SSC Report to NEFMC: Scallops, Groundfish & Skates
12. SSC (January 24-26, 2017)
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SSC Report to NEFMC: Witch Flounder Portsmouth, NH January 25, 2017 Jason McNamee, Chair SSC
Witch Flounder TORs • Taking into account the Council’s Risk Policy Statement, provide the OFL and an ABC for each year for fishing years 2017, 2018, and 2019 that will prevent overfishing and meet the management objective to rebuild the stock, and is consistent with the Council’s ABC control rule for groundfish stocks.
Witch Flounder TORs • The Council requests that the SSC provide a final report by noon on January 23, 2017 so that it can be considered at the January Council meeting that week.
Background • Recent benchmark assessment did not pass peer review, also rejected previously used VPA – large and unexplained retrospective patterns
• Empirical “area swept” approach (like GB yellowtail), was reviewed and recommended by SARC for setting catch advice • Empirical approach suggests biomass has declined from the 1960s to the mid-1990s, increased in the early 2000s, declining to approximately 2005
Background • Biomass relatively stable for the past ten years • Evidence of age truncation in the population based on survey and commercial catch-at-age • PDT noted calculation error in the mean exploitation rate presented at review workshop, corrected and estimated to be 0.060 (not 0.05)
Background • An economic analysis was presented, based on the Quota Change Model (QCM) – QCM showed a loss in total net revenue as ABC increased – ABCs evaluated: 393, 658, and 1600 MT
• QCM generated discussion by the SSC both during meeting and during generation of the report, however SSC did not take net revenues into account in formulating its advice
SSC Comments/Discussion • Accepted use of the empirical approach – Based on FI surveys conducted by NOAA, spring and fall
• Approach precludes formal estimation of reference points and status of the stock, OFL remains unknown • SSC recommendations are therefore to be considered ABC
SSC Comments/Discussion • Empirical approach indicated a period with relatively stable, yet low, biomass • Given signal of stable biomass, average exploitation rate of 0.060 used
– based on 9 yr average
• Bigelow was used for the survey in all years, used exclusively in 8 of the 9 years
SSC Comments/Discussion • Next discussed precision and strategies for dampening variability of trawl survey data • Three decimal precision was appropriate for use in exploitation rate – based on maintaining precision within each calculation and applying most imprecise estimate in final calculation
SSC Comments/Discussion • Appropriate to use a 3 yr running average for the terminal estimate of the trawl survey data
– need to dampen variability in the survey data, but not enough to lose signal
• 3 yr average represented reasonable trade-off between these two risks
– protects against instability in catch advice, doesn’t risk population declining or increasing for multiple years without detection – aligns with the concepts of the NEFMCs risk policy, though not quantitatively
Catch Advice • OFL: – 2017 – 2019 = unknown • Prev OFL recommended at 521 MT in 2016, 732 MT in 2017 • ABC: – 2017 – 2019 = 878 MT • Prev ABC recommended at 460 MT in 2016, 460 MT in 2017 • Static ABC for entire specification period – no projections available nor other information on which to base any change
• Catch specifications will be revisited and possibly adjusted following the 2017 groundfish operational assessments
Additional SSC Discussion • SSC offered research recommendations hoping to shift back to analytical assessment • Explore other data-limited methods
– witch flounder not data-limited but rather has conflicting data – emphasized the importance of the “Plan B” working group’s effort
• Examine influence of environmental factors and unknown sources of mortality both independently and in combination – SSC credits working group for examining these concepts, can provide additional specificity if/when warranted
• Continue to examine the trawl survey design and uncertainties
– particularly important for situations where catch advice is based on survey trends – Gear efficiency work was commended and should be investigated further
Questions?
#1
SSC Report to NEFMC: Witch Flounder Portsmouth, NH January 25, 2017 Jason McNamee, Chair SSC
Witch Flounder TORs • Taking into account the Council’s Risk Policy Statement, provide the OFL and an ABC for each year for fishing years 2017, 2018, and 2019 that will prevent overfishing and meet the management objective to rebuild the stock, and is consistent with the Council’s ABC control rule for groundfish stocks.
Witch Flounder TORs • The Council requests that the SSC provide a final report by noon on January 23, 2017 so that it can be considered at the January Council meeting that week.
Background • Recent benchmark assessment did not pass peer review, also rejected previously used VPA – large and unexplained retrospective patterns
• Empirical “area swept” approach (like GB yellowtail), was reviewed and recommended by SARC for setting catch advice • Empirical approach suggests biomass has declined from the 1960s to the mid-1990s, increased in the early 2000s, declining to approximately 2005
Background • Biomass relatively stable for the past ten years • Evidence of age truncation in the population based on survey and commercial catch-at-age • PDT noted calculation error in the mean exploitation rate presented at review workshop, corrected and estimated to be 0.060 (not 0.05)
Background • An economic analysis was presented, based on the Quota Change Model (QCM) – QCM showed a loss in total net revenue as ABC increased – ABCs evaluated: 393, 658, and 1600 MT
• QCM generated discussion by the SSC both during meeting and during generation of the report, however SSC did not take net revenues into account in formulating its advice
SSC Comments/Discussion • Accepted use of the empirical approach – Based on FI surveys conducted by NOAA, spring and fall
• Approach precludes formal estimation of reference points and status of the stock, OFL remains unknown • SSC recommendations are therefore to be considered ABC
SSC Comments/Discussion • Empirical approach indicated a period with relatively stable, yet low, biomass • Given signal of stable biomass, average exploitation rate of 0.060 used
– based on 9 yr average
• Bigelow was used for the survey in all years, used exclusively in 8 of the 9 years
SSC Comments/Discussion • Next discussed precision and strategies for dampening variability of trawl survey data • Three decimal precision was appropriate for use in exploitation rate – based on maintaining precision within each calculation and applying most imprecise estimate in final calculation
SSC Comments/Discussion • Appropriate to use a 3 yr running average for the terminal estimate of the trawl survey data
– need to dampen variability in the survey data, but not enough to lose signal
• 3 yr average represented reasonable trade-off between these two risks
– protects against instability in catch advice, doesn’t risk population declining or increasing for multiple years without detection – aligns with the concepts of the NEFMCs risk policy, though not quantitatively
Catch Advice • OFL: – 2017 – 2019 = unknown • Prev OFL recommended at 521 MT in 2016, 732 MT in 2017 • ABC: – 2017 – 2019 = 878 MT • Prev ABC recommended at 460 MT in 2016, 460 MT in 2017 • Static ABC for entire specification period – no projections available nor other information on which to base any change
• Catch specifications will be revisited and possibly adjusted following the 2017 groundfish operational assessments
Additional SSC Discussion • SSC offered research recommendations hoping to shift back to analytical assessment • Explore other data-limited methods
– witch flounder not data-limited but rather has conflicting data – emphasized the importance of the “Plan B” working group’s effort
• Examine influence of environmental factors and unknown sources of mortality both independently and in combination – SSC credits working group for examining these concepts, can provide additional specificity if/when warranted
• Continue to examine the trawl survey design and uncertainties
– particularly important for situations where catch advice is based on survey trends – Gear efficiency work was commended and should be investigated further
Questions?
