Terms of Reference
Blackspotted / Rougheye Rockfish (Type I and Type II) stock assessment for British Columbia in 2020
Regional Peer Review – Pacific Region
May 26-27, 2020
Virtual meeting
Chairperson: Greg Workman
Context
The Blackspotted (BSR or Type I) / Rougheye (RER or Type II) Rockfish (Sebastes melanostictus and aleutianus, respectively) species complex (REBS) ranges from northern Japan to southern California at depths of 200 to 800+ m along the shelf break. These two species are among the longest lived Sebastes, with maximum recorded ages of 147 y (Type I) and 125 y (Type II) (based on the areal definitions made below) in British Columbia (BC) waters and 205 y in Southeast Alaska (most likely a Type I specimen), and with a current estimate of natural mortality of M=0.035 (McDermott 1994). The REBS complex is intercepted by trawl nets, hook and line gear, and the Sablefish trap fishery, and is a key species caught in the BC multi-species integrated groundfish fishery. The species complex has been managed as a single population of Rougheye Rockfish, pending advice on species identification methodologies and the implications of various harvest strategies on expected stock status for each species within the complex. Differentiating between these two species is done through genetic sampling because it is not possible to reliably distinguish between these species by visual inspection. Genetic sampling has also determined that these two species hybridize, further confounding the capacity to separate REBS observations in the catch or surveys.
Abundance information for this species in Canadian waters comes from surveys, and the indices are characterized by high relative error and show no trend over time for the combined species complex. The BC commercial fishery has a reported catch of REBS between 690 and 1,340 tonnes annually over the last two decades, with a mean annual catch of 820 t from 2015 to 2019. Survey abundance indices have insufficient species identification information to be able to differentiate between Type I and Type II observations in most years. New methodologies must be developed before stock assessments based on species-specific data can be attempted. Such stock assessments will require developing procedures capable of differentiating historical catches (commercial and survey) by species. This is needed because the large majority of the historical information has been reported as RER but comprises the combined species complex. In the interim, while these methodologies are being developed, each species can be approximately defined by the Pacific Marine Fisheries Commission reporting area, where REBS data from areas 5DE are assumed to be BSR (Type I) and REBS data from areas 3CD5AB are assumed to be RER (Type II). REBS data from area 5C are considered to be in a zone of hybridization (Creamer 2016) and consequently will be omitted from the stock assessment except to proportionately distribute the combined catch among the two species.
A quantitative stock assessment has never been undertaken for either BSR or RER. 'Blackspotted/Rougheye Rockfish Type I and II' are listed as Special Concern under Schedule 1 of the Species at Risk Act and assessed as Special Concern by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC 2007). An assessment of the species complex has also been identified as a condition of the Marine Stewardship Council certification of the Hake and Halibut fisheries.
Fisheries and Oceans Canada (DFO) Fisheries Management has requested that DFO Science Branch assess BSR and RER relative to reference points that are consistent with DFO's Fishery Decision-Making Framework Incorporating the Precautionary Approach (DFO 2009), and provide advice on the implications of various harvest strategies on projected stock status. The advice arising from this Canadian Science Advisory Secretariat (CSAS) Regional Peer Review (RPR) will be used to inform fisheries management decisions to establish catch levels for each population consistent with the DFO Precautionary Approach. This work may also inform decisions external to DFO, including Marine Stewardship Council certification of the Pacific Hake and Pacific Halibut fisheries.
Objectives
The following working paper will be reviewed and provide the basis for discussion and advice on the specific objectives outlined below:
Starr, P.J. and Haigh, R. 2020. Blackspotted / Rougheye Rockfish (Type I and Type II) stock assessment for British Columbia in 2020. CSAP Working Paper 2015GRF03
The specific objectives of this review are to:
- Recommend reference points consistent with the DFO Precautionary Approach (PA), including the biological considerations and rationale used to make such a determination. If possible, these should include the provisional DFO limit reference point (LRP) of 0.4BMSY and the upper stock reference (USR) of 0.8BMSY, or, alternatively, historical reference points (e.g., Bmin) if maximum sustainable yield (MSY)-based ones are not feasible. The choice of reference points is often determined by the complexity of the population model, which, in turn, depends on the quality and quantity of the input data.
- Evaluate the current status of the BSR and RER proxy populations relative to the recommended reference points, or provide rationale why reference points cannot be used.
- Using probabilistic decision tables, evaluate the consequences of a range of harvest policies on projected biomass (and exploitation rate) relative to the reference points and provide additional stock metrics. If the data are insufficient to quantitatively evaluate BC BSR and/or RER in terms of the selected reference points, summarise what is known about the status of these species, and discuss the implications for harvest advice.
- Describe sources of uncertainty related to the model (e.g. model parameter estimates, assumptions regarding catch, productivity, carrying capacity and population status), including uncertainty associated with the separation of the available data into component species.
- Evaluate and provide advice, as time allows, on procedures that may be under development for separating the REBS species complex into component species over time.
- Recommend an appropriate interval between formal stock assessments, indicators used to characterize stock status in the intervening years, and/or triggers of an earlier than scheduled assessment. Provide a rationale if indicators and triggers cannot be identified.
Expected Publications
- Science Advisory Report
- Proceedings
- Research Document
Expected Participation
- Fisheries and Oceans Canada (DFO) (Science and Fisheries Management)
- Commercial and Recreational Fishing Representatives
- Environmental Non-government Organizations
- First Nations
- Province of BC
- USA Government Agencies (NOAA, Alaska Fish & Game)
References
COSEWIC. 2007. COSEWIC assessment and status report on the Rougheye Rockfish type I and II Sebastes sp. in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. viii + 36 pp.
Creamer, J. M. 2016. Using genetic species identification and environmental data to distinguish historical catches of cryptic Blackspotted Rockfish (Sebastes melanostictus) and Rougheye Rockfish (Sebastes aleutianus) in British Columbia. Masters of Resource Management, Simon Fraser University, 40 p.
DFO 2009. A Fishery Decision-Making Framework Incorporating the Precautionary Approach.
McDermott, S. F. 1994. Reproductive biology of rougheye and shortraker rockfish, Sebastes aleutianus and Sebastes borealis (Doctoral dissertation, University of Washington).
Notice
Participation to CSAS peer review meetings is by invitation only.
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