Transcript Slide 1

Stock assessment, fishery management
systems, and the FMSP Tools
-- Summary -FMSP Stock Assessment Tools
Training Workshop
Bangladesh
19th - 25th September 2005
A framework for fishery management (FTP 487)
The management context
The legal regime
• Domestic laws
• International agreements
Fishery Policy
Define management intentions
• Policy goals and operational objectives (biological,
ecological, economic, social, other sectors)
Section 2.5.1
Management approach to
uncertainty
• Precautionary or adaptive
management? Or both?
Management scope
• Single or multi-species?
• Ecosystem approach?
Property rights
• Use rights?
• Control rights?
Stakeholder roles in
management
• State or community control?
• Co-management?
Fishery scale
• Industrial or artisanal?
• Economically important?
Management capacity
• Technical skills, staff, funds?
Sections 1.1 and 2.1 – 2.4
Management process
Fishery Management Plan
Define management standards
For each operational objective:
• Conceptual reference points
(target, limit, precautionary)
• Indicators
• Technical reference points
Set management measures
• Decision control rules defined by
reference points and harvesting strategy
• Management strategy, comprising
one or more control measures
(inputs; outputs; technical, ecological etc)
Monitoring Control and Surveillance
Stock assessment process
Data/Inputs
Intermediate parameters
Indicators
Reference
points
Management advice
in terms of risk,
allowing for uncertainty
Chapters 3 and 4
and Parts 2 and 3
Sections 2.5.2 – 2.5.5
Figure 1.1
The new international legal regime
1992 Convention on Biological Diversity
Chapter 17 of UNCED’s Agenda 21
1995 UN ‘Fish Stocks Agreement’
1995 FAO Code of Conduct for Responsible Fisheries
2002 Johannesburg World Summit on Sustainable
Development (WSSD)
Section 1.1
Examples of goals and op. objectives (3/3)
Goals
Operational Objectives
Biological
To maintain the target species
at or above the levels
necessary to ensure their
continued productivity
To maintain the stock at all times above 50%
of its mean unexploited level
Ecological
To minimise the impacts of
fishing on the physical
environment and on non-target
(bycatch), associated and
dependent species
To maintain all non-target, associated and
dependent species above 50% of their mean
biomass levels in the absence of fishing
activities
Economic
To maximise the net incomes of
the participating fishers
To stabilise net income per fisher at a level
above the national minimum desired income
Social
To maximise employment
opportunities for those
dependent on the fishery for
their livelihoods
To include as many of the existing
participants in the fishery as is possible
given the biological, ecological and
economic objectives listed above
Section 2.3.1
Indicators and reference points
Set indicators and reference points for each operational objective
An indicator is a specific state, or variable, which can be monitored in a
system such as a fishery to give a measure of the state of the
system at any given time (Cochrane, 2002)
A reference point is an estimated value derived from an agreed
scientific procedure and/or an agreed model which corresponds to a
state of the resource and/or of the fishery and can be used as a
guide for fisheries management
Indicators and ‘RP’s should be used in combination to express the
operational objectives in ways that can be measured in quantitative
fisheries assessments.
Section 2.5.2
Catch
Catch
Fishing effort
Catch per
unit effort
(CPUE)
Stock size (biomass)
Long term (equilibrium)
relationships
between Catch, Effort and
Stock size Indicators
or
Stock size
(biomass)
(not directly related!)
Fishing effort
Risk of alternative reference points
Maximum Catch - FMSY
Fcrash riskier
Point at which species
becomes extinct
Size of
Catch
Amount of Fishing
Target or limit reference points?
(defining the objectives and control rules)
Target RP - aim here,
slightly above or
below both OK
Limit RP - avoid
danger zone
below here
Indicator X
Indicator X
E.g. Catch rate
E.g. spawning stock size
Decision control rules – a simple example
FMSY
Fishing
mortality
rate to be
allowed
next year
If Bnow < BMSY,
no fishing
allowed next
year (danger
zone)
If Bnow > BMSY,
fishing
allowed at
rate of FMSY
next year
BMSY
Stock size this year
Section 2.3.3
Precautionary reference points
Such points were adopted in response to the UN Fish
Stocks Agreement (see point 5 of Annex II), to help make
sure that the LRPs are avoided.
Define the point at which managers should take action, to
avoid the LRPs being reached.
The distance by which the precautionary point is removed
from the LRP is usually set according to:
• the uncertainty in the data
• and the risk tolerance of the manager.
Section 2.3.4
And ‘precautionary’ reference points...
Limit
RP
Precautionary
RP
Take action at the
Precautionary RP to
avoid the risk of
getting to the Limit RP
Indicator X
Setting reference points allowing for
uncertainty and risk
Low risk Bpa at ~90th
percentile of Blim distribution
Blim
Bpa
(BMSY)
(%ileBMSY)
Setting reference points allowing for
uncertainty and risk
Higher risk Bpa at ~75th
percentile of Blim distribution
Blim
Bpa
(BMSY) (%ileBMSY)
Management measures
1. Input controls (fishing effort restrictions)
2. Output controls (catch limits)
3. Technical measures (size limits, closed seasons, closed
areas etc)
4. Ecological and integrated management
Input and output controls often vary between years,
depending on harvesting strategy and state of stock
Technical measures usually fixed, or updated every few
years based on long-term assessments
Sections 2.3.5 and 5.4
Process for developing a management plan
Phase IV
Review
How will you know
you are there?
New
plan
Where do you want
to be?
Review
New
plan
Phase II
etc
Do
Plan
Do
Phase I
Where are you now?
Phase III
How are you going
to get there?
See new guidebooks from FMSP project R8468
Summary of the management plan
Purpose
Goals
Phase II
Phase III
Where do you want
to be?
How are you going to
get there?
Objectives
Management
Standards
Management Measures
Indicator
Management
Measures
Reference
Point
Decision
Control
Rules
Biological
Ecological
Social
Economic
How to quantify
the goals and
objectives
How to
achieve the
goals and
objectives
Part 2 - The stock assessment process
Collecting fishery data
( Estimating intermediate parameters )
Estimating the current status of the fishery (performance
indicators)
Estimating technical reference points
Providing management advice
Monitoring and feedback
Chapter 3
Stock assessment – collecting fishery data
1. Catch, effort and abundance (CPUE or survey-based or
fishing experiments)
2. Catch compositions (length and/or age frequencies to
estimate indicator F)
3. Other biological data (maturity, fecundity etc)
Section 3.2
Estimating intermediate parameters
Individual growth rates of fish
(e.g. by LFDA)
Population growth rate and carrying capacity
(e.g. CEDA)
Natural mortality rate
(e.g. by Pauly equation)
Exploitation pattern / gear selectivity
(from LF data)
Catchability
(e.g. by CEDA)
Maturity and reproduction
(from biological samples)
Stock and recruitment
(usually from VPA)
• Not of direct value, but used as inputs to fishery assessments
• Not constants, may vary over time (e.g. q, K etc)
• Values will usually be uncertain, so use sensitivity tests
Section 3.3
Biomass dynamic or analytical?
Biomass dynamic models like Schaefer surplus production
model used in CEDA and ParFish
• relate fishery outputs (catch) directly to inputs (effort)
• Useful where fish are hard to age – used to set quotas and effort
Analytical models used in ‘Yield’ and other ‘per recruit’ and
dynamic pool approaches
• include intermediary processes, both biological and fishery (e.g.
from LFDA)
• may be length-based or age-based
• Needed for management advice on size limits, seasons etc
Neither approach is more right or wrong than the other –
they are just based on different models and assumptions
Section 3.1.3
Data / inputs
Assessment
tools
Intermediate
parameters
Indicators
Length
frequency
data
LFDA
Yield
The
analytical
stock
assessment
approach
using LFDA
and Yield
L∞, K, t0 (growth)
Z(-M)
Fnow(Eq)
Reference
points
Management
advice
Biological data,
management controls
(size limits, closed
seasons etc)
Per recruit
With SRR
Fmax
F0.1
F%SPR
FMSY
Ftransient
Compare to make management advice on F
e.g. if Fnow > FMSY, reduce F by management controls
if Fnow < FMSY, OK
Figure 4.1
Data / inputs
Assessment
tools
Catch / effort
time series
CEDA
Intermediate
parameters
Indicators
Reference
points
Management
advice
Current catch /
effort data
r, K, q
Bnow
fnow
Cnow
The CEDA
stock
assessment
approach
(DRP /
biomass
dynamic
model)
BMSY fMSY MSY
Compare to make management
advice on effort or catches
Figure 4.5
Section 4.5
Data / inputs
Stock assess’t
interview data
or other priors
Catch /
effort time
series
Assessment
tools
ParFish
Intermediate
parameters
r, K, q
Indicators
Reference
points
Management
advice
Preference
interview
data
Current
catch / effort
data
ParFish
The ParFish
stock
assessment
approach
Bnow
fnow
flim
Clim
fopt
Cnow
Copt
Management advice on effort or catch controls, in terms of
limit and target levels. Targets (fopt,Copt) incorporate the
preferences of resource users. Limits are based on the
risk that B will be reduced below a specified % of K.
Figure 4.10
Section 4.6
What do the different FMSP stock
assessment tools estimate? (Table 5 of new guide)
Indicators
Reference
points
x
Beverton
and Holt
invariants
x
Empirical
methods
ParFish
r, K, q
(production model)
K, Linf, t0
(von Bertalanffy growth)
1
M
(natural mortality rate )
Z
(total mortality rate)
YPR / BPR (yield / biomass per recruit)
3
Yield / biomass (absolute, equilibrium )
Bt
(biomass in year t)
Nt
(numbers in year t)
Feq
(fishing mortality rate, Z-M)
CPUA
(catch per unit area)
MSY, fMSY, BMSY, FMSY
Fmax, F0.1, F0.x, F%SPR
(per recruit)
FMSY, F%SSB, Fcrash
(absolute 3)
Ftransient
(risk-based)
flim, Clim
(risk-based, biological limits)
fopt, Copt
(adjusted for ‘preferences’)
Fmax
(max yield per recruit)
3
FMSY
(max absolute yield )
CEDA
Intermediate
Yield
Available FMSP tools
LFDA
Parameters estimated
Type
Parameters
x
x
x
x
x
x
x2
2
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
1
Beverton
and Holt
invariants
Empirical
methods
ParFish
CEDA
Yield
Management measures
Biological
studies
Which tools can be used to provide advice for
different management measures
(Table 6 of new guide)
2
x
Fishing effort (‘input’) controls, e.g. limited vessel licensing
x
x
x
3
2
Catch (‘output’) controls, e.g. quotas or ‘TACs’
x
x
x
x
Closed seasons
x
x
x
Changing size at first capture (e.g. with minimum legal
x
x
x
mesh size or fish size regulations)
Closed areas
x
x
x
1
In combination with LFDA or some other method of estimating current fishing mortality rate.
2
Per unit area.
3
If biomass also known.
1
x
3
x
See also Section 2.5.5 in FTP 487
Data collection training
Why collect data?
Useful references on data collection
-----------------------------------------------------------------------------------Data commonly used in stock assessments (e.g. using FMSP tools)
Data needs of the different SA approaches and FMSP tools
-----------------------------------------------------------------------------------Data collection methods (C/E, LF, biological, ParFish)
System design
Sampling design
Data forms
Database systems
Data needs of the different approaches / tools
Analytical approach (LFDA / Yield) (See FTP 487, Tables 4.1 & 4.3)
• Catch composition data (either from length frequency data – LF, or
ageing studies)
• Biological data (e.g. size at maturity)
• Management advice can be produced from just one seasons’ sampling
(e.g. from a short time-series sample of LF and biological data)
•
But note some reference points also need long-term Stock-Recruit relationship
Biomass dynamic approach and depletion modelling (CEDA)
• Multi-year time series of catch and effort data, or catch data with a
secondary index of abundance (e.g. from a survey)
• Short-term time series of C & E for depletion modelling of N0 and q
ParFish approach
• Uses C/E and/or abundance data as with the other biomass dynamic
models
• Due to Bayesian formulation, can also add other sources of information
to improve the analysis, e.g. where few or no C/E data are available,
and to ‘tune’ the outputs to local users preferences
Data collection - Discussion questions
• What data do you have already that could be used for stock
assessment? In FRSS or in local management units?
• How are catch and effort estimated? How reliable are the data?
• What effort measures are used for different gear types? Would they
provide useful, unbiased indicators of abundance?
• Do you have any routine survey data that could provide abundance
estimates (time series)
• Do you collect length frequency or age frequency data? How often?
For what species, what sample sizes?
• Do you have biological data needed for analytical methods?
• How could national (e.g. FRSS) and local management data
collection systems be integrated, especially in inland fisheries? Are
any data collected in both?
• What other data should be collected, besides C/E, LF, biological?
A framework for fishery management (FTP 487)
The management context
The legal regime
• Domestic laws
• International agreements
Fishery Policy
Define management intentions
• Policy goals and operational objectives (biological,
ecological, economic, social, other sectors)
Section 2.5.1
Management approach to
uncertainty
• Precautionary or adaptive
management? Or both?
Management scope
• Single or multi-species?
• Ecosystem approach?
Property rights
• Use rights?
• Control rights?
Stakeholder roles in
management
• State or community control?
• Co-management?
Fishery scale
• Industrial or artisanal?
• Economically important?
Management capacity
• Technical skills, staff, funds?
Sections 1.1 and 2.1 – 2.4
Management process
Fishery Management Plan
Define management standards
For each operational objective:
• Conceptual reference points
(target, limit, precautionary)
• Indicators
• Technical reference points
Set management measures
• Decision control rules defined by
reference points and harvesting strategy
• Management strategy, comprising
one or more control measures
(inputs; outputs; technical, ecological etc)
Monitoring Control and Surveillance
Stock assessment process
Data/Inputs
Intermediate parameters
Indicators
Reference
points
Management advice
in terms of risk,
allowing for uncertainty
Chapters 3 and 4
and Parts 2 and 3
Sections 2.5.2 – 2.5.5
Figure 1.1