Rock Sole (U.S. and Canada)

Southern Rock Sole (Lepidopsetta bilineata); Northern Rock Sole (Lepidopsetta polyxystra)

Sometimes known as Broadfin Sole, Rock Flounder, Roughback Sole or Roughscale Sole.

These species are wild-caught.

Summary

Southern and Northern Rock Soles are commercially important Pacific groundfish species targeted by U.S. and Canadian trawl vessels. Rock Soles grow at a moderate rate and can live 22 years. Thanks to successful management measures, they are at high levels of abundance, but changes in oceanic conditions may cause Rock Sole populations to decline a little in the future. Destructive bottom trawling for Rock Soles fortunately takes place over their sand/mud habitats, which are not as damaged by trawling as other habitats.

Criterion	Points
Life History	1.75
Abundance	3.25
Habitat Quality and Fishing Gear Impacts	1.25
Management	3.75
Bycatch	3.25
Final Score (average of criteria)	2.65
Color

Final Score	Color
2.60 - 4.00
2.20 - 2.59
1.80 - 2.19
1.40 - 1.79
0.00 - 1.39

Last updated July 18, 2005.

Life History

Core Points (only one selection allowed)

If a value for intrinsic rate of increase (‘r’) is known, assign the score below based on this value. If no r-value is available, assign the score below for the correct age at 50% maturity for females if specified, or for the correct value of growth rate ('k'). If no estimates of r, age at 50% maturity, or k are available, assign the score below based on maximum age.

1.00	Intrinsic rate of increase <0.05; OR age at 50% maturity >10 years; OR growth rate <0.15; OR maximum age >30 years.
2.00	Intrinsic rate of increase = 0.05-0.15; OR age at 50% maturity = 5-10 years; OR a growth rate = 0.16–0.30; OR maximum age = 11-30 years. Intrinsic rate of increase for both species is unknown. Age at 50% maturity in Southern Rock Soles is 8 years for females in the Bering Sea and 5-6 years in the Hecate Strait (Fargo and Wilderbuer 2000). Age at maturity in Northern Rock Soles is 7 years (Fishbase 12/21/04b). Growth rate (k) is 0.15 for Southern Rock Soles (Fishbase 12/21/04a) and 0.25 for Northern Rock Soles (Fishbase 12/21/2004b). Maximum reported age for Southern Rock Soles is 22 years (Fargo and Wilderbuer 2000) and for Nothern Rock Soles is 18 years (Fishbase 12/21/2004b).
3.00	Intrinsic rate of increase >0.16; OR age at 50% maturity = 1-5 years; OR growth rate >0.30; OR maximum age <11 years.

Points of Adjustment (multiple selections allowed)

-0.25	Species has special behaviors that make it especially vulnerable to fishing pressure (e.g., spawning aggregations; site fidelity; segregation by sex; migratory bottlenecks; unusual attraction to gear; etc.).
-0.25	Species has a strategy for sexual development that makes it especially vulnerable to fishing pressure (e.g., age at 50% maturity >20 years; sequential hermaphrodites; extremely low fecundity).
-0.25	Species has a small or restricted range (e.g., endemism; numerous evolutionarily significant units; restricted to one coastline; e.g., American lobster; striped bass; endemic reef fishes).
-0.25	Species exhibits high natural population variability driven by broad–scale environmental change (e.g., El Nino; decadal oscillations). Changing environmental conditions in the Pacific Ocean can impact sole populations by altering ocean productivity, food webs, timing and location of spawning, development of eggs and larvae, larval transport patterns, and distribution and migratory patterns of adult fish (PFMC 2004). Many scientists believe that the Northeast Pacific may currently be oscillating back to cooler temperatures due to a climatic phenomenon known as the Pacific Decadal Oscillation (PFMC 1999), which will likely have a favorable effect on the populations of many groundfish species (PFMC 2000). Changes in ocean temperature can affect species in ways that depend on their use of oceanic habitats during their life histories. For example, wind-driven advection of larvae is critical for the delivery of larvae to settlement areas, particularly for species that settle in different areas than they spawn (e.g., Rock Soles, Flathead Sole, and Arrowtooth Flounder). In these species, changes in wind direction during inter-decadal oscillations have been shown to significantly affect recruitment. For species that settle within the boundaries of their spawning areas, the effects of these inter-decadal oscillations are limited to thermal effects on the survival of eggs, larvae, and juveniles and growth (Wilderbuer et al. 2002).

+0.25	Species does not have special behaviors that increase ease or population consequences of capture OR has special behaviors that make it less vulnerable to fishing pressure (e.g., species is widely dispersed during spawning).
+0.25	Species has a strategy for sexual development that makes it especially resilient to fishing pressure (e.g., age at 50% maturity <1 year; extremely high fecundity).
+0.25	Species is distributed over a very wide range (e.g., throughout an entire hemisphere or ocean basin; e.g., swordfish; tuna; Patagonian toothfish).
+0.25	Species does not exhibit high natural population variability driven by broad-scale environmental change (e.g., El Nino; decadal oscillations).

1.75	Points for Life History

Abundance

Core Points (only one selection allowed)

Compared to natural or un-fished level, the species population is:

1.00	Low: Abundance or biomass is <75% of BMSY or similar proxy (e.g., spawning potential ratio).
2.00	Medium: Abundance or biomass is 75–125% of BMSY or similar proxy; OR population is approaching or recovering from an overfished condition; OR adequate information on abundance or biomass is not available.
3.00	High: Abundance or biomass is >125% of BMSY or similar proxy. Rock Sole populations in the North Pacific are thriving relative to a benchmark level, B40%, set by fishery managers. B40% refers to the size of a population (i.e. biomass) at a level of fishing pressure that reduces the number of spawning fish by 60% of the number that would be present in the absence of fishing (DiCosimo 1998). The most recent assessment found that Rock Sole populations are at a high level of biomass, 303,100 metric tons (mt), which is much greater than the B40% level of 158,600 mt (Wilderbuer and Walters 2002).

Points of Adjustment (multiple selections allowed)

-0.25	The population is declining over a generational time scale (as indicated by biomass estimates or standardized CPUE). During the 1980s, Rock Sole abundance increased dramatically due to low exploitation levels and high survival rates of young fish in the population (i.e. recruitment). Recruitment, which appears to be linked to water temperatures, is expected to be poor for the next several years and cause a slow decline in Rock Sole abundance (Witherell 2000). There is no indication, however, that this decline will push abundance below the minimum threshold set by fishery managers. Nonetheless, managers have incorporated this predicted decline into the current management scheme by calculating catch limits with a model that accounts for the impacts of environmental factors on recruitment (Wilderbuer and Nichol 2002). We chose not to subtract points here because the decline is predicted and not presently occurring.
-0.25	Age, size or sex distribution is skewed relative to the natural condition (e.g., truncated size/age structure or anomalous sex distribution).
-0.25	Species is listed as “overfished” OR species is listed as “depleted”, “endangered”, or “threatened” by recognized national or international bodies. Rock Soles are not overfished (Wilderbuer and Walters 2002).
-0.25	Current levels of abundance are likely to jeopardize the availability of food for other species or cause substantial change in the structure of the associated food web.

+0.25	The population is increasing over a generational time scale (as indicated by biomass estimates or standardized CPUE).
+0.25	Age, size or sex distribution is functionally normal. The age composition of Rock Soles in U.S. waters spans a broad range of ages (2-14+ years) and has remained stable for at least the past 20 years (Wilderbuer and Walters 2002). The sex ratio within Rock Sole populations is 50:50 (Spencer, pers. comm., 2003).
+0.25	Species is close to virgin biomass.
+0.25	Current levels of abundance provide adequate food for other predators or are not known to affect the structure of the associated food web.

3.25	Points for Abundance

Habitat Quality and Fishing Gear Impacts

Core Points (only one selection allowed)

Select the option that most accurately describes the effect of the fishing method upon the habitat that it affects.

1.00	The fishing method causes great damage to physical and biogenic habitats (e.g., cyanide; blasting; bottom trawling; dredging). Rock Soles are typically captured with bottom trawls that are highly destructive to seafloor habitats (Spencer, pers. comm., 2002).
2.00	The fishing method does moderate damage to physical and biogenic habitats (e.g., bottom gillnets; traps and pots; bottom longlines).
3.00	The fishing method does little damage to physical or biogenic habitats (e.g., hand picking; hand raking; hook and line; pelagic long lines; mid-water trawl or gillnet; purse seines).

Points of Adjustment (multiple selections allowed)

-0.25	Habitat for this species is so compromised from non-fishery impacts that the ability of the habitat to support this species is substantially reduced (e.g., dams; pollution; coastal development).
-0.25	Critical habitat areas (e.g., spawning areas) for this species are not protected by management using time/area closures, marine reserves, etc.
-0.25	No efforts are being made to minimize damage from existing gear types OR new or modified gear is increasing habitat damage (e.g., fitting trawls with roller rigs or rockhopping gear; more robust gear for deep-sea fisheries).
-0.25	If gear impacts are substantial, resilience of affected habitats is very slow (e.g., deep water corals; rocky bottoms).

+0.25	Habitat for this species remains robust and viable and is capable of supporting this species.
+0.25	Critical habitat areas (e.g., spawning areas) for this species are protected by management using time/area closures, marine reserves, etc.
+0.25	Gear innovations are being implemented over a majority of the fishing area to minimize damage from gear types OR no innovations necessary because gear effects are minimal.
+0.25	If gear impacts are substantial, resilience of affected habitats is fast (e.g., mud or sandy bottoms) OR gear effects are minimal. Gravel/sand/mud bottom habitats that are typical of those inhabited by Southern and Northern Rock Soles require little recolonization or rebuilding to recover structurally as compared to “live bottom”, reef, or kelp-bed habitats (NRC 2002).

1.25	Points for Habitat Quality and Fishing Gear Impacts

Management

Core Points (only one selection allowed)

Select the option that most accurately describes the current management of the fisheries of this species.

1.00

Regulations are ineffective (e.g., illegal fishing or overfishing is occurring) OR the fishery is unregulated (i.e., no control rules are in effect).

2.00

Management measures are in place over a major portion over the species’ range but implementation has not met conservation goals OR management measures are in place but have not been in place long enough to determine if they are likely to achieve conservation and sustainability goals.

3.00

Substantial management measures are in place over a large portion of the species range and have demonstrated success in achieving conservation and sustainability goals.

Rock Sole fisheries are managed under the Bering Strait and Aleutian Islands Groundfish Management Plan by the North Pacific Fishery Management Council (NRFMC 2002). Rock Sole populations are abundant and at or above historic levels, regulations are strict and enforced, catches are monitored, and the populations are assessed by fishery independent surveys.

There was a brief period (1959-1962) when intensive fishing pressure by foreign fleets, primarily from the former U.S.S.R., caused concern that Rock Sole within the U.S. EEZ (Exclusive Economic Zone) were in danger of overexploitation. The Rock Sole fishery within U.S. waters became entirely domestic in 1990, and the populations have fully recovered.

Currently, the realized fishing pressure is well below the level that the population is considered to be capable of supporting, because bycatch limitations typically restrict Rock sole fishers from capturing their allotted annual quotas (Wilderbuer and Walters 2002; Witherell 2000).

Points of Adjustment (multiple selections allowed)

-0.25	There is inadequate scientific monitoring of stock status, catch or fishing effort.
-0.25	Management does not explicitly address fishery effects on habitat, food webs, and ecosystems.
-0.25	This species is overfished and no recovery plan or an ineffective recovery plan is in place.
-0.25	Management has failed to reduce excess capacity in this fishery or implements subsidies that result in excess capacity in this fishery.

+0.25	There is adequate scientific monitoring, analysis and interpretation of stock status, catch and fishing effort. Catches of Rock Soles are well monitored, and population assessments are conducted (Wilderbuer and Nichol 2002).
+0.25	Management explicitly and effectively addresses fishery effects on habitat, food webs, and ecosystems.
+0.25	This species is overfished and there is a recovery plan (including benchmarks, timetables and methods to evaluate success) in place that is showing signs of success OR recovery plan is not needed. No recovery plan is needed for either Southern or Northern Rock Sole. Rock Sole populations are abundant and at or above historic levels, regulations are strict and enforced, catches are monitored, and the populations are assessed by fishery independent surveys.
+0.25	Management has taken action to control excess capacity or reduce subsidies that result in excess capacity OR no measures are necessary because fishery is not overcapitalized. The Rock Sole fishery is not overcapitalized. There was a brief period (1959-1962) when intensive fishing pressure by foreign fleets, primarily from the former U.S.S.R., caused concern that Rock Sole within the U.S. EEZ (Exclusive Economic Zone) were in danger of overexploitation. The Rock Sole fishery within U.S. waters became entirely domestic in 1990, and the populations have fully recovered. Currently, the realized fishing pressure is well below the level that managers believe the populations are capable of supporting (Wilderbuer and Walters 2002; Witherell 2000).

3.75	Points for Management

Bycatch

Core Points (only one selection allowed)

Select the option that most accurately describes the current level of bycatch and the consequences that result from fishing this species.

The term, "bycatch” used in this document excludes incidental catch of a species for which an adequate management framework exists.

The terms, “endangered, threatened, or protected,” used in this document refer to species status that is determined by national legislation such as the U.S. Endangered Species Act, the U.S. Marine Mammal Protection Act (or another nation's equivalent), the IUCN Red List, or a credible scientific body such as the American Fisheries Society.

1.00	Bycatch in this fishery is high (>100% of targeted landings), OR regularly includes a “threatened, endangered or protected species.”
2.00	Bycatch in this fishery is moderate (10-99% of targeted landings) AND does not regularly include “threatened, endangered or protected species” OR level of bycatch is unknown.
3.00	Bycatch in this fishery is low (<10% of targeted landings) and does not regularly include "threatened, endangered or protected species." Most incidental catch associated with the directed Rock Sole fishery consists of other commercial species for which sound management plans exist. None of these species appears to be overfished (Spencer, pers. comm., 2003; Witherell 2000). Furthermore, discards of commercially important species are monitored and included in the total catch measures of those species (Wilderbuer and Walters 2002). Bycatch of species that are not commercially important is small (3% of total catch) and is composed of species that are also not considered to be at risk (Spencer, unpublished data).

Points of Adjustment (multiple selections allowed)

-0.25	Bycatch in this fishery is a contributing factor to the decline of “threatened, endangered, or protected species" and no effective measures are being taken to reduce it.
-0.25	Bycatch of targeted or non-targeted species (e.g., undersize individuals) in this fishery is high and no measures are being taken to reduce it.
-0.25	Bycatch of this species (e.g., undersize individuals) in other fisheries is high OR bycatch of this species in other fisheries inhibits its recovery, and no measures are being taken to reduce it.
-0.25	The continued removal of the bycatch species contributes to its decline.

+0.25	Measures taken over a major portion of the species range have been shown to reduce bycatch of “threatened, endangered, or protected species” or bycatch rates are no longer deemed to affect the abundance of the “protected” bycatch species OR no measures needed because fishery is highly selective (e.g., harpoon; spear).
+0.25	There is bycatch of targeted (e.g., undersize individuals) or non-targeted species in this fishery and measures (e.g., gear modifications) have been implemented that have been shown to reduce bycatch over a large portion of the species range OR no measures are needed because fishery is highly selective (e.g., harpoon; spear). Fishery managers monitor bycatch closely in U.S. North Pacific fisheries and have set restrictions to reduce bycatch levels. In all areas where Rock Sole fisheries operate, specific bycatch quotas exist for Pacific Halibut, King Crab, and Tanner Crab. When the Rock Sole fishery reaches the management quotas for these species, the fishery is closed (e.g. NMFS 1995).
+0.25	Bycatch of this species in other fisheries is low OR bycatch of this species in other fisheries inhibits its recovery, but effective measures are being taken to reduce it over a large portion of the range.
+0.25	The continued removal of the bycatch species in the targeted fishery has had or will likely have little or no impact on populations of the bycatch species OR there are no significant bycatch concerns because the fishery is highly selective (e.g., harpoon; spear).

3.25	Points for Bycatch

References

DiCosimo, J. 1998. Summary of the Gulf of Alaska Groundfish Fishery Management Plan. Available at: http://www.fakr.noaa.gov/npfmc/Reports/goafmp98.htm#definitions.

Fishbase. 12/21/2004a. Species Summary for Lepidopsetta bilineata. Available at: http://www.fishbase.org/Summary/SpeciesSummary.cfm?genusname= Lepidopsetta &speciesname=bilineata.

Fishbase. 12/21/2004b. Species Summary for Lepidopsetta polyxystra. Available at: http://www.fishbase.org/Summary/SpeciesSummary.cfm?genusname= Lepidopsetta &speciesname=polyystra.

Fargo, J. and T.K. Wilderbuer. 2000. Population dynamics of Rock Sole (Lepidopsetta bilineata) in the North Pacific. Journal of Sea Research 44(1-2):123-144.

DEEP-SEA RESEARCH?

National Research Council (NRC). 2002. Committee on Ecosystem Effects of Fishing: Phase 1 - Effects of Bottom Trawling on Seafloor Habitats. National Academies of Sciences Press.

National Marine Fisheries Service (NMFS). 1995. NMFS Closes Directed Fishing for Yellowfin Sole by Vessels Using Trawl Gear in the Bering Sea and Aleutian Islands Management Area. October 5, 1995. Available at: http://www.fakr.noaa.gov/1995/bsyshb2a.txt.

North Pacific Fishery Management Council (NPFMC). 2002. Fishery Management Plan for the Bering Sea/Aleutian Islands Groundfish. Available at: http://www.fakr.noaa.gov/npfmc/fmp/bsai/bsai.htm.

Pacific Fishery Management Council (PFMC). 2004. Pacific Coast Groundfish Fishery Management Plan for California, Oregon, and Washington Groundfish Fishery; As Amended through Amendment 17. Available at: http://www.pcouncil.org//groundfish/gffmp.html.

PFMC. 2000. Pacific Fishery Management Council Draft Groundfish Fishery Strategic Plan: “Transition to Sustainability.” Prepared by the Ad-Hoc Pacific Groundfish Fishery Strategic Plan Development Committee for Council Family Review and Comment.

PFMC. 1999. Status of the Pacific Coast Groundfish Fishery through 1999 and Recommended Acceptable Biological Catches for 2000: Stock Assessment and Fishery Evaluation.

Spencer, P. 2003. Personal communication. Alaska Fisheries Science Center.

Wilderbuer, T.K. and G.E. Walters. 2002. 2002 Groundfish Stock Assessment and Fishery Evaluation Report for Rock Sole. North Pacific Fishery Management Council (NPFMC) Available at: http://www.afsc.noaa.gov/refm/docs/2002/BSrocksole.pdf.

Wilderbuer, T.K., A.B. Hollowed, W.J. Ingraham, Jr., P.D. Spencer, M.E. Conners, N.A. Bond, and G.E. Walters. 2002. Flatfish recruitment response to decadal climatic variability and ocean conditions in the eastern Bering Sea. Progress in Oceanography 55:235-247.

Witherell, D. 2000. Groundfish of the Bering Sea and the Aleutian Islands Area: Species Profiles 2001. North Pacific Fishery Management Council. Available at: http://www.fakr.noaa.gov/npfmc/Reports/species2001.pdf.