Last updated on 14 October 2016

SUMMARY

SUMMARY

IDENTIFICATION

SCIENTIFIC NAME(s)

Glyptocephalus zachirus

SPECIES NAME(s)

Rex sole

COMMON NAMES

Longfin sole,

Rex sole (Glyptocephalus zachirus) is a right-eyed flatfish occurring from southern California to the Bering sea and ranging from shallow water (<100m) to about 800 meters depth. They are most abundant at depths between 100 and 200m and are found fairly uniformly throughout the Gulf of Alaska (GOA) (NOAA 2011).

Rex sole in the Gulf of Alaska are caught in a directed fishery using bottom trawl gear. Fishing seasons are driven by seasonal halibut PSC apportionments, with approximately 7 months of fishing occurring between January and November. Catches of rex sole occur primarily in the Western and Central management areas in the gulf (statistical areas 610 and 620 + 630, respectively). Recruitment to the fishery begins at about age 5 (Stockhausen et al 2009).

The stock within the GOA is managed as a unit stock but with area-specific ABC and TAC apportionments to avoid the potential for localized depletion. Little is known on the stock structure of this species (Rice et al. 2013, 2014).

This fishery was certified by the Marine Stewardship Council system in June 2010. Click here to link to the MSC fishery page and to learn more about the MSC fishery certification unit.


ANALYSIS

Weaknesses

Current estimates of optimum harvest levels based on Tier 3 calculations (e.g., at FABC harvest rates) are very large but highly uncertain (Rice et al. 2013, 2014).

FISHSOURCE SCORES

Management Quality:

Management Strategy:

≥ 8

Managers Compliance:

10

Fishers Compliance:

10

Stock Health:

Current
Health:

10

Future Health:

NOT YET SCORED


RECOMMENDATIONS

RETAILERS & SUPPLY CHAIN
  • Monitor the performance of the fishery and its management to ensure the fishery continues to be eligible for condition-free MSC re-certification.

FIPS

No related FIPs

CERTIFICATIONS

  • Alaska Flatfish - Gulf of Alaska:

    MSC Recertified

Fisheries

Within FishSource, the term "fishery" is used to indicate each unique combination of a flag country with a fishing gear, operating within a particular management unit, upon a resource. That resource may have a known biological stock structure and/or may be assessed at another level for practical or jurisdictional reasons. A fishery is the finest scale of resolution captured in FishSource profiles, as it is generally the scale at which sustainability can most fairly and practically be evaluated.

ASSESSMENT UNIT MANAGEMENT UNIT FLAG COUNTRY FISHING GEAR
US Alaska US Alaska United States Single boat bottom otter trawls

Analysis

OVERVIEW

Last updated on 14 October 2016

Weaknesses
US Alaska

Last updated on 14 October 2016

Current estimates of optimum harvest levels based on Tier 3 calculations (e.g., at FABC harvest rates) are very large but highly uncertain (Rice et al. 2013, 2014).

RECOMMENDATIONS

Last updated on 1 November 2018

Recommendations to Retailers & Supply Chain
  • Monitor the performance of the fishery and its management to ensure the fishery continues to be eligible for condition-free MSC re-certification.

1.STOCK STATUS

STOCK ASSESSMENT
US Alaska

Last updated on 14 October 2016

In 2006, the Gulf of Alaska rex sole stock was moved to a biennial stock assessment schedule to coincide with the expected receipt of new survey data.

The abundance, mortality, recruitment and selectivity of Rex Sole are assessed with a stock assessment model using the AD Model builder language. The conceptual model is a separable catch-age analysis that uses survey estimates of biomass and age composition as auxiliary information (Rice et al. 2013, 2014).

SCIENTIFIC ADVICE
US Alaska

Last updated on 14 October 2016

Reference Points

Last updated on 14 Oct 2016

Natural mortality (M) was fixed at 0.17 yr-1 for both sexes in all age classes. This value was based on maximum observed age of 27 years (Rice et al. 2013, 2014).

Coefficients of variation (CVs) for length-at-age were also estimated from the survey data, and varied linearly from 0.13 for age 3 to 0.08 for age 20+. Size at 50% maturity was estimated to be 351.7 mm with a logistic slope of 0.0392 mm-1 . The age at 50%-maturity was estimated at 5.6 years (Rice et al. 2013, 2014).

CURRENT STATUS
US Alaska

Last updated on 14 October 2016

Biomass has been increasing over the last decade, while recruitment and catch are variable. The stocks is well above the ABC or MSY biomass target and well below the ABC or MSY fishing mortality rate targets. Additionally, the overfishing levels are not being approached for any of these stocks. Hence, there is no overfishing and the stocks are not in an overfished state (Rice et al. 2013, 2014).

This stock is lightly harvested due to targeting on other species and the regulatory mechanisms related to bycatch with no major shifts in catches in recent years. Similarly, there are no major trends in abundance, i.e. the stocks are fluctuating without trend (Stockhausen et al 2009, 2010).

The total biomass for rex sole for 2008 was estimated at 82,801 t. The total landings in 2007 were 2,609 t. As a Tier 5 stock, FOFL=M=0.17 and FABC=0.75M=0.13. Table 4 below shows the ABC, OFL and total catch for rex sole between 1996 and 2007 (Stockhausen et al 2009).

A preliminary examination of the results of the survey indicates that total survey biomass for rex sole increased by 6% from 95,134 t in 2011 to 100,978 t in 2013. Most of this increase occurred in the Southeast. Although it is not possible to use a Tier 3 approach to making harvest recommendations for rex sole because estimates of F35% and F40% are not considered reliable, the SSC has decided that it is possible to use a Tier 3 approach for determining overfished status because the estimate of B35% = 0.35 ∙ B100% (i.e., 35% of the unfished spawning stock biomass) is considered reliable (it does not depend on the fishery selectivity), as is the estimate of current (2013) spawning stock biomass (Rice et al. 2013, 2014).

Trends

Last updated on 14 Oct 2016

Catch is currently reported for rex sole by management area. Catches for rex sole were estimated from 1982 to 1994 by multiplying the deepwater flatfish catch by the fraction of rex sole in the observed catch. Historically, catches of rex sole have exhibited decadal-scale trends. Catches increased from a low of 93 t in 1986 to a high of 5,874 t in 1996, then declined to about 3,000 t thereafter. Catch in 2008 was 2,703 t and 4,230 in 2009 (as of Sept. 26; 2009). The 2009 catch is the largest since 1996 (Stockhausen et al 2009).

2.MANAGEMENT QUALITY

MANAGEMENT
US Alaska

Last updated on 14 October 2016

The Council has a history of regulations to control bycatch. These include:

  • time and area closures
  • prohibited species catch limits and area closures
  • biodegradable panels on pots to permit juvenile escapement
  • minimum mesh size requirements for trawl codends)
  • legal gear
  • legal fishing practices
  • rationalization programs (NOAA 2011)

3.ENVIRONMENT AND BIODIVERSITY

BYCATCH
Other Species
US Alaska

Last updated on 14 October 2016

Prohibited species such as halibut, salmon, and crab are also taken to some extent in the rex sole-directed fishery. In 2009 (through September), the overall prohibited species catch (PSC) rate for halibut was 384,211 t—more than double that of the 2008 catch of 173,430 and the largest since 2003. The PSC for salmon and crab in the 2009 directed fishery were 2,035 salmon and 10,888 crabs. The majority of salmon caught were Chinook. Most of the crabs caught were Bairdi tanner crab, although a few golden king crab were taken, as well. The 2009 PSC for salmon was the highest since 2003. The 2009 crab PSC was the smallest since 2005 (although the season is not yet complete) (Stockhausen et al 2009).

HABITAT
US Alaska

Last updated on 14 October 2016

Catches of rex sole are widely distributed in the Gulf of Alaska over the past few years. The ecosystem effects of this spatial distribution of fishing activity are unknown (Powers et al 2010).

FishSource Scores

MANAGEMENT QUALITY

As calculated for 1982 data.

The score is ≥ 8.

A control rule is in place based on conservative Tier 5 calculations (Powers et al., 2010).

As calculated for 2012 data.

The score is 10.0.

This measures the Set TAC as a percentage of the ABC.

The Set TAC is 9.40 ('000 t). The ABC is 9.40 ('000 t) .

The underlying Set TAC/ABC for this index is 100%.

As calculated for 2009 data.

The score is 10.0.

This measures the Catch as a percentage of the Set TAC.

The Catch is 4.75 ('000 t). The Set TAC is 9.00 ('000 t) .

The underlying Catch/Set TAC for this index is 52.8%.

STOCK HEALTH:

As calculated for 2012 data.

The score is 10.0.

This measures the SSB as a percentage of the 40%B0.

The SSB is 51.1 ('000 t). The 40%B0 is 22.6 ('000 t) .

The underlying SSB/40%B0 for this index is 226%.

To see data for biomass, please view this site on a desktop.
To see data for catch and tac, please view this site on a desktop.
To see data for fishing mortality, please view this site on a desktop.
No data available for recruitment
No data available for recruitment
To see data for management quality, please view this site on a desktop.
To see data for stock status, please view this site on a desktop.

Download Source Data

Registered users can download the original data file for calculating the scores after logging in. If you wish, you can Register now.

Fishery Improvement Projects (FIPs)

No related FIPs

Certifications

Marine Stewardship Council (MSC)

SELECT MSC

NAME

Alaska Flatfish - Gulf of Alaska

STATUS

MSC Recertified on 1 June 2010

SCORES

Principle Level Scores:

Principle Score
Principle 1 – Target Species – Arrowtooth flounder 98.8
Principle 1 – Target Species – Flathead Sole 98.8
Principle 1 – Target Species – Northern Rock Sole 98.8
Principle 1 – Target Species – Southern Rock Sole 98.8
Principle 1 – Target Species – Rex Sole 87.5
Principle 2 - Ecosystem 89.7
Principle 3 – Management System 99.0

Certification Type: Gold

Sources

Credits
  1. National Oceanic and Atmospheric Administration (NOAA), 2011. Fisheries of the Exclusive Economic Zone Off Alaska; Gulf of Alaska; Final 2011 and 2012 Harvest Specifications for Groundfish. Federal Register /Vol. 76, No. 40 /Tuesday, March 1, 2011.http://www.gpo.gov/fdsys/pkg/FR-2011-03-01/pdf/2011-4402.pdf

  2. Powers, J., G. Tingley, S. Hanna and P. Knapman, 2010. Marine Stewardship Council Public Certification Report for the Gulf of Alaska Rex Sole trawl fishery. Client: Best Use Coalition. Moody Marine Ltd. http://www.msc.org/track-a-fishery/certified/pacific/gulf-of-alaska-flatfish/assessment-downloads-1/20.05.2010-goa-rex-sole-pcr.pdf

  3. Rice, J., Bowen, D., Hanna, S., Blyth-Skyrme, R. 2013. Third Annual Surveillance Report Gulf of Alaska Flatfish Fisheries. Intertek Moody Marine, July 2013, 28pphttp://www.msc.org/track-a-fishery/fisheries-in-the-program/certified/pacific/gulf-of-alaska-flatfish/assessment-downloads-1/20130716_SR_FLA49.pdf

  4. Rice, J., Bowen, D., Trumble, R. J., 2014. Fourth Annual Surveillance Report- Gulf of Alaska Flatfish Fishery. MRAG Americas, Inc., July 2014. 14pphttp://www.msc.org/track-a-fishery/fisheries-in-the-program/certified/pacific/gulf-of-alaska-flatfish/assessment-downloads-1/20140724_SR_FLA049.pdf

  5. Stockhausen, W.T., 2010. Stock Assessment and Fishery Evaluation Report for the Groundfish Resources of the Bering Sea/Aleutian Islands Regions Chapter 6: Assessment of the Rex Sole Stock in the Gulf of Alaska (Executive Summary).http://www.afsc.noaa.gov/REFM/docs/2010/GOArex.pdf

  6. Stockhausen, W.T., M.E. Wilkins and M.H. Martin, 2009. Stock Assessment and Fishery Evaluation Report for the Groundfish Resources of the Bering Sea/Aleutian Islands Regions Chapter 6: Assessment of the Rex Sole Stock in the Gulf of Alaska.http://www.afsc.noaa.gov/refm/docs/2009/GOArex.pdf

References

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