From sushi and ceviche to tuna pasta salad, tuna is one of the most profitable edible fish species in the world.
In order to conserve tropical tuna species and improve the management of their fisheries in the Atlantic Ocean, the International Commission for the Conservation of Atlantic Tunas (ICCAT) in conjunction with the European Union set up the Atlantic Ocean Tropical tuna Tagging Programme (AOTTP) which began in June 2015. The aim of AOTTP is to gather information on the growth, mortality and stock structure of three tropical tuna species – the bigeye (Thunnus obesus), skipjack (Katsuwonus pelamis) and Atlantic yellowfin tuna (Thunnus albacares).
Atlantic Ocean Tropical tuna Tagging Programme
To date the AOTTP has tagged 107 000 tuna. For every 100 tuna tagged, approximately 20 tags are returned to AOTTP by those in the fishing industry and other stakeholders including dockers and sport fishers. Eighty percent of the reclaimed tags are being reported from Dakar (Senegal), Abidjan (Côte d’Ivoire) and Tema (Ghana) since the bulk of Atlantic tropical tuna caught are landed to these three ports.
From the data collected from the tag-recapture, the AOTTP has been able to determine that tropical tuna partake in transatlantic migrations.
Tropical tuna species
The bigeye, skipjack, and yellowfin tuna are exported worldwide. Tropical tuna fetch a high price in the fish markets, with the bigeye tuna being the most expensive and sought after. From the most recent ICCAT assessments, it appears bigeye tuna stocks are under pressure. This tuna is dark metallic blue and lives in relatively deep waters. The yellowfin tuna also grows to a considerable size, 100kgs plus, and is considered a good game fish. The skipjack tuna is commonly used for canned tuna and the fish stocks of skipjack are currently being sustainably exploited.
Tuna are often referred to as the chicken of the sea because of their accelerated growth rate, and some species can reach maturity at three to four years of age. Most tropical tuna are pelagic feeders, feeding on small fish, squid and other marine life. The three main species being studied by AOTTP are most common in deeper water in the open ocean.
Tropical tuna fish stocks in Africa
The port of Abidjan in Côte d’Ivoire is where most African-caught tuna fish are landed, processed and then exported around the world. Despite their large fishing port, Ivorians tend not to have a deep, local fishing culture, and many of the fishermen in Côte d’Ivoire are Ghanaian immigrants. Unlike Europe, many West African communities prefer to eat the coastal tuna species like wahoo (Acanthocybium solandri) and little tunny (Euthynnus alletteratus) which AOTTP is also tagging.
The AOTTP project is focusing on Ghana, Côte d’Ivoire, Senegal, Sao Tome & Principe, South Africa, Brazil, Uruguay, Canary Islands, Azores, Madeira, Cape Verde and the United States of America.
Information supplied by Doug Beare, AOTTP Coordinator. Written by Georgina Lockwood
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