The use and calculation of BRPs for West Coast ground fishes

4.1 National Standard 1 Guidelines

National Standard 1 requires conservation and management measures to prevent overfishing, a critical concern for sustainable fisheries. These measures aim to achieve, on a continuous basis, the Optimum Yield (OY) for each fishery, supporting a viable U.S. fishing industry. The regulation reference is 50 CFR 600.310(a).
Determining OY:
  - The Optimum Yield serves as a critical mechanism to fulfill the objectives of the Magnuson-Stevens Fishery Conservation and Management Act. It implements the objectives of the Fishery Management Plan (FMP) and balances various interests regarding national welfare.   - OY is typically based on a careful assessment of:
    - Maximum Sustainable Yield (MSY), which signifies the largest long-term yield that can be taken from a specific fish stock under prevailing ecological conditions.
    - Adjusted MSY, which considers socio-economic and ecological factors important for sustainable management.   - Key limitation:
    - The management measures associated with the determination of OY must robustly prevent overfishing as delineated in 50 CFR Section 600.310(b).
Considerations suggested for National Standard 1 per National Marine Fisheries Service (NMFS) guidelines include:
  - Accurate estimation of MSY, the biomass necessary to sustain MSY, and the necessary controls around MSY (50 CFR 600.310(c); Section 4.3).
  - Specification of criteria to determine stock status (Minimum Fishing Mortality Threshold (MFMT) and Minimum Stock Size Threshold (MSST)) (50 CFR 600.310(d); Section 4.5).
  - Identification of actions required to end overfishing and rebuild overfished stocks in a timely manner (50 CFR 600.310(e); Section 4.6).
  - Calculation and establishment of OY as well as the apportionment of harvest levels within the fishery (50 CFR 600.310(f); Section 4.7).
For west coast groundfish, the FMP calculates:
  - Overfishing limits (OFLs), which indicate the threshold for sustainable harvesting without causing depletion of fish populations.
  - Acceptable Biological Catches (ABCs) that provide a buffer below OFLs to reduce overfishing risk while accounting for scientific uncertainty involved in population estimates.
  - Annual Catch Limits (ACLs) that regulate the amount of fish that can be harvested annually while still safeguarding fish stock health.
  - OFL is fundamentally linked to the MSY harvest level based on current stock abundance.
Long-term goal:
- If OFLs are fully harvested, it is expected that the average OFL should equal the MSY output, ensuring sustainability over time. - The average long-term OY is derived from the past ACLs of a specific stock or set of stock complexes, looking to maintain a balance between ecological responsibility and industry interests.

4.2 Species Categories

BMSY, OFL, and overfished/rebuilding thresholds can only be determined for some species due to insufficient data.
Categories of species in relation to setting MSY and associated standards:
  1. Category 1 Species:
     - Data-rich, where quantitative assessments derive information based on methodologies such as catch-at-age and catch-at-length analyses.
     - Precise OFLs and rebuilding thresholds are calculable.
     - ABCs are developed based on estimations of biomass uncertainty.
  2. Category 2 Species:
     - Data-moderate, involving some biological indicators and assessments that aren't rigorously comprehensive.
  3. Category 3 Species:
     - Minor species with insufficient data, relying on catch-based methods to estimate OFL.
Ecosystem Component (EC) Species:
- These species are not actively managed or targeted in fisheries.
- They do not face overfishing or an overfished status, but monitoring may occur to assess bycatch levels and mortality reduction strategies.

4.3 Determination of MSY, MSY Proxy, and BMSY

MSY Definition:
- The maximum average catch achievable over time under the existing ecological and biological conditions.
BMSY Definition:
- The long-term average biomass maintained when fishing at the FMSY level, which represents the fishing mortality rate consistent with achieving MSY.
MSY assumes a constant F control rule aimed at maximizing average yield while ensuring sufficient spawning potential.
Understanding of density-dependence in the recruitment process is crucial; estimates are often variable due to outside environmental conditions impacting fish populations.
Default FMSY Proxies (2015):
  - F30% for flatfish species.
  - F40% for whiting.
  - F50% for rockfish (including thornyheads).
  - F50% for elasmobranchs (sharks and rays).
  - F45% for roundfish species (e.g., sablefish, lingcod).
A decline in recruitment linked to FMSY will often result in a decrease in biomass and diminished sustainable catch yields.
Historical Context:
- Previous underestimations of recruitment variables have necessitated adjustments in perceived FMSY levels, highlighting the need for dynamic harvest rate regulations that reflect current scientific findings.

4.4 Determination of OFL and ABC

OYs and ACLs are calculated on the foundational data concerning OFLs and ABCs:
  - OFL is directly linked to current stock abundance and derived using empirical methods.
  - ABC serves as a precautionary threshold below the OFL to significantly mitigate the risks associated with overfishing.
  - The Council determines ABC based on varying levels of risk aversion in correlation with potential overfishing scenarios.

4.5 Precautionary Thresholds and Overfishing Status Determination Criteria

Critical Thresholds:
- Identify two essential thresholds: Maximum Fishing Mortality Threshold (MFMT) and Minimum Stock Size Threshold (MSST).
- MFMT is utilized to evaluate overfishing and to ensure that stock levels are sufficient for sustainable MSY production.
Precautionary Threshold Determination:
- Values are established at biomass levels that effectively prevent overfishing while permitting sustainable resource management.
- The default threshold is 40% of unfished biomass for non-flatfish and a stricter 25% for flatfish species.
Overfishing Threshold Determination:
- Defined when the catch surpasses the established OFL, utilizing MFMT as a pivotal threshold to assess fishing practices.
Overfished/Rebuilding Thresholds Determination:
- Stocks identified as below the MSST are classified as overfished, with common benchmarks established at 25% of unfished biomass for non-flatfish species and 12.5% for flat species types.

4.6 Ending Overfishing and Rebuilding

4.6.1 Default Precautionary and Interim Rebuilding ACL Calculation

Implement precautionary management approaches when stock biomass necessitates rebuilding measures.
Utilize a catch-based approach modeled after International Council for the Exploration of the Sea (ICES) management techniques to regulate catch levels correlating with stock biomass.
Default proxy values include:
  - F30% for flatfish
  - F40% for whiting
  - F50% for both rockfish and elasmobranchs
  - F45% for other groundfish species, such as sablefish and lingcod.
Adjustments to these proxy values will respond to advancing scientific insights and require appropriate documentation, albeit they do not mandate formal amendment approvals.