Hawaii Offshore Handline Fishery a Seamount Fishery for Juvenile Bigeye Tuna David G

Hawaii Offshore Handline Fishery A Seamount Fishery for Juvenile Bigeye Tuna David G. Itano

1. Introduction

This paper describes the recent development of a small vessel fishery that targets juvenile bigeye tuna that aggregate to a productive offshore seamount and four moored deepwater buoys within the Hawaii Exclusive Economic Zone (EEZ). The fishery has been termed the "offshore handline fishery" although vessels utilize a variety of hook and line techniques to land a mix of juvenile bigeye and yellowfin tuna at a ratio of approximately 80% bigeye to 20% yellowfin by weight. The offfshore handline fishery is completely distinct from other handline and hook and line fisheries based in Hawaii as the fishing locations, trip characteristics, fishing methods, markets and catch and effort values are unique. The fishery can be characterized as fishing offshore waters greater than 100 nautical miles from land where very high catch rates allow rapid loading of large quantities of juvenile tuna that supply domestic markets for medium grade tuna for fresh consumption.

2. Hawaii handline fisheries

Hawaii is home port to a variety of pelagic fisheries that concentrate on tuna and billfish taken by all major hook and line gear types, i.e. handline, troll, pole and line and longline. However, caution should be exercised when aggregating and examining catch and effort data from these fisheries by gear type alone. A single gear type may be utilized by completely different fisheries that employ different fishing techniques to target different pelagic species or the same species at different lift stages to supply different markets.

The various handline fisheries of Hawaii are a prime example, with at least three distinct handline fisheries currently exploiting tuna resources in the Hawaii Exclusive Economic Zone (EEZ) (Boggs and Ito, 1993). The first clearly distinct handline method is utilized by the ika shibi fishery, which refers to a night-time handline technique that first developed on the island of Hawaii, evolving from an ika, or night-time squid fishery. Underwater bait attraction lights are used, and two to four lines are normally set per boat. The fishery peaks during the summer months and targets large yellowfin tuna, although considerable catches of large bigeye have been reported in ika shibi landings in previous years (Yuen, 1979). Albacore bycatch can be an important segment of the landed catch during some years. The prime fishing grounds are located close to the east coast of the island of Hawaii, but the technique has spread to other Hawaiian and western Pacific islands. The catch consists of large fish of 18-90 kg., and the fishermen attempt to sell the larger fish on the high value fresh sashimi market. Fishing trips may be one or two days in duration, but usually consist of a single night with four to six large yellowfin tuna caught during a good evening for a total weight of around 150-300 kg. (Anon, 1995). Catches often exceed ten fish per night during the height of the summer season.

Palu ahi fishing is distinct from the ika shibi fishery and method, referring to a daytime handline technique that is a modern adaptation of the ancient Polynesian "drop stone" fishing method. Basically, a weighted handline and single baited hook is lowered in an area where sub-surface tuna are believed to aggregate. Traditional deep handline areas, called koa, or areas adjacent to submarine banks or anchored fish aggregation devices (FADs) are usually targeted. Yellowfin, bigeye and albacore are taken in this fishery of a size typically smaller than palu ahi caught tuna. Metal jigs or weighted feathered hooks are

1 also jigged near FADs which may be considered a variation on this technique. Both techniques are described in Rizutto (1983).

This paper will concentrate on a third and clearly distinct Hawaii domestic handline fishery that concentrates on juvenile bigeye and yellowfin tuna that aggregate to offshore seamounts and anchored buoys that act as FADs. This offshore handline fishery as it is locally referred to utilizes aspects of both ika shibi and palu ahi fishing techniques and other fishing methods unique to the fishery.

3. Fishing grounds

The Cross Seamount is the primary fishing ground of the offshore handline fishery. It is well known that seamounts and submarine features that rise sharply from the sea floor can aggregate commercial concentrations of tuna, although the responsible mechanisms are poorly understood (Fonteneau 1991; Penny, et. al 1992; Rogers 1994; Yasui 1986). The Cross Seamount is located at approximately 18°40' N latitude and 158° 10' W longitude and rises to a charted depth of 330 meters (Anon., 1983). It is the shallowest by far of the Navigator Seamounts that lie south of Oahu and southwest of the island of Hawaii. Other seamounts that surround the Cross include the Bishop, Brigham, Clark, Daly, Day, Dutton, Ellis, Finch, Indianapolis, Jagger, McCall, Palmer, Pensacola, Perret, Powers, Swordfish and Washington. However, none of these seamounts rises to a depth shallower than 761 meters (Bishop Seamount) and most are far deeper. According to offshore handline fishermen, the Cross is the only seamount in the main Hawaiian Islands EEZ that consistently aggregates commercial concentrations of tuna that are vulnerable to their style of fishing gear. However, several of the deeper seamounts nearby are productive longline fishing grounds but for larger sized yellowfin, bigeye and swordfish.

Weather monitoring buoys that are set and maintained by the National Oceanographic and Atmospheric Administration (NOAA) in the outer Hawaii EEZ are also fished by offshore handline vessels. These buoys have become highly productive FADs and can account for large catches of yellowfin and bigeye tuna and other pelagic species. NOAA buoys 51002 and 51003, referred to as Buoy 2 and Buoy 3 by the fishermen, which are located south-southeast and west of the Cross Seamount are frequently fished by the offshore handline fleet. NOAA buoys 51001 and 51004 located northwest of Kauai and southeast of Hilo respectively (Figure 1) are also fished by these vessels. A visit to Buoy 2 or 3 is often combined with a visit to the Cross Seamount. The lines northeast and southwest of the islands in Figure 1 indicate the outer Hawaii EEZ, or 200 mile zone.

2 To^W" 181W 159W 157W 1S5WKi 1S3W TSTW! i 151001 , I23N

I I ; I | | i 22N j : ! I I i W 1 v : i i ; ; Hawaiian Islands t 1 ; 21N I * Honolulu i V i I 1 : : i | \ i i i Honokofwu i '1 Harbor H9N ^ ^ !-—.___ 151003 1 Cross Seamount! !18N i v ' '[ : |17N A 51002 151004 ' Figure 1. Fishing locations of the offshore handline fishery.

4. Fishery development

The area of the Cross Seamount was fished by Hawaii based longline vessels for several years prior to exploitation by the offshore handline fishery. In order to gain a better understanding of the offshore handline fishery, the Western Pacific Regional Fishery Management Council (Council) surveyed key participants with a long history and experience with offshore handlining. Information from these surveys has been used in the drafting of this report.

The earliest handline fishing trip to the Cross Seamount noted by any of the surveyed fishermen was made in 1976. Several sources naming the FVXQXas fishing the area with some regularity by 1978-79. Other vessels named as fishing the area with handline gear during this time included the FV XYXY and FV XXXX. Only the FV XXXX is still active in the handline fishery having recently returned to fishing the Cross Seamount after a recent change in ownership. The FV XXXX operates as a Honolulu based tuna longline vessel.

Fishing effort during the 1980s remained at a low level, with only three to five handline vessels reported to be fishing the Cross Seamount up to 1988. Fishery effort (numbers of vessels) increased rapidly after 1990, and the Hawaii Handliners Association petitioned the Council to implement a limited entry program on the offshore handline fishery in November 1991. In 1992, concerns over market flooding by small sized, poor quality tuna were made to the Council. Suggestions by some fishermen and processors to implement a minimum commercial size on the sale of tuna began that continue to the present day. In July 1992, the Council established a control date of July 2, 1992 for entry into the offshore handline fishery that could be activated at a later time if deemed necessary by the Council. This control date has not been utilized as of May 1998.

In October 1992, the Council initiated the Hawaii Handline Project by hiring an independent consultant to compile information on the offshore handline fishery. Hawaii Division of Aquatic Resources (HDAR) catch and effort statistics from 1988 to 1992 were examined. The catch and effort data generated by this project reflects only the data reported by some fishermen and is considered to be a significant under-representation of true catch and effort during this period. The HDAR data also indicates that yellowfin is three times more abundant in the catch while there is overwhelming evidence that bigeye comprises the majority of the catch by weight and numbers offish. It is likely that both bigeye and yellowfin were both reported as ahi by the fishermen and entered in the databases as

3 yellowfin.

The Hawaii Handline Project reported six and thirteen vessels reporting data to the HDAR in the offshore handline fishery in 1990 and 1991 respectively. Information obtained directly from long term participants in the fishery indicates higher estimates of effort (vessel participation) in the fishery. Figure 2 depicts the author's low and high estimates of the number of fishing vessels in the offshore handline fishery from survey information during the period 1978 to April 1998. It is probable that the lower estimates reflect the number of vessels that were most active in the fishery and the high estimates include part time participants. Data for 1997-98 is based on direct observation and is considered to be accurate.

Figure 2. Estimates of the number of vessels participating in the offshore handline fishery by year.

5. Catch size and species composition 5.1 Fish size by species

Landings from the offshore handline fishery consist primarily of juvenile bigeye and yellowfin tuna, ranging in size from approximately 4-32 kg (10-70 pounds). Data compiled by the Hawaii Handline Project indicated a mean weight of bigeye landed by the offshore handline fishery ranged from 22-30 pounds from 1989-1990. The mean weight of yellowfin landed in 1990-1991 was 19 pounds. These figures are considered to be reasonably accurate, and reflect the targeting of juvenile tuna by the fishery.

Historical length frequency data from the fishery is lacking. However, accurate length frequency data from two tuna tagging projects funded by the Pelagic Fisheries Research Program of the University of Hawaii are useful to examine. Figure 3 indicates the length frequency by ten centimeter size classes of yellowfin (n = 1754) and bigeye (n = 4849) tag releases from the Cross Seamount or NOAA weather buoys 2, 3 or 4 where reliable length measurements were recorded. The relative abundance of small yellowfin and bigeye between 50 and 60 cm is apparent while bigeye to 80 cm are relatively abundant.

It should be noted that this size distribution does not fully represent commercial landings from

4 the fishery but are skewed toward smaller size classes. This is due to the fact that the tagging programs tagged and released many small fish less than 10 pounds in weight that are often released alive by the fishermen while few fish larger than 50 pounds were tagged as they have a higher value and are normally retained by the vessels for commercial sale. Relatively few fish by number are taken by the offshore handline fishery that measure greater than 110 cm but they can contribute significantly to the value of the catch during some seasons. However, Figure 3 should be an accurate representation of the size range and general size distribution of yellowfin and bigeye tuna that are potentially vulnerable to hook and line gear on the Cross Seamount and offshore NOAA weather buoys. Therefore, from an ecological perspective, the tagging data better represents the population of juvenile fish that aggregate to the Cross Seamount and anchored FADs.

Fishermen have reported significant quantities of 40-70 pound yellowfin (approximately 98 - 118 cm) and bigeye (92 - 111 cm) have been taken on the Cross Seamount and the NOAA weather buoys during some years and seasons. However, available data and observations made by the fishermen indicate that most of the catch falls within the 15 to 40 pound range during recent years. Many fishermen have reported a decline in the average size and abundance of bigeye available to the fishery on the Cross Seamount, but these claims are difficult to substantiate with available data. Other fishermen have not noted significant changes in average size but state that every year is different. High grading, or the release offish less than ten pounds is practiced by many of the fishermen for perceived conservation reasons and due to the short shelf life, low market value and difficulty in marketing small fish.

1750 ., 1500 - H ~» - * *•*"•* fa*** >, 1250. •- 1 • VF» BE 1 = 1000 i • Si §• 750 _ - * ^J £ 500 J n J i i" .v^-.^iswh? ^^H 250 J 0 , — H • J J-. - - 30 40 50 60 70 80 90 100 110 >110 Fork Length (cm)

Figure 3. Length frequency of yellowfin (n = 1754) and bigeye tuna (n = 4849) tagged by PFRP funded tagging projects on the Cross Seamount or NOAA weather buoys to

5.2 Species composition

Landing data held by the Hawaii Division of Aquatic Resources (HDAR) for this fishery indicate a higher proportion of yellowfin compared to bigeye in the catch. For example, during 1995, the HDAR catch report data indicates that yellowfin accounted for 68.6% with bigeye accounting for the remainder of the tuna catch. This data is considered to be significantly in error due to the mis-reporting of bigeye as yellowfin, especially during the earlier years of the fishery. This is a common problem in fisheries that land both species at the same ex-vessel price as is the case with most landings from the offshore handline fishery. Both species are sold to the wholesalers and marketed under the Hawaiian name of ahi at the same price and reported as ahi on market forms. The Hawaiians did not distinguish yellowfin from bigeye tuna and the HDAR records all ahi as yellowfin tuna for data purposes. A significant problem

5 with under-reporting also exists for this fishery.

Surveys of experienced fishermen in the offshore fishery estimated that approximately 70-75% of their catch by weight consisted of bigeye with 15-20% yellowfin. Mahi mahi, ono (wahoo), skipjack, striped and blue marlin were believed to contribute approximately 5% to the landings. These bycatch species can contribute significantly to the value of the catch during some years and seasons, particularly for mahimahi.

The National Marine Fisheries Service (NMFS) has conducted limited dock sampling of landings from a long-term participant in the offshore fishery over a three year period. Their data is in close agreement with the claim by fishermen that bigeye account for approximately 75% to 80% of the landed total catch by weight.

Tagging results of both the Seamount Tagging Project and the Hawaii Tuna Tagging Project for fish released on the Cross Seamount or NOAA weather buoys where reliable lengths were recorded (n = 1754 YF, 4849 BE) indicate that 73.4% of tag releases (by numbers offish) were bigeye and 26.6% yellowfin. If the length measurements are converted to estimated weight according to length/weight relationships for central Pacific yellowfin and bigeye derived by Nakamura and Uchiyama (1966), the bigeye account for 82.4% of the total weight of tagged fish from the offshore locations (Table 1).

Table 1. Proportion of yellowfin by numbers and weight being tagged and released on the Cross Seamount and offshore weather buoys by PFRP funded tagging projects to April 1998.

No. of Fish Weight (lbs) % offish % by weight

Yellowfin 1754 12147.9 26.6% 17.6% Bigeye 4849 57040.4 73.4% 82.4%

Totals 6603 69188.3 100% 100%

6. Vessels, gear and methods 6.1 Fishing vessels

An estimate of the numbers of vessels active in the fishery since 1978 is given in Section 3. The fishing vessels in the offshore handline fishery are typically larger and better equipped than ika shibi or palu ahi vessels, though many of the smaller offshore handline vessels participate in the seasonal inshore ika shibi fishery. Most vessels berth or trailer launch from Honokohau or Hilo Harbors on the island of Hawaii or Kewalo Basin on Oahu. The vessels are well equipped with marine electronics, including GPS positioning equipment to locate remote fishing grounds, sophisticated depth sounders for fish location and some vessels are sonar equipped for locating and tracking sub-surface tuna aggregations. The average size of offshore handline vessels is approximately 45 feet, ranging in size from 27 to 68 feet. Hamiltion (1997) interviewed six full-time commercial fishermen who concentrate fishing effort on the Cross Seamount and NOAA weather buoys. The mean length of their vessels was 40.17 feet and cost an average of $150,000. The vessel cost, expenditures for marine electronics, fishing gear and vessel upgrades were significantly higher than for inshore tuna fishing vessels using the palu ahi or ika shibi techniques. Offshore handline vessels must be large enough to carry fuel and ice to visit fishing grounds

6 150-250 miles from port and carry enough ice to maintain catches of 3,000 to 14,000 pounds or more.

6.2 Gear and methods

The offshore handline fishery uses a variety of hook and line gear types, but it has been convenient to categorize the fishery within the handline group. Troll gear is normally used in transit and to locate schools near the fishing grounds. Fishing on the Cross Seamount and the NOAA weather buoys is conducted day and night, with many vessels fishing almost 24 hours a day while at the fishing locations. During a single fishing trip, tuna might be caught by trolling, jigging or handlining or on a specialized form of very short troll/jig gear unique to this fishery. Handline gear is a mix of short baited handlines, daytimepalu ahi type gear or night-time ika shibi or make dog gear. The only common factor is that all fishing methods use a single lure or baited hook on single line gear that is usually hauled by hand. Some of the larger vessels employ hydraulic line haulers or hydraulic reels to puWpalu ahi or ika shibi lines.

The primary fishing method is based on the tendency of juvenile bigeye, and a lesser extent yellowfin, to associate with floating objects, including a vessel (Hampton and Bailey, 1993). Sub-surface tuna schools are located either by trolling or electronic fish finding devices and chummed into association with the fishing vessel. During the daytime, short baited handlines, jigging lines or the troll/jig lines are used. At night, vessels drift slowly on parachute sea anchors with three to five handlines set at varying depths in a similar manner to the inshore ika shibi fishery. Standard trolling lures, barbless pole and line lures or large rubber squids are used. Frozen California anchovies or minced fish flesh is used for chum. Handlines are normally baited with fresh caught squid or fresh or frozen mackerel scad (Decapterus spp.) or California sardines. Shiny metal lures can be vertically jigged when a tuna school is located beneath the vessel. Vessels normally drift past the NOAA weather buoys withpalu ahi handline gear or use metal "diamond" jigs.

7. Catch and effort 7.1 Fishery effort

Trip lengths average 4.87 days (Hamilton and Huffman, 1997), which includes approximately 18 to 20 hours in transit to and from the fishing grounds, with most vessels based from Honokohau Harbor on the Kona side of the island of Hawaii. A few vessels begin and end their trip from Kewalo Basin on Oahu. Actual fishing time varies depending on fishing success and vessel size, but most boats fish for two to three days. Regular participants in the fishery make approximately three trips per month, with fishermen surveys indicating a range of 35 to 44 fishing trips per year. These results are close to that reported by Hamiltion (1997) who lists an average of 35.25 seamount fishing trips made per year from her pool of six offshore handline vessels. The boats operate with a total crew of 2 to 5 persons, including the captain. Fishing may take place during the daytime, at night or both day and night depending on when the fish respond best during a particular trip.

7.2 Reported landings and estimated catch

Catch per trip from this fishery are an order of magnitude higher than for inshore handline trips, due to the productivity of the fishing grounds combined with longer trip lengths. Normal catches can range from 2,000 to 8,000 pounds for a five day trip (three fishing days) with some vessels landing in excess of 14,000 pounds of tuna. Catch rates can exceed 10,000 pounds per day during exceptional fishing episodes.

7 HDAR landings data for 1995, as reported in The Pelagic Fisheries of the Western Pacific Region 1996 Annual Report (Anon 1997) indicate a combined catch of yellowfin and bigeye tuna from the offshore handline fishery of 2,924,000 pounds which included only 146,000 pounds of bigeye. This figure reflects only the reported catch and should not be confused with total catch estimates. Hamilton and Huffman (1997) recorded an average offshore catch from six vessels of 177,750 lbs per year during the 1995 - 1996 period. These six boats alone would have accounted for approximately 1,066,500 lbs of catch for that year or 36% of the total reported catch for that year from the entire Hawaii commercial troll and handline fleet. If the bulk of the offshore catch was bigeye tuna, there is a serious discrepancy between the recorded catch of 146,000 pounds and the catch claimed by the fishermen.

For the purposes of discussion, an attempt to estimate actual catch from this fishery for a single year has been attempted. It should be stressed that this is only an estimate, but it is based on the best available information from the fishery and known participation of vessels in the fishery. A list of vessels active in the offshore fishery during 1995 was developed and divided into three categories based on effort. Group A vessels are considered highliners in the fishery and derive over 90 % of their income from offshore handline fishing. Groups B and C are devote less effort to offshore fishing locations or are not as successful. Each category was assigned estimates of the mean number of fishing trips made to offshore fishing locations during the year based on survey data. Lastly, conservative estimates of average tuna catch per trip were factored in to yield a conservative estimate of 1.53 million pounds of yellowfin and bigeye taken by offshore handline fishery, from the Cross Seamount and NOAA weather buoys during 1995. Industry sources have indicated that this figure is reasonable but suggest it may be conservative. Hamilton and Huffman (1997) data indicating a mean annual catch from six offshore handline fishermen of 177,750 pounds per year further suggests that our estimate of 162,000 lbs per year from Group A fishermen is realistic. Applying a weight ratio estimate of 3:1 for bigeye to yellowfin, which appears conservatively realistic (see Section 5.2), an estimate of 1,145250 pounds of bigeye and 381,750 pounds of yellowfin results. The HDAR landing data for 1995 bigeye of 146,000 pounds represents only 12.7% of that estimated here.

Table 2 summarizes these estimates. The table can be used as a template to refine catch estimates if more accurate catch and effort statistics become available in the future.

Table 2. Estimated catch of bigeye and yellowfin tuna from the Cross Seamount and NOAA weather buoys during 1995 (pounds).

Effort Estimated Estimated Estimated Estimated Estimated Estimated Estimated Group No. Vessels Trips/Year Catch/Trip Vessel Total BE (%75) YF (25%) (lbs) catch/Year catch/Year

A 6 36 4,500 162,000 972,000 729,000 243,000

B 5 30 2,500 75,000 375,000 281,250 93,750

C 6 20 1,500 30,000 180,000 135,000 45,000

17 1,527,000 1,145,250 381,750

7.3 Seasonality of catch and effort

Long term participants in the fishery were asked if they had noted any seasonal trends in the fishery. A well documented reduction in effort occurs during the summer months, when several boats in

8 the offshore fishery join the inshore ika shibi fishery for large yellowfin close to the island of Hawaii. The larger fish bring a higher price per pound and fuel costs are a fraction of that used for an offshore fishing trip. Some fishermen believe that the fishing is poor on the Cross Seamount during the summer months. However, this viewpoint was often expressed by fishermen who did not fish the area during the summer but concentrate on the Hilo based ika shibi fishery. A highly experienced fisherman who has been fishing the Cross Seamount since 1980 and fishes there all year claimed that the summer months can be very good but the price offish is normally low which further discourages effort during the summer. Three highly experienced and successful offshore fishermen felt that each year was different, and that good fishing could occur during any season depending on inter-annual variations in local abundance. However, there was some consensus that fishing during a "normal" year was best from September to April. Two peak fishing periods were identified as falling between September and November and/or February and May.

The HDAR catch data for this fishery is considered to be incomplete and the species identification is questionable. However, the reported catch of yellowfin and bigeye combined appears to accurately represent seasonal trends in the annual catch. Figure 4 clearly indicates the reduced catches during the summer months from five years of combined landing data (1991-1995).

Figure 4. Combined yellowfin and bigeye catch reported to the HDAR from the offshore handline fishery for monthly means of data from 1991 - 1995 in pounds

8. Markets

Landings from the offshore handline fishery flow into a domestic market niche for inexpensive grilling grade tuna, poki' or medium grade sashimi tuna for local consumption. Fish are normally landed whole but some fishermen routinely bleed, gill and gut larger fish to improve quality and ex-vessel value. A significant portion of the catch is marketed to supermarket chains, small seafood retailers or is sold by the roadside. On the island of Hawaii, the primary seafood wholesale companies dealing with offshore handline fish are Flying Seafoods, Marina Seafoods, Hilo Fish Company and Suisan, Inc. Fish landed on Oahu either flow through the United Fishing Agency auction at Kewalo Basin or are marketed to individual markets.

Raw fish marinated in sauces and spices

9 During 1996, an export market to Japan for small, whole fish of high quality was initiated. However, the quality demands of this market have proven difficult to meet by the fishery. Due to the small and cramped storage bins used by most of the fleet and limited ice supplies, the quality offish from the offshore handline fishery can be very poor compared to ika shibi or inshore troll fisheries. Longer trip lengths, inadequate ice supplies and large catches that come very rapidly can result in poor quality fish and have given the fishery a bad reputation with processors and wholesalers. Vessels that have been able to overcome these problems can land high quality product. For example, one large vessel in the fishery is equipped to produce freshwater ice while at sea and can guarantee high quality product to more discerning buyers.

9. Management concerns and recent developments 9.1 Public management concerns

The contribution of the Cross Seamount to local tuna stocks and the impact of the offshore handline fishery has been a subject of heated debate since the beginning of the fishery. Longline and sport fishermen support the view that harvests of juvenile fish by the offshore handline fishery will significantly reduce recruitment of mature yellowfin and bigeye, thus reducing fish available to local fisheries at a larger size. The handline fishermen counter that the longline vessels should be controlled as they are taking large numbers of the spawning stock to the detriment of local tuna populations.

Fisheries science can not support either position at present. However, most scientists support the view that the handline catches of juvenile yellowfin are insignificant in comparison to the high estimates of natural mortality for fish of this size. The problem is that the same reasoning is usually extended to bigeye, when reliable age dependent estimates of natural mortality for bigeye are lacking. Concerns based on the perceived over-harvest of spawning stock are also impossible to support as there is currently no scientific proof that local spawning of yellowfin in Hawaiian waters leads to local recruitment. Also, studies do not currently support significant levels of bigeye spawning in Hawaiian waters, with most of the spawning believed to take place in equatorial waters south of Hawaii. Local bigeye resources are therefore believed to be tied to the overall condition of the greater central Pacific or Pacific-wide stock.

9.2 Council management chronology and discussion

The Council has coordinated numerous meetings and received comments from many sectors of the local fishing industry on the possibility of federal management of the offshore handline fishery. The Council established a control date for the fishery ofJul y 2, 1994, but the control date was not supported by any scientific evidence that there was a biological problem warranting the action. The control date:

• warns fishermen who enter the fishery after the date may be excluded from the fishery if the Council acts to limit entry; • does not bind the Council to use that control date; • allows the Council to use the date or choose a later control date; • allows the Council to establish a management system that does not use a control date; and • allows the Council to take no further action on this issue.

The strongest justification at present for limiting catch and effort in the fishery and establishing a minimum commercial size is economically based. This is due to the fact that the domestic (Hawaii) market for juvenile tuna can be flooded by the fishery as it exists at present, and fish of less than 10-15 pounds have a short shelf life and spoil or bruise easily. When the market is flooded, prices decline,

10 revenues are not maximized and some wastage has occurred due to over supply. On a yield per recruit basis alone, it may be sensible to restrict the take of the very small fish that will double in size very quickly if they do not succumb to natural mortality.

The Scientific and Statistical Committee (SSC) of the Council has not been in a scientifically supportable position to recommend any federal management of the fishery, or any minimum size restrictions in particular. However, in March 1993, the Pelagic Plan Team and the SSC recommended the State investigate setting a minimum commercial sale size for ahi to at least 10 pounds and establish a non-commercial bag limit on ahi. No action has been taken by the state. The SSC unofficially encouraged the fishermen to self-impose a minimum size for yellowfin and bigeye from the offshore fishery if they felt the move was desirable.

In October 1994, the Council's Small-Boat Working Group recommended that:

• the NMFS or appropriate organization conduct a study to determine the dynamics (e.g. resident time) of the population of tuna on offshore seamounts of the main Hawaiian Islands,

• and that NMFS or appropriate organization conduct a tagging study to determine movement patterns of tuna around the main Hawaiian Islands.

The Pelagic species Plan Team, SSC and Council responded that both recommendations were being addressed by the Pelagic Fisheries Research Program. Tag return information from the PFRP funded Seamount Tagging Project and the Hawaii Tuna Tagging Project are beginning to yield useful information on the vulnerability, interaction and residence time of yellowfin and bigeye on the Cross Seamount. However, no published results were available for inclusion in this report.

In November 1996, the Big Island Fishermen's Association expressed concern over a gear interaction problem with some Hawaii based longline vessels on the Cross Seamount. As a result, the Council coordinated four meetings between January 4 and March 28, 1997 with both handline and longline representatives. The interaction problem involved the recent exploitation of the Cross Seamount by a relatively small segment of the Honolulu based longline fleet during the summer and fall of 1996. These vessels employed a very shallow longline configuration that was set at night in a manner that caused direct tangling and hooking of the gear with handline gear and sea anchors.

Both parties to the interaction problem agreed to adopt and fully support a management option arising from both the second and third meetings. This option can be summarized as follows:

No restrictive legislation of any kind be imposed with fishing open to all gear types throughout the year. The Council explores ways to facilitate the co-existence of both fishing fleets in a way to minimize interaction.

10. Summary

The offshore handline fishery of Hawaii has several distinct characteristics that qualify it for consideration apart from all other Hawaii pelagic fisheries. The magnitude of the catch alone would argue that catch and effort data from this fishery be reported separately from inshore handline and troll landings instead of grouped with all troll and handline data as it appears in the Council Pelagics Annual Report. More accurate estimates of catch and effort should be made for the offshore handline fishery, as it undoubtedly accounts for the majority of bigeye landings by all Hawaii troll and handline fisheries

11 and lands a significant proportion of yellowfin taken by non-longline gears. Improved data reporting, correct species identification and separate reporting in fisheries statistics will permit better monitoring of catch and effort trends from all Hawaii pelagic fisheries.

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