Pacific whiting (or Pacific hake) stock assessments are conducted by a U.S.-Canadian Joint Technical Committee. A number of models have been applied, but in recent years a Stock Synthesis (SS) model, the latest iteration of a large, complex tool developed for assessments of all groundfish species along the West Coast of the United States, has been applied in addition to one or more alternative models. The model and methods of the assessment are regularly reviewed by a panel of U.S. and Canadian scientists to identify and resolve problems and areas of uncertainty (Hicks et al., 2013). For the 2014 assessment, the Joint Technical Committee changed the structural form of the base SS model to include time-varying fishery selectivity (Taylor et al., 2014), and this feature was retained for 2015. The 2015 base model is effectively an update of the2014 base model with no major changes (Taylor et al. 2015).

Uncertainty has generally been reported as large, due mainly to unreliable recruitment estimation prior to age 2 (Hicks et al., 2013; Taylor et al. 2015) and in part to problems with acoustic survey data. Particularly in 2009, survey data suffered from difficulties in acoustically distinguishing whiting from Jumbo flying squid (Humboldt squid), and age-composition data are thought to be biased (Martell, 2010). Volatile and poorly estimated recruitment, along with time-varying selectivity in the fishery cause estimates of current stock status and projections of the stock trajectory to be highly uncertain. Results from assessments have differed considerably from year to year. The 2013-2015 assessments have resulted in slight upwards revisions of the spawning biomass series, with the exception of the two recent years in the 2015 assessment, and consistent downwards revisions of fishing intensity.

Some conservation NGOs (Monterey Bay Aquarium and others) have objected the pacific whiting fishery certification by the Marine Stewardship Council, arguing that removals are excessive.

Acceptable Biological Catches (ABCs) were previously defined in the assessments as upper harvest limits and from 2002 recommended catches have been set at considerably more precautionary levels. In spite of this, fishing intensity has in retrospect frequently exceeded its target level in recent years, due to uncertainty in the assessment and projections. Calculation of ABCs has now been replaced by application of the 40:10 harvest control rule. An informal ABC for 2011 was provided in the stock assessment for that year, based on the control rule. The value was 757,738 tonnes, relatively large when compared with recent years’ catches (Stewart and Forrest, 2011), and representing an increase of 302,188 tonnes from the 2010 adopted ABC (455,550 tonnes). Since 2011, the recommended catch based on the harvest control rule has fluctuated considerably, due to uncertainties in the stock assessment and in the biomass estimates. For 2015, and given the stock was estimated in a good condition, the median ABC is 804,580 tonnes, but the range of uncertainty is high (Taylor et al. 2015).

Projections are presented as a decision table for multiple management options, and these indicate that for all 2015 catch levels above 180,000 tonnes, the SSB is expected to decline by 2016 (>68% probability, or >71% based on a model fit with alternative survey indices in 2012 and 2013). However, the probability of dropping below B_10% is 1% or less for catches up to 804,576 tonnes. Following the F_40% default harvest rate and 40:10 harvest control rule would imply a decrease in the stock size with a calculated 95% probability, but the probabilities of dropping to below the target (SB_40%) and the minimum threshold (SB_25%) are only 21% and 6%, respectively (Taylor et al., 2015).

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The unexploited equilibrium spawning biomass SB₀ estimated in the 2015 assessment was 2.269 million tonnes (95% confidence interval: 1.83 – 2.90 million tonnes), a 6% increase on 2014’s estimate, although the uncertainty is broad. SB_40% has previously been used as a proxy for the MSY target biomass and is estimated at 907 thousand tonnes, with the minimum biomass threshold (B_25%) estimated at 567,000 tonnes (Taylor et al. 2015). Fishing intensity (F) is expressed as a relative spawning potential ratio (1-SPR/1-SPR_Target=0.4), and compared to the target F_SPR=40%, used as a proxy of F_MSY (PFMC 2014).

MSY reference points have been determined in addition to the MSY proxy SB_40% points. SB_MSY was estimated as 561 thousand tonnes and MSY as 384 thousand tonnes (Taylor et al. 2015).

According to the latest stock assessment the stock biomass has decreased slightly, but is above it’s target reference point (B_40%), and fishing intensity is below target levels. Spawning stock biomass (SSB) was estimated in 2014 at around 1.70 million tonnes, i.e., at 75% of estimated unfished spawning biomass (SB₀). SSB for 2015 is also forecasted well above target levels (median of forecast for SSB₂₀₁₄) is 1.72 million tonnes). Fishing intensity in 2014 was determined to be at 62% of the target F_SPR=40%. However, as in previous years, there still remains considerable uncertainty on the assessment estimates, in particular for the most recent years (Taylor et al. 2015).

Recruitment for this stock is highly variable, resulting in considerable and rapid variations in stock biomass. The current assessment estimates the stock remains near its highest biomass level since the early 1990’s, resulting from an above average 2008 cohort, and a very large 2010 cohort (Taylor et al. 2015).

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The stock declined to its previous lowest recent level in 2000, then rebounded in 2003 as a strong 1999 year class matured, before declining to a new record low in 2009, owing to a period of low recruitment from 2000 to 2007. An increase in stock biomass is estimated to be have occurred through 2014, mostly related to an above average 2008 cohort and a very large 2010 cohort. Large recruiting classes were also generated in 1980, 1984, and 1999 (Taylor et al. 2015).

Fishing intensity is estimated to have been below the proxy target of F_40% until recently, when the target was likely exceeded in 2008, 2010 and 2011, even though catch limits based on knowledge at the time were not exceeded in any of these cases. Since 2010, fishing intensity is estimated to have steadily decreased, and is currently estimated at well below the management target (Taylor et al. 2015).

The stock is jointly managed by Canada and the U.S. since 2006 under a formalized bilateral Hake Agreement and its constituent committees (Hicks et al., 2013).

In order that the fishery comply with rockfish bycatch limits, managers have maintained total Optimum Yield (OY) far below the recommended ABC. In the past, the coastwide OY represented managers’ judgment of an appropriate harvest level for U.S. and Canadian harvests combined and could be seen as a TAC (Devitt et al., 2009), but from 2012 it is explicitly referred to as a TAC. Actual catches have been constrained below this level by bycatch limits that protect depleted rockfish stocks. The OY for 2009, set at 184,000 tonnes, was down almost 50% from 2008 levels. In 2010, OY was increased to 262,500 tonnes and increased again in 2011 to 393,751 tonnes. The coastwide adjusted TAC adopted for the 2012, 2013 and 2014 Pacific whiting fisheries was set at 251,809, 365,112 and 428,000 tonnes, respectively (Taylor et al., 2014; JMC, 2014; NOAA, 2014a). For 2015, the TAC has been increased just slightly to 440,000 tonnes (Taylor et al. 2015).

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None are currently required under management policy. Should the stock drop below 25% of virgin biomass, it would be legally defined as “overfished”, triggering a recovery plan to accelerate rebuilding. The agreed Harvest Control rule, also anticipates a gradual decrease in catch from the catch target at SSB at B_40% (or above), to zero catch at SSB= B_10% or below (Taylor et al., 2014).

A U.S.-Canada allocation dispute during the 1990s resulted in catches exceeding set quotas (e.g., 1993-1999 catches were 7% above quota, on average) and the two nations began work on a catch-sharing arrangement. This led to a 2003 treaty that divides the harvest as follows: 73.88% U.S., 26.12% Canada. Over the past decade, catches have been generally below the coast-wide catch targets (Taylor et al., 2015). The Canadian management system allow a 15% difference between the quota and total catch, which is then deducted from or carried over to the quota for the following year. In 2012 and 2013, a 15% overage allowance was added due to respective annual quotas not having been fully taken (Hicks et al. 2013). An additional 50,430 tonnes coast-wide allowance (carryover from 2013: 37,258 tonnes added to the US share, and 13,272 tonnes added to the Canadian share) was added to the 2014 quota (JMC 2014); for 2015 an extra 14,793 tonnes and 41,842 tonnes will be added to the Canadian and US shares respectively, for a total 66,635 additional tonnes coast-wide allowance (JMC 2015).

Pacific hake (whiting) discards are not thought to be significant (Stewart and Hamel, 2010), with discards from all fisheries estimated to be less than 1% of landings in recent years (Taylor et al., 2015). Monitoring of these fisheries (either by on-board observers, at-sea electronic monitoring or dockside monitoring) is very strong.

The whiting fishery has few known impacts of significance upon marine mammals. Some biologists and conservationists have speculated that the fishery, by reducing abundance of the stock to approximately MSY levels, may have deprived marine mammals and other predator species of food. The EIS for 2007-2008 groundfish fisheries comments on this potential: “Based on the observation that most resident or migratory marine mammal populations in the California Current have been increasing at modest to substantial rate over the past several decades (including California sea lions, harbor seals, elephant seals, gray whales, and humpback whales), it is similarly difficult to expect that the cumulative impacts of fishing have been detrimental for these guilds (independent of the incidental mortality resulting from fishing activity).”

In the US, NMFS is currently analyzing data on interactions of the groundfish fishery, of which the whiting fishery is part, and marine mammals and seabirds. The most recent assessment indicated that from 2002-2009 incidental takes of marine mammals, seabirds, and turtles occurred on less than 2% of the fishing trips. Although bycatch events for these groups were considered “rare”, they could be important for highly endangered or long-long-lived species (Jannot et al., 2011). For the Canadian fishery, data from DFO for 2006-2011 indicated only two interactions with marine mammals, out of 6,265 hake tows (Devitt et al., 2011). The most recent surveillance MSC report denoted that based on the available information, the fishery impacts on the ecosystem structure within key fishery areas were negligible (Pederson et al., 2013).

Total bycatch in the fishery has averaged one to two percent from 1995 to 2004, according to an analysis prepared by the Pacific Whiting Conservation Cooperative, an industry group. Discard Primary species of concern include Chinook salmon listed under the Endangered Species Act and several species of rockfish (e.g., widow rockfish) that are considered overfished.

From 2009, bycatch limits started to be allocated by sector in the U.S. fishery. Rockfish bycatch in some years has constrained the whiting fishery’s access to the target species, keeping catches below otherwise-allowable levels. For chinook salmon, bycatch has been well below this limit in most years. Should bycatch exceed this threshold, consultations are initiated to determine impacts and consider mitigation measures. In Canada, main retained bycatch species are also subject to catch limits; however, in some cases the status of the stocks against reference points is unknown (e.g., Rougheye Rockfish), and impacts of the fishery on these species cannot be fully evaluated (Pederson et al., 2014). Two conditions were established during the MSC’s recertification of the fishery (certification is held by the Pacific Whiting Conservation Cooperative and the Oregon Trawl Commission) regarding insufficient information to assess and ensure outcomes for Yellowtail Rockfish, Redstripe Rockfish, Walleye Pollock and Rougheye Rockfish (Pederson et al. 2014). Progress on these conditions was considered on target as of the first surveillance audit in January 2016 (Pederson et al. 2016).

A 100% at-sea-monitoring system is in place for on at-sea processors and catcher vessels, in both the Canadian and US hake fisheries. Fishing vessels are also subject to a 100% dockside catch monitoring. Other management measures such as minimum mesh sizes, closed periods and areas have also been put in place to reduce bycatch of unwanted species and sizes (PFMC 2014; Taylor et al. 2014).

The MSC assessment team found that reliance on midwater trawl gear limits impacts on benthic habitat. However, some conservation groups disputed the efficacy of midwater trawls in protecting living structure on the seabed (Cassano, 2009), and they are challenging the view that this fishery has minimal impact. According to recent formal surveys conducted to both Canadian and US hake fishermen, bottom contact occurs generally in less than 10% (median) of the tows conducted, and over muddy/sandy bottom (Pedersen et al., 2013).

Indirect impacts on the ecosystem (e.g. prey competition with marine mammals) was considered and judged unlikely by authors of the 2007-2008 Environmental Impact Statement for this fishery and other groundfish fisheries in the region, because most marine mammal populations have been increasing. More recently, a MSC surveillance report noted that that, based on the available data on the indirect effects of the removal of pacific hake, the fishery has negligible impacts on the ecosystem structure and functioning “within key fishing areas” (Pedersen et al., 2013). Both the U.S. and Canada are moving towards integrated ecosystem-based management, considering ecosystem-wide inputs and impacts (e.g. el Niño effects, fishing impacts on sensitive habitats, bycatch of vulnerable species) in their management strategy (Devitt et al., 2011; Levin & Schwing, 2011).

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Area and temporal restrictions on fishing are in place, aimed at reducing the bycatch of Chinook salmon and depleted rockfish and at minimizing habitat impacts. No trawling is allowed in the Klamath and Columbia River Conservation zones in order to reduce salmon bycatch (PFMC, 2005) and catches are limited in the Eureka INPFC area (Stewart et al., 2012). Processing and night fishing is also restricted in some areas off the US coast (Taylor et al., 2014).

Trawl fishing is forbidden in a number of Rockfish and Cowcod Conservation Areas off the U.S. Pacific coast, aimed at protecting these depleted species (NMFS, 2014). Fifty U.S. areas are closed to bottom trawling (34) or bottom-contacting gear (16) in order to mitigate habitat impacts (PFMC, 2014). Bottom trawling is not permitted in Canada’s 164 Rockfish Conservation Areas (Pedersen et al., 2012) and closures protect coral, sponge reef and tideline areas (Devitt et al., 2009). Two Marine Protected Areas also exist under Canada’s jurisdiction: Bowie Seamount and the Endeavour Hydrothermal Vents, to protect the marine biodiversity associated with these structures (DFO, 2008).