Table 1. — Periods, vessels, and cruises Included In this inventory 



1957: 



1958: 

 1959: 



1960: 

 1961: 



Mar. -Apr. 



June -July 



Sept. -Oct. 



Apr. -May 



July-Aug. 



Jan, -Feb. 



May 



June 



Apr, -May 



Nov. 



Apr, -June 



July 



Aug. 



Sept. -Oct. 



Oct. 



Oct. 



Nov. 



Oct. 



Oct. 



Nov. 



Nov, -Dec. 



Dec. 



Jan, 



Apr. -June 



Nov. -Dec. 



Apr. -June 



May 



Oct. 



Jan. 



Apr. 



May 



Delaware 

 Delaware 



Delaware 

 Golden Eagle 



Crawford 

 Eugenie VIll 

 Bear 

 Eugenie VllI 



Cap'nBill m 

 Delaware 

 Delaware 

 Delaware 

 Cap'n Bill III 



.i7-3 



57-5 



57-8 



58-2 



58-3 



59-1 



59-6 



1 



60-6 



56 



62 



5 



265 



12 



61-1 



61-2 



14 



02-1 



62-2 



62-3 



62-4 



62-5 



6 



63-4 



63-11 



64-3 



64-1 



64-10 



65-1 



65-3 



65-1 



Agency 



BCF 



BCF 



BCF 



BCF 



BCF 



BCF 



BCF 



BCF 



BCF 



WHOI 



WHOl 



WHOI 



WHOI 



WHOI 



WHOI 



WHOI 



WHOI 



WHOI 



WHOI 



WHOI 



WHOI 



WHOI 



WHOI 



BCF, WHOI, NGS 



BCF 



BCF 



WHOI 



BCF 



BCF 



BCF 



WHOI 



^ Agency abbreviations: BCF - Bureau of Commercial Fisheries, WHOI - Woods Hole 

 Oceanographic Institution, NGS - National Geographic Society. 



Generally the presence of tunas is detected 

 directly (sighting the fish) or indirectly (bird 

 flocks, favorable environmental conditions, 

 test fishing). Sight has been used successfully 

 on the Continental Shelf off the northeast coast 

 of the United States aind has figured largely in 

 the development of the Atlantic coast tuna 

 fishery (Murray, 1952, 1955; Wilson, 1965); 

 indirect methods, with gill nets, tramnnel nets, 

 and longlines, in this area have not been as 

 productive (Murray, 1953, 1954). Conversely, 

 sighting of tuna beyond the 100-fath. curve of 

 the Northwestern Atlantic Continental Shelf 

 has been less successful than the indirect 

 method of using longlines to sample subsurface 

 waters (Bureau of Commercial Fisheries, 

 1956; Squire, 1962b). Very few surface schools 

 of tuna or bird flocks have been observed 

 during these investigations. 



Until 1962 the fishery for swordfish in the 

 Northwestern Atlantic was seasonal (June to 

 September), executed with harpoon, confined 

 to waters over the Continental Shelf, ajid 

 limited to visual detection of fish at or im- 

 mediately below the surface. During these 

 explorations considerable numbers of sword- 

 fish were taken with longline gear at night. 

 Subsequently, the swordfish fishery has be- 

 come principally a longline effort undertaken 

 over a much larger area on a 12-month pro- 

 duction basis. Since June 1961 nighttime long- 

 line explorations have been emphasized to 

 determine the distribution, abundance, mi- 

 gration, and availability of swordfish. 



This report summarizes all longline ex- 

 plorations for tuna and swordfish accomplished 

 by BCF and WHOI, some previously unre- 

 ported, within the prescribed area between 

 March 1957 and June 1965. It is within this 

 area of the Northwestern Atlantic that nnost 

 of the effort has been expended. Other longline 

 sets (south and east of the area) made during 

 Sonne of these cruises (Bureau of Connmercial 

 Fisheries, 1957a, 1957b, 1958a, 1958c, 1962, 

 1963, 1965d) and other exploratory longline 

 cruises (south of the area) by WHOI and other 

 agencies (Anonymous, 1960; Bureau of Com- 

 mercial Fisheries, 196l, 1962, 1965a, 1965c, 

 I965e; Tibbo, Lauzier, and Kohler, 1965) are 

 not included in this report. 



These investigations surveyed the distribu- 

 tion and abundance of tunas and swordfish over 

 a large sector of the western North Atlantic; 

 they did not focus entirely on the commercial 

 availability or vulnerability of the species. 

 The resulting effort and catch rates from 

 these explorations should not be nnisconstrued 

 as a singular basis for projection of com- 

 mercial potentials. 



FISHING METHODS 



Longline gear used on cruises between 1957 

 and January 1963 (table 1) was essentially 

 the same as Japamese gear described in de- 

 tail by Shapiro (1950), and modified by the 

 Fish and Wildlife Service's Pacific Oceanic 

 Fishery Investigations (Niska, 1953) and the 

 Bureau's Exploratory Fishing smd Gear Re- 

 search Base, Pascagoula, Miss. (Captiva, 

 1955). The basic unit of longline gear, a 

 "basket" (tub), contained 138 fath. of nylon 

 mainline and ten 5-fath. branchlines (gangions) 

 coiled in a galvanized tub. A commercial 

 Japanese longline hauler was used to retrieve 

 the gear. During Delaware cruises 63-4, 

 63-11, cind 64-3 a l60-fath. manryo mainline 

 and seven 5-fath. branchlines were used. A 

 further modification on Delaware cruises 64- 

 10, 65-1, and 65-3 eliminated the "basket" 

 and Japanese hauler emd provided a continuous 

 manryo mainline with 220-fath. units of eleven 

 20-fath. sections, spooled on a hydraulically 

 powered reel. Ten 5-fath. branchlines were 

 attached to each unit during setout, and re- 

 moved during haulback. On Cap'n Bill III 

 cruises 64-1 and 65-1, a l65-fath. mainline 

 of polypropylene, with ten 1-fath. branchlines, 

 was substituted for the original nylon gear. 



The subsurface (vertical) area sampled in 

 these explorations was within the upper 150 

 fath. Depth at which the gear was fished was 



'' Manryo (kuralon) Is the trade name for synthetic fibers 

 made of polyvinyl alcohol. The material has replaced 

 cotton used for longlines in the Japanese fishery. The 

 trade name manryo referred to in this publication does 

 not imply commercial endorsement of the product. 



