WPEB14 recommended to convene a workshop in 2019 to provide advice on the identification of draft ecoregions to foster discussions on the operationalization of the ecosystem approach to fisheries management (EAFM) in the Indian Ocean Tuna Commission (IOTC) convention area. This workshop entitled “Identification of regions in the IOTC convention area to inform the implementation of the ecosystem approach to fisheries management” took place the 30th, 31st of August and 1st of September 2019 in La Reunion Island. The workshop gathered 17 participants with a wide range of expertise in IOTC species and fisheries and oceanography of the Indian Ocean. Prior to the workshop, a consultant was hired to prepare a baseline draft proposal of ecoregions to be presented and discussed at the workshop by all the participants.

The workshop was structured into seven sessions.

In the first session, the experience of developing and using ecoregions in NAFO, ICES, CCAMLR and the NPFMC in the USA were presented to the Group. The Group discussed the potential benefits and uses of ecoregions in the context of these organizations and in the context of IOTC species and fisheries.

In the second session, an overview of the current existing biogeographic classifications in the Indian Ocean, which are often used to inform the delineation of ecoregion boundaries, were presented to the Group, and their relevance in the context of IOTC species and its fisheries were discussed.

In the third session, a check list of evaluation criteria was presented to the Group in order to inform discussions of what factors and considerations could be used for the development of the draft ecoregions. The Group agreed that ecological factors including (i) major oceanographic patterns, (ii) main distribution of IOTC species (tunas, billfishes, neritics), in combination with (iii) the spatial distribution of IOTC fisheries (coastal and industrial fisheries) should be the primary factors to be considered in the development of initial draft ecoregions. Other considerations such as geopolitical factors were also discussed, but not considered primary factors.

In the fourth session, existing data sets were revised, presented and discussed in terms of availability, quality and completeness to guide the choice of key data inputs for deriving the draft ecoregions. The data sets included (i) existing biogeographic classifications, (ii) spatial distribution and catches of IOTC species (oceanic tunas, neritics, sharks, other bycatch species), (iii) spatial distributions of IOTC fisheries (baitboats, longlines, gillnets, purse seines, etc.) and (iv) “other” potentially relevant data layers. A selection of “good” quality data sets was used as inputs in the quantitative spatial analysis to develop the baseline draft ecoregions to be discussed by the group.

In the fifth session, several quantitative spatial analyses were presented and discussed by the Group. These included several spatial overlap analyses, calculations of fidelity and sensitivity indicators to examine species and fisheries composition across multiple biogeographic provinces, and clustering analyses to group biogeographic provinces according to their similarity in terms of species composition, fisheries composition and both species and fishery composition. The Group provided feedback on the technical aspects and methods used in the derivation of the baseline ecoregions.

In the sixth session, three baseline ecoregions were presented and discussed by the Group. The first ecoregion classification was based on similarities of the spatial patterns in species composition, the second on the spatial patterns of fisheries, and the third on the spatial patterns of both species and fisheries.

In the seventh session, the three baseline ecoregion classifications in combination with expert knowledge were used to derive draft ecoregions within the IOTC convention area, and the Group discussed conclusions and future steps. The draft ecoregions are not intended to be used for management purposes. At this stage, the benefits and potential uses (e.g. development of ecosystem report cards, ecosystem status overviews, etc.) of the draft ecoregions should be tested as a tool to facilitate the operationalization of the EAFM in IOTC.

The Group requested that the WPEB reviews and comments on the delineation of the draft ecoregions and provides ongoing feedback. The Group also requested that the WPEB communicates with the rest of the WPs to solicit feedback on the draft ecoregions. The Group recommended that the WPEB endorses the draft ecoregions for further development as a tool to progress EAFM implementation (e.g. ecosystem report card, ecosystem overviews, fisheries overviews).