Where are the bigeye?
According to recent reports from the fishing front, that question has been uppermost in the minds of the captains and crew of Hawai‘i longline vessels for most of this year.
From January 1 to June 30, longliners took a record number of trips for that period and set a record number of hooks – more than 29 million. What’s more, they substantially increased their effort inside the U.S. exclusive economic zone around the Main Hawaiian Islands (MHI); in 2017, they set 3.7 million hooks in that area for the first six months of the year, while in 2018, it was more than double that, 8.7 million hooks.
The fishermen “are struggling to find fish,” fisheries scientist Russell Ito told the committee that provides scientific and statistical advice to the Western Pacific Fishery Management Council when it met recently in Hilo.
Compounding their problems, he said, was the fact that “when they do catch fish, they’re catching smaller ones.” While most full-size bigeye weigh in at 80 pounds or more, “now it’s 20 to 30 pounds, maybe 40.”
The small fish fetch between $3 and $5 a pound at the auction, while the large fish can bring as much as $12 a pound.
“Also,” Ito added, “it takes a lot more effort for a small fish than a big fish.” In hopes of increasing the auction price, he noted, some fishers stay at sea, waiting for a time when demand may be higher. “There have been quite a few auction days where folks stayed out at sea, with nothing at the dock…. There are days where it’s awfully thin on the auction floor, with boats waiting two to three days to unload.”
“There are poor bigeye catches so far,” he told the Scientific and Statistical Com- mittee. With fishers unable to find the fish, “it’s been like a shotgun blast around the Main Hawaiian Islands. They’ve tried everything but can’t figure it out. The water is warm. They go far north and still they’re running into really warm water.”
Regardless of the “poor” bigeye catches, the fleet was nonetheless expected to hit its limit of 3,554 metric tons, established by the Western and Central Pacific Fish- eries Commission, in November. By November 20, it had reached 99 percent of the quota and had begun catching against the allotment of the Commonwealth of the Northern Mariana Islands.
Regarding the increased effort inside the EEZ, Ito said he was at a loss to explain it. “I was pretty surprised at seeing so much effort in the Main Hawaiian Islands exclusive economic zone. There’s a lot of concern about false killer whale interactions” inside the zone.
This localized effort could, as Ito suggested, account for the fact that the longliners have interacted with more marine mammals, including the endangered population of false killer whales found inside the MHI exclusive economic zone, than in previous years. In July, the determination that at least two of those interactions resulted in death or serious injury forced the National Marine Fisheries Service to close off to longliners a large swath of open ocean south of the islands known as the Southern Exclusion Zone.
Swordfish Bi-Op
In theory, the swordfish fleet, which sets hooks at a much shallower depth than the vessels targeting bigeye, could still fish in the Southern Exclusion Zone even after the tuna longliners were shut out. That fishery, however, was shut down last spring and remains closed for the duration of the year.
The lawsuit that ultimately led to the fishery’s closure involved a challenge to the number of takes of endangered Northern Pacific loggerhead sea turtles allowed annually by the National Marine Fisheries Service.
Because the species is endangered in the Pacific, NMFS sets limits on just how many of these turtles can be hooked by the fishery in a given year. In 2012, NMFS increased the allowed take for North Pacific loggerheads to 34, exactly twice the number of the previously allowed take.
The agency was sued over the change in a lawsuit brought by the Turtle Island Restoration Network and the Center for Biological Diversity. That litigation reached the 9th U.S. Circuit Court of Appeals, which, last December, determined that the biological opinion NMFS had issued to justify the increase was arbitrary and capricious.
NMFS and the Hawai‘i Longline Association, representing vessel owners, agreed to settle rather than appeal. By the time the agreement was struck in April, the fishery was just one loggerhead away from the new limit of 34 and it would have had to close soon anyway.
The settlement calls for NMFS to develop a new biological opinion and, until that is approved and new rules implemented pursuant to it, the old take limit stands.
The Scientific and Statistical Committee had expected to be able to review a draft biological opinion at its October meeting. But, as council staffer Asuka Ishizaki reported, the so-called bi-op was not yet ready.
The SSC did hear, however, from Pacific Islands Fisheries Science Center’s T. Todd Jones, who has been conducting vulnerability assessments for Pacific populations of both loggerhead and leatherback sea turtles. Under the analyses conducted by his team, there was a “positive trend for loggerheads,” with an annual growth rate of its population of around 2 percent.
For leatherbacks, the prognosis was more dire. Looking at a population of nesting females at two beaches in Irian Jaya, believed to represent the largest remaining nesting population, Jones said that at present, they were estimated to number 1,480. But at the current rate of decline – more than 5 percent per year – within 50 years, their numbers would almost certainly fall below half that. And a century from now, the chance that their numbers would fall below 12.5 percent of what they are now exceeded 90 percent.
That analysis, however, is almost certainly more optimistic than it would be if it took account of other factors, including the impact of hookings by foreign fleets and climate change. The U.S. longline fleet represents roughly 5 percent of the vessels in the Pacific that interact with leatherbacks; no good way exists to esti- mate takes by foreign vessels, which generally operate with far fewer restrictions than U.S. vessels.
When Larry Crowder of Stanford University, a renowned expert on sea turtles, was asked to give his assessment of the work being done by Jones’ team, Jones said, Crowder commented that “most of the modeling and analysis that has been done constitutes a valiant effort to compensate for a debilitating lack of data.”
And Still More Takes
On top of the problems longliners face as a result of their take of loggerheads, leatherbacks, and false killer whales, now scientists are seeing increased interactions with two more protected species: the olive ridley sea turtle and the black-footed albatross.
A team of scientists from Florida – Robert Ahrens, Zach Siders, and Nicholas Ducharme-Barth – has been looking at what factors might influence the take of the olive ridley turtles, which enjoy protection as a federally listed threatened species.
“In the last three years,” they told the SSC, “olive ridley interactions longline deep-set fishery are an order of magnitude higher than that for other turtle species.” Among the factors that they have considered are the vessels’ location at the time of the interactions, the sea surface temperature, cloud cover, ocean currents, weather, and lunar phases.
So far, no definite conclusions have been made. Their work is ongoing.
About the same time that the increased interactions with the olive ridley turtles were noticed, observers also began seeing a much higher incidence of interactions between the longliners and black-footed albatross, which are protected under the Migratory Bird Treaty Act. According to Ishizaki, there have been four continuous years of higher levels of interactions with the albatross. While populations for both Laysan and black-footed albatross “are stable or slightly increasing,” she said, “they’re not increasing at the same rate as the increase in interactions.”
Among the possible causes, she suggested, were “fleet dynamics” (where the vessels fish), “captain effects” (some captains have higher interaction rates than others), and “changes in black-footed albatross behavior” (the birds may be learning over time that the longliners are associated with prey or offal discards).
In September, the council held a seabird bycatch mitigation workshop, which looked at current mitigation measures and considered possible changes or additions to them. Increased training of captains and crew, heavier weights on branch lines, and the use of streamer lines to deflect birds were among the op- tions that merit further consideration, Ishizaki said.
— Patricia Tummons