Download WP4&5_Workshop29630June2009_PLarge

DEEPFISHMAN
Stock assessment (WP 4) and
Biological Reference Points (WP 5)
Phil Large
Brief background
• Deep-water species in NE Atlantic are extremely diverse.
• In a data rich situation - biology & life history characteristics
(LHCs) pose severe problems for assessments
• In data poor situation, where until 2003 fisheries developed
without monitoring & management in place.
Overview of major assessment
problems
• Last 10 yrs - greater level of research and biological
sampling but still ‘data-poor’.
• Stock identity, migration & recruit processes.
• Paucity of biological data – where present often short time
series & ageing problems
• Observer data – sparse
• Discards
• Fisheries-independent surveys:•
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Scottish deepwater survey – 1998 to present
Irish deepwater survey - 2006 to present
Iceland autumn survey - 1996 to present
Faroes Autumn survey – 2000 to present.
Azores longline survey – 1995 to present
Spanish Porcupine Bank survey – 2001 to present
• Sequential depletion & expansion of effort to new grounds
and depths
• Need estimates of virgin/current biomass & sustainable
catches (MSY – stock reduction)
Progress to date
• Often only time-series data available are total international
landings and fleet CPUE.
• Provisional assessment units based on;
Theoretical separation of populations in relation to the
hydrological and geological structures
Distribution of species
Comparison of trends in catch rates
Consistency with management units.
• Exception tusk (genetics studies)
• Exploratory assessments - surplus production &
depletion models, Sep VPA and XSA, Catch Survey
Analysis (CSA), stock reduction, catch curves etc.
• Fringe methods – software often not very robust &
diagnostics are poor.
• Increasing stakeholder involvement (French CPUE &
blue ling (POORFISH))
• ICES advice based on abundance indices and LHCs.
What can DEEPFISHMAN do?
• Use case studies as tools to develop and trial methods
• Data – review existing monitoring & observer schemes
• Data and information – from Stakeholders
• Recommendations for surveys (ICES PGNEACS).
• Review & make recommendations for research
• Existing assessment methods – migrate these to FLR improve
diagnostics, user-friendly.
• Trial alternative assessment methodologies and develop
new approaches.
•
Bayesian models
•
Multi-species models (linked to conserving current
species composition or depleted species)
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Life history rule-of-thumb models
•
Length-based methods
•
Ecosystem assessment of impact of fisheries on
vulnerable/indicator species and VMEs.
ICES Benchmark Assessment
• Aim – To develop and standardise assessment methodologies
• Standardised methodologies should be used in subsequent
years for “update” assessments (exploratory assessments?)
• Stakeholder participation is encouraged
• Includes a 1 day “data compilation” workshop
• Provisionally, Feb 2010 at ICES
• ICES WGDEEP and DEEPFISHMAN resources will be
optimised
Biological reference points (BRPs)
• WGDEEP in 2005 reviewed BRPs used since 1998.
• Proposed for data-poor situations by ICES SGPA and NAFO in
1997 and are as follows:Ulim = 0.2 * Umax
Upa = 0.5 * Umax
Where U is the index of exploitable biomass.
• Aim is to maintain Ucurrent > Upa
• WGDEEP proposed BRPs should take into account
differences in LHCs between species
• ICES concerned that Umax may not represent virgin
biomass and BRPs not used
• DEEPFISHMAN - global review of candidate (biological,
ecological and socio-economic) reference points.
• Aim to move beyond single target-species approach & test
alternative fishery and ecosystem reference points.
• Key issue - multi-species nature of many deep-water
fisheries & need to capture this in management framework.
• Review the potential use of existing and multi-species
biological reference points e.g. status of indicator species,
biodiversity indicators
• Also consider simplistic metrics such as changes in mean
length, proportion of large fish in catches etc
Interaction with stakeholders
• Data – skipper logbooks
CPUE series from haul by haul
data from French Fishermen’s
personal logbooks (source,
PROMA IFREMER cooperative
work)
Data from Skippers
private logbooks
Ling
in
Division
IIa.
Estimates of Norwegian
longline cpue (kg/1000
hooks) based on skippers’
logbooks (pre-2000) and
from the entire fleet
(2000–2006).
• Qualitative views on abundance and distribution.
• Sentinel fishers
• What you would see as suitable reference points based
on actual catch-rates?
Thank you