REFM Report AMJ '99

Groundfish Fisheries Observer Program

During the quarter, 160 observers were trained, briefed, and equipped for deployment to fishing and processing vessels and shoreside plants in the Gulf of Alaska, Bering Sea, and Aleutian Islands region. They sampled aboard 238 fishing and processing vessels and at 16 shoreside processing plants. The observers were trained or briefed at various locations. The AFSC Observer Program in Seattle briefed 59 observers with prior experience. The University of Alaska Anchorage (UAA) Observer Training Center briefed 53 observers, and another 20 first-time observers were trained there. At the Observer Program’s field offices in Dutch Harbor and Kodiak, 13 more observers were briefed, and 15 were excused from briefing because they had just completed a cruise successfully and were returning immediately to the field. The second quarter 1999 observer workforce comprised 13 percent new observers and 87 percent experienced observers.

The Observer Program conducted a total of 204 debriefings during the quarter. Six debriefings were held in Kodiak, 4 in Dutch Harbor, 35 in Anchorage, and 159 were held in Seattle. No debriefings are conducted at the UAA.

Implementation of an expanded Community Development Quota (CDQ) program and implementation of provisions of the recently enacted American Fisheries Act (AFA) continued. The CDQ program was developed for the purpose of allocating fishery resources to eligible western Alaska communities to provide the means for starting or supporting commercial fishery activities that would result in ongoing, regionally-based, commercial fisheries or related businesses. The CDQ program was initiated in 1992 for walleye pollock and expanded to include fixed-gear halibut and sablefish in 1995. In 1998, the program expanded further to include multiple species (MS) of groundfish and crab (MSCDQ). In 1999, NMFS is responsible for monitoring the groundfish (including pollock and sablefish) and halibut CDQs, and the state of Alaska is responsible for monitoring crab CDQs.

The AFA, enacted by Congress in late 1998, made changes to the pollock fishery in the Bering Sea and Aleutian Islands region (BSAI). These changes reallocated fish among industry segments, provided for the formation of fishing cooperatives, and increased observer coverage levels on some components of the fleet. The offshore component of the fleet has organized a fishing cooperative.

The MSCDQ and AFA catch-accounting for offshore processors is based entirely on data collected by observers and, unlike the open access fisheries where observer data is used to manage a fleet-wide quota, industry participants in the MSCDQ and AFA fisheries require individual accounting of fish harvested in each haul or set. This change has required much staff effort in developing special selection criteria and training requirements for observers, new sampling strategies and regulations to enhance the observer’s working environment, and changes to the data collection and data management software systems.

By Bob Maier.

Socioeconomic Assessments Program

During this quarter, Center economists were involved principally in support activities for the Pacific and North Pacific Fishery Management Councils (PFMC and NPFMC, respectively) and other cooperative efforts within the agency.

Council Activities

The tasks identified in each scope of work will be done principally by contractors, and the Center will provide a technical monitor for the NPFMC contracts. The Center has assisted the Alaska Regional Office and the Alaska Department of Fish and Game (ADF&G) in developing a proposal to improve the Alaska Commercial Operators Annual Report (COAR) in support of AFA data requirements. A new cooperative agreement between NMFS and the Pacific States Marine Fisheries Commission was developed in part to use AFA funds both to verify data from the cost, earnings, and employment survey that will be conducted in the summer of 1999 and to conduct a similar survey next year (see feature article in this issue).

Other Activities

To develop a better understanding of the concept of fishing capacity and methods for measuring capacity, program members designed and initiated a research project to investigate how random variation in catch rates may impact the precision of estimates of fishing capacity derived by alterative estimation methods. The two methods being investigated are Data Envelopment Analysis (DEA) and Stochastic Production Frontier (SPF). These methods have been proposed by the NMFS task force on fishing capacity for potential widespread use in measuring fishing capacity in U.S. fisheries. Both methods have been widely used for measuring relative efficiency of firms; but to date, they have not been used in estimating total capacity of an industry group. Monte Carlo analysis is used to quantify the level of bias in capacity estimates that can be expected with different levels of noise in the data as sample size and other factors vary. The initial phase of this research is largely completed.

In cooperation with economists at the University of Alaska, a program member continued to develop and estimate models that can be used to value recreational fishing experiences. These models include Random Utility Models (RUM) and are estimated using random and fixed parameter multinomial discrete choice estimators.

By Joe Terry.

Age and Growth Program

Estimated releases of production ages for January to June 1999 were 50 rock sole, 236 rex sole, 1,004 northern rock sole, 670 yellowfin sole, 870 arrowtooth flounder, 5,904 walleye pollock, 1,212 sablefish, 152 Atka mackerel, 3,282 Pacific whiting, 948 Pacific ocean perch, and 466 northern rockfish, for a total of 14,794. Also, 4,984 were tested, 2,539 were updated, and 115 were examined and determined to be unreadable.

By Dan Kimura.

RESOURCE ECOLOGY & ECOSYSTEMS MODELING PROGRAM: Program Activities

Fish stomachs collected totaled 3,608 for the eastern Bering Sea and 633 for the Gulf of Alaska. Laboratory analysis was performed on 717 stomachs from the Bering Sea, 1,036 from the Aleutian Islands region. Fourteen observers returned with stomach samples (527 cod) collected from the Bering Sea.

Sleeper Shark Diet in the Gulf of Alaska

In response to concerns about the possible linkage between increasing sleeper shark populations and the decline in Steller sea lion populations, a study was performed to examine the diet of sleeper sharks in the Gulf of Alaska to determine if there was evidence of predation on juvenile Steller sea lions. Stomach contents were examined of 13 sleeper sharks collected June-August 1996 from longline and bottom trawl vessels fishing at bottom depths of 86-267 m . The stomach contents consisted primarily of bottom-dwelling fish and invertebrates such as arrowtooth flounder and octopus. Fish processing offal also contributed largely to the diet composition by weight (Table 1 above).

The sleeper sharks collected during this study were of intermediate size (218-295 cm total length) and were collected in areas close to Steller sea lion rookeries and haulouts. There was no evidence of predation on juvenile Steller sea lions. The sleeper sharks appeared to feed primarily on benthic prey that was likely encountered on or near the ocean bottom.

By Patricia Livingston.

STATUS OF STOCKS & MULTISPECIES
ASSESSMENTS: Improving Trawl-based Assessments of Shortraker and Rougheye Rockfishes

A long-term research project was recently completed which focused on ways of improving the trawl-based assessments of shortraker, Sebastes borealis, and rougheye rockfishes, S. Aleutianus, in the Gulf of Alaska. First, a retrospective analysis of the available survey and fishery information was conducted to identify areas of high shortraker and rougheye rockfish densities. Using geographic information system (GIS) mapping software and statistical approaches, catch per unit of effort (CPUE) data were compared and contrasted by depth strata, bathymetric features, and broad-scale geographic areas. The results indicated that both species prefer the continental break and slope areas, usually preferring depths between 300 and 500 m. Rougheye rockfish, however, were found to occur over a much wider, shallower depth range than shortraker rockfish. In terms of coastwide distributional patterns, both species appear to have a preference for the eastern portion of the Gulf of Alaska. This information will prove useful in establishing more refined and efficient survey stratification and sampling allocation schemes in the future.

A major factor that contributes to the success of any type of trawl survey is the ability of the gear to effectively sample the habitats of the target species. Shortraker and rougheye rockfishes are known to inhabit areas of rough bottom. Unfortunately, many of these areas are inaccessible by the current survey trawl. As such, research also focused on the design, construction, and evaluation of an alternative footrope to sample shortraker and rougheye rockfish populations that inhabit the rugged continental slope regions. At-sea gear trials were conducted to assess the performance of this alternative sampler using a net mensuration system and an in situ video camera assembly. The video system was used successfully to document trawl and fish behavior, as well as provide a quantitative estimate of capture efficiency. The results showed that the alternative footrope performed well in shortraker and rougheye habitats and that the capture efficiency in the center section of the footrope was on the order of 80 percent for the shortraker/rougheye complex.

To assess the overall efficiency of the alternative footrope, a two-phase depletion experiment was implemented. During Phase I, repeated trawling in a very narrowly defined area was conducted during a 48-hour period. This area was then revisited after 7 days and again trawled for another 48 hours, representing Phase II of the experiment. A simple analytic model was developed to estimate initial population size and trawl efficiency within the depletion zone. Detailed hydroacoustic information was also collected concurrently with a scientific echo sounder during all depletion tows. The resulting efficiency estimates were comparable with the video-based efficiency estimates. Furthermore, the hydroacoustic indices were strongly correlated with the depletion catches, suggesting that hydroacoustic approaches may hold promise for eventually providing a cost-effective, noninvasive means of measuring absolute or relative abundance of shortraker and rougheye rockfish stocks in waters off Alaska.

(This research was completed by Daniel Ito and was published as a Ph.D. dissertation at the University of Washington.)

By Daniel Ito.

AFSC/ADF&G Research Planning Meeting

AFSC scientists attended the first AFSC/ADF&G Joint Research Planning meeting on 10-11 May in Juneau. The purpose of the meeting was to improve communication and identify opportunities for joint research between the two institutions. Discussion topics covered a range of subjects including trawl and echo intergration survey plans for the eastern Bering Sea, Gulf of Alaska, and inside waters of Southeast Alaska; rockfish research; stock identification studies; sea lion research projects; and an overview of the current stock assessment and allocation issues. The meeting was well received by both research entities and will likely lead to future collaborative activities.

By Anne Hollowed.

Application of Age-structured Stock Assessment Model to Southern Minke Whale Stocks

James Ianelli attended the International Whaling Commission (IWC) scientific meetings in May (see NMML report in this issue). He participated as an invited participant to comment specifically on the assessments for southern minke whale stocks and for the Bering Sea bowhead whale stock. James has worked closely with scientists on alternative analyses for the bowhead whale assessment which was presented at the 1998 IWC meeting.

The issue regarding minke whales dealt with the application of an age-structured model to this stock. The interpretation in the change of recruitment, which apparently increased after commercial fishing began, is linked with alternative hypotheses about how the fishery catchability may have changed during the course of the commercial fishery. This assessment is particularly important since it is linked to the continuation of limited scientific harvests by Japanese vessels.

In collaboration with Professor Doug Butterworth, University of Cape Town, South Africa, Ianelli developed a statistical age-structured model. The model has time-series effects as part of the trend between age- and year-specific fishing mortality rates. The model allows for the inclusion of age-specific tag-recapture data in addition to a variety of survey and CPUE indices. The model was applied to southern bluefin tuna data and is intended to contrast with the VPA-type model that is currently used for management. Ianelli presented this paper at the 50th International Tuna Conference held at the University of California at Los Angeles’s Lake Arrowhead Conference Center in May.

By James Ianelli.

Resource Ecology & Fisheries Management

Resource Ecology &
Fisheries Management