Last month, delegates of the International Commission for the Conservation of Atlantic Tunas (ICCAT) agreed on a landing ban for the heavily overfished shortfin mako (Isurus oxyrinchus). This ban had been under discussion for years, with a decision postponed conference after conference (as reported by ElasmOcean). In 2020, it was stated that even with a complete fishing ban, the shortfin mako would only have a 54% chance of recovering by 2045.
The decision is now being celebrated as a milestone by various environmental organisations. However, there is a catch:
Although a landing ban is the only effective measure because it is controllable, realistically, it is not equivalent to a fishing ban. The ban merely means that animals already caught must be released back into the sea. However, on the longlines with which the vast majority of mako sharks are caught, survival rates are low. Of the approximately 60% that survive the struggle to get on board, another fifth die from the ordeal after being released.
Additionally, the landing ban is initially limited to two years – a very short period for a population where females only reach sexual maturity after about six years and reproduce only every three years.
In our view, the measures still fall short. In an ideal world, longliners would be more heavily regulated or even banned entirely, as they make selective, sustainable fishing virtually impossible.
According to the Standing Committee of ICCAT, catch figures are to continue to be reported - in the coming years, we will therefore have to rely on the honesty of the fishing fleets to estimate how the mako sharks are faring.
The outlook remains bleak.
Sources:
ICCAT (10/2021): Report of the Standing Committee on Research and Statistics
J.D. Stevens: The Biology and Ecology of the Shortfin Mako Shark, Isurus oxyrhinchus. In: Sharks of the Open Ocean: Biology, Fisheries and Conservation, Blackwell Publishing Ltd. 2008.
