Bluefin tuna finally catch a break

By Carl Safina and Shana Miller

Thirty-three years ago, international fishery managers agreed to stop targeted fishing for giant Atlantic bluefin tuna in the Gulf of Mexico, the only known spawning area for the western population.  Their decision was grounded in one of the basic tenets of fisheries management – catching fish when they aggregate to spawn is a very bad idea if you want that species to have a chance at a bright future.  The tightly schooled spawning fish make an easy target, and catching them kills the fish just before they contribute to the next generation.

Despite this “closure,” spawning bluefin continued to be incidentally caught in the Gulf in longline fisheries targeting swordfish and other tunas, to the tune of approximately 220,000 pounds of bluefin per year.  The National Marine Fisheries Service (NMFS) set a limit on this incidental bluefin catch, but once it’s reached, NMFS simply required fishermen to discard the bluefin, dead or alive. The outcome?  More than three decades of waste of an ocean icon – bluefin are one of the largest, fastest, and deepest diving fish in the sea.

But that’s about to change.

NMFS announced last month that it will prohibit longlining in the bluefin’s two Gulf spawning hotspots during April and May, the two months of peak spawning activity – and peak incidental catch.

Graphic depicts bluefin tuna interaction rates with longline fishing gear in the Gulf of Mexico and the two areas where surface longline fishing will be restricted (red boxes).

This was a hard-fought victory borne out over decades, beginning with the targeting ban in 1982.  Stanford University professor, Dr. Barbara Block, first documented the scale of the problem.  Block’s team chartered longline vessels each spring from 1999 to 2002.  The goal?  To catch spawning bluefin and release them with sophisticated electronic tags that would tell the scientists about the fish’s migrations, behavior and habitat preferences, and hopefully even provide the first documentation of bluefin spawning.  Unfortunately, things did not go as smoothly as planned.

Despite drastic modifications to the way longline gear is fished, including slashing the number of hooks and the hours fished, scientists had a difficult time catching bluefin tuna in good enough condition to tag and release.  More than 30 percent of the fish died on the line. Puzzled, Block went back to her lab’s roots in physiology to get the answer.  She found that the Gulf of Mexico’s warm waters were the upper bound of bluefin’s habitable temperature range. As a result, bluefin in the Gulf would regularly dive into deeper, cold water to cool off, something that was impossible when hooked on a longline. Unable to regulate their temperature, hooked bluefin were dying of cardiac arrest, or tuna heart attacks.

Block’s findings were published in a landmark paper in Nature in 2005, and environmentalists reacted quickly.  In June that same year, environmental law powerhouse Earthjustice petitioned NMFS on behalf of Blue Ocean Institute (now The Safina Center), Monterey Bay Aquarium Foundation, National Coalition for Marine Conservation (now Wild Oceans), Natural Resources Defense Council, and Oceana to close the Gulf longline fishery in the northern Gulf during April through June.  NMFS announced in 2006 that it would not act on the petition due to an analysis which suggested that bluefin mortality would actually increase during the closure due to a dubious assumption about redistribution of the fleet. In November 2006, Blue Ocean Institute, now called The Safina Center, filed a lawsuit against NMFS on that decision, but the judge sided with NMFS when the verdict came out one year later.

In the meantime, scientists conducted more research, and an irrefutable case was growing in support of time-area closures in the Gulf of Mexico to protect spawning bluefin.  By 2010, a large coalition of strange bedfellows, including scientists, environmentalists, anglers and commercial fishermen, had aligned in favor of restricting longlining in the Gulf.

From May 2012 through July 2013, The Pew Charitable Trusts teamed up with scientists from Nova Southeastern University in Florida and commercial fishermen to conduct a trial of more selective gears, namely greenstick gear and buoy gear, in the Gulf of Mexico. They wanted to see if there was a way to keep fishermen fishing and to maintain market supply of swordfish and yellowfin tuna, in the event of a longline closure.  The results were encouraging, indicating that these gears were viable alternatives to longlines.

All the while, it turns out, NMFS was listening.  In August 2013, the agency released a proposed amendment that included a two-month longline gear restricted area in the northwestern Gulf of Mexico.  NMFS received nearly 200,000 public comments on the proposal.  The message was clear – bluefin matter.

On August 29, 2014, NMFS issued its final proposed amendment – a cause for celebration at the end of a long journey.  The two Gulf gear restricted areas are 30 percent larger than originally proposed and will create a 26,858-square-mile protected area for spawning bluefin tuna each April and May.  Longlining will also be restricted in an additional 5,679 square miles off the coast of Cape Hatteras, North Carolina during December through April, providing enhanced protections in a key bluefin feeding ground.

The closed area reflects the warm-colored pixels indicating higher bluefin tuna catch.

The new amendment also places a cap on total longline mortality, which will tie the fleet to the dock if reached.  This part of the rule creates a strong incentive for longliners to avoid bluefin and will finally put an end to the paper closures, which resulted in bluefin being thrown back dead or dying once the longline quota was reached.  Combined with a requirement for 100 percent video monitoring of the longline fishery, this incidental bluefin fishery will at last be held accountable for its bluefin mortality.

While the new amendment is a huge step in the right direction, which will hopefully help put severely depleted western bluefin tuna on the road to recovery, spawning bluefin tuna will still be vulnerable to Gulf longlines.  The new gear restricted areas cover two months and two hotspots, but bluefin spawn throughout the northern Gulf for six months of the year.

Even so, when bluefin tuna gather in the Gulf of Mexico to spawn in 2015, there will finally be a safe haven waiting for them, making decades of work well worth the effort.