The Hawaiʻi-based longline fishing fleet has chafed for years under a management plan that limits the number of animals belonging to the Hawaiʻi pelagic population of false killer whales that the fleet can seriously injure or kill in the normal course of hauling in the miles-long fishing lines the vessels set out. Should a certain number of false killer whales be seriously injured or killed by the fleet inside the Exclusive Economic Zone, a large portion of the fishing area south of the Main Hawaiian Islands is to be closed to longline fishing for the rest of the year in which the animals are injured.
That number is calculated on the basis of what the National Marine Fisheries Service (NMFS) determines is the number of animals belonging to the Hawaiʻi pelagic FKW population that can be removed without harming the long-term viability of the population – a number known as the “potential biological removal,” or PBR. For the Hawaiʻi pelagic false killer whale population within the EEZ, estimated to be as low as 1,567 animals, that number has been set at 16.
It goes without saying that the vessel owners and captains are unlikely to report interactions with false killer whales on their own. As a result, NMFS calculates the number of actual interactions by extrapolating the number of interactions recorded by observers to the fleet as a whole. In the past, about 20 percent of the deep-set (tuna-targeting) longline vessels have carried observers. Last year, the percentage declined, to the point that this year, NMFS estimates only 13.5 percent of the fleet will carry observers.
So, multiplying the current estimated PBR of 16 by 13.5 percent (the percentage of longliners carrying observers), NMFS has now set the trigger at 3 observed takes within the EEZ that result in a mortality or serious injury. (For more information on the most recent trigger value and how it was determined, see the notice in the Federal Register of February 23, 2024.)
Changing the Numbers
Until now, PBR has been calculated on the basis of the estimated number of pelagic false killer whales within the EEZ. This was because so little was known about the population outside that area, even though most of the longliners’ fishing effort, and most of the observed takes, occur outside the EEZ. As a result, a PBR for the Hawaiʻi pelagic false killer whale population could not be derived for the entire area fished by the longliners.
For years, the Western Pacific Fishery Management Council and the Hawaiʻi Longline Association had pressed NMFS to acquire better information on the pelagic false killer whale stocks. If the population were to increase, the thinking went, then so, too, would the number of false killer whales that the fishery could seriously injure or kill over the course of a year.
Last year, NMFS published an updated stock assessment report for the pelagic FKW population, based on ship surveys and other information taken across almost all of the area fished by the Hawaiʻi-based tuna longliners. That report, still in draft form, states that the minimum population estimate is 4,152 pelagic false killer whales, with 1,531 of that number being the portion found inside the EEZ.
With an estimated population in hand, NMFS could now calculate a new PBR for the pelagic population, which turned out to be 33.
The mortality and serious injury rates, however, are significantly higher than that, according to the stock assessment report. “The estimated mortality and serious injury [in the area outside the EEZ] in 2019 and 2021 were the highest recorded since before the [false killer whale take reduction plan] was implemented, with annual M&SI rates exceeding 60 animals per year,” the draft stock assessment report states. Over a period of five years, the average number of M/SI taken annually has been 47, nearly one and a half times the PBR.
The pelagic false killer whales, unlike the much smaller population around the Main Hawaiian Islands, are not protected under the Endangered Species Act. Instead, they fall under the Marine Mammal Protection Act, with recommendations for management issued by a Take Reduction Team. On the basis of the TRT’s recommendations, NMFS promulgates rules. Should the TRT be unable to come to agreement on management measures, NMFS does have the ability, on its own, to undertake rule-making.
GAMMS
Also last year, the National Marine Fisheries Service issued Guidelines for Assessing Marine Mammal Stocks. Under those guidelines, “whenever possible, a single demographically independent population of marine mammals should be designated and managed as a stock.” That stock’s range “should not be based on anthropogenic boundaries (e.g., political boundaries such as the U.S. EEZ) as such areas do not represent true biological and ecological ranges and are counter to the [Marine Mammal Protection Act] objective of maintaining stocks as functioning elements of their ecosystems.”
Taking this guidance to heart, NMFS biologists Erin M. Oleson, Amanda L. Bradford, and Karen K. Martien prepared a report describing a management area “that reflects what we know of Hawaiʻi pelagic false killer whale distribution and allows for a more complete assessment of fishery impacts on this stock.” The management area “accounts for what is known about the distribution of Hawaiʻi false killer whales outside the Hawaiian Islands EEZ,” they write.
“With an assessment approach currently based on the Hawaiian Islands EEZ, the impact of the deep-set fishery on the portion of the stock outside of U.S. waters cannot be assessed or managed effectively. This report serves to provide the rationale for the new management area along with additional datasets available to support this boundary choice.”
Last month, the Scientific and Statistical Committee of the Western Pacific Fishery Management Council met and, among other things, considered the management area report for the pelagic false killer whale stock.
The members were not impressed. A press release issued by the council described the SSC’s criticisms of the expanded area.
“The SSC determined the available scientific information was not suitable for estimating the abundance of the Hawaiʻi offshore population of false killer whales in areas outside of the U.S. EEZ,” the press release stated.
The committee had established a working group to review the proposal during the meeting. Its report found that the “limited biological data outside of the EEZ were not sufficient to delineate a biologically based area that defines the pelagic stock, or for applying the modeling approach used to estimate the number of animals inhabiting that area.” Based on the working group’s findings, the SSC recommended that NMFS “not use the approach for any management purpose, and instead recommended prioritizing gathering additional tagging and genetic data outside of the EEZ.”
A year ago, another scientific advisory group – the Pacific Scientific Review Group, which advises the National Oceanic and Atmospheric Administration on compliance with the Marine Mammal Protection Act – considered an early draft of the proposed management area. Two “potential sources of uncertainty” concerned its members: uncertainty over predictions of populations in regions that had not been surveyed; and uncertainty over the “magnitude and influence” of the bycatch of false killer whales by foreign fishing fleets on the high seas.”
The unsurveyed areas, however, which lay west of the EEZ were eliminated in the proposed management area preferred by NMFS since no longline fishing occurs there.
As to the impact of foreign fishing, the authors agreed that foreign fishing effort and bycatch rates are “important to consider as part of a full assessment of human-caused M/SI for this stock.” But, they added, estimates of ‘hours fished’ obtained from Global Fishing Watch “indicate that the magnitude of foreign longline effort near the Hawaiian Islands EEZ is relatively low compared to that of the Hawaiʻi-based fleet.” What’s more, the foreign longline vessels fishing nearest to Hawaiʻi operate mainly to the southwest of the EEZ and, to the east, north of 30 degrees N latitude.
It is unclear at this point what immediate impact the expanded management area for pelagic false killer whales will have on the operation of Hawaiʻi-based longliners. Until a new PBR is set by NMFS to cover the estimated population within the management area, and until a new rule is set to redefine the trigger for closure of the southern exclusion zone, it would seem that the longline fleet can continue to interact with pelagic false killer whales outside the EEZ with little consequence.
Record Fishing Effort
At the March meeting of the Western Pacific Fishery Management Council, NOAA’s Pacific Islands Fisheries Science Center provided an overview of longline fishing by the Hawaiʻi- and California-based longline fleets in 2023. (About four of the 150 vessels covered in the report are based in California.)
It was a record year, both in terms of the number of sets made (22,954) as well as the number of hooks (67,298,936).
Even so, the number of bigeye tuna hauled in by the fleet continued on a downward trend from the peak catch in 2014. In 2023, just over 197,000 bigeye were caught, as compared to 2014, when roughly 225,000 were landed.
Also in the mix: six takings of false killer whales. Five were outside the EEZ. NMFS had made a determination of M/SI for just one animal – the one taken inside the EEZ. For all the rest, the determination of whether the animal was or was not mortally wounded was still to be determined, even though the earliest interaction occurred more than nine months earlier.
So far this year, there have already been two observed false killer whale takes outside the EEZ. In the first incident, in January, the line was cut and the animal was released with about 13 feet of line, swivel weight, and hook still attached to it. In the second incident, in March, the crew was able to straighten the hook and release the animal. All gear was retrieved.
— Patricia Tummons
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