E - Iccat

ICCAT REPORT 2012-2013 (I)
The majority of spawning activity has been reported only in the Gulf of Mexico and the Mediterranean Sea.
However, larvae collected east of the Yucatan Peninsula, and off the east coast of the U.S. originated from
outside the Gulf of Mexico, possibly from the Caribbean Sea. Also, bluefin tuna tagged in New England and
Canada did not enter the Gulf of Mexico, suggesting spawning elsewhere, near the Gulf Stream margin, possibly
the Bahamas, and Caribbean Sea. Confirmation of the reproductive activity of bluefin tuna in the Atlantic is
important for obtaining an accurate assessment of spawning stock biomass for western Atlantic bluefin tuna.
Therefore, the Committee recommends that the CPCs support the continuation of these studies in order to
properly identify and characterize spawning grounds of western Atlantic bluefin tuna, and improve the
standardized abundance indices for the next western Atlantic bluefin tuna stock assessment or intersessional
meeting.
− To evaluate the bluefin tuna national observer programmes conducted by CPCs and to provide advice on
future improvements [Rec. 10-04, paragraph 90] (see Item 18.2 of the 2012 SCRS Report).
No new specific information has been provided. However, the data collection form for national observer
programmes included some information regarding bluefin tuna observer programmes and a few flag States
provided comments. The Committee recommended that the CPCs respond to [Rec. 10-04] and provide
information on their national observer programmes.
− To explore operationally viable technologies and methodologies for determining the size and biomass at the
points of capture and caging [Rec. 10-04, paragraph 87] (see Item 18.10 of the 2012 SCRS Report).
This Recommendation requests the CPCs to initiate pilot studies on how to better estimate both the number and
weight of bluefin tuna at the point of capture and caging, including through the use of stereoscopic systems and
report the results to the SCRS. The following SCRS documents regarding the use of stereoscopic camera
systems were presented to the 2012 SCRS meeting:
240
◦ SCRS/2012/052: Stereoscopic camera to measure the length of fish in the cage and during the transfer to
another cage through a gate. The authors affirmed the validity of utilization of the stereoscopic camera for
counting and measuring bluefin tuna and made several suggestions for improving the procedure and
equipment.
◦ SCRS/2012/136: Stereoscopic camera was applied at the point of first transfer into the farm cage. The
authors suggested that further work is required to improve the accuracy of measurement and better define
the mathematical models needed.
◦ SCRS/2012/133: A video-camera and acoustical system were used in tandem during the transfer of
bluefin tuna from one cage to another. The authors described the various different equipment options
available for the application of this technique and practical considerations for improving the accuracy of
the system.
The SCRS was encouraged by the progress made in the practical application of stereoscopic cameras and
alternative techniques. The SCRS noted that a number of factors may affect the accuracy of the stereoscopic
camera measurements. Nevertheless, the Committee stressed that measurements made by stereoscopic cameras
are potentially more precise than the current catch at size reported for the purse seine fleet. The Committee
recommended moving beyond the pilot study phase and setting up a technical working group to establish
procedures for implementing stereoscopic camera systems by 2013.
− To provide guidance on a range of fish size management measures for western Atlantic bluefin tuna and their
impact on yield-per-recruit and spawner-per-recruit considerations [Rec. 10-03, paragraph 19] (see Item
18.11 of the 2012 SCRS Report).
The Committee recognized that Y/R and SSB/R could be improved by changing the selectivity pattern
(decreasing the selectivity of ages 1-6 by 40% resulted in only modest improvements), but these would imply
allocation changes with implications beyond strict Y/R and SSB/R considerations. The Committee was
concerned that such changes in selectivity would affect the availability and utility of indices of stock sizes
currently used in the assessment.
6. Measures for the conservation of stocks and implementation of the ICCAT Criteria for the Allocation of
Fishing Possibilities [Ref. 01-25]
6.1 East Atlantic and Mediterranean bluefin tuna
Recommendation 10-04 required the Commission to review and, if considered to be acceptable, endorse the
fishing plans for eastern Atlantic and Mediterranean bluefin tuna submitted by CPCs. These plans are presented