By Atuna
The Indian Ocean Tuna Commission released an interesting report on Ecosystems and Bycatch regarding its 10th meeting, which took place last October in
The report brings a special section about the by-catch and discards of the European purse seine tuna fishery in the
The numbers represent estimation for the 2003-2007 period and they were used by the Working Party on Ecosystems and Bycatch (WPEB) to formulate recommendations on marine conservation associated with tuna fishing.
The data was collected through French and Spanish observer programs representing a total of 1.958 observed fishing sets.
Results showed 10.487 tons of annual discards and bycatch associated with tuna fishing during that period.
Considering an annual tuna production of 293.401 tons, this amount can be also read as 3.6% of discards and bycatch per year.
Tuna discards represent 72.4 % of the total amount (7.589 tons), followed by fish 19.5%, sharks 6% (2.2 t/1000 t), billfishes 1.5 % (0.5 t/ 1000 t) and rays 0.6 % (0.2 t/1000 t).
“Tuna discards†are the major tuna species and small tunas that are discarded for commercial reasons. “By-catch†are the other associated species caught incidentally that may be discarded totally or be partially valorized.
The source of the data presented in the WPEB report is the paper By-Catch and Discards of the European Purse Seine Tuna Fishery in the
According to the paper, skipjack and frigate are the predominant tuna discards species on all type of sets and adds: “It can be seen that main tuna species like bigeye, yellowfin and skipjack are generally discarded when length is less than 40-45 cm. The minor tuna species are discarded at all lengthâ€.
The paper gives a good profile of tuna discards and associated species by-catch in the European purse seine fisheries: “It shows and confirms the well known fact that fishing on FADs is the main source of by-catch associated species that are mainly fishes and sharksâ€, conclude the authors.