It’s been said over and over again: Eastern bluefin tuna cannot handle the pressure they face from overfishing. These sleek and powerful fish are unlucky enough to be among the world’s most coveted seafood species, and for years scientists have called for a moratorium as a last-ditch effort to save these genetically pure, irreplaceable creatures. While strict quotas have been in place for years, poor quota enforcement and illegal fishing have driven the bluefin to the brink of extinction.

On Monday, the European Union ended the fishing season for most of the Mediterranean’s purse seine fleet — the ships that are responsible for 70 percent of the tuna caught in the Mediterranean. This move could save up to 100,000 bluefin this year alone.

My organization, Oceana, has been carefully monitoring the purse seine fleet with our new boat, the MarViva Med. We have recorded rarely-seen images of bluefin fattening pens and documented purse seiners illegally using spotter planes in their pursuit of the fish.

I didn’t anticipate that the E.U. would react so quickly and shut down the season well before its original July 1 end-date. But our work is far from over. The next step is to make sure that the closure is enforced, and that non-E.U. fishing outfits don’t start targeting tuna as well. We will be watching.