La pêche des céphalopodes pélagiques offre de nouvelles possibilités de développement économique. Il semblerait que leurs traits d’histoire de vie les rendraient moins sensibles à l’exploitation que d’autres ressources halieutiques. La majorité des céphalopodes ont un cycle de vie très court (<1 an) mais avec une vitesse de renouvellement de biomasse élevé. Les stocks mondiaux de céphalopodes sont actuellement en augmentation, tout comme leur exploitation.

In the Indian Ocean, estimated annual cephalopod catches rose from 250,000 metric tons in 2000 to 400,000 metric tons in 2016. To date, this resource has not been exploited in the waters around Réunion, and little applied research has been conducted on this topic.

DECAPOT is a project aimed at studying the diversity of squid, the characteristics of their populations, and assessing the commercial potential of certain species.

What species of cephalopods inhabit the waters around Réunion?
What is the commercial potential of this resource?
How can this resource be harvested while preserving biodiversity and stock levels?

Objectives:

🦑Assess and study squid diversity in the pelagic waters off Réunion,
🦑Create a reference list of these species and identify rare and iconic species,
🦑Assess the importance of Réunion’s waters as a key habitat for these species,

🦑Improve our understanding of the biology and ecology of the main species found in Réunion’s waters (life cycle, role in food webs)

🦑Assess the fishery potential of common and abundant species and develop a "small-scale squid fishing" industry

🦑 Work toward diversifying the fishing industry to provide new development opportunities for small-scale fishermen, while also expanding the range of seafood products available to consumers.

Exploratory squid fishing in Réunion:

As part of its efforts to support the fishing industry and advance scientific knowledge, Citeb has focused the project heavily on developing an innovative fishing technique for targeting pelagic squid.

Description of the fishing gear used

• ➔ Fishing gear used in the Pacific: vertical jigging line (“taru-nagashi”); more information here
• ➔ Feasibility test for squid fishing aboard a coastal fishing vessel under 12 meters in length, using 3–7 longlines per trip
• ➔ Assessment of squid populations around Réunion in three study areas: Sainte-Marie, Le Port, and Sainte-Rose
• ➔ Assessment of the resource in terms of seasonal availability through 30 field trips spread across the winter and southern summer
• ➔ Study of the habitat using temperature-depth (TDR) sensors installed along the line

These fishing operations resulted in the catch of 61 squid: 60 flying squid with an average weight of between 3 and 5 kg; and 1 rhomboid squid with an average weight of 19.6 kg.

Compared to similar projects conducted in the Pacific by the SPC (Secretariat of the Pacific Community), Réunion has a similar catch rate: 11 squid caught per 100 jigs. However, the distribution by species is more balanced in Pacific catches than in Réunion, as there are nearly as many flying squid as rhomboid squid, whereas we caught only a single specimen of rhomboid squid. The tests conducted in Fiji, New Caledonia, Tonga, the Cook Islands, and French Polynesia are presented in the SPC Fisheries Newsletter No. 144 . In order to truly compare these tests, fishing effort in Réunion would need to be increased by expanding the number of sites.

Analysis of stomach contents from biological samplers to study squid diversity in Réunion

Top predators, such as tuna, swordfish, and sharks, inhabit the same areas but feed on prey of varying sizes and species. Thus, studying the prey they consume allows us to identify different species of squid found around Réunion based on the feeding habits of these predators. Undigested hard parts, such as squid beaks, allow for the identification of the species, or at least the genus.

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This study has thus made it possible to compile a list of the cephalopods found in Réunion (see below)—a first!

Genetic barcoding analyses have thus identified 29 species of cephalopods. Eight of these had never been recorded in the Indian Ocean but had been found in the Atlantic, demonstrating that these two oceans are interconnected. Similarly, two species known from the Pacific Ocean were discovered around Réunion.

These highly encouraging results thus represent a major breakthrough for science and the study of Réunion’s biodiversity.