Third Tuna Data Workshop TDW3

1
Third Tuna Data Workshop (TDW-3) 22-25 June 2009,
Auckland, New Zealand
SESSION 5 Methods for determining Annual Catch
Estimates
Oceanic Fisheries Programme (OFP) Secretariat
of the Pacific Community (SPC)
2
Introduction

• What are Annual Catch Estimates ?
• are simply the total catches by species for a
  fishing fleet covering a calendar year.
• Catch is expressed in units of metric ton
• Total number of active vessels in the fleet is
  also required

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Introduction

• Members of the WCPFC must provide annual catch
  estimates for their National fleet covering
  activities in the WCPFC Convention Area on an
  annual basis
• Annual catch estimates for 2007 for national
  fleets must be provided before the
• 30th April 2008

4
2006 Provision of Annual Catch Estimates to the
WCPFC
http//www.spc.int/oceanfish/html/wcpfc/statistics
/StatProv.asp
Required by 30th April 2007
5
2007 Provision of Annual Catch Estimates to the
WCPFC
Required by 30th April 2008
6
Annual Catch Estimates

• The main points of the WCPFC data provision are
• Prepared for the NATIONAL FLEET
• The area is the WCPFC CONVENTION AREA
• The deadline is 30th APRIL each year.

7
Introduction

• Why are annual catch estimates important ?
• Provides a summary of actual catch at the highest
  level
• Provides a summary of data collected in the tuna
  fishery at the highest level
• Provides an indication of the evolution of WCPFC
  fisheries
• Provides easy comparisons between years, fleets,
  gears, fisheries, etc.
• Determine the value of the catch for economic
  purposes
• Used in determining future management measures
• Used to calculate fees for access to the fishery
• Provide an indication of coverage of other data
  collected

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Presentation 1 COVERAGE Outline

• The importance of Coverage
• What is Coverage ?
• Why is Coverage important ?
• What components are needed to determine the
  actual fishing activity (used for Coverage) ?
• How do you obtain the value representing actual
  fishing activity (used for Coverage) ?
• Comparison of data types used to determine actual
  fishing activity (for Coverage)

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Coverage

• In general terms, coverage is defined as -
• The extent or degree to which something is
  observed, analyzed, and reported
• With certain tuna fishery data collection, we
  strive to achieve 100 coverage which provides
  the most accurate reflection of the fishery

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Coverage

• Why is Coverage important ?
• Coverage provides an indication of the
  reliability of the different types of data
  collected and the degree that it represents
  actual fishing activity
• Lower coverage usually means more bias
• Coverage is a key component in estimating
  annual catches, and the level of coverage will
  determine the accuracy of the annual catch
  estimate

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Coverage

• What components are needed to determine the
  actual fishing activity ?
• STEP 1. Select the national fleet
• STEP 2. Compile a list of the active or
  licensed vessels fishing in the fleet for the
  calendar year.
• STEP 3. Check that all licensed vessels
  conducted at least one trip during the year
  i.e. they were active !
• you may also obtain more detail on individual
  vessel activity with this step
• STEP 4. Use a reliable source of
  information/data that accurately represents the
  fishing activity of a vessel in a calendar year
  this has been referred to as base data in the
  past - this is the most difficult step !

12
Coverage

• Five potential base data to determine actual
  fishing activity
• Annual Fishing Trip and Port Visit Log
• Port Authority Departure and Entry information
• Boat Census information
• Logsheet data
• Unloadings data

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Coverage
Annual Fishing Trip and Port Visit Log
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Coverage

• Annual Fishing Trip and Port Visit Log
• Characteristics
• Specifically designed to determine coverage
• Covers all periods of activity and inactivity
  (unique)
• Value obtained to determine coverage is vessel
  trips
• How it is used
• Firstly, check data quality
• all active vessels have completed the form
• there are no gaps in the periods of activity or
  inactivity
• Then, the sum of all trips from all vessels
  represents actual fishing activity and is used
  to determine coverage of other types of data.

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Coverage

• Port Authority information
• Characteristics
• If collected consistently, indicates fishing trip
  periods
• Provides good indication of activity and
  inactivity
• Value obtained to determine coverage is vessel
  trips
• How it is used
• Firstly, check data quality
• All licensed vessels are covered
• For each vessel, there are consistent patterns of
  entry and departure
• There are no unusually long gaps away from the
  port
• The sum of all trips derived from this type of
  data represents actual fishing activity and is
  used to determine coverage of other types of
  data.

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Coverage

• Boat Census data
• Characteristics
• Specifically designed to determine coverage
• May be undertaken every day, or at a certain
  frequency of days
• Value obtained to determine coverage is
  sea-days
• How it is used
• Firstly, check data quality
• All licensed vessels are covered
• If monitoring is not possible every day, then
  ensure it is appropriate enough to obtain a good
  estimate of sea-days
• Covers all ports ?
• Sum of vessel sea-days not in port, which may
  be raised by the monitoring coverage, becomes the
  value for which to determine coverage of other
  types of data.

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Coverage

• Logsheets
• Characteristics
• Used to determine annual catch estimates, but not
  usually coverage
• Can provide patterns of monthly fishing activity
• Logsheet trips reconciled with unloadings can
  provide indicate of activity
• Value obtained to determine coverage can be
  trips, catch, sea-days, fishing days
• How it is used
• Firstly, check data quality
• All licensed vessels have provided at least one
  logsheet
• Check monthly vessel activity from logsheets
  (with industry liaision)
• Ensure there are few gaps ! (more gaps more
  bias in estimates !)
• The value (trips, catch, etc.) obtained can then
  used to determine coverage of other types of
  data.

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Coverage - Logsheets
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Coverage - Logsheets
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Coverage

• Unloadings
• Characteristics
• Used to determine annual catch estimates, but not
  usually coverage
• Logsheet trips reconciled with unloadings can
  provide indicate of activity
• Value obtained to determine coverage can be
  trips or catch
• How it is used
• Firstly, check data quality
• Review the logsheet and unloadings reconciliation
  report for gaps
• Ensure that there are few gaps ! (more gaps
  more bias in estimates !)
• Beware the logsheet / unloadings reconciliation
  may not represent actual fishing activity !
• The value (trips, catch, etc.) obtained can then
  used to determine coverage of other types of
  data.

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Coverage Logsheets Unloadings
22 logsheet trips and 20 unloadings ? 22 actual
fishing trips ??
22
Coverage

• Field staff monitoring
• Characteristics
• Requires field staff based at port to monitor
  when vessels leave and return
• Specifically focuses on determining coverage
• Value obtained to determine coverage is vessel
  trips
• How it is used
• Firstly, check data quality
• Can field staff adequately monitor all port
  activity in the year ?
• Are all active vessels are covered ?
• The sum of all trips from all vessels represents
  actual fishing activity and is used to
  determine coverage of other types of data.

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Coverage

• Fishing Company records
• Characteristics
• Assumes fishing company keeps accurate records
  which are available
• No work involved !
• Value obtained to determine coverage can be
  vessel trips or catch, etc.
• How it is used
• Firstly, check data quality
• Can you verify fishing company data with your
  data
• The sum of all trips or catch represents actual
  fishing activity and can be used to determine
  coverage of other types of data.

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Coverage

• VMS data
• Characteristics
• Highly accurate independent source of
  information
• Value obtained to determine coverage is vessel
  trips or sea-days
• How it is used
• Firstly, check data quality
• Are there gaps in the data (compare to other
  types of data) ?
• Are all vessels covered ?
• (if problems, then this type of data cant be
  used)
• The sum of all trips or sea-days represents
  actual fishing activity and can be used to
  determine coverage of other types of data.

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Table 1. Types of data used to determine actual
fishing activity
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Presentation 2 Outline

• Methods to determine Annual catch estimates
• Number of active vessels and an average vessel
  catch
• Fishing Companies data
• Logsheet data
• Unloadings data
• Combination of Logsheet and Unloadings data
• Improvements to estimates using other types of
  data
• Which method should be used ?
• What needs to be prepared for the WCPFC ?

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Methods Annual Catch Estimates Number of active
vessels and an average vessel catch

• Background
• Crude way of estimating annual catch
• Used when no other information is available
• Provides a way of cross-checking estimates
  determined from other methods, or to produce
  provisional estimates when data are not yet
  available
• Information required
• Number of vessels active in the fleet for a
  calendar year
• Indication of the average vessel catch, for
  example,
• Average vessel catch (mt) per year, or
• Average vessel catch (mt) per month, or
• Average vessel catch (mt) per trip, or
• Average vessel catch (mt) per fishing (and
  searching) day

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Methods Annual Catch Estimates Number of active
vessels and an average vessel catch

• Method - simple calculations (for example)
• Number of active vessels X Average vessel
  catch per year
• Number of active vessels X Average vessel
  catch per month X 12
• Advantages
• It is simplistic
• Requires minimal effort to obtain the information
• Can be used for fisheries where it is difficult
  to collect data
• Problems
• Requires consistency in catch over time and
  amongst vessels
• It doesnt provide a good indication of species
  composition
• This method is perhaps the only viable means of
  obtaining an indication of annual catch estimates
  for large artisanal fisheries, distributed over
  wide, remote areas, with many (small) fishing
  craft (e.g. Philippines and Indonesia),

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Methods Annual Catch Estimates Fishing company
data

• Method
• Simply ask the fishing companies to provide the
  annual catch estimates
• Advantages
• Easy ! especially with a good relationship
  with the fishing companies
• Problems
• Fishing company may not have complete information
• Are their catches reliable (is there motivation
  for under-reporting ?)
• The species composition of the catch may not be
  as complete as required
• Other information (e.g. effort in fishing days or
  hooks) may not be available
• Are they accounting for discards ?
• Suggest this is done to check estimates
  determined by other methods

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Methods Annual Catch Estimates Logsheet data

• Method
• Collect and process logsheet data using a
  database system
• Database system to facilitate data quality
  control
• Have a system to ensure highest coverage possible
  (target 100)
• Use database system reports to summarise logsheet
  catch data
• Determine and apply coverage to summarised
  logsheet data to produce annual catch estimates

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Methods Annual Catch Estimates
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Methods Annual Catch Estimates Logsheet data

• Advantages
• Provision of Logsheets are usually enforced, so
  data are readily available
• Provides high-level of detail to the set level
  (includes effort)
• Specifically designed to be a source of annual
  catch estimates
• Problems
• Catches are usually a visual estimate
• Bigeye purse-seine catches are rarely reported
  accurately on logsheets
• Discards rarely reported accurately on logsheets
• May be difficult to determine coverage

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Methods Annual Catch Estimates Unloadings data

• Method
• Collect and process unloadings data using a
  database system
• Database system to facilitate data quality
  control
• Have a system to ensure highest coverage possible
  (target 100)
• Use database system reports to summarise
  unloadings data
• Determine and apply coverage to summarised
  unloadings data to produce annual catch estimates

34
Methods Annual Catch Estimates Unloadings data

• Advantages
• For the longline fishery, catches are usually
  weighed on landing these data provide accurate
  catch in weight data !
• More concise that logsheet data, so easier to
  manage
• Specifically designed to be a source of annual
  catch estimates
• Problems
• Doesnt account for discards
• May be difficult to determine coverage
• Does not provide effort data

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Methods Annual Catch Estimates Combination of
Logsheet and Unloadings data

• Method
• Collect and process logsheet and unloadings data
  using a database system
• Use unloadings data to correct logsheet data
• Correct using unloaded average weights by
  species
• Correct for processed weight
• Correct for under-reporting on logsheets
• Facilitated by a database system
• Link and reconcile each logsheet with the
  unloading (via database system)
• The best combination of logsheets and unloadings
  provides an improved annual catch estimate
  (database system report)
• Determine and apply coverage to best
  combination of logsheets and unloadings data to
  produce annual catch estimates

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Methods Annual Catch Estimates
Combination of Logsheet and Unloadings data
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Methods Annual Catch Estimates
Combination of Logsheet and Unloadings data
However, it is important to note that these
estimates may still not correspond to catches
from the actual fishing activity and more
work on determining actual fishing activity is
required !
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Methods Annual Catch Estimates Using other
types of data to improve estimates

• Method
• Using unloadings data to improve catch in weight
  for longline fleets
• Using port sampling and observer data to improve
  species composition of the catch (e.g. purse
  seine bigeye catches)
• Using observer data to estimate discard rates
• Using observer data to estimate the catch of
  bycatch species.

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Which method should be used ? This will depend
on what data you have available !

• However, you should work towards the following
• A system that allows you to easily determine the
  level of actual fishing activity (see Section 2
  of the paper)
• A system that ensures logsheet data representing
  every trip (100 coverage) are provided and
  available
• A system that ensures unloadings data
  representing every trip (100 coverage) are
  provided and available
• In the absence of the previous two data types a
  port sampling system that will provide
  representative data to determine annual catch
  estimates

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What needs to be prepared for the WCPFC ? Annex 1
of the paper provides the details Submission for
your National Fleet must be received before April
30th All information should be relative to the
WCPFC Convention Area

• Total number of active vessels
• Total catch by species and all species combined
• (the primary species are Albacore, Yellowfin,
  Bigeye, Skipjack, Blue marlin, Black marlin,
  Striped marlin and Swordfish)
• The type of data used to determine the annual
  catch estimates
• The coverage of the data used
• The methods used to estimate annual catch
  estimates.

(Other optional information may be provided, for
example, effort, CPUE) Data to be sent to the
WCPFC Executive Director and Data Managers (SPC)
41
2006 Provision of Annual Catch Estimates to the
WCPFC
http//www.spc.int/oceanfish/html/wcpfc/statistics
/StatProv.asp
Required by 30th April 2007
42
Annual Catch Estimates

• The main points of the WCPFC data provision are
• Prepared for the NATIONAL FLEET
• The area is the WCPFC CONVENTION AREA
• The deadline is 30th APRIL each year.

43
Annual Catch Estimates
EXERCISES 1. GROUP Exercise In small
working groups, you will undertake three separate
exercises to determine annual catch estimates a
handout will be provided. Ample time will be
provided to complete these exercises. Results to
be presented by each group !
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Annual Catch Estimates

• EXERCISES
• Individual Exercise
• You will be required to estimate the 2007 catches
  for your National Fleet, and document the methods
  used and the coverage of the data used.
• If you do not have a National fleet, then you
  will be asked to estimate the 2007 (or 2006)
  annual catches of foreign fleets operating in
  your waters.
• Assistance will be provided !