1. Presentation to the MSFD Descriptor 3+ Meeting
Way forward: data-limited stocks
Presentation to the MSFD Descriptor 3+ Meeting
24th – 25th April 2012
Paris, France
Dr Carl O’Brien
ACOM Vice-chair & Co-chair WKLIFE

2. Outline of presentation
Quality of information
Stock status
Data-limited / model-poor
Stocks without population size estimates
ICES’ WKLIFE approach
ICES’ expert stock assessment working groups
On-going within ICES during the current round of stock assessments and advice drafting for 2013 TACs and quotas

3. 1. Quality of information – stock status
Robust quantitative assessment
Preliminary quantitative assessment
Estimates of fishing mortality / exploitation (F) from catch curves (age / length data)
Trends in catch-per-unit-effort (CPUE)
Uncertainty
increases

4. Reduced quality and utility of advice for management
ICES’ annual presentation to EC: September 2011
Data-limited / model-poor %
Analytical 38
Trends based 10
Trends, survey only 39
Catch only 13
Reduced quality and utility of advice for management

5. The data available are inadequate to:
Challenge – stocks without population size estimates
The data available are inadequate to:
estimate the current population size; and
the catch resulting from fishing at a desired F.
Past ICES’ practice has been to base advice on recent average catches when there is neither quantitative nor qualitative evidence of declining abundance.
MSY ? – the maximum average long-term catch that may be taken from a fish stock under prevailing environmental conditions

6. Issues that ICES has not satisfactorily dealt with:
... stocks without population size estimates continued
ICES’ MSY approach calls for a determination of the status of exploitation relative to FMSY and considerations of the stock trend.
Issues that ICES has not satisfactorily dealt with:
Data-limited / model-poor stocks
What is FMSY?
What is the current stock exploitation?
How should we manage future exploitation?
Without a radical change in approach … implies that approximately 60% of the 188 (158) stocks will have no useful scientific advice w.r.t. MSY

7. Question: What are the prospects for the future?
Common
name
Latin Name L
max
(cm)
Demersal
/ Pelagic
Fmax
F0.1
Fspr30
Fspr35
Fspr40
Dab
Limanda
limanda 37 D
0.79
0.43
0.47
0.4
0.34
Flounder
Platichthys
flesus 46
0.66
0.36
0.29
Lemon sole
Microstomus
kitt
Pollack
Pollachius
pollachius 87
0.38
0.23
0.25
0.22
0.18
Brill
Scophthalus
rhombus 63
0.5
0.31
0.27
Turbot
Psette
maxima 68
0.3
0.26
Witch
Glyptocephalus
cynoglossus 50
0.61
0.37
0.32
Question: What are the prospects for the future?
On-going ICES’ studies
What is FMSY?
life history characteristics include, among other things, longevity, fecundity and recruitment variability
What is the current stock exploitation?
Harvest ratio proxies and survey (DCF / FSP) catch curves
How should we manage future exploitation?
simple trend-based rules (survey / catch)

8. ICES’ WKLIFE

9. Predicting fisheries reference points with minimal data:
ICES’ WKLIFE – starting point
Predicting fisheries reference points with minimal data:
1) For many species we know a lot about fish biology and life-history relationships in general. 2) Yield-per-recruit and spawner-per-recruit models can be developed with simple life-history information and reference points can be defined in relation to population dynamics. 3) This provides an opportunity to develop data-limited stock reference points with respect to MSY.
(although originally developed for species of conservation concern)

10. Gislason et al 2008. ICES J Mar
Life-history based population models To construct a YPR model: Size at age (VBGF)* - different for teleosts/elasmobranchs M at age Maturity at age* Recruitment to fishery The life-history traits are correlated, and correlated to Lmax - an easily measured parameter.
Gislason et al ICES J Mar
Sci 65:

11. Model reference points Predicted YPR and SPR reference points
Model reference points Predicted YPR and SPR reference points Reference values decline with increasing Lmax Knife-edge recruitment to fishery at age 1
Teleosts
Elasmobranchs

12. Model reference points Knife-edge recruitment to fishery at age 1
Model reference points Knife-edge recruitment to fishery at age 1 Reference points can be calculated for specific species

13. Report ICES CM 2012/ACOM:36
WKLIFE attempted to categorise the amount and quality of information available for each stock which is now guiding ICES in the process of identification of appropriate assessment methods/approaches.
Categorisation of stocks into one of seven basis types:
Data rich stocks (quantitative assessments)
Negligible landings stocks
Stocks with analytical assessments that are treated qualitatively
Stocks for which survey indices (or unbiased CPUE) indicate trends
Stocks for which reliable catch data are available for short time-series
Truly data-poor stocks (landings only)
Stocks caught in minor amounts as by-catch
Category 7 – stocks that are part of stock complexes and are primarily caught as by-catch species in other targeted fisheries. The development of indicators may be most appropriate for such stocks; e.g. NS brill in the targeted NS plaice and sole fishery.

14. Follow-up to ICES’ WKLIFE
Current work by ICES’ stock assessment working groups:
Examining the category description for available stock information that WKLIFE has provided (Section 2.5); together with the consequent categories to which the stocks have been assigned (Sections and Tables ), and providing feedback on any misclassification or stock that the WG consider has been omitted.
Initial proxies for sustainable fishing mortalities were proposed by WKLIFE (Sections 3.1, 4.1 and 5.1) based on life-history parameters. In order to make these parameters operational for advice, the WGs are the appropriate experts to agree these parameters. It is necessary to agree stock specific Lmax values and once agreed, the corresponding proxies for sustainable fishing mortalities can be obtained by reference to the appropriate WKLIFE spreadsheets.

15. Category 3 stocks
If a stock falls within category 3 (Section 2.5.3), an assessment model is fitted but only the trends are accepted for the provision of advice, the WG is asked to provide within its report, along with the trends information, estimates of potential reference points.
It is considered that within this category 3 the assessment estimates, forecasts based on them and their status relative to reference levels are consistent with each other (although not necessarily on the correct scale) and can therefore be used to provide relative management advice on the direction and relative scale of the changes required to achieve targets.

16. Categories 4 and 5 stocks
If a stock is considered to fall within category 4 (Section 2.5.4), survey information only, the WG is asked to highlight within its report the time series that should be used to determine the status of the stock and provide catch advice.
Currently, assessment methods/approaches for category 5 are under investigation and apart from considering and commenting on the appropriateness of the placement of stocks within this category there is little more that can be inferred until further stock specific work is completed.

17. Returning to an earlier slide
Question: What are the prospects for the future?
On-going ICES’ studies
What is FMSY?
life history characteristics include, among other things, longevity, fecundity and recruitment variability
What is the current stock exploitation?
Harvest ratio proxies and survey (DCF / FSP) catch curves
How should we manage future exploitation?
simple trend-based rules (survey / catch)
Early indications that for the majority of the 122 stocks ICES will be able to provide useful scientific advice w.r.t. MSY