Terms of Reference

Bocaccio (Sebastes paucispinis) stock assessment for British Columbia in 2019, including guidance for rebuilding plans

Regional Peer Review – Pacific Region

December 17-18, 2019
Nanaimo, BC

Chairperson: Greg Workman

Context

Bocaccio has been the subject of two detailed data reviews (Stanley et al. 2001; Stanley et al. 2004) and was formally assessed by Fisheries and Oceans Canada (DFO) in 2008 (Stanley et al. 2009). This assessment was updated in 2012 (Stanley et al. 2012). Bocaccio was assessed by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) as Threatened in 2002 and re-assessed as Endangered in 2013. In 2011, a decision was made to not list Bocaccio under Schedule 1 of the Species At Risk Act (SARA). While DFO will continue to manage this species under the Fisheries Act, actions to address conservation concerns were outlined in the order not to list (SI/2011-56 July 6, 2011). In 2016, the Commissioner of the Environment and Sustainable Development found that for 12 of the 15 major fish stocks in Canada requiring rebuilding plans, DFO had neither plans nor timelines for developing them. DFO accepted the Commissioner’s recommendation to set out priorities, targets, and timelines for putting in place rebuilding plans and will include any relevant measures respecting rebuilding fish stocks that will be established under a revised Fisheries Act.

Bocaccio (Sebastes paucispinis) is ubiquitous along the British Columbia (BC) coast and most catches are taken close to the bottom over depths of 60-200 m near the slope break of the continental shelf as well as gully edges in Queen Charlotte Sound and Hecate Strait (Stanley et al. 2009). These authors noted that because Bocaccio is semi-pelagic and schooling, the adults likely do not occupy specific sites other than preferring high-relief boulder fields and rocks (Love et al. 2002). The species appears to be a relatively short-lived compared to other Sebastes species such as Pacific Ocean Perch (S. alutus) or Rougheye Rockfish (S. aleutianus), a characteristic shared with other pelagic Sebastes species (e.g., Widow Rockfish, S. entomelas). This species generally only reaches maximum ages of 40-50 years; however, our records indicate one specimen reaching age 70. Genetic studies have shown no strong evidence for stock differences between the west coast of Vancouver Island and central California, but suggested that a Hecate Strait sample might have differed from those to the south (Matala et al. 2004).

The most recent stock assessment of Bocaccio placed this species in the DFO Critical Zone (Stanley et al. 2012) and Total Allowable Catches (TACs) were set at minimum acceptable harm levels in order for the multispecies trawl fishery to be able to continue operating (most other rockfish are well clear of the Critical Zone, with most in the Healthy Zone) while still allowing rebuilding. The history of trawl TACs since the 2012 stock assessment update are: 2013-14 = 150 t, 2015 = 110 t, and 2016-19 = 80 t (DFO IFMPs).

Data for Bocaccio appear to be sufficient (index series and age structures) to conduct a statistical catch-at-age analysis using a model variant of Coleraine called ‘Awatea’. This model has been used successfully to assess various stocks in BC – Pacific Ocean Perch, Yellowmouth Rockfish (S. reedi), Silvergray Rockfish (S. brevispinis), Yellowtail Rockfish (S. flavidus), Rock Sole (Lepidopsetta bilineatus), Redstripe Rockfish (S. proriger), and Widow Rockfish. The model used for both the 2008 and the 2012 Bocaccio assessments was a Bayesian surplus production model, which relied entirely on abundance indices and was only able to include information on population composition (age or length data) through the use of an informed prior on r (the productivity parameter in the model). The current authors hope to rectify this by using a catch-at-age model, or failing this, a delay-difference model (the latter has limited predictive capability compared to the former). Composition data should give estimates of recruitment events, which will improve the determination of the probability of success for rebuilding the stock. As well, the authors will review the assumptions made in the previous stock assessments for early historical levels of catch, expecting to bring them more in line with more recent rockfish stock assessments.

In the absence of updated science advice, there is uncertainty about the risks posed to the BC Bocaccio stock by current levels of catch. DFO Fisheries Management has requested that DFO Science Branch provide advice regarding the assessment of this stock relative to reference points that are consistent with the DFO’s Fishery Decision-Making Framework Incorporating the Precautionary Approach (DFO 2009), including the implications of various harvest strategies on expected 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 the species. This work will also inform and supplement decisions external to DFO, specifically COSEWIC.

Objective

The following working paper will be reviewed and provide the basis for discussion and advice on the specific objectives outlined below:

Paul J. Starr and Rowan Haigh. 2019. Bocaccio (Sebastes paucispinis) stock assessment for British Columbia in 2019, including guidance for rebuilding plans. CSAP Working Paper 2018GRF03

The specific objectives of this review are to:

1. Recommend reference points consistent with the DFO Precautionary Approach (PA), including the biological considerations and rationale used to make such a determination. These might include the provisional DFO limit reference point (LRP) of 0.4BMSY and the upper stock reference (USR) of 0.8BMSY, or historical reference points (e.g., Bmin). The choice of reference points is often determined by the complexity of the population model, which, in turn, depends on the quality of the input data.
2. Assess the current status of Bocaccio in BC waters relative to the reference points recommended above. If necessary, provide evidence to support the separation of this species into spatially distinct stocks, and if required, provide advice on the status of these stocks.
3. 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 Bocaccio in terms of PA reference points and decision tables, summarise what is known about the status of this species, and discuss the implications for harvest advice.
4. Provide guidance to be used by a management rebuilding plan under the PA framework for Bocaccio to satisfy recent legislation (Fisheries Act). Specifically, provide probabilistic decision tables that demonstrate a high probability of the stock growing out of the Critical Zone (i.e., above the LRP) within a reasonable timeframe (usually 1.5-2 generations).
5. Provide probabilistic decision tables to inform a COSEWIC assessment or a subsequent DFO Recovery Potential Assessment. This includes projections up to 1.5-2 generations to address COSEWIC’s assessment criteria (assessment indicators A1 and A2) using probability tables of future population status (with respect to the reference criteria) at various catch levels, as well as estimates of the time taken to attain them (with different levels of confidence).
6. Describe sources of uncertainty related to the model (e.g. model parameter estimates, assumptions regarding catch, productivity, carrying capacity, and population status).
7. Recommend an appropriate interval between formal stock assessments (i.e. this should occur every 4 years, as per the order not to list), 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

DFO. 2009. A Fishery Decision-Making Framework Incorporating the Precautionary Approach

Love, M.S., Yoklavich, M. and Thorsteinson, L. 2002. The Rockfishes of the Northeast Pacific. University of California Press, Berkeley and Los Angeles, California.

Matala, A.P., Gray, A.K. and Gharrett, A.J. 2004. Microsatellite variation indicates population structure of bocaccio. N. Amer. Jour. Fish. Manage. 24: 1189-1202.

Stanley, R.D., Starr, P. and Olsen, N. 2004. Bocaccio update. . DFO Can. Sci. Advis. Sec. Res. Doc. 2004/027: vii + 64 p.

Stanley, R.D., McAllister, M. and Starr, P. 2012. Updated stock assessment for Bocaccio (Sebastes paucispinis) in British Columbia waters for 2012. . DFO Can. Sci. Advis. Sec. Res. Doc. 2012/109: ix + 73 p.

Stanley, R.D., McAllister, M., Starr, P. and Olsen, N. 2009. Stock assessment for bocaccio (Sebastes paucispinis) in British Columbia waters. . DFO Can. Sci. Advis. Sec. Res. Doc . 2009/055: xiv + 200 p.

Stanley, R.D., K. Rutherford and N. Olsen. 2001. Preliminary status report on bocaccio (Sebastes paucispinis). Canadian Stock Assessment Secretariat Research Document 2001/148.