Download REPORT OF THE 2007 MEETING OF THE SUB-COMMITTEE

REPORT OF THE 2007
MEETING OF THE SUBCOMMITTEE ON
ECOSYSTEMS (Madrid, Spain February 19 to 23, 2007)
2. Considerations on prioritising
future work and data needed to
support that work
• Ecological Risk Assessment (ERA) framework may be a
good way to prioritize research activities
• The goals of CLIOTOP research concerted with the ToRs
of the SC
• Data needs: observer data in combination with other
sources of information, such as logbooks, are necessary
for the activities of the Sub-Committee which includes
assessing the impact of tuna fisheries on the ecosystem.
The Sub-Committee recognized that one of the present
limitations for using existing observer data is the lack of
access at the Secretariat, and it was recommended to
build an observer program metadatabase.
3. Development of a Workplan for a
seabird assessment
• 3.1 Data on seabird bycatch, seabird
distribution and seabird population status
and trend
3.1 Data on seabird bycatch,
seabird distribution and seabird
population status and trend
– Bycatch rates were provided for longliners
operating in Brazilian EEZ, Benguela current,
Chinese Taipei fishing in ICCAT area, and
Spanish longliners targeting swordfish in the
Mediterranean.
– Birdlife Global Procelariiform Tracking
database for albatross and petrels.
3.2 Assessment of the impact of
ICCAT fisheries on seabird
populations
1) Identify seabird species most at risk
2) Collate available data on at-sea distribution of these
species;
3) Analyze the spatial and temporal overlap between species
distribution and ICCAT longline fishing effort
4) Review existing by-catch rate estimates for ICCAT
longline fisheries
5) Estimate total annual seabird by-catch (number of birds)
in the ICCAT Convention area
6) Assess the likely impact of this bycatch on seabird
populations.
3.2 Assessment of the impact of
ICCAT fisheries on seabird
populations
1) Identify seabird species most at risk:
Risk prioritization exercise: high priority for 41
populations
3.2 Assessment of the impact of
ICCAT fisheries on seabird
populations
3) Analyze the spatial and temporal overlap
between species distribution and ICCAT
longline fishing effort
Preliminary LL effort estimates were computed.
4. Examination of the impact of
different hook types on by catches
There is a long debate regarding the positive or
negative effects of using circle vs. J hooks. Besides
hook type, there are other factors such as shape of the
hook, degree of offset and hook size that can affect the
results obtained. In many experiments comparing the
performance of each hook type, bait type was also a
key element. In addition, the experimental design, the
methodology selected to analyze the data, area-timedepth factors, fishing patterns, etc. could affect the
outcome of the experiments. Therefore, the SubCommittee considered that a simplification of the
debate regarding hook types is not appropriate.
Review of 23 studies in 12 fisheries
4. Examination of the impact
of different hook types on by
catches
According to available information, circle hooks generally tend to reduce the
catch rate and increase survivorship of incidentally caught species (e.g., sea
turtles, marlin), however, in some cases this result was conditional on the bait
type used (i.e. blue sharks). In the case of targeted species for which
information is available, catch rates seemed to be higher for some tuna species.
But, in the case of other targeted species such as swordfish and bigeye tuna the
circle hook effect was also dependent on the bait type (mackerel vs. squid).
Overall, the Sub-Committee felt that the results of the studies reviewed during
the meeting are encouraging and encourages the continuation of these types of
studies since it is not clear that use of circle hooks alone, is the best
technological solution to minimizing bycatch while maintaining productive
fisheries in all cases.
5. Other matters
6. Recommendations
-Observer and logbook programs to quantify total catch
(including bycatch) composition and disposition.
-Construct a metadatabase describing the different national
observer programs carried out in the past. Evaluate
consistency in information.
-Hiring a bycatch coordinator and include experts in seabird
and turtle biology in the different delegations.
-Develop educational materials identifying conservation
issues and easily implemented mitigation measures.