Striped Marlin in the Northeast Pacific -A Case for Local Depletion and Core Area Management J.L. Squire and D.W.K. Au Commercial and recreational fishermen have were fishing over most of the tropical and sub- been fishing billfish along the west coast of the tropical areas of that area (Fig. I). During this Americas from California to Chile for several same period, Japanese exploration and longline decades. Game-fish fishermen using rod-and- fishing for tunas and billfishes had also ex- reel have fished for sailfish (Isriophorus pla- panded into the Atlantic and Indian oceans. typrerus) in major catch areas off Mexico, Costa In 1963, the Japanese shifted considerable Rica, and Panama; for blue marlin (Makairu longline effort into the northeast tropical Pacific nigricans) and black marlin (Makaira indica) (north to 27"N lat.), where they had already off Panama, Ecuador, and Peru; and for striped found concentrations of striped marlin, sailfish, marlin (Tetrapturus audax) off southern Cali- fornia USA, Baja California Sur-Mexico, and 7\00130° 1100 900 Ecuador. There are also commercial harpoon fisheries for swordfish (Xiphias gladius) off southern California and Chile and hook-and-line 40° fisheries for marlin and sailfish at localities along the east coasts of the Pacific Ocean. Since 1980, a commercial offshore drift-gill-net 30° fishery has expanded off California, increasing the catches of swordfish and incidentally-caught 200 striped marlin. These are localized fisheries that are dwarfed by Japanese longline operations in 100 the eastern Pacific that began after 1960. This paper reviews the development of the 00 eastern Pacific longline fishery for striped marlin and its impacts upon recreational fishing. It pre- 100 sents some arguments for *'core area" manage- ment of the striped marlin resource for providing 2 00 a suitable level of catch necessary for both longline and recreational rod-and-reel fisheries. 30° Eastern Pacific Billfish Fisheries Commercial Fishery After World War 11, the Japanese expanded their longline fishing operations from the western Pacific into the southwest and central Figure 1. The 1956-1968 expansion of the Japanese Pacific. They began exploration into the eastern longline operations into the eastern Pacific (E of 130%'). Pacific (east of 130"W) in 1956 and, by 1963, adapted from Joseph, Klawe, and Orange. 1974. 199 -- 200 PLANNING THE FUTURE OF BILLFISHES and swordfish as well as minor amounts of blue to 38,000 fish. due in part to findings of methyl- marlin and black marlin. Billfish catches in- mercury in the fish (the "mercury problem"). creased in the eastern Pacific (Fig. 2), with the Sailfish catches rose rapidly to 417,000 fish in fleet concentrating on sailfish in areas from 1965. but declined to 19.000 fish by 1980. southern Mexico to Panama and on striped mar- The catches noted preceding are less than the lin and swordfish in an area from the Clarion true totals by the amounts caught by Korean and and Socorro Islands to the southwestern coast Taiwanese longliners. tuna purse seiners (in- of Baja California Sur, and the lower mouth of cidental catch). recreational anglers fishing from the Gulf of California. During 1962-1980, the Peru to California. and by the commercial catch of tunas and billfishes in the eastern Pacific swordfish fleet. Some of these fisheries are ex- amounted to 23.8 million fish, ofwhich approxi- panding. The new drift-gill-net fishery off mately 69% were tunas and 3 1% billfishes. California landed over 75.000 swordfish in Fishery statistics of this expansion into the 1986, well above the 1978- 1980 annual average eastern Pacific have been collected by the Japan of 4,500 fish taken by the traditional harpoon Fisheries Agency, which requires that all fishery. Japanese longliners prepare daily fishing logs. Even so, the Japanese longline fleet and its The results are published annually and give the associated joint-venture operations still com- total species catches and hook effort by 5" prise the major fishery for billfish in the eastern longitude and latitude intervals (Anon 1962- Pacific. Moreover. it is the only oceanic longline 1980). Unfortunatly, the Japan Fishery Agency fishery there that has maintained acceptable fish- has not released these detailed catch-and-effort ing records over a long period of time. data for the years since 1980. Striped marlin, swordfish, and sailfish catch Rereational Fishe? trends in the Japanese longline fishery are shown The billfish catch in the eastern Pacific taken in Figure 3 for the period 19.56-1980. Striped otherwise than by longline is relatively minor. marlin catches peaked in the eastern Pacific at The recreational catch of striped marlin off 338,000 fish in 1968, but have declined since. California takes about 800 fish per year. [In Swordfish catches increased to I12,OOO fish in contrast. an estimated I ,500 other striped marlin the late 1960s. then declined by the early 1970s have been taken incidentally there in recent years 1.500 - I 1962- 1980 TUNA I - Bigeye - 10.129.000 1.250 Yellowfin - 4.093.000 Albacore - 2,027,000 Skipjack - 211,000 1.000 - v,= A TUNAS LL LL 0 (I) 0.750 - z 2-I 5 0.500 - I /'1962-1980 BILLFISH I ' / Striped Marlin - 3.097.000 ..-- I 0.250 - I 1 Sailfish a-Short-billed . I Spearfish 2.895.000 .. ,----I Swordfish - 807.000 Slue Marlin - 5 12,000 I Black Marlin - 54,000 I 1/1111,11I 1956 58 60 62 64 66 68 70 72 74 76 78 80 YEAR Figure 2. Catch by year for billfish and tuna. 1956-1980. by Japanese longline east of 130"W. N.E. PACIFIC STRIPED MARLIN 20 1 500.000 r 400.000 - h Sailfish 8 I v, a w 100.000 - 811111 1956 58 60 62 64 66 68 70 72 74 76 78 80 YEAR Figurn 3. Eastern Pacific Japanese longline catch of sailfish and short-billed spearfish. swordfish, and striped marlin by the drift-gill-net fishery for swordfish and is unrealistic to expect such management in the thresher shark (Alopias sp.).] A preliminary near future. The only international agency that estimate of the recreational catch off Mexico has investigated management for billfish on an (Joseph, unpubl. MS’) indicated 40,000 to ocean-wide basis is the International Commis- 90,000 billfish taken per year. Most are Pacific sion for the Conservation of Atlantic Tunas sailfish, high production areas of which occur (ICCAT). That organization was formed before off Acapulco, Zihuatanejo, and northward to the widespread adoption of 200-mile economic Mazatlin. The estimated annual Mexican or fishery zones in most areas of the world. The recreational catch of striped marlin is 7,000 to recent adoption of such by many Pacific coun- 15,000 fish, the majority from around the tries complicates development of a single mul- southern tip of Baja California Sur. High angler tilateral international agency for the Pacific. catch rates for striped marlin (0.4 or more fish Countries having substantial catches of per angler day), plus occasional catches of blue billfishes and high catch-per-unit effort (CPUE) marlin and black marlin, attract anglers to that rates within their 200-mile zones readily foresee area from the United States and many other that localized restrictions upon foreign fisher- countries. men can have a measurable impact upon their Commercial companies that service recrea- own billfish fisheries. Economic conflicts tional anglers are very important to the economy among different billfish fisheries within these of the southern tip of Baja California, and catch countries’ extended boundaries also heighten the rates must meet anglers’ expectations. Recently, incentive for management. Interest in manage- operators from the major sport fishing locations ment of a pelagic resource at a localized level there have complained of declines in billfish thus gains momentum. catches, which they have blamed on newly de- The striped marlin resource around the southern veloped, joint-venture longline fisheries. tip of Baja California, Mexico, constitutes such The Striped Marlin Fishery a fishery. It supports a very productive localized commercial longline fishery having the highest Management Approaches reported CPUE in the Pacific. It also supports Although Pacific-wide management of an economically important and productive recre- pelagic billfishes has long been considered, it ational billfish fishery. Localized management ‘Joseph. J. 1981, Report on the development of a Mexican that is restricted to this “core area” of striped long1inc fishery, unpublished . marlin distribution (core-area management), and 202 PLANNING THE FUTURE OF BILLFISHES which provides for both fisheries, would thus early 196Os, a moderate increase from 1964 to appear feasible. Demonstrations of area de- 1974, and a greater increase since then (Fig. 4) pletion (or local depletion) of stock as grounds -from about 62.0 million hooks fished in 1964, for this kind of management must, however, be to a 102.5 million hook-effort in 1980 (the latest viewed within the context of the entire exploited data available). stock. The CPUE for catches of tunas and billfishes Management actually began in 1976 when the (all species) (Fig. 5) reflects a decline in tuna government of Mexico proclaimed a 200-mile CPUE prior to the increased emphasis on billfish exclusive economic zone (EEZ). In early 1977, fishing in 1964. Mexico made a concerted effort to enforce its The longline catch of striped marlin is in- conditions. Japanese and US. longliners, as cidental to the catch of tunas in most areas of well as other foreign nationals operating within the eastern Pacific. There are greater than aver- the 200-mile limit, were not allowed to continue age catches off Mexico, however, around and fishing. In 1980, however, a number of permits south of the Galapagos Islands, and in an area were issued, thereby allowing the operation of about 400 miles west of Peru during the southern several foreign longliners in a joint-venture summer (northern winter).