few specimens less than 20 inches long, 

 the fish were caught from late June to mid- 

 October. We have followed the metiiod of 

 Westman and Neville in measuring the fish to 

 the nearest inch with a tape from the snout to 

 the fork of the tail, following the curvature of 

 the body. Where we used calipers for determining 

 length, we estimated the "curved" measurement 

 from a conversion factor.-' The measurements for 

 fish more than 20 inches long, for all localities 

 and years combined, are listed by half monthly 

 periods in table 3. The data for smaller fish 

 were gathered from more diverse localities and 

 extend over a greater portion of the year, hence 

 are listed in more detail in table 4. 



Table 4. — Lengths of bluefin tuna less than 20 inches long, 

 with dates and localities of capture and so^trces 



See footnotes at end of table 



> A straight line fitted by inspection to a i)lot of straight (cali|)er) length 

 against curved (tai)e) length, based on measurements tor 185 individuals 37 

 to 257 cm. long, indicated that straight length was 0.958 ot curved length. 



