Alaska pollock

An age-structured assessment model is used to evaluate Eastern Bering Sea (EBS) Pollock. The assessment is regularly reviewed by experts, and results and methods are publicly available. Although the EBS Pollock is considered the most data-rich species of the region, there are still some research needs that would contribute to better understand the stock dynamics and to support improved fisheries management; these include for example: 1) examining the spatial distribution of pollock by season, including the vertical dimension and how this impacts the availability of pollock to survey gear; 2) investigating the relationship between climate and recruitment, and 3) trophic interactions of pollock within the ecosystem; 4) conducting further large scale genetic studies to better understand the stock structure (Ianelli, J et al. 2017). 

Scientific advice for this fishery incorporates multiple precautionary measures that are designed to ensure that the resource is maintained well above critical thresholds. Acceptable biological catch (ABC) levels are advised by the assessment authors based on spawning stock biomass (SSB) estimates for the projected year and involving harvest control rules with six tiers, related with the degree of information availability (NPFMC, 2016).

According to the latest information (ABC) for 2018 was set at 2,592,000 tons (based on tier 3; more conservative) resulting in a TAC of 1,364,341 tons. An ABC for 2019 has been preliminarily set at 2,467, 000 tons which will result in a TAC of 1,383,000 tons, but this could be changed  during the next update in Fall 2018 (NPFMC 2017).

Last updated on 22 Jun 2018

Reference point estimates from the 2018 assessment were defined as follows: 

Biomass target reference point (B_trp) = Biomass at maximum sustainable yield (B_MSY). 
B_lim = B_20%. Given that walleye pollock is considered a key prey of Steller sea lions, directed fishing on pollock is prohibited when spawning biomass levels are below 20% of estimated virgin biomass B₀. Nonetheless, this does not change the specifications of the harvest control rule of ABC and OFL (NPFMC 2017) 

F_trp = FMSY (arithmetic mean) = F_OFL. F_OFL is the fishing mortality at the overfishing limit.

Based on current reference points, the stock is not overfished or being subject to overfishing. Estimated spawning biomass in 2016 (3,870,000 tons) remains well above the stock's B_MSY, of 2,042,000 tons. Fishing mortality (average F_{ages 3-8}) has been decreasing since 2011, and remains well below the target fishing mortality (Ianelli, J et al. 2017). 

Last updated on 06 Jun 2018

Throughout the modern history of the fishery (since the 1970s), pollock biomass has been dependent on a few strong year-classes. After a historical low in 2008, SSB has been increasing and has been above the target reference point since 2011. This was mainly due to the contribution of the strong 2008 year class, which in 2014 was estimated to represent 56% of the spawning stock biomass (Ianelli et al., 2014). Results from the latest stock assessment suggest  that the 2008 year-class is slightly higher than assessed before and that the 2012 year-class to be above average. Stock is near an all time high SSB (Ianelli, J et al. 2017).

Fishing mortality (F) has been well below target levels since the start of the time series. Average F (ages 3-8) dropped sharply from around 0.4 in 1979 to a historical low (0.09) in 1987, and has since been oscillating between 0.1 and 0.3. In the late 2000s F increased due to stock declines, but since then has been decreasing due to conservative reductions in the TACs relative to maximum permissible ABC and an increase in the stock biomass. Recently F has increased to near 2011 levels, but this value is uncertain as it is a terminal year of the assessment (Ianelli, J et al. 2017).

Alaska pollock is captured in the groundfish fishery, which is managed by the North Pacific Fisheries Management Council through a Fishery Management Plan (FMP). The FMP is in place since 1982, is reviewed periodically, and includes a number of management measures to protect both targeted and incidentally captured species (e.g., closed seasons/areas, fishing gear restrictions such as non-pelagic trawl prohibition in the directed pollock fishery, TACs, prohibited species bycatch limits) (NPFMC 2015).

In terms of Total Allowable Catch (TAC) specifically, managers have historically kept the TACs at or below scientists’ recommended limit, the ABC. The 2018 TAC (1,364 thousand tons) was set at 53% of the ABC (2,592 thousand tons: (NPFMC 2017). An ABC for 2019 has been preliminarily set at 2,467, 000 t which will result in a TAC of 1,383,000 t, but this could be changed during the next update in Fall 2018.

Last updated on 06 Jun 2018

Not applicable because the stock is not overfished, nor is overfishing occurring.  A control rule is in place which rebuilds the stock should the SSB fall below ½ B_MSY and sets the F at zero should the stock fall below 10% of ½ B_MSY (NPFMC 2017).

Catches in the eastern Bering Sea pollock fishery have consistently hovered within a few tons below or above the TAC (Ianelli, J et al. 2017), an indication of effective and precise catch controls. Compliance measures include onboard observers throughout the fishery, enforcement patrols, extensive port sampling, and fines for vessels caught operating in closed waters or in violation of fishing regulations. For serious violations of fishing regulations, fishing licenses may be suspended or annulled. 

Comprehensive outreach and education programs are also in place to make sure the fishing industry understands the rationale behind all regulations, in order to increase the likelihood of voluntary compliance with the regulations (NPFMC 2017). These seem to be working as removals are close to what is allotted. 

The primary protected species of concern in the Eastern Bering Sea pollock fishery is Alaska’s western population of Steller sea lion (SSL), which is listed as endangered (FWS 2012). Other protected species in the region include northern fur seals (NFS), northern right whales, sea otters, Cook Inlet beluga whales, several species of seabirds, and some salmon (which are covered below under Other Target and Bycatch Species). 

Considerable research has been conducted to evaluate the effects of the EBS pollock fishery on the populations of western stock of Steller sea lions and northern fur seals. The result was that here was no evidence of negative impacts of the pollock fishery on the dynamics of SSL or NFS. Estimates of interactions of the pollock fishery with these and other marine mammal species are below national Potential Biological Removals (PBR). It was concluded in the latest MSC assessment reports that the fishery was “unlikely to create unacceptable impacts” on these species (Rice et al. 2013; Bowen et al. 2015). 

Pollock are an important prey species for some marine mammal particularly seals. Ianelli (et al. 2016) noted that there’s been a 12% decline in St. Paul Island pup production from 2014-2016 which indicates an estimated 2.5% decline in the overall Eastern Stock fur seal population. They suggest that "Maintaining prey availability may provide better foraging opportunities for the fur seal stock to minimize further declines".  

The 2010 North Pacific Groundfish Fishery Biological Opinion resulted of the determination of the consistency of the National Marine Fisheries Service (NMFS)/NOAA actions with the Endangered Species Act. The conclusions motivated fishing restrictions to minimize the impact of the pollock fishery (and others) on the western population of Steller sea lion, claiming that the population and the critical habitat could be compromised by fishing operations. These measures were considered to be unjustified by the Center for Independent Experts (Stewart, 2012) – hired by NMFS to guarantee scientific support and robust decision process – and the State of Alaska. A decision of the U.S. District Court judge, indicated that management measures in place were adequate, but thant an Environmental Impact Statement (EIS) should be published in two years (from late 2012). A new EIS was published in May 2014, and included a number of alternative protection measures (e.g., fishery closures and catch limits in specific areas), as well as the respective expected environmental, social, and economic effects (NMFS, 2014). After analyzing each of the alternatives and the associated environmental consequences, the National Marine Fisheries Service (NMFS) concluded alternative 5 provided the most “reasonable and practical” means to avoid and mitigate any potential adverse effects of fishing (namely pollock, Atka mackerel and Pacific cod) on the key food resources of SSL populations (NMFS, 2014b). The most recent MSC (Bowen, D et al. 2017) surveillance audit confirms suggesting that “comparison of species-specific estimates with the Potential Biological Removals for marine mammal species indicates that interaction with the pollock fishery is highly unlikely to cause serious harm”.

In terms of other groups such as seabirds, the trawl fisheries for pollock (and other species) account only for a small fraction of the total seabird bycatch in the Alaska region. The most affected seabirds by the pelagic trawl fisheries are Northern fulmars Fulmarus glacialis (IUCN red list: "Least Concern"; BirdLife International 2015); the pelagic trawl fisheries accounted for 4-10% of the total estimated fulmar bycatch from 2007-2010 (Bowen et al. 2015). Several measures are in place to record and minimize seabird bycatch (NOAA undated). As cited by (Bowen, D et al. 2017) some interactions with both the endangered short-tailed albatross and the threatened Alaska breeding population of Steller’s eider are known to occur. However, a Section 7 consultation found the impact of these interactions did not jeopardize the stocks.

Bycatch of non-target species is considered to be small relative to the magnitude of the Bering sea pollock fishery. Bycatch of retained species in the directed pollock fishery represent less than 1% of the total. Bycatch is dominated by Pacific cod, rock sole, flathead sole, and yellowfin sole, whereas jellyfish, squid, skates and other miscellaneous fish dominate the bycatch of non-retained species (Ianelli et al. 2015). Prohibited species (e.g. halibut, herring, salmon) must generally be returned to the sea. In the most recent assessment report, it has been noted that discards of many species have decreased, and that there has a continued effort to minimize bycatch (Ianelli et al. 2016). 

Salmon bycatch in the EBS pollock fishery has been of some concern. Chinook salmon bycatch became a concern when these interactions increased in the early 2000s, with a peak in 2007. Several measures to reduce salmon bycatch went into effect since then, and since 2008 Chinook salmon bycatch in the pollock fishery have been well below the long term average; in 2015 for example Chinook salmon bycatch was 54% of the 2003-2015 average (Ianelli et al. 2015). Concerns over the impact of the pollock fishery on the Chinook salmon stocks have led to the creation of two conditions as part of the MSC re-assessment of the fishery (Rice et al., 2010). The two conditions were recently closed, as information available was considered sufficient to evaluate and conclude that both direct and indirect effects of the fishery on Chinook salmon populations are “highly unlikely to create unacceptable impacts” (Rice et al. 2013). Although some concerns persist over Chinook and chum salmon bycatch, the most recent salmon genetics data is not yet available. Besides NPFMC’s regular review of Chinook salmon bycatch in the pollock fishery, Amendment 110 was submitted and approved (March 2016) to the BSAI groundfish FMP. The amendment includes a comprehensive salmon bycatch avoidance program that is expected to improve the management of Chinook and chum salmon bycatch in the Bering Sea Pollock fishery (NOAA 2015c). Despite this, bycatch mortality of non-Chinook salmon increased ~44% in 2016 and nearly doubled during the period 2013-2017 (Ianelli et al. 2016) and (Ianelli, J et al. 2017).

In response to a recent increase in the bycatch rates of halibut in groundfish fisheries, the North Pacific Fisheries Management Council (NPFMC) released a Proposed Amendment 111 for the BSAI groundfish FMP in June 2015. The proposed amendment, which focused only in the halibut bycatch problem, included a number of alternatives to minimize halibut mortality in the commercial groundfish fisheries. The proposed regulations to implement Amendment 111 to the FMP were released in November 2015 (NOAA 2015a) and approved in January 2016. During this same year, observed halibut mortality in the EBS pollock fishery declined by ~30% (Ianelli et al. 2016), and in 2017 is at its lowest point of the time series (Ianelli, J et al. 2017).

The Bering sea is home to a very productive and diverse ecosystem, including sensitive bottom habitats comprised of deep-water corals and sponges. There has been extensive research and monitoring to evaluate the potential impact of this and other fisheries on the bottom habitats structure and function in the Bering Sea. Most recently (2014), NOAA conducted a survey to map densities of deep-water corals, sponges, and sea whips, and document fishing gear impacts to invertebrates (Rooper et al. 2015). The study confirmed that most coral habitat occurs inside the Pribilof Canyon and along the Bering Sea slope to the west of Pribilof Canyon. With the exception of these two areas, coral densities were low even where corals occurred. Direct evidence of fishing occurred in 12.8% of the sampling sites. Proportion of observed damage was 9% for sea whips, 2.9% for corals, and 0.3% for sea sponges. Based on these results, the council concluded later that no further management action was necessary for the moment (NOAA 2015b). 

In the directed pollock fishery in particular, regulations require use of pelagic trawls (NPFMC 2017), in order to reduce the potential for damage to sensitive seafloor habitats such as deep-water corals. According to Ianelli at al. (2015), “Habitat degradation has been minimized in this fishery by converting the industry to pelagic-gear only.”  Other available information suggests that this fishery is unlikely to pose an irreversible harm to sensitive habitats (sponges, corals, sea whips, etc.) in the Bering sea (Rice et al. 2010; Bowen et al. 2015). 

However, there are still some concerns over the potential long-term impacts of pelagic trawling in these sensitive habitats, particularly in the canyons. In 2005, the National Fisheries Marine Service (NMFS) estimated that ‘mid-water trawls’ permitted to catch pollock come in contact with the bottom 44% of the time (NMFS, 2005). Research continues to map the distribution of sensitive habitats in the Bering sea, and evaluate potential fishing impacts and needed protection measures (NOAA 2014c).  Overall however habitat impacts of pelagic trawl gear are thought to be low, especially in this fishery (Bowen, D et al. 2016)(Bowen, D et al. 2017). As reviewed during the MSC assessment and the latest surveillance audit. The NPFMC (North Pacific Fishery Management Council) has concluded that the impact of this fishery on essential fish habitat is minimal (NPFMC and NMFS 2017), and that there is little impacts to corals present in the Pribilof and Zhemchug canyons and adjacent slope areas. They did however expect a full update during the Stock and Fishery Evaluation report annually. Further work has indicated that less than 2% of EBS pollock fishery occurs in areas with predicted corals (Bowen, D et al. 2016)(Bowen, D et al. 2017). 

Several time and area restrictions are in place in the Bering sea region, where the pollock fishery operates. The Crab and Halibut Protection Zone and the Pribilof Island Habitat Conservation Area are closed to trawling at all times. There is also a year-round closure to trawling in the Nearshore Bristol Bay. The Chum Salmon Savings Area is closed to trawl gear from August 1 through August 31. Regulations implementing the FMP may include temporal and spatial closures around areas important to marine mammals and essential fish habitats (NPFMC 2017). The most recent management initiative included the designation of six known areas of skate-egg concentrations as Habitat Areas of Particular Concern (HAPC). The designated areas encompass approximately 82 nautical square miles of habitat (i.e., less than 0.1 percent of the total BSAI management area ) (NOAA 2014d).   

Ecosystem information and analysis are abundant for this region. As outlined by (Bowen, D et al. 2016)(Zador, S (ed) 2013) The BSAI (Bearing Sea Aleutian Island) trawl survey documents many aspects of the ecosystem as well as trophic relationships. As reviewed by (Bowen, D et al. 2016) a full ecosystem model is operational and an ecosystem plan is in effect. Reporting and analysis are also part of this plan.  The ecosystem plan includes both management measures and reporting infrastructure as outlined below (Bowen, D et al. 2016).

Management measures:

• Optimum yield cap on total groundfish yield; Arctic FMP reduces optimum yield to 0 (based on the results of an ecosystem assessment)
• Individual TACs for all species or species groups (based on lowest common denominator species)
• Groundfish control rule with automatic rebuilding Ecosystem considerations included qualitatively in each stock assessment
• No directed fishing for forage fish
• Habitat, marine mammal/seabird, bycatch protections
• Broad time/area closures, bottom trawl restrictions
• Gear modifications (biodegradable panels, salmon/halibut excluder devices, seabird deterrents, elevated trawl sweeps)
• Bycatch limits on non-FMP species (salmon, halibut, herring, crab, forage fish)

Ecosystem reports and Fisheries Ecosystem Plans:

• Annual ecosystem considerations report prepared as part of annual harvest specifications, including assessments by ecosystem region.
• Aleutian Islands Fishery Ecosystem Plan adopted in 2007, which identifies key ecosystem interactions and includes a preliminary risk assessment
• Bering Sea Fishery Ecosystem Plan well underway (see https://www.npfmc.org/bsfep/)

In addition to these measures, pollock is an important food source for several important species in the region, particularly Steller sealions (Bowen, D et al. 2016)(Ianelli, J et al. 2017). According to (Ianelli, J et al. 2017) a number of additional management measures have been implemented to reduce competition between the fishery and the Steller sealion population including; 1) pollock fishery exclusion zones around sea lion rookery or haul out sites; 2) phased-in reductions in the seasonal proportions of TAC that can be taken from critical habitat; and 3) additional seasonal TAC releases to disperse the fishery in time and space. These are in addition to the precautionary quota setting which is specifically implemented to ensures an adequate population size for predator removals (Ianelli, J et al. 2017).