F 



MATHER, JONES and BEARDSLEY: MARLINS IN ATLANTIC 



CUE'S for each 5°-quadrang-le-month stratum 

 were obtained by summing its yearly CUE's and 

 dividing by the number of years. 



The Japanese longline fishery in the Atlantic 

 Ocean is directed primarily toward catching yel- 

 lowfin tuna, Thunnus albacares, and albacore, 

 T. alalunga, (Wise and Le Guen, 1969). Since 

 marlins form only a small part (<3%) of the 

 total catch of scombroid fishes, fishermen prob- 

 ably do not select specific fishing areas for mar- 

 lins or adapt their fishing gear to catch marlins 

 more eflfectively than other species. Possibly 

 the catch rates for marlins are influenced by 

 variations in the availability or the catchability 

 of the fish, but the effects of such variations can- 

 not be- distinguished on the basis of the available 

 data. We believe, therefore, that the catch rates 

 by the longline fishery represent reasonably well 

 the relative apparent abundance of marlins in 

 the areas and seasons of intensive fishing. On 

 this basis, we discuss distribution of white mar- 

 lin and blue marlin in the Atlantic Ocean in the 

 next sections. 



WHITE MARLIN 



The catches of the wide-ranging Japanese 

 longline fishery show that white marlin are dis- 

 tributed over a much broader area than that in- 

 dicated by returns from fish tagged in the sport 

 fishery in the western North Atlantic Ocean. 

 White marlin have been caught in all consistently 

 fished areas of the Atlantic Ocean from lat 40 °N 

 to lat 40 °S (Figure 6). The available data in- 

 dicate that white marlin are scarce in both the 

 north and south temperate zones in their respec- 

 tive winters (December-February and June- 

 August) . 



Catch rates above 0.5 fish per 100 hooks are 

 reported more often in the western than in the 

 eastern Atlantic Ocean. We therefore conclude 

 that although the distribution of white marlin 

 is oceanwide, the species is more abundant in 

 the western Atlantic. Sport fishermen report 

 that white marlin are often concentrated at the 

 edge of the continental shelf. Data from the 

 longline fishery support this conclusion, inas- 

 much as the catch rates are generally higher 

 in 5 "-quadrangles adjacent to, or including, the 



edge of the shelf than in quadrangles in mid- 

 ocean. No evidence has been found to date to 

 suggest that the relative apparent abundance of 

 white marlin in the Atlantic Ocean has been 

 markedly affected by the longline fishery (Wise 

 and Le Guen, 1969). 



North Atlantic 



In winter (December-February) white marlin 

 are concentrated in the eastern Caribbean Sea 

 and off the north coast of South America as far 

 south as the equator. In spring some of these 

 fish move northward into the Antilles Current 

 beginning in March, and others move westward 

 into the western Caribbean beginning in May 

 and June. The northward movement of the first 

 group conforms to the migrational pattern de- 

 duced previously from tag returns, but the sec- 

 ond group appears to move into the northern and 

 western Gulf of Mexico in summer, a pattern 

 not supported by tagging data. 



High catch rates in October, 300 to 1,200 

 miles oflF the east coast of the United States, 

 support the hypothesis derived from tag returns 

 — that white marlin summering off the U.S. mid- 

 Atlantic coast move offshore in fall. In the Gulf 

 of Mexico, however, white marlin are relatively 

 abundant through October. 



South Atlantic 



In summer (December-February) white mar- 

 lin are concentrated in the central South Atlantic 

 Ocean and off the coast of Brazil. In the latter 

 area, catch rates are among the highest known, 

 occasionally reaching 3.8 white marlin per 100 

 hooks. In autumn (March-May) catch rates are 

 generally lower than in summer and the marlin 

 are not caught as far south. Because large areas 

 of the South Atlantic are not fished in the au- 

 tumn, catch rate data may not reflect a true pic- 

 ture of distribution. From June through Sep- 

 tember white marlin in the South Atlantic are 

 concentrated in the South Equatorial Current 

 and off the southwest coast of Africa. This sea- 

 son is the only one in which white marlin ap- 

 parently are concentrated along the coast of 

 Africa. From September through November, 



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