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

Transcription

1 ROCK SOLE, SOUTHERN AND NORTHERN Lepidopsetta bilineata (Southern Rock Sole), Lepidopsetta polyxystra (Northern Rock Sole) Sometimes known as Broadfin Sole, Rock Flounder, Roughback Sole, Roughscale Sole SUMMARY Southern and Northern Rock Soles are commercially important Pacific groundfish in Alaskan waters. Rock Soles grow at a moderate rate and can live up to 30 years. Thanks to successful management measures, Rock Sole are at high levels of abundance throughout their range. Bottom trawling for Rock Soles takes place over sand/mud habitats, which are not as damaged by trawling as other habitats can be. There is limited bycatch associated with this fishery. Criterion Points Final Score Color Life History Abundance Habitat Quality and Fishing Gear Impacts Management 4.00 Bycatch 3.50 Final Score 3.20 Color

2 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 Intrinsic rate of increase <0.05; OR age at 50% maturity >10 years; OR growth rate <0.15; OR maximum age >30 years Intrinsic rate of increase = ; OR age at 50% maturity = 5-10 years; OR a growth rate = ; OR maximum age = years. There are two species of Rock Sole, northern and southern. Southern Rock Sole are found in the North Pacific from Baja California to the eastern Aleutian Island and southeastern Bering Sea (Fishbase 2010a). Northern Rock Sole are distributed in the North Pacific from Puget Sound, WA through the Bering Sea and Aleutian Islands to the Kuril Islands (Mecklenburg et al. 2002; Fishbase 2010b). The two distributions overlap from the southeastern Bering Sea to Puget Sound (Fishbase 2010b). In the Gulf of Alaska, Northern Rock Sole reach sexual maturity around 7 years, while Southern Rock Sole reach maturity at 9 years of age (Stark and Somerton 2002). In the Bering Sea, Southern Rock Sole reach sexual maturity around 8 years (Fargo and Wilderbuer 2000). Growth rates of Northern Rock Sole (k=0.25) are higher than for Southern Rock Sole (k=0.15) (Stark and Somerton 2002). Northern Rock Sole can live up to 30 years and reach lengths of 53 cm for females and 60 cm for males, while Southern Rock Sole can live up to 22 years (Fargo and Wilderbuer 2000; Munk 2001; Matarese et al. 2003; Wilderbuer and Nichol 2009). In Canada, female and male Northern Rock Sole reach sexual maturity at younger ages of 3-4 and 4-5 respectively, and the maximum age is 21 years (Fargo et al. 2000) 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) 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.) 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).

3 -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) Species exhibits high natural population variability driven by broad-scale environmental change (e.g. El Nino; decadal oscillations) 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) 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). Northern Rock Sole spawn from January through March in the Bering Sea/Aleutian Islands (Wilderbuer and Nichol 2009). In the Gulf of Alaska Northern Rock Sole spawn at depths of 43 to 61 m in the midwinter with peaks in the spring and Southern Rock Sole spawn during the summer at depths of 35 to 120 m (Stark and Somerton 2002). The numbers of eggs females produce increases with age and can range from 400,000 to 1.3 million per year (PFMC 2005). In Canada peak spawning occurs at depth of m from March through April (Shvetsov 1979). We consider this to be medium fecundity so we have not added any points Species is distributed over a very wide range (e.g., throughout an entire hemisphere or ocean basin; e.g., swordfish; tuna; Patagonian toothfish). Southern Rock Sole are found in the North Pacific from Baja California to the eastern Aleutian Island and southeastern Bering Sea (Fishbase 2010a). Northern Rock Sole are distributed in the North Pacific from Puget Sound, WA through the Bering Sea and Aleutian Islands to the Kuril Islands (Mecklenburg et al. 2002; Fishbase 2010b). The two distributions overlap from the southeastern Bering Sea to Puget Sound (Fishbase 2010b). Rock Sole are commonly caught off the Kamchatka Peninsula (Shubnikov and Lisovenko 1964), British Columbia (Forrester and Thompson 1969), the central Gulf of Alaska and in the southeastern Bering Sea (Alton and Sample 1975). In the Gulf of Alaska they are most commonly found in the Kodiak and Shumagin areas (DiCosimo 1998). Northern Rock Sole make up the majority of the Rock Sole population in the Bering Sea and Aleutian Islands (Wilderbuer and Nichol 2009). This distribution is considered a medium range, so no points were added Species does not exhibit high natural population variability driven by broad-scale environmental change (e.g., El Nino; decadal oscillations) Points for Life History

4 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) Medium: Abundance or biomass is % 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 High: Abundance or biomass is >125% of BMSY or similar proxy. Northern Rock Sole are not considered overfished or undergoing over fishing in either the Bering Sea/Aleutian Islands or the Gulf of Alaska (Turnock et al. 2009; Wilderbuer and Nichol 2009). The Biomass in the Bering Sea/Aleutian Islands in 2010 was more than 200% of that needed to produce the Maximum Sustainable Yield (MSY) and the catch in 2009 was around 15% of that needed to produce MSY (Wilderbuer and Nichol 2009). In the Gulf of Alaska, Northern Rock Sole biomass in 2010 was over 150% of that needed to produce MSY and the catch in 2009 was around 70% of that needed to produce MSY (Turnock et al. 2009). In Canadian waters, specifically Hecate strait, the last population assessment was conducted in 2000/2001 and found both recruitment and biomass had declined from 1996 (Fargo et al. 2000). The core point reflects the more recent estimates of abundance from the US fisheries. Points of Adjustment (multiple selections allowed) The population is declining over a generational time scale (as indicated by biomass estimates or standardized CPUE). Estimates of Northern Rock Sole female spawning biomass in the Bering Sea/Aleutian Islands increased from 1982 to 1992, leveled off from 1994 to 1998 and has remained stable through 2008 but declined to the lowest levels since 1995 in 2009 (Wilderbuer and Nichol 2009). However the female spawning biomass is projected to increase in the near future due to the strong recruitment observed in year-classes and the current level of abundance is very high. In the Gulf of Alaska, Northern Rock Sole biomass increased from 1999 to 2007 but then decreased slightly in 2009, while Southern Rock Sole biomass has increased through 2009 (Turnock et al. 2009). Due to the variable trends in abundance and recent declines we have not subtracted points until additional information is available Age, size or sex distribution is skewed relative to the natural condition (e.g., truncated size/age structure or anomalous sex distribution).

5 -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) 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 The population is increasing over a generational time scale (as indicated by biomass estimates or standardized CPUE) Age, size or sex distribution is functionally normal. Northern Rock Sole in the Gulf of Alaska reach a theoretical maximum size of 430 mm, while Southern Rock Sole reach a larger size of 520 mm (Stark and Sommerton 2002). The fishery tends to catch larger females than male Rock Sole (Turnock et al. 2009). The sex ratio appears to be near 50/50 (Turnock et al. 2009). There is no indication of changes in the age, size or sex distribution in the fisheries over time Species is close to virgin biomass Current levels of abundance provide adequate food for other predators or are not known to affect the structure of the associated food web. Rock Sole larvae eat plankton and larvae and juveniles food preference changes from zooplankton to invertebrates such as clams, worms, and crabs as adults (Wilderbuer and Nichol 2009). There is no indication that the abundance of Rock Sole negatively impacts the food web in the Bering Sea/Aleutian Islands or Gulf of Alaska Points for Abundance

6 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) The fishing method does moderate damage to physical and biogenic habitats (e.g., bottom gillnets; traps and pots; bottom longlines). Rock Soles are targeted by bottom trawls for the high value roe fishery in February and March (NPFMC 2009a; Wilderbuer and Nichol 2009). Trawling nets, and their attachments, are designed to maximize contact with the seafloor and therefore can modify benthic habitats and affect benthic fauna, diversity and community structure (Morgan and Chuenpagdee 2003). However, there is no evidence of destruction of habitat from trawling on Rock Sole (Anonymous 2010) and there are many management measures in place to protect bottom habitat in this region from any potential negative impacts. We have therefore given Rock Sole a medium score instead of a 1, which is usually attributed to bottom trawl fisheries 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) 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) Critical habitat areas (e.g., spawning areas) for this species are not protected by management using time/area closures, marine reserves, etc 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) If gear impacts are substantial, resilience of affected habitats is very slow (e.g., deep water corals; rocky bottoms).

7 +0.25 Habitat for this species remains robust and viable and is capable of supporting this species. Essential Fish Habitat (EFH) for Rock Sole larvae includes pelagic waters along the shelf of 0 to 200 m depth and in the upper slope in depths of m throughout the Bering Sea and Aleutian Islands (BSAI) (NPFMC 2009a). Juvenile and Adults are found in the lower portion of the water column along the inner (0-50 m), middle ( m) and outer ( m) shelf of the BSAI above soft substrate (i.e. sand, gravel, and cobble) (NPFMC 2009a). There is no indication that this habitat cannot support Rock Sole Critical habitat areas (e.g., spawning areas) for this species are protected by management using time/area closures, marine reserves, etc. Several time/area restrictions are in place for the Bering Sea Aleutian Islands trawl fisheries (NPFMC 2009a). In Canada half of the fishing grounds for Rock Sole have been closed to protect Dungeness crab (Fargo et al. 2000) 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. Bottom contact gear is prohibited in the Aleutian Islands Coral and Alaska Seamount Habitat Protection Areas year round and the use of mobile bottom contact year is prohibited year round in the Bowers Ridge Habitat Conservation Zone (NPFMC 2009a). In the Gulf of Alaska anchoring and bottom gear are prohibited in the Gulf of Alaska Coral and Alaska Seamount Habitat Protection Areas (NPFMC 2009b). In 2011, all vessels fishing for flatfish in the Bering Sea will be required to use disks on the trawl sweep wires where they contact the seafloor to reduce benthic disturbance 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) Points for Habitat Quality and Fishing Gear Impacts

8 MANAGEMENT Core Points (only one selection allowed) Select the option that most accurately describes the current management of the fisheries of this species Regulations are ineffective (e.g., illegal fishing or overfishing is occurring) OR the fishery is unregulated (i.e., no control rules are in effect) 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 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 (BSAI) Groundfish Management Plan (NPFMC 2009) and the Gulf of Alaska (GOA) Fishery Management Plan for groundfish (NPFMC 2009b) by the North Pacific Fishery Management Council (NRFMC 2002). There are two species of Rock Sole, northern and southern but the northern species makes up the majority of the Bering Strait/Aleutian Islands population and they are managed as a single population (Wilderbuer and Nichol 2009). In the Gulf of Alaska Rock Sole are managed as a unit with other shallow water flatfish (NPFMC 2009). However, overlapping distributions of the northern and southern Rock Sole in the Gulf of Alaska suggest they may eventually need to be managed separately (Turnock et al. 2009). Management measures included in the Bering Strait and Aleutian Islands plan are: optimum yield, total allowable catch, vessel permits, authorized gear, time/area restrictions, prohibited species, flexible in season adjustments to management plans, record keeping and reporting, and fisheries observers (NPFMC 2009a). In the Gulf of Alaska, management measures included, total allowable catch, vessel permits, authorized gear, time/area restrictions, prohibited species, bycatch reduction programs, in season adjustments to gear, closures, or quotas, recordkeeping and reporting, and observer programs (NPFMC 2009b). In Canada Rock Sole are managed through annual quotas, trip limits and area closures (Fargo et al. 2000). Points of Adjustment (multiple selections allowed) There is inadequate scientific monitoring of stock status, catch or fishing effort.

9 -0.25 Management does not explicitly address fishery effects on habitat, food webs, and ecosystems This species is overfished and no recovery plan or an ineffective recovery plan is in place Management has failed to reduce excess capacity in this fishery or implements subsidies that result in excess capacity in this fishery 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 updated yearly (Wilderbuer and Nichol 2002) Management explicitly and effectively addresses fishery effects on habitat, food webs, and ecosystems. Management measures in the Bering Sea/Aleutian Islands and the Gulf of Alaska address fishery effects on the ecosystem and food webs (NPFMC 2009a,b) 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 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 50 years ago ( ) 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, but 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) Points for Management

10 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 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 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 (Witherell 2000; Wilderbuer and Nichol 2009). Furthermore, discards of commercially important species are monitored and included in the total catch measures of those species (Wilderbuer and Walters 2002). Prohibited species that are caught as bycatch include halibut and red king crab, which make up 27% and 82% respectively of the total bycatch in the Rock Sole fishery (Wilderbuer and Nichol 2009). This fishery is considered to be a minor contributor to prohibited species mortality and has a very minor take of marine mammals and a minor impact on non-target species (Wilderbuer and Nichol 2009). Points of Adjustment (multiple selections allowed) 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 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 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 The continued removal of the bycatch species contributes to its decline.

11 +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). In the Gulf of Alaska and Bering Sea/Aleutian Islands, fishing is limited around areas that are considered important to marine mammals (NPFMC 2009a and b) 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) 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. Rock Sole used to be discarded in large amounts until the implementation of Amendment 80 in 2008 (Wilderbuer and Nichol 2009). The first year the Amendment was in place 90% of Rock Sole were kept (Wilderbuer and Nichol 2009) 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) Points for Bycatch

12 REFERENCES Alton, M.S. and Sample, T.M Rock sole (Family Pleuronectidae) p In: W.T. Pereyra, J.E. Reeves and R. Bakkala (PI) Demersal fish and shellfish resources in the Bering Sea in the baseline year US Department of Commerce, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Northwest and Alaska Fish Center, Seattle, WA. DiCosimo, J Summary of the Gulf of Alaska Groundfish Fishery Management Plan. Available at: Fishbase. 2010a. Species Summary for Lepidopsetta bilineata. Available at: org/summary/speciessummary.cfm?genusname=lepidopsetta&speciesname=bilineata. Fishbase. 2010b. Species Summary for Lepidopsetta polyxystra. Available at: base.org/summary/speciessummary.cfm?genusname=lepidopsetta &speciesname=polyystra. Fargo, J. and T.K. Wilderbuer Population dynamics of Rock Sole (Lepidopsetta bilineata) in the North Pacific. Journal of Sea Research 44(1-2): Fargo, J., Kronlund, A.R., Schnute, J.T. and Haigh, R Stock assessment of rock sole and English sole in Hecate Strait for 2000/2001. Fisheries and Oceans Canada Research Document 2000/166. Forrester, C.R. and Thompson, J.A Population studies on the rock sole (Lepidopsetta bilineata) of northern Hecate Strait, British Columbia. Fisheries Research Board of Canada, Canadian Technical Report 109. Matarese, A.C., Blood, D.M., Picquelle, S.J., and Benson, J.L Atlas of abundance and distribution patterns of ichthyoplankton in the northeast Pacific Ocean and Bering Sea ecosystems based on research conducted by the Alaska Fisheries Science Center ( ). US Department of commerce, NOAA Professional paper NMFS p. Morgan, LE. And Chuenpagdee, R Shifting gears: addressing the collateral impacts of fishing methods in US waters. Pew Science Series. Washington D.C., Island Press. Munk, K.M Maximum ages of groundfishes in waters off Alaska and British Columbia and considerations of age determination. Alaska Fishery Research Bulletin pp. National Research Council (NRC) Committee on Ecosystem Effects of Fishing: Phase 1 - Effects of Bottom Trawling on Seafloor Habitats. National Academies of Sciences Press. North Pacific Fishery Management Council (NPFMC). 2009a. Fishery Management Plan for groundfish of the Bering Sea and Aleutian Islands management area. Anchorage, AK. 160 p.

13 North Pacific Fishery Management Council (NPFMC). 2009b. Fishery Management Plan for groundfish of the Gulf of Alaska. Anchorage, AK. 142 p. Pacific Fishery Management Council (PFMC) Pacific coast groundfish fishery management plan essential fish habitat DEIS. Pacific Fishery Management Council, Portland, OR. Shvetsov, F.G Reproduction of flounder Lepidopsetta bilineata off the Okhotsk Sea coast near Paramushiro and Shumshu islands. Journal of Ichtyology 19: Shubnikov, D.A. and Lisovenko, L.A Data on the biology of rock sole in southeastern Bering Sea. Tr. Vses. Nauchno-issled. Inst. MOrsk. Rybn Khoz. Okeanogr. 49: Stark, J.W. and Somerton, D.A Maturation, spawning and growth of rock soles off Kodiak Island in the Gulf of Alaska. Journal of Fish Biology 61: Turnock, B.J., A mar, T. and Wilderbuer, T.K North Pacific groundfish Stock Assessment and Fishery Evaluation Reports for 2010: Gulf of Alaska shallow-water flatfish. Anchorage, AK. 30 p. Wilderbuer, T.K. and G.E. Walters Groundfish Stock Assessment and Fishery Evaluation Report for Rock Sole. North Pacific Fishery Management Council (NPFMC) Available at: Wilderbuer, T.K. and Nichol, D.G North Pacific groundfish Stock Assessment and Fishery Evaluation Reports for 2010: Bearing Sea Aleutian Islands Northern rock sole. North Pacific Fishery Management Council, Anchorage, AK. 80 p. Witherell, D Groundfish of the Bering Sea and the Aleutian Islands Area: Species Profiles North Pacific Fishery Management Council. Available at: npfmc/reports/species2001.pdf.