body formations, indicating recent spawTiing. 

 The stomach contained a mussel, Brachidontis 

 recurv2is (Rafinesque), a piece of marl (no 

 doubt ingested accidentally), and a digenetic 

 trematode ; gills and other tissues were free of 

 parasites. 



The fish had entei'ed the waterway through 

 a shallow navigation channel from the adjacent 

 grass flats. The waterway, a network of chan- 

 nels cut through marl, consists of several 161 m 

 by 15 m "fingers" branching from a 1370 m by 

 22 m central channel, with depths averaging less 

 than 5 m at low tide. Surface salinity in the 

 waterway, tested at a sub.^equent low tide, was 

 27.0 '/i,; surface temperature in the adjacent 

 Gulf was 26° C. 



This occurrence, although admittedly irreg- 

 ular, may help to fill a gap in our emerging 

 picture of the origin and distribution of Gulf of 

 Mexico bluefin tuna stocks. 



Bluefin tuna are taken from the Greater 

 Antilles in spring, with substantial numbers of 

 large adults being reported from the Windward 

 Passage in April (Bullis, 195.5: 6) . During May 

 they begin their dramatic migration through 

 the Straits of Florida toward the summer feed- 

 ing grounds (Rivas, 1954, 1955). 



The occurrence of large bluefins at Grand 

 Cayman and east of Cozumel in April (Bullis 

 and Mather, 1956: 9) suggests that at least 

 a component of these Cariljbean stocks may 

 undertake a similar northward movement 

 through the Yucatan Straits and into the Gulf 

 of Mexico. The occurrence of ripe or nearly 

 ripe females in the Gulf in May and of small 

 juveniles (less than 8 cm) in the northern Gulf 

 in late May and early June (Mather, 1962: 5) 

 implies that these stocks sjiawn in the Yucatan 

 Straits or in the Gulf of Mexico proper. Our 

 spent female on the Florida shelf could be from 

 the Caribbean stock or from a stock wintering 

 in the Gulf (Bullis, 1955: 13; Wathne, 1959: 16). 



We are indebted to Gordon D. Marston, St. 

 Petefsburrj Times, for informing us of the in- 

 cident, to Bud and Marvin Mattix and others 

 for allowing us to examine the fish and viscera, 

 to Richard B. Roe for providing information on 

 specimens collected during exploratory fishing 



by U.S. Fish and Wildlife Service vessels in the 

 Gulf of Mexico and Caribbean, to Alice Gennette 

 for preparing histological sections, and to Frank 

 J. Mather, III for critically reviewing the man- 

 uscript. 



Literature Cited 



Bullis, Harvey R., Jr. 



1955. Preliminary report on exploratory long-line 

 fishing for tuna in tlie Gulf of Mexico and the 

 Caribbean Sea. Part I - Exploratory fishing 

 by the Oregon. Commer. Fish. Rev. 17(10) : 1-15. 



Bullis, Harvey R., Jr., and F. J. Mather, III. 



1956. Tunas of the genus Thunnus of the northern 

 Caribbean. Amer. Mus. Nov. 1765, 12 p. 



GiBBS, Robert H., Jr., and Bruce B. Collette. 



1966. Comparative anatomy and systematics of the 

 tunas, genus Thunnus. U.S. Fish Wihil. Serv., 

 Fish. Bull. 66(1) : 65-130. 

 Mather, Frank J., III. 



1962. Distribution and migration of North Atlantic 

 bluefin tuna. Proc. 7th Int. Game Fish Conf. 

 Pap. 6, 7 p. 

 Rivas, Luis Rene. 



1954. A preliminary report on the spawning of 

 the western north Atlantic bluefin tuna (Thunnus 

 thynmis) in the Straits of Florida. Bull. Mar. 

 Sci. Gulf Carib. 4(4): 302-322. 



1955. .A comparison between giant bluefin tuna 

 (Thunnus thynnus) from the Straits of Florida 

 and the Gulf of Maine, with reference to migra- 

 tion and population identity. Proc. Gulf Carib. 

 Fish Inst., 7th Annu. Sess., p. 133-149. 



Wathne, Fredrick. 



1959. Summary report of exploratory long-line 

 fishing for tuna in the Gulf of Mexico and Car- 

 ibbean Sea, 1954-1957. Commer. Fish. Rev. 21 (4) : 

 1-26. 



Robert W. Topp and 

 Frank H. Hoff 



Florida Department of Natural Resources 

 Marine Re.iearch Laboratory 

 Sf. Petrrshurg, Fla. 337.31 



252 



