Representatives of 15 Members of the Commission, observers from seven FAO member nations and from four intergovernmental organizations attended the Session. 

The Secretariat is now fully staffed and all core activities were undertaken as planned in 1999.

The Commission took note of the report of the Scientific Committee and endorsed the recommendation that the western boundary of the IOTC statistical areas be changed from 30ºE to 20ºE and that the southern boundary be extended southward to the Antarctic convergence. The Commission agreed that the eastern boundary should remain at 150ºE, since changing it to 141ºE would reduce the IOTC area of competence and would thus involve amending the Agreement creating the IOTC. The Commission decided the port sampling scheme outlined in the report of the Committee be implemented as soon as possible, noting the vital importance of reliable and comprehensive information on catches for the activities and decisions of the Commission.

The Commission approved the research recommendations of the Scientific Committee regarding tropical tunas and the proposed tagging programme, noting the importance of the programme and the need to put it into effect as soon as possible. No management recommendations were made for skipjack and yellowfin tunas, but the Commission noted that, if catches of bigeye tuna continue at high levels, the stock is likely to become over-exploited. The Commission adopted a resolution on the management of fishing capacity and on the reduction of the catch of juvenile bigeye tuna by vessels, including "flag of convenience" vessels, fishing for tropical tunas in the IOTC area of competence (Resolution 99/01). The Commission also adopted a resolution on the elaboration of a control and inspection scheme for IOTC (Resolution 99/03).

The Commission approved the creation of the Working Party on Tagging, and also the terms of reference for the Working Parties on Billfish, Neritic Tunas and Tagging. The principle of the creation of a Working Party on Temperate Tunas was generally supported, contingent upon appropriate terms of reference being adopted, on the understanding that it should concentrate on the management of albacore tuna.

The Commission adopted a resolution on the status of cooperating Non-Contracting Parties (Resolution 99/04). Japan reported that it had implemented the reduction in the number of Japanese large-scale tuna longline fishing vessels by 20 % in accordance with the FAO Plan of Action on Fishing Capacity. The Commission adopted a resolution calling for actions against fishing activities by large-scale "flag of convenience" longline vessels (Resolution 99/02). Australia informed the Commission of the mandate of, and progress by, FAO in developing an International Plan of Action to curb illegal, unregulated and unreported (IUU) fishing.

FAO reported on the progress in the consultations with China concerning data from Taiwan Province of China, noting that the People's Republic of China had accepted that a non-governmental organization representing the fishing interests of Taiwan Province of China be invited to participate in IOTC meetings. The Commission encouraged the Scientific Committee to carry out research on the predation by marine mammals and sharks on tunas caught on longlines, including those proposed at this session.

CCSBT presented a report to the Commission on its activities, noting that a Trade Information Scheme has been adopted and will be implemented in 2000. The Commission agreed on a number of actions between the Secretariats of tuna RFBs and Programmes that will improve coordination in a situation where highly mobile fleets move from one ocean to another in response to management pressures.
The Commission endorsed the programme of work of the Secretariat and approved the budget and scale of contributions, following a reallocation of funds to cover the cost of the preliminary study to plan a tagging programme. The Commission also noted that transfer of technology and training activities are within its mandate, and requested that the Secretariat take into account these activities in future work programmes.

Several delegations from developing nations bordering the IOTC area of competence stressed the fact that the Commission should take actions to guarantee that developing coastal Members should be able to share in the exploitation of the tuna resources of the Indian Ocean. It was also stressed that nationals of these States should not be constrained by lack of funds in participating in the technical activities of the Commission.
The Commission decided that the Third Session of the Scientific Committee would be held in Seychelles on December 4-8, 2000, followed by the Fifth Session of the Commission on December 11-15. The report of the Fourth Session of the Indian Ocean Tuna Commission was adopted on 16 December 1999.