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IV) How will the tagging be carried out?. A wide variety of dart and archival tags will be used Large pole and line vessels will tag during 2 years A wide diversity of small tagging vessels will also be used. Tagging should be conducted over the entire area of stock distribution.

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Iv how will the tagging be carried out
IV) Howwill the tagging be carried out?

  • A wide variety of dart and archival tags will be used

  • Large pole and line vessels will tag during 2 years

  • A wide diversity of small tagging vessels will also be used

Iv how will the tagging be carried out

Tagging should be conducted over the entire area of stock distribution

Average catches of yellowfin and bigeye by longliners from Japan and from Taiwan, period 1994-98



  • Adults from these two species caught by longliners show awide habitat covering the entire Indian Ocean

  • The IOTC tagging program will try to cover all this habitat.

Large pole and line vessels will be essential
Large pole and line vessels will be essential distribution

Large numbers of dart tags will be released by large vessels in the East and West Indian Ocean, and by smaller vessels closer to land

(photos Barbaroux, IFREMER)

Live bait availability a serious potential problem in the indian ocean
Live bait availability: a serious potential problem in the Indian ocean?

  • Live bait is necessary for pole and line vessel tagging

  • Potential live bait resources are quite rare, but they do exist in various locations of the Indian Ocean

  • All the information will be gathered by bait experts on live bait availability in the Indian Ocean.

  • The IOTTP will organize live bait collection and stocking in selected zones for the IOTTP P&L vessels

(photos Barbaroux, IFREMER)

Opportunistic tagging is also planned using a wide range of vessels
Opportunistic tagging is also planned using a wide range of vessels

  • Small pole & line vessels in Maldives and Laccadives

  • Handline and trolling artisanal vessels in various fisheries (Oman, Iran, Comoros, Mayotte, etc)

  • Various sport fisheries

  • Small longliners (Seychelles, India, etc..)

  • Purse seiners (JAMARC)

  • Research vessels

Tagging by sport fisheries
Tagging by sport fisheries vessels

  • The IOTTP is planning cooperation with Indian Ocean sport fishermen

  • Such tagging has provided very interesting results on tuna movement in other areas, at a very low cost.

  • Active communication between scientists and sport fishermen, training of taggers, and provision of equipment is planned.

The west to east migration of Atlantic

yellowfin was shown by sport fishery

tagging on the US coast & systematic

recoveries off Africa (probably a homing

behavior of spawning yellowfin).

Following this result, the ICCAT moved

from a 2 stock to a 1 stock hypothesis.

Tagging by sport fisheries1
Tagging by sport fisheries vessels

This could be done in various locations where sport fisheries are active

La r union a very interesting location for small scale tagging
La Réunion: vesselsa very interesting location for small scale tagging

  • Good potential to collect and to keep live bait for tagging

  • Chartered longliners (15 to 25 m) available to tag large yellowfin and bigeye and small swordfish.

  • Chartered sport fishing and artisanal vessels available to conduct tagging on coastal FADs.

  • Opportunistic tagging done by sport fishermen (skipjack and yellowfin)

  • Powerful scientific background: IFREMER, IRD & university

  • Potential help by the fisherman training school and its vessel

Indian Monsoon

gyres province


Eastern Africa costal province

Indian South Sub-tropical gyre province

La Réunion

Subtropical Convergency

Tagging in mayotte

Mayotte vessels

Tagging in Mayotte

  • Good potential to tag yellowfin (3 to 30 kg) and skipjack (March to May)

  • Good potential to do yellowfin archival tagging

  • Artisanal vessels available for charter

  • Tagging could be managed by the Mayotte fishery & environment department using their patrol boat

  • This tagging could demonstrate interactions between artisanal and purse seine fisheries.

Average fishing map of purse seiners (1991-1999)

& position of Mayotte Island

Patrol vessel available for tagging

V recommended tagging programme the iottp indian ocean tuna tagging program
V- vesselsRecommendedtagging programme: the IOTTP(Indian Ocean Tuna Tagging Program)

Why is such a large scale tagging program necessary

A broad geographical basis vessels is required in order to cover all the Indian Ocean stocks in order to:

properly evaluate the interaction between fisheries,

estimate mortality rates as a function of age,

properly evaluate the population parameters

Atwo year taggingprogram is required to:

tag the Tunas with same ages during several years

ensure a good probability of success, e.g. tagging enough tunas, covering the various areas and sizes of tunas well, independently of environmental anomalies.

Why is such a large scale tagging program necessary?

Iottp an international tagging programme
IOTTP vesselsAn international tagging programme

  • This planned tagging program will be similar to the two very successful tagging programmes done by SPC (Secretariat of the Pacific Community) in the Western Pacific in the early 80s and 90s(the second with EU funding)

  • Project staff will be recruited and supported by IOTC: tagging technicians, logistic and publicity personnel

  • Tagging will be done by the IOTTC team , but also by participating countries (probably France, EU, Japan, Australia, India, Maldives, others?) in a coordinated way

  • A provisional target would be to tag about 100,000 tunas with dart and archival tags

Iottp the ideal way to ensure training of indian ocean technicians and scientists
IOTTP: the ideal way to ensure training of Indian Ocean technicians and scientists

  • Presently none of the tuna stock has been evaluated thoroughly, because data are lacking

  • Results obtained from the IOTTP will provide for all interested countries a perfect laboratory for high level training in modern tuna stock assessment

  • Specific training of technicians and scientists will be organized by the IOTC through various themes: tagging, data handling and stock assessment, using data obtained by the IOTTP

  • Such training cannot be organized now (no data!)

Iottp requirements in the iotc framework
IOTTP: requirements in the IOTC framework technicians and scientists

  • Application of available tagging technologies

  • Commitment to a standardized methodology in order to produce a high standard of tag releases

  • Commitment to a thorough and ongoing publicity and liaison effort to maximize reporting of tag recaptures and provision of high quality size, date and location data

  • Commitment to handle the tagging & recovery data in an optimal database framework

  • Active international training and cooperation

Agenda of iottp planned activities
Agenda of IOTTP planned activities technicians and scientists

  • September 2001  end of 2002: pilot studies

  • 2003 2005: tagging operation with pole & line and various smaller vessels

  • 2006 2007: end of tag recoveries and full analysis of results

June 2001 2002 tagging pilot studies
June 2001-2002: tagging pilot studies technicians and scientists

  • Training of tagging technicians

  • Evaluation of the feasibility of using non conventional tagging platforms, such as purse seiners, longliners, trollers, artisanal and sport fisheries

  • Organizing coastal bait facilities in selected locations such as La Réunion, Seychelles and Madagascar.

  • Evaluation of the tagging feasibility in various locations such as La Réunion, Oman, Mayotte, Seychelles, India, etc….

  • Initiation of publicity on tagging and recoveries

  • Planning the final tagging programme

2003 2007 iottp
2003-2007: IOTTP technicians and scientists

  • Full scale tagging throughout the Indian Ocean during 2 years

  • One extra year of limited tagging

  • Two additional years needed to recover most tags and to fully analyze the recoveries

  • First useful results obtained after one year of tagging

  • Full results of IOTTP planned for 2007

Recommended iottp budget
Recommended IOTTP budget technicians and scientists

Cost of thesix-yearsIOTTPestimated atUS$18.5 million.

  • This represents less than 1% of the annual landed valueof the fishery

  • Given the immense social and economic value of the fishery, this investment isfully justified in economic terms.

  • A majority of the costs is

    from the charter of taggingvessels

  • the second important item of the budget corresponds to salaries ofexpertsand tagging technicians

  • In kind contributions could reduce these costs

Conclusion an urgent need to initiate the iottp
CONCLUSION: technicians and scientists An urgent need to initiate the IOTTP

  • The results expected from this programme will beessential to manageand to conserve the Indian Ocean tuna stocks

  • Thecostof this program, 18 million US$, isminimalin comparison with the huge potential benefit obtained from the sustained long term exploitation of such valuable tuna stocks

  • In the context ofresponsible fisheries, there is no doubt that the IOTTP should be launched urgently

Iv how will the tagging be carried out

  • As stock assessment cannot be done at present, there is an technicians and scientistsincreasing risk of overfishing and/or of stockcollapse

  • Unless this IOTTP is done, it would be impossible to estimate this risk

  • Following the principle ofinter generation equity-natural resources should be kept for future generations- there is an absolute need for a safe conservation of Indian Ocean tuna stocks.

  • It is a primary responsibility of industrialized countries to maintain tuna resources at levels which areviable for the artisanal fisheries active in various developing countries: avoiding overfishing and doing the scientific research highly recommended by IOTC

Could iottp costs be reduced
Could IOTTP costs be reduced? technicians and scientists

  • The duration of planned tagging could be reduced, but this would increase the risk of unsuccessful tagging.

  • Reducing the IOTTP scientific staff might compromise the efficiency of the programme

  • Reducing the area of tagging, concentrating tagging in the main fishing zones, could introduce serious bias in the data analysis and modelling

  • Countries interested in the conservation of IO tunas are welcome to provide all possible in kind contributions, primarily tagging vessels, experts & technicians to the IOTTP.