LONGLINES AND BILLFISH John S. Gottschalk The introduction of longlin fishing g ar point below the 1 vel rLC ssary for attractive for the taking of pelagic sp ci s op ned th sport angltng, some brolow h > lr>vels of world's billfish stocks to significant exploi­ profitable eommpI'cial r turn, and some t(J tation. Billfishes are scatt red v r wide th p0int wh l'~ t J IT' fllturp. as a stoc~' or as areas and so were never taken in large num­ a sp .cies may IJI In d()ul)t. Bl'caus. th y ber by customary fishing methods. The rangp. wid y ovr l' th> oc ans, and are rela­ world commercial fisheries were quick to tiv ly seal' ,sci ntlfic study of billftsh as seize the opportunity to "skim he cream" IJ en inordillat ly xp 'nsiv,. 1 h r for', in­ from these lightly harvested populations. The formation nr> d d () ans v T' th > qu shon" ar_ pressure of longlining immediately rais d billfish bing OV( rfi h d"!" IS lac..ktng. 1 hlS the question of overexploitation, particularly pap I' at empts to surnmarlZ th g II ral in those areas where angling for sailfish, knowl dg'> of th probl rn. swordfish, and the marlins was w 11 estab­ lished. Japan PlOn red Longllmng Stocks of fish may b overexploit d to Longlin' g ar was nginated and d velop d varying degrees. Some may be r duced to a in Japan's home at rs 10 th 1 50s. Table 1 - Common and Sci ntlfic 1 'am s of h 13illfl hes and The ir n ~ral DistributIon Common arne Sci nitfic i "arne I{ang Swordfish Xiphias glauius Ltnn. \ orid 'lId Sailfish Istiophorus platypterus ('ha\\ and 1 ropical > Todd r) \ orld \ lde Black mar lin l\Iakaira lI1dica (CUVl r) Troplcal Ind 0-PaCIfic Blue marlin I\Iakaira nigricans Troplcal (Lac.) World dde Whi te mar lin Tetrapturus albidus PO€'y. Tropical Atlantic Shore bill spearfish Tetrapturus augustirostris Tropical Tanaka Indo-Pacific Striped marlin Tetrapturus audaz Tropical (Philippi) Indo-Pacific Longbill spearfish Tetrapturus pfleugeri Tropical Robins and deSylva Atlantic Mediterranean spearfish Tetrapturus be lone (Raf.) Mediterranean The author is Assistant for Sport Fisheries to the Director of NMFS. This article is condensed from one he presented at the 1972 Convention of the Outdoor Writers Association of America Mazatlan Mexico, June 26, 1972. ' , MARINE FISHERIES REV Reprint No. 950 20 21 DIAGRAM OF A JAPANE SE lONGlI NE * E =en UP TO 400 "BASKETS " MAY BE TIED TOGETHER TO MAKE A SINGLE SET . SUCH A SET WOULD BE APPROXI MATELY 50 NAUTICAL MILES IN LENGTH AND WOULD CONTAIN 2000 HOOKS . * FROM MERRETT , "JAPANESE TUNA LONGLINING " WORLD FISHING , JULY 1966 . (FOR A DETAI LED HISTORY AND DESCRIPTION OF THE JAPANESE LONGLINE FISHERY SEE "THE JAPANESE LONGLINE FISHERY FOR TUNA" BY SIDNEY SHAPIRO , FISHERY LEAFLET 317 , U.S. FISH & WILDLIFE SE RVICE , NOV . 1950) Fig. 1 - Diagra m of long line gear in use. By the early 1960s, Japanese longline ves­ There have been only four areas in which s els had extended their operations to the longline fishermen have intruded into areas E a stern P acific and into the Atlantic. Then, normally considered the province of sport as now, the principal quarry for the long­ fishermen: along the Pacific Coast of the liners was not billfish as such but rather tuna Americas from Northern Peru to Northern a nd, in the Atlantic, broadbill swordfish. In Mexico, in the Atlantic along the Coast from the early days, billfish taken incidental to Florida to New Jersey, the North Central tuna fishing had little value. The development Gulf of Mexico and, for the broadbill sword­ of "fish saus ages" in Japan induced a limited fish, the Atlantic from Cape Hatteras to New­ market, but since 1966 most Japanese fishing foundland. vesse ls have been e quipped with quick -freez­ ing s y stems. The resultant improvement in For years swordfish have been harvested quality increas ed demand. Now billfish com­ by harpooning. Longlining was introduced in mand high prices in Japan because the flesh 1962. The catch increased from 2100 metric of striped marlin is considered equivalent to tons in that year to 7500 in 1963. In 1969, that of the e xpensive tunas. The Japanese the total catch in the Atlantic was 13,800 fishing effort has spread throughout the world metric tons. A pronounced reduction in the and takes about 70 percent of the world catch. catch of swordfish by U. S. and Canadian fish­ Other countrie s n ow fishing longlines are ermen resulted from the finding in 1969 of Taiwan, Soviet Union, Mexi co, and Cuba. mercury in swordfish flesh in excess of es­ tablished limits in several countries. 22 Table 2 - \ arid 'ateh of Hillflsn, 1 r 64 -70 in Thousands of ;\Lt ric rons (From F AO Ycaruook of I Ish rt S • C,70) 19G4 19G5 1 ( r, b 1 G7 19 8 1 6 1 7 U Sailfish 8 16 • 5 16 15 11 Atlantic 1 2 2 1 2 1 1 Pacific 7 14 12 14 1 10 White marlin 4 5 j 1 Blue & Black marlin 38 33 31 ~8 26 26 26 Atlantic 8 ti 4 3 3 3 Pacific 30 27 27 25 2 23 23 Striped marlin 28 26 24 2 25 25 25 S", ordfish 34 32 33 33 38 Fate of Virgin Fish Popt..iatlon '>00 EAS TERN PACIFIC OCEAN REGION The record of the annual catch of bl11flsh exemplifies the fate of any virgin fish popu­ lation when 1t is first opened to exp.oltation. Greater fishing pressure immediately in­ j creases the catch, sometimes to extraordi­ 400 /', ," , I narily high levels, after which it tends to / , .", / , stabilize at a lower level. For example, as / , .... : ~ SAilfiSH ,.. , / , shown in Figure 2, the Japanese longline catch / , I • •• / of sailfish in the Eastern PaCific region 10- / ., .I '. / , ' / . 10 , I ' creased from 8,000 fish in 1962 to 417,000 I \ I • 1965. Declines in 1966 and 1967 were fol­ /: ' I • 300 l­ / lowed by another peak at 397,000 in 1968. I , I. ', ,/ I ' ,I ', The 1969 and 1970 catches again dropped to I ,, ., 194,000 and 263,000. The same phenomenon /• , ,, I is recorded for the striped marlin catch. / , ,\ , I "" I , \ ' Datafor the Atlantic Ocean catches shown in I I I Figure 3 exhibit the same characteristics, ,/ I 200 ,I except that catches apparently have stabi­ ., lized at a relatively low level. ,I I I To account for the recorded fluctuations I I I in catch, it is neces sary to consider not only I the size of stocks but the maneuverability of ,i the fishery and the amount of effort. In the 100 , Easterr.. Pacific, the number of hooks was doubledin 1963, compared with 1962, and i n­ creased subs tantially agai n i n 1964. TOTAL HOOKS The s e incre a s e s in fis hing eff ort, although pres umably dir ect ed toward tuna, e vidently O~ __-L ____ L- __-L ____ L- __-L ____ ~ __-L __ ~ produced great i ncre ase s in the b illfish c atch. 1962 '64 '65 '66 '67 '68 '69 '70 L ikewis e , the fis hing effort inc reased from Fig. 2 - Japanese catch of billiish in the Eastern Pacific Ocean 42 million hooks t o 50 million hooks (19 0/0 ) Region, 1962-70. To tal hooks includes all fishing effort, bill­ fish and tunas, give n in millions of hooks per year. Catch shown f rom 1967 t o 1968--with an i ncrease in the in thousands of fish. (Annual Report On Japanese Tuna Longline marlin c atc h of 4 7 percent, and of sailfish 40 Fishery, Research Division, Fisheries Agency of Japan, 1970). 23 200r-------------------------------~ Evidence of Population Changes ATLANTIC OCEAN REGION . Other i.ndices that give evidence of changes In populatlOn and characteristics are shifts in average size of fish and rates of catch. In the East ern Pacific, there has been a decline in average size, indicating a reduced stock. 150 The average weight for striped marlin taken by the Southern California sport fishery was about 150 pounds from 1952 to 1958, then dropped gradually through 1965 to about 130 pounds, where it has remained. In 1959, marlin taken during a Japanese scientific cruise averaged 143 pounds. Another scien­ tific cruise in 1964 reported an averaged weight of 110 pounds (Talbot, 1970). Marlin taken off Mazatlan averaged 103 pounds in 1967, and 107 pounds in 1968 (Ware, 1970). There is evidence that the success rate in the Eastern Pacific Fishery has also declined, an indication of fewer fish. An analysis of sailfish data shows catch rates ranging from 50 slightly more than 10 fish per 100 hooks in 1964 toslightly lessthan6 fish per 100 hooks in 1966 (Talbot, 1970). Anglers fishing from Mexican sport -fish­ ing centers report that fishing success has " declined. Talbot and Squire (personal com­ " ---.....-,..,..--- munication) estimated t hat in 1963 about 25,000 striped marlin a nd sailfish were taken 1~6~2~~~--~--~~---L----· 6L7----· ~L----· 6L9--~· 70 along the Mexican coast. A more recent Fig. 3 - Japanese catch of billfish in the Atla ntic Oc ean Region, estimate is not available, but the concensus 1962- 70. Total hooks includes all fishing effort, billfish a nd is that catch pe r boat per day has declined. tunas, given in millions of hooks per year. Catch shown in Ne vertheless, these waters continue to sup­ thousands of fish .