The Secretariat of the Pacific Community (SPC) conducts region-wide tuna tagging projects to collect critical information for the assessment of tuna species in the Western and Central Pacific Ocean. The specific objectives of this research are to obtain information on the growth, movements, natural mortality and fishing mortality of the tuna.
Tuna tagging involves the capture, tag and release of large numbers of tuna with numbered plastic dart tags, and the documentation (time, location, fishing method, fish size) of subsequent recaptures of these fish by the various types of fisheries across the region. Tagging is carried out mainly using the pole-and-line fishing method, in which fish are caught, tagged and released in a matter of seconds. Information is recorded on the fish’s species and size, along with the date and location of the tagging.
Four types of tag are used by SPC:
- archival tags and satellite tags to measure a range of environmental parameters,
- sonic tags used in monitoring the behaviour of tuna around FADs;
- conventional tags (the most commonly used type) to monitor movement, growth and fishery interaction studies or just to indicate the presence of the other types of tags.
Recaptures of these tagged fish occur throughout the region, from Indonesia and Philippines in the west, to the central Pacific near Tahiti and beyond. Considerable resources are devoted to the documentation of recaptures and rewarding those who return tags.
Getting maximum return of recaptured tags is crucial to the success of tagging programs.
Considerable efforts are occuring to publicize the project and establish tag recovery procedures in the main locations where recoveries are likely to occur.
Tagging posters, providing information to finders on what information to collect, where to send the tags and information, and the rewards that will be paid, have been produced in 13 languages. Posters are regularly sent to industry and Government contacts throughout the Pacific and East Asian regions, and other media, e.g. radio, TV, newspapers have been used to publicize the project where possible.
Tag Recovery Officers have been appointed in key locations, including PNG ports, other Pacific Island landing sites, Philippines, Thailand, Japan and Korea, to publicize the programme, collect tags, pay rewards, and arrange for the tags and recovery data to be sent to SPC.
SPC staff have made regular visits to key recovery locations throughout the programme to review procedures and deal with any issues arising.
Wide publicity, attractive rewards, lotteries, in-country tag recovery officers are conducted to achieve (and verify) high rates of tag reporting.
Tag releases and returns are processed and stored in an established database. Tag return data are cross-checked against other data sources (logsheet, vessel monitoring systems) to verify reported data and estimate missing data.
The work to collect tag recovery data and to verify, correct and compile those data contributes to the conservation and management of the WCPO tuna fishery, one of the world’s largest capture fisheries.