Global population trajectories of tunas and their relatives

Tunas and their relatives dominate the world’s largest ecosystems and sustain some of the most valuable fisheries. The impacts of fishing on these species has been debated intensively over the past decade, giving rise to divergent views on the scale and extent of the impacts of fisheries on pelagic ecosystems. We use all available age-structured stock assessments to evaluate the adult biomass trajectories and exploitation status of 26 populations of tunas and their relatives (17 tunas, 5 mackerels and 4 Spanish mackerels) from 1953 to 2006. Overall, there has been a 48% global decline in total adult biomass over the last half century. The trajectories of individual populations depend on the interaction between life histories, ecology and fishing pressure. The steepest declines are exhibited by two distinct groups: the largest longest-lived temperate tunas and the smaller short-lived mackerels, both with most of their populations being overexploited. The remaining populations, mostly tropical tunas have been fished down to approximately maximum sustainable yield levels preventing further expansion of these fisheries. Fishing mortality has increased steadily to the point where around 15% of the tunas and their relatives are killed each year globally. Overcapacity of these fisheries is jeopardizing the long-term sustainability of these species. To guarantee higher catches, stable profits, and reduce collateral impacts on marine ecosystems requires rebuilding of overexploited populations and stricter management measures to reduce overcapacity.

JUAN-JORDÁ Maria José;  MOSQUEIRA SANCHEZ Iago;  COOPER Andrew B.;  FREIRE Juan;  DULVY Nicholas; 

2012-02-09

NATL ACAD SCIENCES

JRC65146

0027-8424,   

http://www.pnas.org/content/108/51/20650.full.pdf,    html?sid=74b1fab2-9c35-45b1-b17f-139211944e3b,    https://publications.jrc.ec.europa.eu/repository/handle/JRC65146,   

10.1073/pnas.1107743108,