INTERNATIONAL PACIFIC HALIBUT COMMISSION

SEVENTY- SECOND ANNUAL MEETING

Embassy Suites Hotel, Bellevue, Washington

January 22 - January 25, 1996

PUBLIC SESSION - January 22, 1996

REGENCY ROOM

9:00 a.m. OPENING

9:15 a.m. DIRECTOR'S REMARKS

9:30 a.m. STAFF PRESENTATION

10:30 a.m. COFFEE

11:00 a.m. - 12 Noon QUESTIONS AND DISCUSSION

(Continued after lunch ANNOUNCEMENTS AND ADJOURNMENT if needed)

6:30 p.m. RECEPTION (No Host) - Ballroom

TOTAL REMOVALS OF PACIFIC HALIBUT IN 1995

by

Heather L. Gilroy

The total 1995 removals of halibut off the Pacific coast were 68 million pounds. This represents a decrease of 13 million pounds from 1994; and the majority of the decrease occurred in the commercial catch. The total removal is now close to the average of the last thirty-four years and similar to the 1985 level. The total removals from 1986 to 1994 were at all time high levels, with amounts over 80 million pounds. The 1995 removals of halibut by commercial catch, sport catch, bycatch mortality, wastage, and personal use were 43.8, 7.7, 14.9, 1.1, and 0.5 million pounds, respectively. A summary of the various types of removals of halibut by regulatory area is provided in Table 1.

Commercial catch is the directed removal by the halibut fleet. Sport catch is fish caught with a single line or spear, which cannot be sold, and is generally limited to two fish per person per day (with the exception of some Areas in 2A, where it is one fish). Bycatch mortality consists of losses of halibut discarded in other fisheries. Wastage results from lost gear, abandoned gear, and the mortality of sublegal halibut in the halibut fishery. Personal use includes removals from a variety of sources such as Indian food fish in Canada and landings with commercial gear for personal use in both Canada and United States that are not included in commercial or sport statistics. In 1995, the fish taken-home by the commercial halibut fishermen were included in the commercial catch, not as personal use as it had been done previously.

Trends of each of the removals will be summarized in this report. The commercial catch will be discussed in detail; however 1995 data are preliminary. Details of bycatch and sport catch and special research projects will be discussed in a later report. The data sources are from the International Pacific Halibut Commission (IPHC), National Marine Fisheries Service (NMFS), and Department of Fisheries and Oceans (DFO).

A detailed summary of the 1995 catch and seasons by regulatory area (Figure 1) is provided in Table 2. The IPHC research catch has historically been included in the commercial catch but not identified separately. In 1995, the research catch has been separated so a comparison can be made between the catch and catch limits in the quota fisheries. For comparisons between years the total catch should be used.

Area 2A

There were several significant changes to the management of the Area 2A non-treaty commercial fishery requested by the Pacific Fishery Management Council. First, the commercial fishery was divided into; a directed catch and an incidental catch while salmon trolling, each with a separate catch limit. At the completion of the salmon troll fishery in June, the remaining catch limit would 'roll' into the directed catch limit. Vessels could participate in only one of the fisheries. Secondly, the directed fishery was restricted to waters south of Point Chehalis, WA.

The directed commercial fishery is an open access fishery. The fishery consisted of seven 10-hr fishing periods with fishing period limits (Table 3). In spite of issuing 352 licenses for the fishery, fishermen showed little interest in halibut. During some periods, very few vessels fished as there were conflicts with sablefish openings, or meetings between fishermen and plant personnel to sort out salmon prices. Also, bad weather played a part during one period. Additional fishing periods were added to the original openings announced in the regulations as the catch limit had not been taken at the end of the August 15 period. The fishery closed September 26 with a total catch of 105, 000 pounds.

The incidental catch in the May and June salmon troll fishery was only 2,000 pounds. In 1996, the number of halibut to salmon kept will be examined in an attempt to increase the catch.

The treaty Indian catch of 175,000 pounds exceeded the catch limit by 2%. This fishery consisted of three unrestricted longline fisheries, one restricted fishery with a 3,000 pound trip limit, and incidental halibut catch with the sablefish and salmon troll fisheries.

The IVQ and IFQ Fisheries

Area 2B

An Individual Vessel Quota (IVQ) fishery was in effect in Area 2B from March 15 to November 15. The 1995 IVQ regulations were similar to those of 1994 with the exception of a quality control tagging program discussed later. The IVQ fishery allowed each vessel to catch a predetermined poundage of halibut as calculated by the DFO, based on the 9.52 million pound catch limit approved by IPHC. There was also an additional 131,000 pounds available as carryover from the 1994 fishery to vessels which did not take their total allotment. This poundage was from the underage/overage program where underages of up to 10% of the IVQ were carried to the next year.

There were 435 vessels which received quota shares, and these quota shares were split into two equal blocks or shares. A vessel could fish up to 4 shares or blocks. The fleet was down in 1995 to 286 vessels, since 42% or 184 of the licenses or quota shares were transferred. The fleet in 1994 consisted of 313 vessels; but in 1991 and 1992, before transferability was allowed, 433 and 431 vessels landed halibut.

A dockside tagging program was initiated by DFO and fishing organizations in 1995. All IVQ Canadian halibut were tagged on the tail by the port monitors as the fish were offloaded. The tags were blue and coded so the fish could be identified as being caught in Canadian waters. The program was initiated for enforcement and marketing purposes. It is anticipated that in 1996, U.S. halibut landed in Canada will be tagged but with a tag of a different color. It was hoped that the tagging of U.S. fish would have been in effect in 1995 as the tags were already produced; however the legislation to allow this was not available.

Alaska

The IPHC set the Alaskan catch limits by regulatory area and a season of March 15 to November 15 as shown in Table 2. The North Pacific Fisheries Management Council (NPFMC) passed the regulations for an Individual Fishing Quota (IFQ) Fishery in Alaska and NMFS implemented the program in 1995. The IFQ fishery allowed quota share (QS) recipients to catch a predetermined poundage of halibut known as their IFQ. For a comparison of the general concepts of the Alaskan IFQ and the Canadian IVQ fisheries see Table 4.

The implementation of the IFQ program was a major change to the management of the Alaskan commercial halibut fishery. Since it was a new program, some of the regulations have been under review and are still being defined by the NPFMC. The program will continue to be reviewed and updated for the next several years, IPHC staff will review the changes.

Landing Patterns

One advantage of QS fisheries is spreading out landings over time. The three fishing days in 1994 for Areas 2C and 3A expanded to 245 fishing days in 1995. The U.S. fishery got off to a slower start than the Canadian IVQ fishery (Figure 2). The Alaskan fishery landed only 8% of the catch in the first 1.5 months. This was because of severe weather and sablefish ex-vessel prices that were much higher than halibut prices. The majority of the U.S. fleet with both halibut and sablefish IFQs targeted sablefish early in the year. The Alaskan fishery landed the greatest amount of pounds in September. The Canadian fleet emphasized fishing in early spring, April had the highest monthly landings (by weight), but the last two weeks in March were busier on a daily basis.

Kodiak and Homer have been the leading ports for processing halibut since 1986 and remained the leading ports under the IFQ program (Table 5). Although Table 5 does not directly compare total Alaskan landings it illustrates changes. Changes occurred to ports where tenders landed, within Area 4, and where the sablefish vessels landed. In the first year of the IFQ fishery, offloads to tenders were only allowed if the tenders became registered buyers, which meant they had to be able to send the landing weight information to NMFS within 6 hours of a catcher vessel's offload. As expected ports such as King Cove, with a history of tenders, processed less fish under the first year of the IFQ fishery. The Area 4 ports together, Dutch Harbor and Akutan, processed more halibut as vessels made more than one trip in Area 4, and Dutch Harbor was an important sablefish landing port. The top sablefish landing ports were Seward and Sitka, presumable mixed halibut and sablefish trips increased Sitka's importance to halibut landings.

The top three landing ports for Canadian halibut were Prince Rupert, Port Hardy, and Vancouver. These three ports have been the most important ports since 1991; the initial year of the IVQ program. They also receive over 80% of the landings by weight.

IPHC relies on state and federal agencies to provide sport harvest data. Washington/Oregon/California harvest data are obtained from creel census and telephone surveys and are available the year of the fishery. IPHC considers the data accurate. In British Columbia, no new harvest data of acceptable quality are available so averages from 1987 to 1992 are used. The Alaskan harvest data from creel census and postal surveys are considered good estimates, but the 1995 data for Alaska are unavailable, so the 1995 harvest projections are based on the 1994 average weight of sport caught fish and applied to a regression of the catch in numbers for the last six years. The total estimated 1995 sport harvests from Alaska, British Columbia, and Washington/Oregon/California were 6.8, 0.66, 0.24 million pounds respectively. Only Area 2A has a catch limit for sport harvest, 0.23 million pounds in 1995.

IPHC began accounting for sport catch in 1977 and the estimated catch has increased yearly, with the exception of 1992 and 1994, when slight decreases from the previous years occurred. In 1995, projected sport catch represented 11% of the total removals. This is slightly above the 8 to 9% of the last few years. As the halibut stocks decrease, the commercial catch limits also decrease; if the sport catch continues to increase it will continue to represent a greater proportion of the total removals.

Bycatch mortality estimates are obtained from data collected by the observer programs in Alaska and Canada. No observer program is currently in place off of Washington and Oregon, so the 1987 observer data are used to calculate the bycatch mortality estimates. Total bycatch in 1995 was 14.9 million pounds and the amount has not changed significantly in the last five years. Bycatch represented 22% of the total removals in 1995, where it has represented between 18 to 20% over the last five years.

Wastage in the halibut fishery dropped to approximately one million pounds in 1995, which is less than half of 1993 or 1994 levels. The drop in wastage may reflect improved fishing practices with the implementation of the IFQ fishery in Alaska. First, lost or abandoned gear in the Alaskan commercial fishery dropped significantly from 1994 to 1995. The ratio of lost skates to hauled skates decreased to a level similar to the ratio observed in Canada, where there has been a quota fishery for several years. Secondly, the rate of discard mortality of sublegal halibut used in 1995 was 16% instead of the 25% previously used. The 16% rate is from observations in the Bering Sea and Aleutians sablefish hook and line fishery where the pace is similar to the individual quota fisheries. The 16% rate has been used for the Canadian IVQ fishery since 1991.

Total personal use estimates for 1995 accounted for approximately half a million pounds. Personal use has only been accounted for in the last five years. One improvement in the 1995 estimates from those of 1994 was that take-home fish in all of the commercial halibut fisheries are now required to be recorded on the fish tickets. Personal use fish in the halibut fisheries outside of Alaska have been recorded on tickets and with the implementation of the IFQ fishery, this is now the case in all areas. Since, these data are recorded on fish tickets they are now included as commercial catch. The remaining personal use harvest is from the Canadian Indian food fish and the Alaskan non-commercial and non-sport landings from which little documented data are available.

Table 1. The 1995 removals of Pacific halibut by regulatory area in net weight (thousands of pounds).

NEW DEVELOPMENTS AND MANAGEMENT IMPLICATIONS FOR NONCOMMERCIAL REMOVALS OF PACIFIC HALIBUT

by

Robert J. Trumble

The Halibut Commission uses estimates of total removals from the halibut resource to perform stock assessment and to recommend catch limits for the fishery. We estimate removals for commercial catch, bycatch mortality, sport catch, personal use, and wastage, and look for patterns that may suggest removals in the near future. This section will report on special projects or management actions involving noncommercial removals that have significance for the halibut resource. Bycatch mortality and the sport fishery are the two areas of focus for 1995. Improvements that Individual Fishing Quotas in Alaska made in understanding and estimation of personal use and wastage were reported in the previous section by Heather Gilroy, and will not be covered here.

As usual, we used data from observers aboard groundfish vessels to estimate the halibut bycatch rates, discard mortality rates, and total bycatch mortality for the groundfish fisheries off Alaska. The recent observer coverage in Canada has provided updated values for bycatch rates and discard mortality rates for some fishing areas. No observer coverage occurs off Washington and Oregon, so bycatch mortality estimates use 1987 research data. Coast-wide estimates of bycatch mortality decreased from 15.7 million pounds in 1994 to 14.9 million pounds in 1995, about a 6% change. Small declines occurred in Areas 3 and 4; in spite of the bycatch mortality reduction program in Area 2B, bycatch mortality increased slightly (Table 1). No significant change has occurred in the past five years as bycatch mortality has fluctuated between about 15 and 16 million pounds (Figure 1).

Alaska

The U.S. implemented a series of management measures over the past several years in Alaskan waters to limit halibut bycatch mortality and better monitor or control the bycatch mortality limits. Reductions to halibut bycatch limits in the North Pacific that would significantly constrain the ability of the groundfish fleet to harvest available groundfish may not be seriously considered in the near future by the NPFMC unless an effective incentive program can be devised.

Three programs are under evaluation in Alaska that may lead to lower bycatch mortality limits: Individual Bycatch Quotas; Vessel Incentive Program; and Careful Release. The NPFMC is evaluating the legal and technical problems with incentive programs, and will prepare an analysis of individual bycatch quota alternatives for the NPFMC in 1996. A concept under development as a potential alternative to individual bycatch quotas allocates bycatch mortality to pools of fishermen, rather than to specific fisheries.

The Vessel Incentive Program was implemented by the NMFS in 1991 to penalize groundfish fishermen who caught halibut and other bycatch at higher than standard rates. The program began in 1991, and the first two cases were resolved in 1995. In the first case, an Administrative Law Judge imposed a $50,000 fine on a vessel for exceeding the Bering Sea-Aleutian Islands (BSAI) halibut VIP rate standard during May 1991 while fishing in the flatfish fishery. The owner and fishmaster appealed portions of the decision, and the decision on the appeal is pending. In the second case, the owner and the NMFS settled for a penalty of $35,000 for exceeding the BSAI halibut VIP rate standard in September 1991. Decisions on two other cases from 1991 are pending following hearings before an Administrative Law Judge.

The NPFMC approved in 1993 a recommendation from the IPHC staff to require all groundfish longline vessels to use prescribed methods of careful release for discarding halibut bycatch. The requirements did not work well during the first two years after implementation, with discard mortality rates at the same level as before the requirement, around 18-20%. The assumed 12.5% discard mortality rate for in-season management used in the previous two years for the Bering sea Pacific cod longline fishery continued in 1995, so the NPFMC asked the IPHC and NMFS to monitor the rate in-season and report back to the Council in June 1995, so that any necessary retroactive adjustments in the rate could be made. Observers reported viability data to IPHC weekly throughout the season, and many vessel captains also sent their data to a consultant. The consultant provided reports of discard mortality rates to individual vessels and the fleet, thus providing opportunity for those with high rates to change fishing practices. At the end of the season, analysis by IPHC showed an average discard mortality rate of 11.5%.

The NPFMC received in 1995 a proposal from the IPHC to require on-deck sorting of halibut bycatch from factory trawlers and catcher vessels that dump to stern tanks for sorting below decks. Support for the concept is widespread, as improved survival would allow increased groundfish harvest for a given bycatch mortality limit, or increased halibut harvest for as given amount of groundfish harvest. However, opposition to on-deck sorting occurred primarily because of 1) increased work load for the groundfish observers, increased safety problems for observers working on deck, and inability of the observer data base to accept data from deck-sorted halibut; 2) incompatibility of deck-sorting with the VIP, as data from deck-sorting does not follow the VIP sampling protocol; 3) reduction in the quality of bycatch estimates, and 4) difficulties in confirming that vessels adhere to the deck-sorting requirements when observers are not actually monitoring a haul. The NPFMC is scheduled to take final action on the proposal in January, 1996. The IPHC Commissioners recommended to the NPFMC that on-deck sorting not be approved unless it is part of another program that addresses the problems identified.

Canada

Canada has developed a bycatch reduction plan and identified a bycatch reduction target of 1 million pounds of halibut bycatch mortality by 1997. For 1996, this plan calls for a reduction of the bycatch mortality limit for Hecate Strait to 500,000 pounds, from the 1995 value of 580,000 pounds. In addition, a trawl bycatch mortality limit of 380,000 pounds will be introduced for the west coast of Vancouver Island. DFO will also implement an individual bycatch quota for trawl vessels in the groundfish fisheries in 1996. Bycatch mortality limits for the remaining portions of Area 2B will occur in 1997. Additional reduction measures will be introduced, as necessary, to reach the 1.0 million pound target.

Washington-Oregon-California

The Pacific Fishery Management Council accepted in 1995 a procedure developed by the University of Washington and the Oregon Department of Fish and Wildlife (ODFW) that uses CPUE of halibut and total effort in groundfish and shrimp trawls to estimate bycatch. The final estimate, from 1987 data, was 910,000 pounds of bycatch, equivalent to 455,000 pounds of mortality. An updated estimate using 1992 effort data is in progress at ODFW. The Oregon Trawl Commission is working with ODFW to implement a voluntary observer program for the trawl fisheries off Oregon and Washington.

Even though the IPHC has recommended a 10% per year bycatch limit reduction, we recognize that major reductions in U.S. fisheries are not likely to be approved by the NPFMC in the near future without some method that also allows groundfish harvest at or near current levels. The IPHC staff had been a strong supporter of in-season individual incentive programs, such as an Individual Bycatch Quota, as a mechanism to reduce bycatch but maintain groundfish harvest. A post-season incentive program, such as the on-going Vessel Incentive Program in Alaska, has yet to show effectiveness. Progress on developing incentive programs has been slow in previous years, so IPHC staff research has emphasized bycatch reductions in much smaller steps through time-area management and reduction on halibut discard mortality rates. Renewed emphasis on an individual bycatch quota (IBQ) program by the National Marine Fisheries Service is encouraging, and the IPHC staff will provide research assistance if an IBQ proves feasible.

In 1995, we continued tagging operations to improve estimates of discard mortality rates of trawl-caught halibut by tagging nearly 5,000 trawl-caught halibut near Kodiak Island. As part of a cooperative study, the University of Washington placed halibut in sea-bottom cages to monitor short term mortality. In 1993 and 1994, IPHC staff tagged 13,000 longline-caught halibut to improve estimates of discard mortality rates. Tags from these fish are now coming in. We encourage all fishermen to watch for and return tags to us, as the accuracy of the results will improve as we get more tags. Many of the tagged halibut will be sublegal in 1995, and it is important that tags from these smaller halibut be returned. Fishermen using any gear can legally bring in undersized, tagged halibut, but cannot sell them.

Since the early 1980s, the IPHC has accounted for the effects of bycatch mortality on the halibut resource by reducing the catch limits in the halibut fishery. The procedures have been improved and updated over the years. Two more modifications to the procedure are now being considered for 1997. First, legal-sized halibut bycatch will be treated as removals in a way similar to commercial catch. The quantity of bycatch mortality and its length composition will go into the stock assessment model to estimate exploitable biomass. The quantity of legal-sized halibut bycatch mortality will be subtracted out of the area in which the bycatch occurred. Second, catch limit reductions to compensate the resource for lost reproduction will occur only for sublegal-sized halibut bycatch mortality. The catch limit reductions will be distributed among regulatory areas according to the young halibut migration pattern, rather than be pooled over all areas. A migration model determines the movement of sublegal halibut for the purpose of catch limit reduction. The new bycatch compensation procedure will affect the estimate of exploitable biomass, will change the amount of catch limit reduction, and will change the distribution of the reductions. We cannot determine the amount of these changes until the legal-sized halibut are incorporated into the stock assessment model, and that will occur when historical data on bycatch mortality by size is available this spring.

The IPHC staff convened a workshop on November 30 for researchers working on halibut bycatch. Twenty-two scientists attended the workshop and discussed 19 projects that are underway or in planning concerning halibut bycatch. The group concluded that an individual incentive program would allow fishermen to more easily implement bycatch reductions, and that solutions for obstacles to incentives are a high priority. The participants supported a functional research approach to bycatch consisting of projects to 1) reduce encounters of gear with halibut; 2) increase selectivity of target species and reduce retention of halibut; 3) reduce discard mortality; 4) understand basic biological responses; 5) improve estimates of bycatch and bycatch mortality; 6) educate fishermen and managers; and 7) provide research coordination and communication. These research areas often overlapped, and some recommended projects touched several areas. Participants agreed to hold future workshops annually.

Sport catch estimates in Alaska are made by Alaska Department of Fish and Game (ADF&G) from postal and creel census surveys. ADF&G provides the estimates with a one year lag to allow for receiving and processing postal data. Current estimates for Canadian sport estimates are not used because of data quality concerns. Most sport fisheries in Area 2A have in-season estimates made from creel census surveys, and others have post-season estimates but within the year of record. Washington Department of Fish and Wildlife and ODFW provide the estimates.

Alaska

The coast-wide halibut sport catch decline from 8.0 million pounds in 1993 to 7.4 million pounds in 1994 was driven by lower catches in Area 3 of about 15% (5.3 to 4.5 million pounds). The decline was attributed partially to reductions in estimated mean weight of sport halibut in central and southern Cook Inlet. Smaller halibut were also observed in southeast Alaska. Sport catch was estimated in 1994 by stratifying private and charter catches. Smaller halibut, on average, were landed by private anglers than charter anglers. Unstratified estimates made prior to 1994 gave more emphasis to the charter harvest, which tended to raise the total catch. The ADF&G is evaluating the effects of these changes. The pattern of increasing sport catch in Alaska may be slowing. The quality of the sport estimate, based on a postal survey with follow up mailings to non-respondents, is very good.

Later in 1996, the NPFMC is scheduled to discuss possible allocation of halibut catch between sport and commercial halibut fisheries. Allocation discussions have occurred with the Council and with Council work groups, but no analysis of specific alternatives has yet occurred.

Canada

Since 1981, IPHC has used estimates of sport-caught halibut in waters off British Columbia, Canada (IPHC Area 2B) from a postal survey ("Tidal Diary") conducted by the Pacific Region of the Department of Fisheries and Oceans (DFO). During 1993 and 1994, DFO and IPHC biologists discussed alternative estimates, and in 1994 IPHC received an alternate estimate for the 1993 sport catch based on a variety of data, such as reports from fishing lodges, reports from fishery officers, and anecdotal information. The IPHC staff has concluded that the procedures used for the estimate recommended by DFO for 1993 are not adequate, and that a scientifically and statistically credible sport catch estimation procedure for Area 2B is needed. In 1995, the IPHC staff recommend using the six-year (1987-1992) average from the postal survey of 657,000 pounds for future years until a better procedure is available. While the six-year average suggests that halibut catch is stable, we have received reports that halibut sport catch is increasing as salmon catch declines.

The Canadian Department of Fisheries and Oceans (DFO) currently has inadequate resources for surveying sport halibut catch, and efforts to estimate sport catch are currently part of the process to estimate other recreational species, especially salmon. Estimates of future halibut sport catches will continue to be difficult without a program to collect sufficient data specific to halibut. A Recreational Catch Working Group within DFO is addressing a comprehensive program for sport catch estimation, including halibut, but has not reached a conclusion on future methods of estimation.

Washington-Oregon-California

Allocation of halibut among sport, commercial, and treaty Indian fisheries in the Washington-Oregon-California area is decided by the Pacific Fishery Management Council (PFMC). Only in Area 2A does specific allocation occur between sport and commercial fisheries. The IPHC does not participate in the allocation decision. In-season management of many of the Area 2A sport fisheries has led to implementation of in-season catch estimates of sport catch, which are timely and high quality. Post-season catch estimates are made for a few regions without in-season management. Washington Department of Fish and Wildlife and Oregon Department of Fish and Game are the only agencies that provide sport catch data during the year of the fishery.

Bycatch mortality estimates have fluctuated somewhat over the past four years, but without a trend. Only minor changes in the level of bycatch are likely in the near future. Serious evaluation of an individual bycatch quota system in Alaska offers hope that effective incentives, and subsequent bycatch mortality reductions, may be coming. Canada has implemented a bycatch reduction program to bring down bycatch mortality, and is on schedule to reach 1 million pounds by 1997. The IPHC staff has released nearly 20,000 tags over the past three years to help improve estimates of discard mortality rates, and we encourage fishermen to look for and return tags. The bycatch compensation model will affect both estimates of exploitable biomass and the distribution of catch limit reductions among areas.

We have seen the sport fishery grow substantially in the recent past, and IPHC staff work closely with state and federal biologists to improve the data and our understanding of the sport fishery. The slight decline in sport harvest in 1994, decreasing average size of sport-caught halibut, and new estimates from stratification by charter and private catch, suggest that the increasing trend of Alaska sport catch may be slowing. A method for accurately estimating sport catch in Area 2B is needed, as we suspect that halibut catch is growing there. Changes in sport catch in Area 2A depend on allocation decisions made by the PFMC.

Table 1. Estimates (thousands of pounds, net weight) of bycatch mortality of Pacific halibut (Hippoglossus stenolepis) for 1991 through 1995.

CLIMATE CHANGE AND HALIBUT BIOLOGY

by

William G. Clark and Steven R. Hare

During this century there have been dramatic and persistent changes in the growth and recruitment of Pacific halibut that cannot be readily explained by changes in stock size. The staff has taken account of these medium-term changes in recommending an optimal exploitation rate, but we have not known the reason (or reasons) for them.

Recent climatological research has detected the occurrence of abrupt changes in North Pacific atmospheric and oceanic circulation, the most recent event occurring in the mid-1970s. It is increasingly apparent that the entire biota of the North Pacific, including halibut, underwent a major change beginning around that time. Similar regime shifts, detectable from various data series, occurred earlier in the century.

The staff is proposing a research project to relate the biological changes observed in the stock to the physical changes observed in the ocean. The aim is to identify distinct climatic regimes and the behavior of the stock under each. The benefits would be a better understanding of how the environment affects the stock and possibly a small increase in long-term yield.

Over the last fifteen years the growth of halibut has decreased dramatically, especially in Alaska. An eleven-year-old female landed in Kodiak was a 40 lb fish in 1980. Now it is less than 20 lb (Figure 1). Fifteen years ago fish of a given age were substantially larger in Alaska than in British Columbia; now there is no difference. In both respects, halibut growth is similar to what was observed in the 1920's and 1930's. An increase occurred sometime during the 1940's, and the present decrease began in the mid-1970's. Fish are also maturing at a smaller size now than they used to (Figure 2), while the age at maturity is quite close to what it has always been.

There have been clear decadal variations in halibut recruitment all through the century, or at least since about 1935. Most recently we saw a run of good year-classes spawned in the late 1970's and early 1980's, apparently followed by a run of poor year-classes. This kind of alternation has sometimes been viewed as a cycle, but could just as well reflect distinct periods of different environmental conditions.

The climate of the North Pacific is driven by the location and intensity of seasonally varying atmospheric pressure cells. During the most climatologically active months of November to March, the Aleutian Low pressure system covers much of the North Pacific, while the Subtropical High pressure system is most active in the summer months. Each of these systems can cover an area of several million square kilometers. In addition to creating conditions that establish seasonal weather patterns, these atmospheric systems affect oceanic conditions via changes in vertical and horizontal flow driven by surface wind stress. Examples of wind-driven flow changes include redirection of surface currents, mixed layer depth turnover, and enhanced or suppressed coastal upwelling. These processes in turn affect biological primary production and, ultimately, upper-level trophic species in an ecosystem driven from the bottom up.

Recent convincing evidence has accumulated that the climate of the North Pacific, and in particular the activity of the Aleutian Low pressure system, has changed markedly from 20 years ago. Since the winter of 1976/77, winters in the North Pacific have generally been marked by intense, large-scale Aleutian Low events. The center of the Low has deepened (i.e. lower central pressure) and shifted eastward by several hundred kilometers. The physical impacts of this change in behavior are numerous, but include the following: warmer air and sea surface temperatures in Alaska and Alaskan waters, more frequent and severe storm activity, increased vertical advection (upwelling) and decreased mixed layer depth across most of the Gulf of Alaska. Several investigators have speculated that the 1976/77 regime shift is but the most recent in a succession of events. In the 20^th century, it has been proposed that four distinct climatic regimes have occurred. The regimes have averaged 25-30 years in duration, with the transitions taking place in the mid-1920s, mid-1940s and mid-1970s.

Biological changes associated with these climatic regime shifts have been spectacular. Sharp increases have been noted in primary and secondary (zooplankton) production, as well as in salmon and several groundfish species. Concurrently, other populations including king crab, shrimp, Steller sea lions and several species of marine birds, declined sharply with the onset of the new regime. A dramatic decline in average size of Pacific halibut across much of its range also began following the winter of 1976/77. These differences have been noted in populations ranging from southern California to the Hawaiian Islands to the Bering Sea. A very close linkage has been established between changes in oceanic conditions driven by Aleutian Low variability and Alaskan salmon production. Recent research has pinpointed the first year of marine residence as the most likely period of influence. Increased marine growth resulting from elevated zooplankton production within the Alaska Gyre is hypothesized to have driven the production increase.

It seems clear that the halibut stock, along with other fish stocks, has been affected in important ways by climate change in this century. With global warming almost surely on the way, the next century is likely to be even more eventful.

At present we do not know the actual mechanisms by which climate change affects halibut growth, maturation, and recruitment. Nor can we distinguish the effect of physical factors, such as ocean currents and temperature, from biological factors such as the abundance of prey species, other fish species, and halibut themselves. We can and do manage the stock by allowing for these medium-term changes without knowing their causes, but we could better justify our management strategy and perhaps increase yield somewhat if we understood the mechanisms involved.

The Halibut Commission does not have the wherewithal to launch a research program of its own in fishery oceanography, but we have the opportunity to capitalize on the international research programs now in progress by engaging an expert to apply recent research results to Pacific halibut and to collaborate with other researchers in the design of large-scale studies. Moreover, it is very appropriate for the Commission to be active at least to this extent, because it is the best way to assure that the international effort will address questions about halibut, and because we have some of the longest data series to contribute to the international effort.

CHANGES TO STOCK ASSESSMENT METHODOLOGY

by

Ana M. Parma and Patrick J. Sullivan

Pacific halibut have undergone a rapid reduction in body growth in recent years, with average length-at-age now being 20-25% lower than what it was 15 years ago. This has a number of consequences for halibut stock assessment and management that have led us to reconsider our procedures, and to develop an alternative assessment model which takes these effects into account. Here we discuss some problems observed in past years' assessments that may have resulted from these changes in size-at-age, and outline the key features of the new method developed to address these problems.

Stock assessments conducted since 1985 and up through last year used a method for the analysis of catch-at-age known as CAGEAN. A peculiarity of catch-at-age analysis is that the complete time series of estimates of stock abundance is updated every year as new data become available for the analysis. We can then compare successive estimates of the biomass for any year by contrasting assessments over successive years. The assessments produced over the last six years exhibited a troublesome problem: while biomass estimates indicated a declining trend in every area, the absolute level of biomass was successively adjusted upwards as more years of data entered in the analysis. As a consequence, the initial estimates of biomass used to set quotas were substantially lower than the revised ones obtained for the same years in subsequent assessments, and so the quotas did not decrease as anticipated.

The variability among successive assessments reflects the combined effects of changes in methodology, on the one hand, and the yearly expansion of the data series, on the other. In order to uncouple these two effects, CAGEAN was applied retrospectively to data for 1974-1988 to reproduce a 1988 assessment, and then to data for 1974-1989, to reproduce a 1989 assessment and so on up to including data for 1995. This exercise resulted in the same pattern of errors as the one exhibited by the actual historical assessments, namely, biomass estimates were adjusted upwards in each successive assessment (Figures 1 and 2, top). We concluded that the problem was not due to changes in methodology, but was inherent to the procedure used through 1994. Interestingly, this pattern in the retrospective estimates for recent years is opposite to that of the previous decade, when initial biomass estimates were consistently higher than the revised ones obtained in subsequent years.

Retrospective patterns of this sort have been observed in other fisheries and have puzzled stock assessment scientists around the world. They may have many different causes among which are: (1) trends in catchability, commercial CPUE not tracking population abundance, and (2) changes in the age composition of the catches not accounted for by the model. Trends in catchability are very likely for Pacific halibut considering the changes undergone in the fishery. However, catch rates obtained in research surveys show relatively similar trends to the commercial CPUE. The observed changes in size-at-age, on the other hand, may indeed be responsible for some of these retrospective errors, as we discuss below.

Catch-at-age methods estimate trends in stock abundance from the analysis of the number of fish caught at each age in each year over a relatively long period of time. Estimating the historical abundance of year classes that have passed completely through the fishery is relatively simple, as it basically amounts to summing up all the corresponding catches, while correcting for the number of fish that died from other sources. The assessment of current stock biomass, on the other hand, is much more difficult, as it involves estimating the abundance of year classes that are currently being exploited and have been observed only a few times. This is further complicated by the fact that the age composition of the catch differs from that of the population because some age classes are more vulnerable to fishing than others. In the case of halibut, fish begin to show up in the commercial catches at about age eight, which has been defined to be the age at recruitment, and they are still fairly abundant at age 17 and older. Older age classes are more vulnerable to fishing because setline gear is selective for larger fish. Thus, we cannot estimate the relative abundance of the different year classes directly from their numbers in the catch but need to make some assumptions about their relative vulnerability to fishing. The latter is known as selectivity.

Most catch-at-age models assume that selectivity is related to age. Indeed, a central assumption of CAGEAN is that the relative vulnerability of the different age-classes exploited stays constant over time. This assumption is valid when organisms recruit to the fishing grounds at a certain life stage, or when fish maintain roughly a constant size-at-age and other factors such as type of gear used and targeting practices remain stable. Given the recent changes observed in halibut growth, however, the assumption is problematic; it can lead to underestimation of the young age-classes, and to the retrospective patterns exhibited by recent halibut assessments.

A more sensible assumption in the face of changing growth rates is that selectivity depends directly on fish size, rather than age. In reality, the relative vulnerability of the different age classes must depend on both gear selectivity (presumably a function of fish size) and the distribution of fishing effort relative to the distribution of fish on the grounds. Beyond these considerations pertaining to the catch process, there is a restriction on the minimum size of fish that can be landed. This must also affect the representation of the youngest age classes in the market samples, at least those age classes whose size distribution extends below the size limit. Size-at-age data collected during research longline surveys in Area 3A indicate that the declines in growth have led to a significant decrease in the proportion of fish of legal size in the youngest ages (Figure 3). The proportion of legal fish in the catch of eight-year-olds has dropped from around 65% in the late seventies to less than 20% in recent years. To a lesser extent this problem also affects other age classes. Even for age 13, 10-15% of fish caught in the surveys of 1993 and 1994 were below legal size while they were all legal 15 years ago. In contrast, surveys conducted in Area 2B showed much weaker trends in size-at-age, with an initial decrease bottoming out in the mid 1980's, followed by a recovery in the last survey of 1993 (Figure 4). By not accounting for these changes and by assuming that selectivity at age is constant, a lower representation of the youngest age classes in the market samples would be attributed to lower abundance of those year classes, when in fact it reflects, at least in part, a diminished vulnerability or an increased rate of discarding. Indeed, the steep declines in recruitment estimated by CAGEAN in recent years would be exaggerated by these problems.

Model Assumptions

The main difference between CAGEAN and the new assessment model is in how fishing mortality affecting each age class in each year is modeled. In CAGEAN, fishing mortality is assumed to separate into two factors: the selectivity-at-age, assumed to be constant, and a year-dependent component, assumed to be proportional to commercial fishing effort. Fish of age 15 and older were considered to be fully-selected. In contrast, the selectivity of the different age-classes in the new model is not constant but depends on the fish length distribution at age, which may change over time, and on a constant size-specific selectivity function. The oldest age-classes are not forced to have a selectivity equal to one, as some of the fish in these age classes may be smaller than the size at which full vulnerability is achieved. The model predicts also how the distribution of fish length at age changes as growth rates change over time. The effect of the legal size limit, which reduces the numbers of the smallest age classes in the commercial landings, is explicitly represented. Figure 5 illustrates how the decreasing trends in predicted length-at-age result in lower age-specific selectivities (top panel), when a fixed size-selectivity function (bottom panel) is assumed. Parameters in this illustration correspond to estimates obtained for Area 3A using the new size-age model. The changes in age-specific selectivities are much less pronounced in Areas 2A and 2B (Figure 6, top), as growth rates have not changed that much in those areas and fish are estimated to become selected at a much smaller size (bottom panel).

Retrospective Performance

A series of eight retrospective assessments, simulating the assessments of 1988 through 1995, were conducted using the new size-age method, as was done before using CAGEAN. The results are encouraging: the variability of biomass estimates among successive assessments was substantially reduced when the new size-age method was used (Figures 1 and 2, bottom panels). In addition, at least in Area 3A, revised biomass estimates obtained in successive assessments are no longer consistently biased relative to previous estimates. Some amount of variability, as that shown by the new method, is inherent to any stock assessment method and we cannot expect to remove it completely.

Future Developments

The new assessment method is better for Pacific halibut than the old one because it accounts for the effects of changing growth rates. The improved performance in the retrospective analysis is very encouraging in this sense. However, the model is much more complex and flexible, and we need to explore further the effects of changes in some model assumptions and of using additional sources of data. For example, more flexible growth models than the one explored thus far may be needed to fully account for the observed trends in size-at-age. A difficulty in the areas that have shown the steepest growth declines is that the estimated selectivity of the young age classes becomes so low in recent years that it is difficult to estimate their abundance reliably based on commercial catch-at-age data alone. To address this problem we plan to use the age distributions sampled from research survey catches, which are not affected by the legal size limit, and so have the youngest age classes better represented. Additional modifications to the stock assessment procedures planned for 1996 include: (1) incorporation of catch removals corresponding to halibut bycatch of fish of legal size; (2) use of survey CPUE, in addition to commercial CPUE, as an index of abundance.

The management strategy used by IPHC since 1993 as a basis for catch quota recommendations consists of applying a 30% exploitation rate to the exploitable biomass to compute the so called constant exploitation yield (CEY), from which other removals are subtracted. In addition, a minimum size limit of 81 cm is imposed on the commercial landings. The exploitable biomass, defined as the biomass that is effectively vulnerable to fishing, has been computed using a set of age-specific selectivities once estimated by CAGEAN, which may no longer be adequate. Changes in selectivity resulting from growth trends imply that the definition of exploitable biomass must be reconsidered. The changes in stock assessment methodology, together with the changes in Pacific halibut growth and maturity schedules, require a re-evaluation of the whole management strategy used for Pacific halibut, including both the exploitation rate and the size limit.

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Figure 1. Retrospective estimates of exploitable biomass of Pacific halibut in Area 3A obtained using CAGEAN (top) and the new size-age model (bottom). Data from 1974 through the year of the assessment are used in each case, with separate catchability coefficients estimated for the period before and after 1983.

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Figure 2. Retrospective estimates of exploitable biomass of Pacific halibut in Areas 2A-2B obtained using CAGEAN (top) and the new size-age model (bottom). Data from 1974 through the year of the assessment are used in each case, with separate catchability coefficients estimated for the period before and after 1983.

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Figure 3. Frequency distributions of total length of fish ages eight through ten caught in longline grid surveys in Area 3A. Shaded area shows of fish above legal size.

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Figure 4. Frequency distributions of total length of fish of ages eight through ten caught in longline grid surveys in Area 2B. Shaded area shows fish above legal size.

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Figure 5. Changes in age-specific selectivity (a) resulting from estimated trends in length-at-age (b) and a size-specific selectivity function (c) assumed to be time-invariant. Parameters estimated using data for Area 3A.

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Figure 6. Changes in age-specific selectivity (a) resulting from estimated trends in length-at-age (b) and a size-specific selectivity function (c) assumed to be time-invariant. Parameters estimated using data for Areas 2A and 2B.

POPULATION ASSESSMENT, 1995

by

Patrick J. Sullivan and Ana M. Parma

INTRODUCTION

IPHC staff annually provide an assessment of stock status on Pacific halibut. Last year, we noted that certain trends in the biology of the halibut stock and in the prosecution of the fishery would force us to re-evaluate some assumptions made in the assessment. Since that time, modifications to the assessment model were made to address some of these issues. The Pacific halibut stock assessment procedure now incorporates growth as well as directed harvest mortality and recruitment (Parma and Sullivan, 1995). The procedure utilizes catch at age, length at age, and weight at age from both commercial and IPHC survey landings (Figure 1). These data were re-estimated this year for all areas and years (Clark, personal communication). The stock assessment procedure also includes, as it has in the past, commercial catch per unit effort recorded from IPHC logbook data. The newly developed procedure is useful in interpreting some trends that potentially bias assessments, although certain aspects of the procedure need to be more thoroughly explored and other components need further development. It is in this context that this year's assessment is given. Results from the new procedure are examined with reference to the previous procedure, general trends are noted in catch statistics and assessment results, and developments slated for the upcoming year are outlined.

The Pacific halibut stock assessment (under both current and previous methods) continues to show a downward trend in stock biomass (Figures 2-8). Both procedures reflect trends caused by strong year classes passing through the fishery, followed by poorer year classes resulting from poorer recruitment. The current method follows changing trends in growth, and takes account of changes in gear selectivity which are likely to occur concurrently. In areas where this change in size is great (e.g. Areas 3A and 3B), the result is generally an increase in the current absolute level of abundance as the assumption made in previous assessments likely underestimated stock size as was indicated in last year's assessment. Unfortunately, it is this absolute level of abundance for which greater caution in interpreting results must be exercised, as these estimates are more sensitive to assumptions made in the procedures. For this reason, and to provide some perspective on the differences between estimates, time trends, and other aspects of this change in methodology, both the assessment under the previous model and the assessment under the current model are given. First, however, we shall examine commercial and survey catch statistics.

Commercial catch per unit effort (CPUE) trends are on the upturn this year, with a coast-wide increase of 12% from 244.2 pounds per skate in 1994 to 282.7 pounds per skate in 1995. Last year's coast-wide values were the lowest since the early 1980's when the stock was believed to have first begun rebuilding. CPUE on an area-by-area basis increased 23% in 2A, 5% in 2B, 25% in 2C, 13% in 3A, 11% in 3B and 23% in 4. IPHC systematic survey CPUE has also shown an upturn in recent years with a 40% increase in Area 2B from 119 pounds per skate in 1993 to 167 pounds per skate in 1995, and with an 18% increase in Area 3A from 313 pounds per skate in 1994 to 370 pounds per skate in 1995. Survey CPUE in Area 2B has more than doubled since the mid-1980s averaging 57 pounds per skate in 1985-1986 compared with the 143 pounds per skate average for the two most recent surveys. On the other hand, survey CPUE in Area 3A has dropped on average over that same time period averaging 439 pounds per skate over the years 1984-1986 while averaging 332 pounds per skate during 1993-1995. Survey and commercial CPUE estimates are shown in Figures 9 and 10 with stock estimates from the current size-age based procedure for Areas 2B and 3A. Note the consistency between the survey and the commercial CPUE indexes for the two areas. This suggests that in a broad sense both are tracking the same pattern in the fishery.

Trends in halibut size at age may be examined using the 1994 to 1995 change in weight-at-age of twelve-year-old fish in the catch: 23.4 to 26.0 pounds in 2A, 23.5 to 25.5 pounds in 2B, 27.2 to 40.3 pounds in 2C, 25.0 to 25.5 pounds in 3A, 31.4 to 25.6 pounds in 3B, and 34.2 to 28.4 pounds in 4. Size at age in the commercial catch has generally decreased in the last 15 years although Area 2B size at age has shown an upturn for younger age classes in recent years. Note that statistics given on an age-specific basis are generally more variable than stock-wide statistics. Nevertheless, it appears that weight-at-age may be leveling off or reversing in trend in some areas and in particular among younger age classes.

Exploitable stock biomass trends and total recruitment biomass can be examined relative to commercial catch-per-unit-effort trends coast-wide and area by area in Figures 2-8. The current size-age based estimates (shown in black) can be contrasted with previous CAGEAN estimates (shown in gray). The size-age based estimates better represent the changing trends in the halibut fishery (Parma and Sullivan, 1995). However, further development of this approach must take place before it can accurately be used in setting absolute harvest limits. Biomass trends, however, can continue to be monitored using this approach. Exploitable biomass trends continue to show a downward trend coast-wide and in all areas except Gulf of Alaska, where in Areas 3A and 3B strong recruitment trends indicate the beginning of an upturn. Estimates under the current size-age based procedure generally indicate a historical decline that is not nearly as steep as that shown by estimates calculated using previous methods.

The 1987 year class, indicated as a strong year class in abundance as pre-recruits in National Marine Fisheries Service trawl surveys, appears now to be entering the fishery. The presence of this year-class is most apparent in IPHC Areas 3A and 3B although some indication of it can be seen in other areas. Recruitment biomass estimates, it must be noted, are highly variable in the most recent years, when cohorts have been observed only once or twice in the fishery. Furthermore, given the generally smaller size of these fish, the percentage available for harvest is estimated to be very low, which in turn implies that the estimates themselves may be quite unreliable as only a very small fraction is observed in the catch. Recruitment estimates for the most recent year were constrained to remain below maximum levels of estimated recruitment abundance obtained for earlier years. An additional consequence of the reduced size-at-age is that the overall contribution to exploitable biomass of these year classes is likely to be smaller in the long term than the strong year classes of larger individuals observed in the mid-1980s. Thus, while the biomass of 8-year-old halibut estimated to be in the population appears to be increasing, the portion of that biomass available to fishing (8-year-old exploitable biomass) continues to appear low. The upturn in recruitment, such as it is, is a positive sign for the fishery.

In last year's assessment, a contrast in signals was noted in the assessment for Area 2B. Changes in catchability were cited as a likely cause for the increase in CPUE observed in the fleet relative to the decline in biomass estimated for the stock. Subsequent analysis and additional IPHC scientific setline survey data now suggest that whatever changes did result from the implementation of the IVQ management system their influence on IPHC statistics is not broadly apparent. CPUE from the commercial fleet can be compared with and without adjusting for changes in fleet dynamics that occurred before and after initiation of the halibut individual vessel quota in British Columbia. While vessel movement by area and over season as represented in the analysis was noticeable and significant, the net effect was not sufficient to explain away an increasing trend observed in CPUE. Recent survey CPUE data also indicate that this change occurred independent of fleet dynamics. Inspection of catch-at-age data from the area for the years 1993-1994 now suggests several year-classes may be stronger (as 11-15 year-old fish) than what earlier estimates of recruitment may have indicated. One explanation for this is that halibut recruited later to the fishery. Another is that targeting on small fish may have shifted over that period. Still another is that halibut, over that time period were actually too small to be represented as recruits. Such scenarios, while still only hypotheses, would likely explain the conflict seen in the fit to the data and possibly raise estimated biomass levels for that area. Some of these possibilities will be explored in the upcoming year.

Estimated exploitable biomass levels have increased in Area 4 this year under both assessment procedures, thus reflecting information in the data used by both. A significant upturn in the Area 4 CPUE index, as indicated in the 1995 value, accounts for about half the overall increase, while updates to the age-composition data made while re-evaluating and re-estimating the base-line market sample data for the size-age based estimation procedure accounts for the rest. A retrospective analysis of Area 4 exploitable biomass estimates indicates greater variability in the estimate for the most recent year and the performance of the procedure (as indicated by various fitting criteria) is the poorest of any IPHC area. This may in part be due to the current lack of survey information available for that Area. It is likely that lower exploitation levels in the late 1970s and early 1980s may also contribute to the lack of stability in these estimates as less information is available on the early cohorts.

Further development of the size-age based approach is planned for the upcoming year. Anticipated extensions include a model of the change in growth rate, inclusion of scientific survey CPUE, and inclusion of bycatch removals as a source of legal-sized halibut mortality. Current implementations indicate that such modifications are likely to result in biomass estimates that are generally higher than those now estimated. But, as noted in the discussion on recruitment, the current definition of exploitable biomass must be re-evaluated in conjunction with a re-evaluation of the constant harvest rate policy given the new estimates.

Parma, A. M., and P. J. Sullivan. Unpub. Changes to stock assessment methodology. Int. Pac. Halibut Comm. Report of Assessment and Research Activities 1995: this volume.


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Figure 1. Overview of Pacific halibut stock assessment procedure.

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Figure 2. Coastwide size-age based estimates of exploitable stock biomass and recruitment contrasted with CPUE and exploitable biomass estimates from catch-age analysis.

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Figure 3. Area 2A size-age based estimates of exploitable stock biomass and recruitment contrasted with CPUE and exploitable biomass estimates from catch-age analysis.

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Figure 4. Area 2B size-age based estimates of exploitable stock biomass and recruitment contrasted with CPUE and exploitable biomass estimates from catch-age analysis.

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Figure 5. Area 2C size-age based estimates of exploitable stock biomass and recruitment contrasted with CPUE and exploitable biomass estimates from catch-age analysis.

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Figure 6. Area 3A size-age based estimates of exploitable stock biomass and recruitment contrasted with CPUE and exploitable biomass estimates from catch-age analysis.

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Figure 7. Area 3B size-age based estimates of exploitable stock biomass and recruitment contrasted with CPUE and exploitable biomass estimates from catch-age analysis.

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Figure 8. Area 4 size-age based estimates of exploitable stock biomass and recruitment contrasted with CPUE and exploitable biomass estimates from catch-age analysis.

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Figure 9. Area 2B exploitable biomass estimates compared with commercial and IPHC systematic survey CPUE estimates.

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Figure 10. Area 3A exploitable biomass estimates compared with commercial and IPHC systematic survey CPUE estimates.

STAFF REGULATORY PROPOSALS: 1996

by

Stephen H. Hoag

In 1995, the Commission staff reviewed the methods used for estimating biomass and setting catch limits. The method that has been used in recent years appeared to underestimate recruitment of young halibut and the biomass of adult fish because of changes in growth rate that have occurred recently. A new method of estimating biomass has been developed, which confirms that the old method tended to underestimate biomass. Unfortunately, the staff is still evaluating the new method and the degree of underestimation The staff plans to spend 1996 completing the testing of the new method and will present the results to the Commission and the halibut industry in the fall of 1996. In addition the staff plans to implement a new procedure in 1996 for compensating the stock for losses due to bycatch mortality. These changes may well affect catch limits in 1997, but it is too early to fully assess the magnitude of the changes. Given these considerations, the staff recommends that the catch limits that were in place in 1995 continue through 1996. The staff considers these catch limits to be conservative and this approach will allow the staff time to fully explore technical aspects of the new methods while not putting the stock in jeopardy of over fishing The 1995 catch limits which would continue through 1996 along with the 1995 catches are provided below:

Individual quota fisheries will be in effect for all areas except Area 2A. The staff is still in favor of a winter closure from November through March to reduce the interception of fish that move between regulatory areas during spawning migrations. However, we have no evidence that any significant interceptions occurred during the 1995 fishing season which ran from March 15 through November 15. The staff will not object to a similar season in 1996 if this is what the industry prefers.

On a related issue, the North Pacific Fishery Management Council ( NPFMC) has approved a year-round Aleutian Island sablefish season that would open with the regular IFQ halibut and sablefish season (e.g. March 15, 1996) and close the day before next year's season begins (e.g. March 14, 1997). Participation in this extended season requires Aleutian Island sablefish quota share holders to also possess sufficient halibut quota shares to cover their halibut bycatch and have observer coverage. The NPFMC has requested that the Commission consider allowing halibut retention by adjusting its seasons or allowing a bycatch allowance for these few vessels. The staff does not see any significant conservation problem as long as the number of vessels is as small as expected. However, we would object to a year-round fishery that would land large quantities of halibut during the winter. The staff recognizes that social or economic concerns are also involved and suggests the Halibut Conference Board comment on this matter.

In Area 2A, the staff recommends fishing periods similar to those in effect in 1995: a series of 10-hour periods, with fishing period limits to be sure that the catch limit is not exceeded. The size of the fishing period limit will be determined later when more information is available on fleet size.

A catch sharing plan for halibut in Area 2A was developed by the Pacific Fishery Management Council for 1995 and we anticipate a similar plan to be in effect for 1996. Highlights include:

The NPFMC has approved a catch sharing plan which calls for allocating the Area 4 catch limit among subareas using the same percentage that was in effect last year as long as the total catch limit is not increased. These percentages are: 4A-33%, 4B-39%, 4C-13%, 4D-13%, 4E-2%. In the event that the total Area 4 catch limit is increased, the first 80,000 pounds would be allocated to Area 4E.

The staff recognizes that allocation regimes are important in Area 4 and that some of the subareas were created primarily for allocation reasons. However, we continue to support the management policy of setting catch limits in proportion to biomass. We are continuing to work on developing biomass estimates for each subarea and intend to have a report available for the NPFMC by April, 1996. We also intend to make recommendations on biomass-based catch limits to the Commission for implementation in 1997. Although we expect to have biomass estimates for each subarea, it is likely that we will recommend that the Commission set catch limits for Area 4A, Area 4B, and a combined Area 4C, 4D, and 4E. The reason for the Commission combining 4C, 4D, and 4E is that this previously was a single area that was split largely for allocation purposes. The staff will recommend that the NPFMC consider biomass when making allocation decisions.

The staff also recommends changes in clearance procedures in Area 4 to eliminate unnecessary regulatory burden on the industry. Clearance procedures were implemented in Area 4 during the 1960's and 1970's to help assure that vessels were, in fact, in Area 4 rather than fishing in Areas 2 or 3 and claiming their catch from Area 4. This enforcement device was needed because Area 4 required longer running time from major ports of landing and because fishing conditions tended to be more difficult in Area 4. This was particularly important in Area 4B. With the IFQ program some of the incentives to falsify fishing location have been eliminated and there is generally better enforcement today in Area 4 than when clearances were initiated.

The staff makes the following recommendations:

1. Eliminate clearance requirements for vessels that fish for halibut only in Area 4A and land their entire annual halibut catch in Area 4A. Clearance requirements should similarly be eliminated for vessels that fish and land their halibut only in Area 4D. This provision is already in effect in Areas 4B, 4C, and 4E and extending it to the other subareas should ease any regulatory burden on primarily small vessels that tend to fish and land all of their halibut in one area.
2. Eliminate the requirement that vessels clear out of an area when fishing is completed. Eliminating out-going clearances should not increase violations.
3. Change the location of clearances for Areas 4C and 4D from Dutch Harbor or Akutan to St. George or St. Paul. Present regulations call for clearing out of St. Paul or St. George, but the staff is recommending eliminating out going clearances so the location for in-coming clearances needs to changed.
4. Allow vessels to clear into multiple areas if an observer is on board and fish are separated by area in the hold of the vessel. The staff needs to maintain the accurate landing statistics and estimates of the age-size composition by area. Allowing vessels with observers on board to clear for multiple subareas should assure accurate data for assessment as long as the fish can be separated at the time of landing. Vessels without observers or that can not keep halibut from each area separate would be required to only clear for a single area.

The staff is very pleased with the IFQ program in Alaska, but has minor concerns that landing statistics and our sampling for size and age composition may be compromised by vessels fishing several regulatory areas during a single fishing trip unless additional regulations are put in place. Presently IFQ regulations allow a vessel to fish in multiple areas even without observers although the amount of catch is restricted if observers are not on board. (Without an observer, a vessel can not have on board more halibut than the IFQ for the area that is being fished even if some of the catch occurred earlier in a different area.) Further, landings from multiple areas are not required to be separated in the hold of a vessel.

Issues of fishing multiple areas and separating landings directly involve the IFQ program in Alaska and perhaps should best be addressed by the NPFMC or NMFS. However, these issues also have conservation implications, and the staff suggests that the Commission consider the need for either additional IPHC regulations or recommending that additional regulations be adopted in the U.S.. Sampling problems associated with fishing multiple areas are not critical at the present time, but could become worse over time. The staff would like advice from the Halibut Conference Board on how best to resolve this problem. Regulatory changes could be delayed beyond 1996 without jeopardizing the resource.

The Staff is considering dropping the IPHC license requirement for commercial halibut vessels fishing in Alaska for 1997. The present license will be maintained in 1996 and a license system for recreational charter vessels and commercial vessels fishing in Area 2A would continue indefinitely.

The Commission stopped licensing the Canadian commercial fleet after the IVQ program was in effect. Information obtained from the license application is needed to contact fisherman and is helpful in associating the vessel with landings. However, we have been successful in obtaining this information from other sources in Canada and we anticipate being able to do the same in Alaska by 1997.