Hawaii's Pelagic Fisheries

Item Type article

Authors Boggs , Christofer H.; Ito , Russell Y.

Download date 03/10/2021 23:40:31

Link to Item http://hdl.handle.net/1834/26499 Hawaii's Pelagic Fisheries

CHRISTOFER H. BOGGS and RUSSELL Y. ITO

Introduction of tuna, billfish, and other tropical pe­ than are covered by Hawaii's fisheries lagic species supply most of the fish (Skillman, 1989a, 1989b; Suzuki, 1989, Hawaii's pelagic fisheries are small consumed by Hawaii residents and sup­ In press; Miyabe, In press). in comparison with other Pacific pe­ port popular recreational fisheries. Availability probably depends on lagic fisheries (NMFS, 1991), but they In recent years (1987-91) the com­ overall abundance, but the availability are the largest fisheries in the State position and magnitude of Hawaii's of fish to Hawaii's pelagic fisheries is (Pooley, 1993b), and much larger than commercial pelagic fisheries have also highly seasonal (Shomura, 1959; other U.S. island-based fisheries in the I changed. The longline fishery greatly Yoshida, 1974; Skillman and Kamec4), western Pacific (Hamm et al. ). Stocks expanded and the troll, handline, and suggesting that highly mobile pelagic pole-and- line fisheries declined (It02). fish change their distribution in re­ ID. C. Hamm, R. S. Antonio, and M. M. C. The expansion of the longline fishery sponse to environmental conditions Quach. 1992. Fishery statistics of the western Pacific. Vo!. VII. U.S. Dep. Commer., NOAA, was consistent with fishery develop­ (Seckel, 1972; Mendelssohn and Roy, Nat!. Mar. Fish. Serv., Southwest Fish. Sci. ment plans that viewed pelagic fish 1986), or to enter different areas for Cent., Honolulu Lab., Southwest Fish. Sci. Cent. Admin. Rep H-92-06, var. pag. resources as underexploited (State of reproduction. Availability may also be Hawaii Division of Aquatic Resources confounded with catchability, defined (HDAR) 1985). Pelagic fish resources as the vulnerability of fish to being Christopher H. Boggs and Russell Y. Ito are with the Honolulu Laboratory, Southwest Fish­ available to Hawaii fisheries may be caught by a given type of fishing gear. eries Science Center, National Marine Fisher­ capable of sustaining even greater Catchability is also influenced by en­ ies Service, NOAA, 2570 Dole Street, Honolulu, yields. However, the decline of the troll vironmental conditions (Sharp, 1978; Hawaii 96822-2396. Mention of trade names or commercial forms does not imply endorsement and handline fisheries has raised con­ Hanamoto, 1987). by the National Marine Fisheries Service, cerns regarding the continued avail­ The limited mobility of most island NOAA. ability of pelagic species and local fishermen causes yield to be poor when overfishing (Boggs3, It02). availability is low. Intense local fish­ Pelagic fish availability is synony­ ing effort is not likely to cause a de­ mous with local abundance, here de­ cline in overall abundance unless there ABSTRACT-Hawaii's diverse pelagic fisheries supply the bulk of the State's to­ fined as the amount of fish present are discrete stocks residing in, or peri­ tal catch. The largest Hawaiifishery is the within the range of the local fishery. odically returning to, island waters. recently expanded longline fishery, which Overall abundance refers to popula­ Otherwise, the fishing mortality caused now lands about 4,400 metric tons (t) of tion size, which is greater than local by Hawaii fisheries is minor compared broadbill swordfish, Xiphias gladius; abundance unless the entire popula­ with overall fishing mortality caused by 1,500 t of bigeye tuna, Thunnus obesus, and 3,000 t ofother pelagic species annu­ tion resides within range of the local larger Pacific fisheries. Thus, local fish­ ally. The increased catch of these other fishery. The stock structure of large ing pressure is unlikely to cause a signifi­ species has raised concerns regarding the pelagic species is unclear, but a com­ cant reduction in overall abundance. continued availability of yellowfin tuna, mon assumption is that pelagic popu­ Even though locally exploited pe­ T. albacares; blue marlin, Makaira mazara; and mahimahi, Coryphaena hippurus, in lations extend over much wider areas lagic stocks may be wide-ranging, and the small-vessel troll and handline fisher­ relatively invulnerable to local fishing ies which target those species. pressure, catch per unit effort (CPUE) Analysis ofcatch per unit effort (CPUE) 2R. Y. Ito. 1992. Western Pacific pelagic fish­ in local fisheries may decline if local statistics from Hawaii's fisheries did not eries in 1991. U.S. Dep. Commer., NOAA, Nat!. fishing effort is so intense that most provide strong evidence ofrecent declines Mar. Fish. Serv., Southwest Fish. Sci. Cent., in availability related to local fishery ex­ Honolulu Lab., Southwest Fish. Sci. Cent. pansion. A more influential factor was Admin. Rep. H-92-15, 38 p. variation in Pacific-wide CPUE, repre­ 3c. H. Boggs. 1991. A preliminary examina­ 4R. A. Skillman and G. L. Kamer. 1992. A tion of catch rates in Hawaii's troll and handline correlation analysis of Hawaii and foreign fish­ senting overall population abundance and fisheries over a period of domestic longline ery statistics for billfishes, mahimahi, wahoo, catchability. Exogenous factors, including fishery expansion. U.S. Dep. Commer. , NOAA, and pelagic sharks, 1962-78. U.S. Dep. Pacific-wide fishing pressure, may over­ Nat!. Mar. Fish. Serv., Southwest Fish. Sci. Commer., NOAA, Nat!. Mar. Fish. Serv., South­ whelm the influence of local fishing pres­ Cent., Honolulu Lab., Southwest Fish. Sci. Cent. west Fish. Sci. Cent., Honolulu Lab., Southwest sure on fish availability. Admin Rep. H-91-05, 62 p. Fish. Sci. Cent. Admin. Rep. H-92-05, 44 p.

55(2), 1993 69 fish entering the local area are soon lin, Makaira mazara; annual commer­ The Longline Fishery caught. It is hypothesized (Sathien­ ciallandings (all species) now average drakumar and Tisdell, 1987; Boggs, In about 2,300 t (5.2 million Ib). No valid Fishing Methods press) that if fish availability depends estimates exist for current recreational on immigration, increases in local fish­ or subsistence landings (Pooley, Longline fishing gear consists of a ing effort result in an asymptotic yield, 1993a). main line strung horizontally across beyond which further increases in lo­ Up until 1980 distant-water 1-100 km of ocean, supported at regu­ cal effort do not increase the catch, longliners from Japan caught between lar intervals by vertical float lines con­ and local CPUE declines. The possible 1,300 and 5,000 t of tuna and billfish nected to surface floats. Descending impact of local fishing effort on the annually within the Exclusive Eco­ from the main line are branch lines, CPUE and profitability of Hawaii's nomic Zone (EEZ) around Hawaii each ending in a single, baited hook. pelagic fisheries is currently an issue (Yong and Wetherall, 1980) but since The main line droops in a curve from of great concern to Hawaii's fishery 1980 there has been no legal foreign one float line to the next and bears managers (Boggs3, In press). longline fishing conducted in the EEZ. some number (2-25) of branch lines This paper describes Hawaii's The Fishery Management Plan (FMP) between floats. Fishing depth depends longline, troll, and handline fisheries enacted by the Western Pacific Re­ on I) the lengths of the float lines and for pelagic species, trends in landings gional Fishery Management Council branch lines, 2) the sag in the main and CPUE over time, and problems (WPRFMC) was designed to regulate line, and 3) the position of the branch with the data used to monitor these billfish catches by these foreign dis­ line, the deepest branch line positions fisheries. Changes in the apparent rela­ tant-water longliners (WPRFMC5). The being in the middle of the droop. Fish­ tive availability of fish (local CPUE) Japanese distant-water pole-and-line ing depth affects the efficiency with are reviewed in relation to local fish­ fishery for skipjack tuna that operated which different species are captured ery expansion and overall abundance in the Northwestern Hawaiian Islands (Hanamoto, 1976, 1987; Suzuki et aI., (Pacific-wide CPUE). Current attempts (NWHI) through 1992 was the only 1977; Boggs, 1992). at managing for optimum yield and the foreign fishery operating legally within One longline "set" is made per day outlook for these fisheries are de­ the EEZ after 1980 (Boggs and of fishing, and for long main lines the scribed. The Hawaii skipjack tuna fish­ Kikkawa, 1993). deployment and retrieval may take al­ ery is covered in a separate paper Although the primary target species most 24 hours. Often the end of the (Boggs and Kikkawa, 1993). of the domestic longline fishery are line deployed first is retrieved last, so different from those of the troll and individual hooks may fish for a few handline fisheries, the longline fishery hours, or all day (average ca. 12 hours). Synopsis of the Fisheries also catches about 1,300 t (2.8 million Traditionally the gear was set so that it The fishing methods, target species, Ib) of yellowfin tuna, blue marlin, and fished primarily during daylight. For vessel sizes, yields, and operational ar­ mahimahi (combined). This creates a bait, Hawaii longliners used locally eas of Hawaii's domestic pelagic fish­ potential for fishery interaction be­ caught scad, Decapterus and Selar spp.; eries are diverse. The commercial tween the longline and small-vessel imported squid, Loligo sp.; sardines, sectors are largely composed of the troll and handline fisheries. Potential Sardinops caerulea; herring, Clupea pole-and-line and longline fisheries uti­ interactions, impacts on endangered pallasi; and saury, Cololabis saira. lizing large (> 12 m) vessels. The small­ species, the possibility of localized The Hawaii longline fishery began vessel troll and handline fisheries in­ overfishing, and gear conflicts (Pooley, in 1917 off Waianae, Oahu, using tech­ clude poorly differentiated commercial, 1990) prompted the WPRFMC to es­ niques imported from Japan. Hawaii recreational, and subsistence compo­ tablish regulations for the domestic longline vessels evolved from the nents. The pole-and-line fishery tar­ longline fishery in 1990 (Dollar and wooden sampan-style baitboats used gets skipjack tuna, Katsuwonus pelamis, Yoshimot06). A moratorium on entry in the pole-and-Iine fishery for skip­ and lands about 1,000 metric tons (t), oflongline vessels into the Hawaii fish­ jack tuna (June, 1950). The sampans (2.2 million Ib) annually for sale to the ery and prohibited areas for longline used in the early years of the fishery local market (Boggs and Kikkawa, fishing were established in 1991. (ca. 1950) were 12-19 m (40-63 ft) in 1993). The longline fishery targets length, high-bowed, and diesel-pow­ broadbill swordfish, Xiphias gladius; ered. They carried about 12 t of ice to 5WPRFMC. 1986. Fisheries management plan and bigeye tuna, Thunnus obesus, and for the pelagic fisheries of the western Pacific chill an average catch of about 3 t now lands about 9,000 t (20 million Ib, Region. Western Pacific Regional Fisheries (7,000 Ib) of fish caught over an aver­ including all species) much of which Management Council (WPRFMC), Honolulu, age trip of 10.5 days (June, 1950). HI 96813,380 p. is exported. The commercial, recre­ 6R. A. Dollar and S. S. Yoshimoto. 1991. The Old-style longlines were made of ational, and subsistence troll and federally mandated longline fishing log collec­ rope and composed of individual units handline fleets primarily target yellow­ tion system in the western Pacific. U.S. Dep. called "baskets" named for the bam­ Commer., NOAA, Natl. Mar. Fish. Serv., South­ fin tuna, T. albacares; mahimahi, west Fish. Sci. Cent., Honolulu Lab., Southwest boo containers they were stowed in Coryphaena hippurus; and blue mar­ Fish. Sci. Cent. Admin. Rep. H-91-12, 35 p. (June, 1950). Each basket was made

70 Marine Fisheries Review up of the float line, main line, and In the early years most of the catch audax, in the early 1950's but striped branch lines necessary for one segment was reported to have been in HDAR marlin became more predominant from of longline (one droop of the line). statistical areas 2-20 n.mi. (3.7-37 km) the early 1960' s to the present (Fig. Poles with flags were attached to the off Waianae, Oahu, and off Kona, Hilo, 1A). Both marlin species are also called floats to mark the gear, and longlining and Hamakua, Hawaii (June, 1950). au (the Hawaiian name) or "sword­ was generally referred to as "flagline" Shomura (1959) reported greatly im­ fish," but they should not be confused fishing. proved catch rates for bigeye tuna by with broadbill swordfish (Fig. IB), longline vessels fishing off the wind­ which became the primary target spe­ ward coasts (i.e., Hilo) in winter as cies in the 1990's (Dollar?). Local com­ Historical Development opposed to the traditional practice of mon names for the pelagic species are and Decline fishing off sheltered leeward coasts often used for reporting catch statis­ Historically, the longline fishery was (i.e., Waianae, Kona). Hida (1966) re­ tics, resulting in some confusion. the second largest commercial fishery ported a growing number of longliners The decline of the Hawaii longline in the state after the pole-and-line fish­ extending their range 100--400 n.mi. fishery in the late 1950's through mid­ ery. By the 1930's longliners landed south ofOahu, and noted that CPUE was 1970's was characterized by a lack of most of the 1,000 t (ca. 2 million Ib) of better than average in the southern area. new investment. Only a few new steel yellowfin tuna, bigeye tuna, and alba­ The species composition of longline or fiberglass boats were built or added core, Thunnus alalunga, landed in the landings changed over time. During to the fleet between 1950 and 1982. Territory of Hawaii (June, 1950). Af­ 1951-64, more than 50% of longline Only 3 out of 11 boats surveyed in ter a hiatus during World War II the landings (by weight) were bigeye tuna, 1982 were built after 1970 (Hawaii fishery quickly recovered, landing 900 t also called ahi (a Hawaiian name), ahi OpinionS). Most longline vessels oper­ (2 million Ib) of tuna, and 700 t (1.5 mebachi, or "bluefin." True bluefin million Ib) of billfish and other species in tuna, Thunnus thynnus, are rarely 7R. A. Dollar. 1992. Annual report of the 1991 1948. Landings continued to rise, reach­ caught by Hawaii fishermen. Before western Pacific longline fishery. U.S. Dep. ing a record level of 2,000 t (4.4 million 1950 and in the 1970's bigeye tuna Commer., NOAA, Nat!. Mar. Fish. Serv., South­ west Fish. Sci. Cent., Honolulu Lab., South­ Ib) in 1954 (Fig. lA). The longline fish­ and yellowfin tuna (also called ahi) west Fish. Sci. Cent. Admin. Rep. H-92-II, 26 p. ery declined in the late 1950's through made up roughly equal proportions of 8Hawaii Opinion, Inc. 1984. A cost earnings the mid-1970's to reach a similar level of the catch (Fig. lA). The proportion of study of the longline and handline fishing fleets in Hawaii, a summary of the survey. Prepared landings as the commercial troll (Fig. 2) blue marlin in the catch was higher for NMFS, 2570 Dole St., Honolulu, HI 96822­ and handline (Fig. 3) fisheries. than that of striped marlin, Tetrapturus 2396, contract number 81-ABC-00267, 113 p.

5 -'- '­ 11 A B ~ Other species ~ Swordfish - 10 "...... ? E] Yellowfin tuna - "0 4 - 9 ;9 ~ ~ Bigeye tuna c:l - 8 0 ~ lSI Blue marlin ~ - 7 ] ~ 3 Striped marlin t­ - 2 :3 ..... )< :3 - 1 XX 0 f-:­ ...... X .­ 0 1950 1955 1960 1965 1970 1975 1980 1985 1990 1985 1990 Year

Figure 1.- Longline landings (in t and Ib) in Hawaii from 1948-91, including A) component species except broadbill swordfish and B) broadbill swordfish. Total landings are the sum of stacked components. Dashed lines show corrected 1979-86 estimates for total landings, other species (0), yellowfin tuna (Yo, and bigeye tuna (Be). Sources: 1948-86, HOAR data; 1987- 91, NMFS estimates.

55(2), 1993 71 registered longline vessels in 1950. Yoshida (1974) states that participa­ • Other species tion declined from 42 vessels in 1952 1.6 9 IZI Yellowfin tuna to31 in 1964,andto20in 1970. Yuen 1.4 D Mahimahi reported that the longline fleet in Ho­ 3 nolulu numbered 15 in 1977, and by lSI Blue marlin 1.2 1983 HDAR records showed only 13 Striped marlin IZa registered longline vessels (10 in Ho­ 1.0 ~ Skipjack tuna nolulu). ~ 2 0.8 Wahoo (ono) The decline in vessels corresponded with the declining trend in longline 0.6 landings reported to HDAR between 0.4 1954 and 1982 (Fig. lA). However, visual inspection of the Honolulu fleet 0.2 in 1983 found 37 vessels carrying longline gear (Honda10) as opposed to 10 registered with HDAR. Incomplete 1970 1975 1980 1985 1990 reporting to HDAR prompted the es­ Year tablishment of a NMFS market sam­ pling program in late 1986 (Pooley, 1993b) and a Federallongline logbook Figure 2.- Troll landings in metric tons (t) and pounds (lb) in Hawaii 6 from 1970-91. Total landings are the sum of stacked components. Source: program (Dollar and Yoshimoto ) was HDAR data. instituted by the WPRFMC in 1990 to collect more detailed data. A compari­ ating through 1982 were veterans of years is difficult to document because 9H. S. H. Yuen. 1977. Overview of fisheries for the 1940's and 1950's. Low profitabil­ many vessels fished part-time while the billfishes in Hawaii. U.S. Dep. Commer., NOAA, Natl. Mar. Fish. Serv., Southwest Fish. ity probably contributed to the lack of participating in other Hawaii fisheries. Cent., Honolulu Lab., Southwest Fish. Cent. investment in new vessels. June (1950) identified 49 vessels as Admin Rep. H-77-l9H, 14 p. Local sale of fresh fish, mostly for primarily longliners (30 in Honolulu), IOY.A. Honda. 1985. An updated description of the Hawaiian tuna longline fishery. NMFS, 300 raw consumption, provided a limited whereas Hawaii Division of Aquatic Ala Moana Blvd., Honolulu, HI 96850-4982, market that was easy to saturate, driv­ Resources (HDAR) records indicate 76 unpubl. manuscri. ing down the price (Otsu, 1954). The Hawaii fresh-fish market was the only outlet, because mainland U.S. consum­ ers did not accept tuna as a fresh prod­ 2.4 uct. The Japan "sashimi" market was ,...... " Other species .... 1.0 ,...... " distant and exacted hard-to-meet prod­ "t:l •IZI Yellowfin tuna :9 2.0 uct standards. Prices offered by tuna !a r:: CI) ~ Other tuna canneries were too low to provide ad­ ;::3 0.8 0 D Mahimahi equate profits. 05 1.6 '-' '-'t Although the number of vessels de­ CI) onCI) 0.6' on clined, the amount of fishing gear de­ .5 1.2 .5 ployed in an average trip nearly "t:l "t:l doubled between the 1950's (Shomura, !a 0.4 !a 1959) and the early 1980's (Hawaii -Q) 0.8 -Q) 8 :E Opinion ). The number of hooks per :E "t:l "t:l 0.2 basket, and consequently the length of !a 0.4 !a main line between float lines, also in­ ::r: ::r: creased, resulting in a deeper gear con­ 0 0 figuration. A similar shift in gear configuration characterized the distant­ 1970 1975 1980 1985 1990 water longline fleets of Japan and Ko­ Year rea (Suzuki et aI., 1977; Yang and Gong, 1988). Figure 3.- Handline landings in metric tons (t) and pounds (lb) in Hawaii The number of vessels participating from 1970 to 1991. Total landings are the sum of stacked components. in the Hawaii longline fishery over the Source: HDAR data.

72 Marine Fisheries Review son between NMFS estimates of first exceeded the record set in 1954 to shallow nighttime fishing, targeting 2 longline landings at wholesale markets (Fig. 1A) and by 1991 landings reached broadbill swordfish in the 1990's (It0 ). and landings reported to HDAR in 1987 9,000 t (20 million Ib), including 4,400 t Both daytime and nighttime methods showed that less than 20% of longline (9.6 million lb) of swordfish (Fig. IB). are still practiced using the same 2 landings were reported (It0 ). New entrants in the longline fishery monofilament longline system. In tar­ The best available estimates of Ha­ were mostly steel-hulled vessels up to geting bigeye tuna 12-25 hooks are waii longline landings over time (Fig. 33 m (107 ft) in length, and the major­ deployed between floats with lots of lA) are based on three data sources ity of these vessels and their operators sag to reach as deep as 400 m (Boggs, and a correction to account for were former participants in U.S. east 1992), whereas in targeting swordfish underreporting (Pooley, 1993b). coast tuna and swordfish fisheries (Dol­ only a few hooks are deployed between 7 HDAR longline data are believed to be lar ). The present fleet uses modem floats and the line is kept relatively taut relatively complete through 1978 electronics (Radar, Loran, Global Po­ so that it stays in the upper 30-90 m of (Pooley, 1993b). NMFS estimates sitioning System (GPS» to navigate, water. Night fishing employs lumines­ based on market sampling and log­ and uses radio beacons, strobe lights, cent "light sticks" which attract broadbill books (It02; Pooley, 1993b) are used and radar reflectors to mark the gear. swordfish and bigeye tuna or their prey for 1987-91 (Fig. lA and lB). Esti­ Some vessels obtain sea-surface tem­ (Berkley et aI., 1981). Large imported mates for 1979-86 (dashed lines, Fig. perature maps by radio-facsimile squid, lllex sp., are used for bait. 1A) are interpolated values between (FAX) and most have electronic ther­ A special "line thrower" is required HDAR reported landings in 1978 and mometers for use in finding fish asso­ to put sag into a monofilament longline NMFS estimates for 1987 (Pooley, ciated with temperature fronts. as it is deployed (Kawamoto et a1. 11; 1993b). In contrast, HDAR troll (Fig. Changes in fishing methods and Boggs, 1992) so that it can fish deeply 2) and handline (Fig. 3) landings re­ greater amounts of fishing gear char­ for bigeye tuna. Many new entrants to ported to HDAR through 1991 are very acterized the expansion of the longline the fishery in 1989-91 did not invest similar to NMFS estimates (Pooley, fleet. In 1988 most vessels still used in line throwers. These vessels fished 1993b), and HDAR troll and handline basket-type, rope longline gear, but shallow even when targeting tuna (day­ data are used in this paper without cor­ they deployed over 3 times as much time fishing) and probably contributed rection. The corrected longline data gear on an average trip as vessels in to the increase in the relative propor­ indicate that the nadir of the 10ngline 1982 (Hawaii Opinion8, Kawamoto et tions of yellowfin tuna, blue marlin, fishery occured in 1975 (not 1982, a1. II). A few vessels used "bin" gear in and other shallow-swimming species Fig. lA). which the rope mainline is continuous, caught by longliners in recent years rather than composed of baskets, and (Fig. lA). The increasing longline catch Revitalization and Expansion these vessels deployed similar amounts of these species was cause for concern The longline fishery expanded rap­ of gear as those using basket gear by the small-vessel troll and handline idly in the late 1980's to become the (Kawamoto et aLII). Continuous ny­ fisheries that target them (B oggs3). largest fishery in the state. The revital­ lon monofilament main lines stored on The fishing grounds of the Hawaii ization was due to the development of spools and used with snap-on longline fishery expanded in the 1980's the local markets and export markets monofilament branch lines were first and 1990's. Hawaii fishermen inter­ for fresh tuna on the U.S. mainland used in 1985, and by the end of 1988, viewed in 1982 reported that they had and in Japan (Kawamoto et aLI I) and 29% of the fleet used this new system to fish farther away from port in order the introduction of new swordfish fish­ (Kawamoto et aLII). Monofilament to make good catches (Hawaii Opin­ ing methods in the late 1980's (Dol­ gear was popular among new entrants ion8). In 1986 Hawaii longliners began 7 lar ). Participation in the Hawaii to the Hawaii fishery and became the exploring fishing grounds up to 800 longline fishery approximately doubled most prevalent gear type in the fleet. n.mi. from the main Hawaiian Islands, from 37 vessels in 1987 to 75 in 1989 Longliners using monofilament gear and distant-water fishing is becoming 2 (lt0 ) and doubled again to 156 (ves­ tended to deploy over four times as more common in the 1990's. Logbook sels with permits) by the end of 1991 much gear per trip in 1988 (Kawamoto data from the first quarter of 1991 in­ (Dollar and Yoshimot06). Permits were et a1. II) as was typical of the fleet in dicate that over half of longline sets required by the Federal moratorium on 1982 (Hawaii Opinion8). were more than 50 n.mi. away from new entrants established in 1991. Only Monofilament longline gear is more the main Hawaiian Islands, and <2% 140 of the vessels with permits were flexible in configuration and can be of sets were made outside the EEZ 12 active in 1991. In 1988 landings data used to target various depths more eas­ (NMFS ). ily than basket gear because the amount Conflicts with other fisheries and "K. E. Kawamoto, R. Y. Ito, R. P. Clarke, and of main line, the number of branch interactions with protected species led A. E. Chun. 1989. Status of the tuna longline lines, and the sag between floats are to the exclusion of the longline fishery fishery in Hawaii, 1987-88. U.S. Dep. Commer., adjustable. This flexibility was dem­ NOAA, Natl. Mar. Fish. Serv., Southwest Fish. 12NMFS Honolulu Laboratory, 2570 Dole St., Cent., Honolulu Lab., Southwest Fish. Cent. onstrated by the switch from traditional Honolulu HI 96822-2396, unpubl. longline log­ Admin. Rep. H-89-10, 34 p. deep daytime fishing for bigeye tuna book data.

55(2), /993 73 from nearshore waters in the 1990' s. transiting the Hawaii EEZ to fish for influence the species composition of In early 1991 longline fishing was pro­ albacore, Thunnus alalunga, in the the total reported catch (Fig. 2). hibited within a radius of 50 n.mi. off North Pacific participated briefly in the Charter vessels in the troll fishery the NWHI (Dollar?) to prevent inter­ Hawaii troll fishery, and vessels from numbered 102 and 119 in 1976 and actions between endangered Hawaiian the lobster and bottomfish fisheries also 1982, respectively (Cooper and monk seals, Monachus schauinslandi, participate intermittently in the Hawaii Adams 13; Samples et al. 14), compared and surface-fishing longliners that tar­ troll fishery. Troll fishing is conducted to an estimated 160 full-time commer­ geted aggregations of swordfish near throughout the Hawaiian islands, gen­ cial, and 1,544 part-time and recre­ those islands. In 1989 an informal erally within 20 n.mi. of shore. ational-subsistence trollers (combined) agreement was negotiated between Commercial catch reports to HOAR in 1976 (Cooper and Adams!3). Pro­ small-vessel fishermen and longline do not distinguish between different portions of the total troll catch by these fishermen whereby longliners would types of troll fishing (i.e., part-time, sectors in 1976 were 21 % charter, 44% keep >20 n.mi. from the coasts of the charter); only fishermen who sell their part-time commercial and recreational­ main Hawaiian Islands and>10 n.mi. catch are required to file reports. Re­ subsistence (combined), and 35% full­ from fish aggregating devices (FAD's). ported annual commercial troll catches time commercial. About 70% of the Some vessels, especially subsequent were <200 t (0.4 million lb) until 1974 charter catch and 60% of the part-time entrants to the fishery, did not comply (Fig. 2). During 1975-84 catches commercial and recreational-subsis­ with the agreement. To mitigate con­ ranged between 540-790 t (1.2-1.7 tence catch was sold (Cooper and flicts between longliners and small-ves­ million lb) per year, and then the catch Adams 13). Growth of the troll fishery sel troll and handline fishermen, the rose to a record peak of almost 1,700 t makes it unlikely that these propor­ WPRFMC in mid-1991 established a in 1987. Annual catches declined after tions represent the current situation but buffer zone prohibiting longline fish­ 1987 but remained >1,000 t (2.2 mil­ the charter fishery is believed to have ing within a radius of 75 n.mi. off the lion lb) through 1991 (Fig. 2). grown with the expansion of tourism, coasts of Kauai and Oahu, or within a The troll fishery catches more and the recreational-subsistence fishery radius of 50 n.mi. off the coasts of mahimahi and wahoo, Acanthocybium remains important (Pooley, 1993a). Maui, Molokai, Lanai, Kahoolawe, and solandri, than all the other Hawaii pe­ The Handline Fishery Hawaii (Dollar and Yoshimot06). lagic fisheries, about half the blue mar­ lin, and about 20% of the yellowfin There are several types of pelagic The Troll Fishery tuna landed. Yellowfin tuna composed handline fishing in Hawaii today. Day­ Troll and handline fisheries in Ha­ almost half the commercial troll catch handline fishing is a revitalization of waii have not been studied as exten­ from 1975 to 1980, after which its pro­ an ancient Hawaiian method called sively as the long1ine fishery. Trolling portion in the catch declined. The pro­ "palu-ahi" for the use of "palu" (chum) involves towing lures or baited hooks portion of mahimahi and skipjack tuna to attract and hook ahi (yellowfin tuna). behind a moving vessel, whereas in the troll catch increased through the Palu-ahi fishing is also called "drop handlining involves dangling baited 1980's and 1990's. The charter sector stone" fishing. A baited hook on the hooks from a stationary or drifting ves­ of the troll fishery targets blue marlin, end of the handline is laid against a sel. The evolution and operation of the and this species accounted for 54% stone and the line wound around it. Hawaii troll fishery are poorly docu­ and 39% of estimated charter catches Additional pieces of chum are also mented. Trolling with lures for pelagic in 1976 (Cooper and Adams 13) and wound into the bundle which is then species was a traditional Polynesian 1982 (Samples et aI. 14), respectively. tied in a slip knot (Rizzuto, 1983). The fishing method, and Hawaii has since In contrast, 87% of full-time commer­ bundle is lowered to the preferred depth been the site of important innovations cial troll catches were yellowfin tuna (commonly 20-30 m). Then the line is in big-game troll fishing techniques (Cooper and Adams!3). Changes in the jerked to untie the knot so that the (Rizzuto, 1983). relative size of the different commer­ baited hook and chum are released. The troll fishery has several compo­ cial sectors (i.e., charter, part-time) may Night-handline fishing is called "ika­ nents: 1) a recreational-subsistence sec­ shibi" from the Japanese names for 13J. C. Cooper and M. F. G. Adams. 1978. tor which is poorly differentiated from Preliminary estimates of catch, sales, and rev­ squid (ika) and tuna (shibi). The ika­ a part-time commercial sector, 2) a enue of game fish for the fishing conservation shibi fishery is an outgrowth of a squid charter sector which is recreational for zone around the main Hawaiian Islands, by fishery that probably began in the types of troll and longline vessels and by spe­ its patrons but commercial for the op­ cies. U.S. Dep. Commer., NOAA, Natl. Mar. 1920' s and did not target tuna until erators who sell the catch, 3) a part­ Fish. Serv., Southwest Fish. Cent., Honolulu after World War II (Yuen, 1979). Ika­ time commercial sector, and 4) a full­ Lab., Southwest Fish. Cent. Admin. Rep. 24H, shibi fishermen attract squid to the fish­ 10 p. time commercial sector. Most troll 14K. C. Samples, J. N. Kusakabe, and J. T. ing vessel with a light and catch the vessels are small (5-8 m, 15-25 ft in Sproul. 1984. A description and economic ap­ squid on jigs or with a gaff. The squid length), although charter boats range praisal of charter boat fishing in Hawaii. U.S. are then used as bait. Ika-shibi or palu­ Dep. Commer., NOAA, Natl. Mar. Fish. Serv., up to 18 m (59 ft). In the mid-1980's Southwest Fish. Cent., Honolulu Lab., South­ ahi were not distinguished as separate large (20-26 m, 65-85 ft) troll vessels west Fish. Cent. Admin. Rep. H-84-6C, 130 p. fishing methods in HOAR statistics

74 Marine Fisheries Review prior to 1982. Subsequently (1982-91) sels and larger commercial troll vessels fish (Pooley, 1990; Boggs3, In press; only a fraction of handline landings have also done some handline fishing. Skillman et aI., 1993). Increased were reported as palu-ahi or ika-shibi, Day-handline fishing was concen­ catches by Hawaii's pelagic fisheries and so the handline catch statistics have trated around the Island of Hawaii and over the last two decades could hypo­ been combined for this report (Fig. 3). ika-shibi fishing was concentrated off thetically have reduced the abundance All handline catches were sold on the Hilo coast of Hawaii in the mid­ of local stocks, if such stocks exist. It the Island of Hawaii where the fishery 1980's. Traditionally, handline fishing is more likely that Hawaii's fisheries was primarily located until 1971 when was conducted within a few km of the exploit locally available fractions of the rising price for tuna and reduced coast at locations called "ahi koas" Pacific-wide stocks (Wetherall and 4 shipping costs made air shipment to where yellowfin and bigeye tuna were Yong l6; Skillman and Kamer ; Boggs, Honolulu economically feasible. The especially available. The State (HDAR) In press). In the latter case immigra­ increasing market for fresh fish boosted encouraged expansion into new areas tion may limit yields and excessive the development of Hawaii's fisheries in the late 1980' s. Handline fishing fishing effort might result in reduced in the mid-1970's (Pooley, 1993a). techniques have spread and are now CPUE (Sathiendrakumar and Tisdell, Annual commercial handline landings practiced on Kauai and Maui. Some of 1987; Boggs3, In press). In either case, reported to HDAR increased from 45 t the largest handline vessels have ex­ excessive local fishing pressure should to almost 1,000 t between 1970 and tended their range to fish around sea­ be evidenced by corresponding declines 1981. Since 1981 commercial handline mounts and weather buoys 100-200 in local CPUE. landings have ranged between 500 and n.mi. from the coast. This new expan­ Several studies suggest that local 1,000 t (1.1-2.2 million pounds) with sion of the fishery may have contrib­ fishing pressure can reduce local CPUE major peaks in 1981, 1983, 1986, and uted substantially to the peak in catch for wide-ranging pelagic species 1991 (Fig. 3). The magnitude of the reported in 1991, which followed four (Wetherall and Yong l6, Squire and Au, recreational-subsistence sector of the years of continuous decline (1987-90, 1990; Boggs3, In press; Skillman and 4 handline fishery is unquantified, but Fig. 3). Some fishermen feel that there Kamer ). Many of these studies also important (Pooley, 1993a). may soon be too many participants in found that the relative abundance The composition of the handline the handline fishery, and the WPRFMC (CPUE) offish over a wider geographic catch is almost exclusively tuna; yel­ has been asked to institute a control area could statistically account for lowfin tuna is the predominant species date for this fishery in anticipation of much of the variation in local CPUE. (Fig. 3). Mahimahi and other nontuna possible limited-entry management. Relative abundance estimated as CPUE species make up less than 10% of the The increasing cost of insurance has is confounded with catchability, so that catch. Bigeye tuna are an important been a problem for small-vessel com­ widespread environmental effects on component of the handline catch (Yuen, mercial fishermen. Many operators catchability, as well as true changes in 1979) that is not reflected in HDAR could not afford to keep up with rising stock-wide abundance, could explain statistics. The ika-shibi catch of big­ insurance costs in the late 1980's and the statistical relationships between eye tuna ranged from 63 to 120 t (139­ some, who weren't willing to risk their Pacific-wide CPUE and local CPUE. 265 thousand lb) in 1973-75 (Yuen, assets, stopped fishing. Another eco­ The following examination of Ha­ 1979), but HDAR records indicate <23 nomic problem for the commercial troll waii CPUE time series extending from t of tuna other than yellowfin landed and handline fisheries is a condition the early years of each fishery to the by all handline fishing gears in 1973­ called burnt tuna syndrome (BTS) present was undertaken to show 75 (Fig. 3). This may represent a lack which discolors and gives a bad taste whether or not the expansion of of reporting, but it is also likely that to sashimi as well as reduces its shelf Hawaii's pelagic fisheries over the last handline fishermen are lumping both life (Nakamura et a!., 1987). BTS is two decades, 1970-91, corresponded bigeye and yellowfin catches as ahi in prevalent in troll and handline-caught with declines in local CPUE. Major their catch reports since these species fish over 35 kg and uncommon in declines in local CPUE were often have the same Hawaiian name. longline-caught fish. Proper handling found to predate local fisheries expan­ Most handline vessels are 6-9 m in can ameliorate BTS (Nakamura et aI., sion and corresponded with declines in length and are often crewed by 1-2 1987) and research is under way to the CPUE of more widespread fisher­ persons. Surveys by Yuen (1979) and find means to prevent it (Watson et a!., ies. Over the last few decades the time Ikehara 15 indicate that the ika-shibi 1988). series indicated much interannual varia­ fishery grew from 30--40 boats in 1976 tion and little net change in CPUE. to at least 230 boats by 1980. In recent Abundance and Availability years some of the smaller longline ves- Background 16J. A. Wetherall and M. Y. Y. Yong. 1983. An ISW. N. Ikehara. 1981. A survey of the ika­ The primary concern in Hawaii's analysis of some factors affecting the abun­ shibi fishery in the State of Hawaii, 1980. U.S. pelagic fisheries today is whether fish­ dance of blue marlin in Hawaiian waters. U.S. Dep. Commer., NOAA, Natl. Mar. Fish. Serv., Dep. Commer., NOAA, Natl. Mar. Fish. Serv., Southwest Fish. Cent., Honolulu Lab., South­ ing effort should be limited to protect Southwest Fish. Cent., Honolulu Lab., South­ west Fish. Cent. Admin. Rep. H-82-4C, 12 p. the local abundance or availability of west Fish. Cent. Admin. Rep. H-83-16, 33 p.

55(2), 1993 75 Calculation of Hawaii CPUE additional work is needed to catego­ The lack of data on the number of rize the subset of the longline trips in trips that caught no pelagic species may Longline CPUE was calculated from 1990-91 that targeted tuna. The Ha­ have caused errors in the effort esti­ a combination of data sources includ­ waii swordfish fishery has developed mates, but the CPUE time series based ing published literature, HDAR data too recently (Fig. IE) for any trend in on those data may still be indicative of summaries, and NMFS market sample CPUE to be indicative of availability. relative changes in availability. The estimates. Troll and handline CPUE HDAR data summaries for the troll number of zero-catch trips should have was calculated solely from HDAR data and handline fisheries from 1970 to been negatively correlated with catch summaries because these data identify 1991 were used to calculate CPUE time per successful trip (CPUE) since both troll and handline gears (NMFS esti­ series for these fisheries (e.g., Fig. 4B). were dependent on fish availability. mates do not). HDAR summaries do Prior data are not very important be­ Thus, the CPUE time series should still not differ substantially (in total) from cause the troll and handline fisheries reflect real trends, especially if zero­ NMFS estimates for combined troll and were so small before 1970. catch trips represented a modest frac­ handline (Pooley, 1993b). All avail­ CPUE was calculated as the total tion of total effort. No bias was caused able summary statistics (HDAR and annuallongline, troll, or handline catch by changes in the fraction of zero-catch NMFS) were used in the present study, (by weight) of a species divided by trips reported because none were but no new analyses of raw data were total annual effort. Effort was estimated counted. Uchida (1976) found a high conducted. either as the annual number of fishing correlation between Hawaii pole-and­ To calculate CPUE in the early long­ trips (troll and handline fisheries) or line CPUE including zero-catch trips line fishery (e.g., Fig. 4A), Hawaii the annual number of hooks (longline and CPUE excluding zero-catch trips. longline data on two size-classes of fishery). Longline hook totals were cal­ vessels for 1948-56 (Shomura, 1959) The effort data for the troll and culated from the number of trips mul­ were combined, and catch was con­ handline fisheries contained no stan­ tiplied by estimates of hooks per trip verted from number of fish to weight. J7 dardization of trips as a unit of effort, (Boggs and Hawn ). Changes in the The results were similar to 1948-52 and the 10ngline effort data were stan­ amount of gear deployed per trip ob­ CPUE data published by Otsu (1954). dardized only to account for changes tained from descriptions of the fishery The CPUE based on combined data in the number of hooks per trip (Boggs (J une, 1950; Otsu, 1954; Shomura, differed little from the data for large J7 1959; Hida, 1966; Yoshida, 1974; Ha­ and Hawn ). Changes in troll or vessels (Shomura, 1959), and although handline fishing power, (number of waii Opinion8; Kawamoto et al. 11; H02) vessel size is important, it was ignored lines, hooks, or hours, per trip, etc.) or were used to estimate and interpolate in the present study because data sum­ the typical quantity of hooks per trip changes in 10ngline, troll, or handline maries by vessel size for subsequent I7 efficiency (class of vessel, gear type, from 1947-89 (Boggs and Hawn ). years were not available. target depth, fishing strategy) may have Longline data summaries for 1959­ Corrections for changes in efficiency with fishing depth are being developed resulted in biases in the CPUE time 89 and NMFS market sample 10ngline l7 series, obscuring trends or giving the (Boggs, 1992; Boggs and Hawn ) but estimates for 1987-89 (H02; Pooley, appearance of trends where none ex­ are not used here. 1993b) were used to calculate longline isted. Although much of the data pre­ CPUE for later years (e.g., Fig. 4A). The NMFS market sampling pro­ gram counted fishing trips as each oc­ sented here are decades old, the es­ HDAR longline data after 1978 are be­ timates of CPUE must be considered lieved to represent only a fraction (ca. casion that a vesse11anded and sold its catch. HDAR data summaries included preliminary until the raw data are re­ <20% Fig. 1A) of the fishery, but com­ analyzed and effort standardized to ac­ plete coverage is not required to calcu­ each unique date of landing for each unique license number in the records count for changes in efficiency (e.g., late a representative CPUE index. No Uchida, 1976; Suzuki, 1989). other data were available for 1979-86. as a trip if any pelagic species were Two longline CPUE indices for caught. Trip counts from both NMFS Despite problems with the nonstan­ a~d 1987-89 were calculated, one from HDAR data did not include trips dardized CPUE indices, they are the With no catch of any pelagic species HDAR data, and another from NMFS only data currently available. Nonstan­ estimates (e.g., Fig. 4A). The HDAR (prior to 1992). Such trips were sel­ dardized Hawaii CPUE data for sev­ dom reported. For any given species eral different gear types often show a series from 1979 through 1989 best 4 indicates the longline CPUE trend for the count of trips did include trips that similar pattern (Skillman and Kamer ) those years, whereas the 1987-89 did not catch that species but caught or reflect a pattern similar to that of NMFS data best indicate recent CPUE another pelagic species. more sophisticated CPUE indices from nearby fisheries (Wetherall and for comparison with the earlier years 16 1947-78 (e.g., Fig. 4A). Longline Yong ). These examples suggest that CPUE was not calculated for 1990-91 17C .. H. Boggs and D: R. Hawn. Changes in some true information on relative avail­ flshmg power and .estimates of fishing effort ability is represented by nonstandard­ because in these years a fraction of the for the HawalllonglIne fishery, 1948-91. NMFS longline fishery changed fishing meth­ Honolulu Laboratory, 2570 Dole St., Honolulu ized CPUE indices for Hawaii's ods to target broadbill swordfish, and HI 96822-2396, un pub!. man user. fisheries.

76 Marine Fisheries Review A - 700 Shomura 1959 -600 ..-- HDARdata XJ 0 NMFS estimates -= 500 0 ..cl "':400 § ..... / . ,...;ft .:". -=300 ...... : --: :e . j 200 -­'-' ...... / - 100

ot...... J...... -'-'-.e.-L...... L ...... J.~-'-'-.L...... J...... J...... L...... J.~...... :::J 0

240,...... ,"""T""T.."...... ,...,.,....."""T""T .,...... ,....,."T""'T"",....,"""T""T,...... ,...,...,...,"""T""T..,..,...... ,...,...... ,"""T""T~ 500 B 200 Handline 400 ..-­ Troll c.. 300 °E "<;;­ 200 :e'-'

100 40

oc...... --'-'-...L...... --'-'-...... L...... L...l...... u...... --'-'-...L...... l....l.-'c..J...... L..J....l....l.-'...-....L...... J 0 2O ...... ,..,.....,...... ,-.--r"T"T"""~.,...... ~,..,....~,..,....,...... ,."j"'T'"~..,...~,..,."T"""T""..,.,...,..,...... , c 16

12

8

4

1950 1955 1960 1965 1970 1975 1980 1985 1990 Year

Figure 4.- Yellowfin tuna CPUE time series showing A) Hawaii longline CPUE (kg and Ib per 1,000 hooks) from 1948-55 (Shomura, 1959), 1959-89 (HDAR data), and 1987-89 (NMFS estimates); B) Hawaii handline and troll CPUE (in kg and Ib per trip) from 1970 to 1991 (HDAR data), and C) western Pacific longline CPUE (in no. fish per 1,000 hooks) in the Japanese fishery from 1952 to 1986 (Suzuki, In press).

CPUE Time Series The 1980-87 decline in yellowfin creased from 1970 to 1978 and subse­ tuna CPUE for the Hawaii longline quently declined through 1984. After Yellowfin tuna CPUE in the Hawaii fishery occurred during a period of troll 1984 Hawaii handline and troll CPUE 10ngline fishery declined between the (Fig. 2) and longline (Fig. lA) fishery increased to peaks in 1986 and 1987, 1950's and the early 1960's and then expansion. However, the subsequent respectively, and then declined (Fig. ranged between 90-210 kg/l ,000 hooks increase in longline CPUE in 1988-89 4B). These declines coincided with ex­ with no clear trend from 1959-81 (Fig. occurred during the period of greatest pansion of Hawaii's longline, troll, and 4A). Yellowfin tuna CPUE based on longline fishery expansion, while troll handline fisheries. However, handline HDAR longline data declined from and handline fishing levels remained very CPUE subsequently increased from 1980-87, recovering somewhat in high. Thus low levels of Hawaii longline 1884 to 1986 and troll CPUE increased 1988-89. The more accurate longline CPUE did not correspond consistently from 1984 to 1987 despite continued CPUE index based on NMFS estimates with periods of higher fishing pressure. expansion of the troll and longline fish­ indicated a return to average longline Yellowfin CPUE in the Hawaii troll eries. During the period of greatest ex­ CPUE in 1988-89 (Fig. 4A). and handline fisheries (Fig. 4B) in­ pansion of the longline fishery

55(2), 1993 77 (1987-89) troll and handline CPUE (Fig. 4A). In more recent years (1983­ than shallow gear in catching bigeye declined (Boggs3). However, troll 88), Hawaii troll CPUE followed a pat­ tuna (Hanamoto, 1976; Suzuki et aI., CPUE returned to a typical level in tern that was similar to Japanese 1977; Boggs, 1992). 1990 and handline CPUE reached a western Pacific purse-seine CPUE Bigeye tuna CPUE in the Hawaii high level in 1991 (Fig. 4B) despite (Suzuki, In press; Boggs, In press; longline fishery (Fig. 5A) and in the continued high levels of fishing by all Skillman et aI., 1993). Environmental wide-ranging Japanese longline fish­ three pelagic fisheries. Thus availabil­ anomalies affecting catchability may ery (Fig. 5B) (Miyabe, In press) both ity (CPUE) of yellowfin tuna in Ha­ contribute much of the corresponding showed downward trends from the late waii did not appear to be closely related variation seen in CPUE time series, 1950's through the 1960's, a distinct to changes in local fishing pressure. such as the peak in yellowfin tuna CPUE drop in CPUE in 1970, a stable period Local availability of yellowfin tuna that occurred in 1978 (Fig. 4A and 4B). in the mid-1970's, record low levels in seemed to follow patterns in the over­ An initial increase in bigeye tuna 1980-81, and a slight recovery in the all abundance or catchability of the CPUE in the early years of the Hawaii mid 1980's. The correspondence be­ stock as indicated by CPUE in wide­ fishery (Fig. 5A) was explained by tween the bigeye tuna CPUE statistics ranging Japanese longline and purse Shomura (1959) as the result of a for the entire Pacific and for Hawaii is seine fisheries. Standardized yellow­ change in the area fished during winter remarkable, and strongly suggests that fin tuna CPUE in the longline fishery as fishermen learned to target bigeye local pelagic fish availability is linked of Japan in the western Pacific from tuna. Set depth also changed between to the abundance of a widespread popu­ 1952 to 1986 (Suzuki, In press) indi­ the late 1940's and early 1950's as the lation. An alternative hypothesis that cated a drop in CPUE between the practice of buoying up the middle of could apply to all of the pelagic spe­ 1950's and early 1960's, and a decline each basket of gear with an extra float cies is that CPUE variation is due to in the early 1980's (Fig. 4C) similar to (June, 1950) was abandoned. Deep gear widespread changes in catchability as­ that seen in Hawaii longline CPUE data has been shown to be more efficient sociated with environmental trends.

A 3,500 Shomura 1959 HDARdata 3,000 ..-. ," , 1,200 : .... NMFS estimates . 2,500 ~ ,'"'" " ..=o 900 2,000 § ,/' 1,500 ,. g ,,...... 1,000 . .... " ...... 500 -- . . O --'-'c..J.....o "'-'-"'-'- '-'-"-'- O

14 ,...... ~..,....~~,...... ~..,....~~,...... ~..,....~~,...... -~..,....~~,...... -~..,....~-..,

12 B

10

8 6

4

2

1950 1955 1960 1965 1970 1975 1980 1985 1990 Year

Figure 5.- Bigeye tuna CPUE time-series showing A) Hawaii longline CPUE (in kg and Ib per 1,000 hooks) from 1949 to 1956 (fiscal years ending in June, Shomura, 1959), 1959-89 (HDAR data), and 1987­ 89 (NMFS estimates), and B) Pacific-wide longline CPUE (in no. fish per 1,000 hooks) in the Japanese fishery from 1952 to 1987 (Miyabe, In press).

78 Marine Fisheries Review l6 4 For bigeye tuna, the Hawaii longline 6A) showed peaks and minima for the and Yong and Skillman and Kamer . CPUE continued to recover in the late same years as the Hawaii troll CPUE This correspondence was not limited 1980' s (Fig. 5A), whereas Japanese time series (Fig. 6B). The close corre­ to the long-term decline in CPUE char­ CPUE declined (Fig. 5B). The increas­ spondence between blue marlin CPUE acteristic of longline fisheries in all ing trend in Hawaii bigeye tuna CPUE in these two fisheries suggests that both oceans. Rather, for striped marlin both in the 1980's brought the CPUE index CPUE time series reflected true increases and decreases in CPUE in based on NMFS wholesale market changes in availability or catchability the Hawaii longline fishery (Fig. 7A) sample back up to a level slightly higher despite the limitations of the available corresponded with CPUE changes in than the average for 1970-78 (Fig. 5A) statistics. the North Pacific Japanese longline suggesting that local longline fishery Blue marlin (Fig. 6A) and striped fishery (Fig. 7B). expansion in the 1980' s did not nega­ marlin (Fig. 7A) CPUE in the Hawaii The sharp increase in longline CPUE tively affect bigeye tuna availability. longline fishery followed a pattern for blue and striped marlin in 1989 The blue marlin CPUE time series similar to Japanese longline CPUE data probably reflected the increased use of for the Hawaii longline fishery (Fig. (Fig. 6C and 7B), as noted by Wetherall monofilament longline gear without

I I I I I '- 300 A - 250 HDARdata NMFS estimates -200

- 150 ...... ­ 100 ) - SO ...... , . o L....J...... L....J...... L....1-.J...... L-L....J.....J....I...J...... --'-L....J.....J....I...J...... --'-L....J.....J....I...J... -.J...L....J.....J....I'-'-' 0

B

0L...... J.....l...J-'-l...l...... J....J...... l...l--'-...... l....L...... J.....J...... L...L...... J....J...... l.....L--'-~ 1955 1960 196.5 1970 1975 1980 1985 1990 Year

Figure 6.- Blue marlin CPUE time-series showing A) Hawaii longline CPUE (kg and lb per 1,000 hooks) from 1959 to 1989 (HDAR data), and 1987-89 (NMFS estimates), B) Hawaii troll CPUE (in kg and Ib per trip) from 1970 to 1991 (HDAR data), and C) Pacific-wide longline CPUE (in t per 1,000 hooks per 5° square) in the Japanese fishery from 1955 to 1985 (Suzuki, 1989).

55(2), 1993 79 200- HDARdata NMFS estimates ­ 400 :i 160 ­ o - 300 ] 120 ­ § f\ - 200 ,...,~ 80­ ..... ;S '-" 40­ ...... - 100

1960 1965 1970 1975 1980 1985 1990 Year

Figure 7.- Striped marlin CPUE time series showing A) Hawaii longline CPUE (in kg and Ib per 1,000 hooks) from 1959 to 1989 (HOAR data), and 1987-89 (NMFS estimates), and B) North Pacific longline CPUE (in t per 1,000 hooks per Y square) in the Japanese fishery from 1955 to 1985 (Suzuki, 1989). line-throwers, which resulted in shal­ (Shomura, 1959; Yoshida, 1974; fishing power, expansion into more 4 lower sets and increased the efficiency Skillman and Kamer ), suggests that productive fishing grounds, economic of the gear for marlin (Suzuki, 1989; pelagic fish availability in Hawaii was influences on fishing operations, and Boggs, 1992). Blue marlin CPUE in most strongly affected by factors other environmental influences on local the troll fishery appears to be at a nor­ than local fishing pressure. Anomalies abundance and catchability. Further mal level and relatively stable (Fig. in whatever factors control seasonal analysis of catch and effort data as 6B) despite the expansion of Hawaii's availability could also be the major well as an improved data collection pelagic fisheries. source of interannual variation in system are needed to attempt to ac­ Mahimahi CPUE in the Hawaii CPUE. Research leading to an ability count for such biases. However, the longline fishery (Fig. 8A) reached a to forecast changes in pelagic fish avail­ parsimonious explanation of the avail­ peak in 1972 and a minimum in 1988 ability could ameliorate fishermen's able data is that locally exploited stocks that were mirrored in the Hawaii troll concerns that local fishing pressure has have not yet been impacted by the ex­ and handline CPUE data (Fig. 8B). Troll decreased fish availability. Develop­ pansion of Hawaii's pelagic fisheries. and handline CPUE data corresponded ment of new methods to locate or pre­ Long-term declines in the overall with each other very closely. Mahimahi dict productive fishing areas could apparent abundance of many pelagic CPUE appears to be increasing in both increase the yield and efficiency of species occurred several decades ago the troll and handline fisheries. Hawaii's pelagic fisheries. However, (Figs. 4C, 5C, and 6C), before the lat­ greatly increased fishing efficiency and est (1970-91) expansion of Hawaii's Outlook for the Pelagic Fisheries yield might then have some negative pelagic fisheries. Pacific-wide declines The absence of clear declining trends impact on local fish availability. in CPUE do seem to affect Hawaii's in local CPUE associated with local Decreases in fish availability caused fisheries, and could reflect full exploi­ fishery expansion, combined with dis­ by local fishing pressure may have been tation or even overexploitation of the tinctly seasonal variations in CPUE obscured by biases such as increased stocks. However, reduction of local

80 Marine Fisheries Review A - SO HDARdata NMFS estimates -40 1J ­ 0 -30 0 .J:l 8 0 - 20 ,...; ~-- J -10 0 0 15 !§ B 30 l:l.< 12 Troll U Q) Handline Q.. 9 20 Q.. ~ 't::- -'t:: ~ ~ 6 ~ .J:l "-" " .. "'d .." ' ".. , ' 10 ..., " ,~ " .... , I ::::l ...... '" 3 " ' "',' '...... "\.. .. ' ...0 '" Eo-< 0 0 1960 1965 1970 1975 1980 1985 1990 Year

Figure 8.- Mahimahi CPUE time series showing (A) Hawaii longline CPUE (kg and Ib per 1,000 hooks) from 1962 to 1989 (HOAR data), and 1987-89 (NMFS estimates), and (B) Hawaii troll and handline CPUE (in kg and Ib per trip) from 1970 to 1991 (HOAR data).

fishing effort from current levels would eration of all fishery sectors, then Literature Cited not substantially affect stock-wide Hawaii's pelagic fisheries should con­ abundance because of the relatively tinue to expand. No strong evidence Bartoo, N. W., and A. L. Coan. 1989. An as­ sessment of the Pacific swordfish resource. small scale of Hawaii's pelagic fisher­ suggests that the local availability of In R. H. Stroud (Editor), Planning the fu­ ies. An exception might be the night­ fish is a factor limiting further expan­ ture of billfishes, research and management time longline fishery for broadbill sion. However, this optimistic assess­ in the 90' s and beyond. Part 1. Fishery and stock synopses, data needs, and management. swordfish, which has been operating ment is based on statistics and analyses Mar. Rec. Fish. 13: 137-151. Natl. Coalition for too short a time to evaluate. How­ that may be inadequate; therefore, bet­ Mar. Conserv., Savannah, Ga. ever, with annual landings of 4,400 t ter fishery monitoring systems are Berkley, S. A., E. W. Irby, Jr., and J. W. Jolley, Jr. 1981. Florida's commercial swordfish and continued growth, the Hawaii needed. fishery: Longline gear and methods. Florida swordfish fishery may be expected to Sea Grant College and Florida Cooperative contribute significantly to total fishing Extension Service, Marine Advisory Pro­ Acknowledgments gram Bulletin MAP-14, 21 p. mortality on the stock. Historically, Boggs, C. H. 1992. Depth, capture time, and maximum total Pacific yields of sword­ We thank Reggie Kokubun of hooked longevity of longline-caught pelagic fish: timing bites of fish with chips. Fish. fish have been on the order of 20,000 t HDAR for producing the data summa­ Bull. 90:642-658. per year (Bartoo and Coan, 1989). ries for Hawaii's longline, troll, and _:--_ . In press. Methods for analyzing If fishery managers can prevent handline fisheries for 1970-91. This interactions of limited-range fisheries: Hawaii's pelagic fisheries. In R. S. Sho­ physical conflicts between the longline paper is dedicated to Justin Rutka, long­ mura, J. Majkowski and S. Langi (Editors), and small-vessel troll and handline fish­ time member of the WPRFMC's Pe­ Proceedings of the FAa expert consultation eries in Hawaii (Pooley, 1990; Skillman lagic Fishery Management Plan Team, on interactions of Pacific tuna fisheries, Noumea, New Caledonia, 3-11 December et aI., 1993), and if adequate markets in response to his unswerving quest to 1991. Food and Agric. Organ. U.N., FAa continue to support the profitable op­ examine local pelagic CPUE time series. Fish. Tech. Pap.

55(2), 1993 81 ____ and B. S. Kikkawa. 1993. The devel­ Memo. NMFS-SWFSC-165, 78 p. of billfishes, research and management in opment and decline of Hawaii's skipjack Otsu, T. 1954. Analysis of the Hawaiian long­ the 90's and beyond. Part 2. Contributed tuna fishery. Mar. Fish. Rev. 55(2):61-68. line fishery, 1948-52. U.S. Fish. Wildl. Serv., papers. Mar. Rec. Fish. 13:199-214. Natl. HDAR (Hawaii Division of Aquatic Resources). Commer. Fish. Rev. 16(9):1-17. Coalition Mar. Conserv., Savannah, Ga. 1985. Hawaii fisheries plan. Department of Pooley, S. G. 1990. Hawaii longline fishing Suzuki, Z. 1989. Catch and fishing effort rela­ Land and Natural Resources, Division of controversy. Southwest Fish. Sci. Cent., Natl. tionships for striped marlin, blue marlin, and Aquatic Resources, State of Hawaii, Hono­ Mar. Fish. Serv., La Jolla, CA 92038, Tuna black marlin in the Pacific Ocean, 1952­ lulu, HI, 163 p. Newsletter 97:6-9. 1985. In R. H. Stroud (Editor), Planning the Hanamoto, E. 1976. 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