None of the council members seemed particularly bothered by what pre-eminent marine scientist Jeffrey Polovina just told them — that there is clear evidence longline fishers in Hawaiian waters are “fishing down the food web.” The term refers to fishery-induced reductions in an ecosystem’s trophic structure.
Now, 40 percent of the catch by Hawai`i-based vessels targeting tuna is composed of unmarketable species, such as escolar (a.k.a. the laxative fish), the fanged noodle known as snake mackerel, or the watery-muscled lancetfish (edible if you don’t mind a squishy bite). About 16 years ago, those fish accounted for no more than 30 percent of the catch.
When given the chance to question Polovina after his presentation at the June meeting of the Western Pacific Fishery Management Council, no one did, at first. Council member Ed Ebisui just grinned for a while. Finally, council member and fish auction representative Mike Goto piped up, mainly to say that Hawai`i fishermen are still making good money catching tuna, so the fact that they’re catching large batches of undesirables isn’t really anything more than a curiosity.
The Hawai`i longline industry has only seen an increase in value across the board, Goto said. And as far the continued increase in unmarketable bycatch goes, Hawai`i is “probably not going to see any significant effect on the fishery itself, in my opinion,” because large tunas will always retain their value, he said.
Polovina pointed out that once smaller species become more abundant than apex predators, “you’re going to see a lot of fluctuation.”
To Goto’s comments that the fishery is still doing well economically, Polovina stressed that he and his Pacific Islands Fisheries Science Center (PIFSC) colleague Phoebe Woodworth-Jefcoats are trying to point out a change in the structure of the whole North Pacific ecosystem.
Overall prices for tuna are increasing substantially and the fishery can still turn a profit, so the industry is not concerned it’s seeing more escolar? Polovina asked Goto.
“It’s always something we’ve been interested in,” Goto said. “Your presentation may explain why. … If the trend is also showing a decrease in apex species, we want to correlate it with effort versus climate change. … In the present, [tuna are] a very viable resource across the board,” Goto replied.
Polovina, however, suggested that the fishery might want start finding markets for lancetfish and snake mackerel.
A New Regime
“We joke it’s no longer the longline fishery for bigeye. It’s the longline fishery for lancetfish,” Polovina said. In 1996, he said, large apex predators like tuna and swordfish represented 70 percent of observed catches. By 2012, they represented only 40 percent.
What now makes up most of the catch? Mainly, it’s been mahimahi, escolar, lancetfish, snake mackerel, and sickle pomfret. Lancetfish now has a higher catch rate than bigeye tuna in the longline fishery, he said.
According to Polovina, it’s not easy to dislodge apex species (such as blue shark, bigeye and albacore tunas, swordfish, and striped marlin) from their place in the ecosystem.
“One of the things interesting about the [North Pacific] pelagic food web is there’s a lot of duplication, replication [in] the food web. Many of these apex species have very similar diets, so if you remove one or two of them, the others would just fill in that void and the ecosystem wouldn’t change much,” he said.
But if you substantially reduce the top group, you will see changes. And judging by the results of recent ecosystem modeling of the longline fishery’s impact on the food web and years of fishery data, Polovina said the ecosystem probably has changed.
His model didn’t make a lot of assumptions — mainly just that large fish eat small fish and the longliners go after a certain size of fish. But it confirmed that the substantial removal of large fish from an ecosystem results in an increase of smaller fish. In the case of waters around Hawai`i, longlining is not impacting the food web down to the primary productivity level, but it is affecting species composition “orders of magnitude down,” Polovina said.
While foreign vessels account for most of the tuna catch in the North Pacific, the number of sets in the Hawai`i-based fishery has also grown exponentially, tripling over the past decade and a half. The number of hooks has quadrupled.
“Moving forward, climate is going to be an issue,” Polovina added. He recently modeled the impacts of climate change on commercially targeted pelagic stocks
and found that toward the end of this century, they will decline significantly.
“The combined impacts of increased fishing effort and future climate change are projected to be additive and accelerate a shift of ecosystem size structure to smaller sizes,” he wrote in a April 2013 Plos One paper he co-authored with Woodworth-Jefcoats (“Fishery-Induced Changes in the Subtropical Pelagic Ecosystem Size Strucutre: Observations and Theory”).
“Many of these small fishes have faster growth rates and shorter life spans than the larger fishes and hence may be more responsive to inter-annual environmental changes,” they wrote.
To head off or at least minimize the likelihood of such a future, Polovina suggested that international fishing organizations, perhaps the Western and Central Pacific Fisheries Commission, pursue a multi-species fishing quota, rather than the current regime of having maximum sustainable yields (MSY) set for each individual species.
Wespac staffer Eric Kingma asked whether the Pacific Island Fisheries Science Center, an agency of the National Marine Fisheries Service, had the ability to develop a multi-species MSY on its own. No, Polovina responded. To do this would require international catch-and-effort information, which the PIFSC lacks, he said.
In the end, the council approved a recommendation of its staff calling for the PIFSC to model changes in the abundance of North Pacific pelagic fish and how this is influenced by fishing pressure, climate change, and oceanographic factors. The council also asked the center to consider the development of a multi-species MSY.
So Long, Stingray?
Polovina’s talk and the resulting discussion centered mainly on the decline of commercially targeted species. The Plos One paper, however, also points out that pelagic stingrays and oceanic white-tip sharks are in big trouble. The sharp decline in their populations “presents concern of collapse for these species,” they wrote.
Oceanic white-tips are already recognized as vulnerable to over-exploitation and are critically endangered in parts of the Atlantic. In their study, Polovina and Woodword-Jefcoats found that the sharks are declining in the North Pacific at a rate of 6.9 percent a year.
Pelagic stingrays, however, are generally thought to be one of two species of elasmobranchs (which include sharks, rays, and skates) facing a low extinction risk due to their life history characteristics, Polovina and Woodworth-Jefcoats wrote. However, they added, their data suggest “this may not be the case.”
One might expect that a decrease in apex predators — which eat stingrays — would result in an increase in the stingray population. It hasn’t. In fact, catch rates of pelagic stingrays have steadily decreased, suggesting that fishing may be killing more stingrays than their natural predators kill, they wrote.
“While this paper has focused on changes in ecosystem structure, it is clear that with increases in escolar and snake mackerel [catch rates] of 12 and 15 percent per year respectively and declines in pelagic stingray and oceanic white-tip [catch rates] of 5.4 and 6.9 percent per year respectively, we are also seeing changes in the ecosystem composition with potential significant impacts on ecosystem function,” they wrote.
Council Team of Experts Finds
Pelagic FKW Population is Growing
In the eyes of Wespac, one of the biggest threats, if not the biggest threat, to the Hawai`i longline fishery is its interaction with endangered false killer whales. If it kills or seriously injures even a small number of whales in a short time frame, a huge swath of fishing ground gets closed off until the National Marine Fisheries Service decides to reopen it.
During Wespac’s meetings and those of its Scientific and Statistical Committee, the true abundance of the animals and the methods used to calculate it often comes into question. Scientists with NOAA’s protected species division, however, have stood by their estimate that there are some 1,500 false killer whales in pelagic waters around the main Hawaiian islands.
Unsatisfied, the council recently convened its own group of experts, including some of its SSC members, to produce a new abundance estimate. No scientists from NOAA’s Pacific Islands Fisheries Science Center attended the March workshop as they were, coincidentally, at another meeting the days the Wespac group met.
Using an age-structured population model developed by fisheries scientist Ray Hilborn, the group determined that even with current levels of take by the longline fishery, Hawai`i’s pelagic false killer whale population is likely growing at a rate of about two percent a year.
“Eighty-five percent of the time, there’s a chance the pelagic population is either stable or growing,” Wespac’s Asuka Ishizaki told the council at its June meeting.
“In 2010, this model predicts a median population of 1,858, with a mean of 2,023,” compared to NOAA’s current estimate of 1,503, she said.
The group also developed a framework for a risk analysis for false killer whales that Ishizaki said could be easily adapted to the insular and Northwestern Hawaiian Islands populations of false killer whales, which are even smaller than the pelagic population.
Ishizaki said the model “will not replace getting out into the field and getting data.”
NMFS Pacific Islands Regional Office director Mike Tosatto asked what the council intends to do with the modeling results.
“I don’t know what your goal is,” he said.
Ishizaki responded that the council is looking into asking Hilborn to publish the results in a peer-reviewed journal. She also said that if NOAA knows with a level of certainty that the FKW stock is increasing rather than decreasing, perhaps it could factor that into its abundance calculations.
Monk Seal Update
The 200 or so endangered Hawaiian monk seals living in the Main Hawaiian Islands probably eat a tiny percentage of the fish biomass here, according to a recent National Oceanic and Atmospheric Administration assessment. But they do interact regularly with fishermen and their gear. And Jeff Walters, NOAA’s Hawaiian monk seal recovery coordinator, wants fishermen to report those interactions so his agency can start building case files on “trouble” seals that may require management, including relocation.
During his update to the council at its June meeting, Walters noted that six seals had been hooked on Kaua`i since January, an average of one a month. Fisherman Ed Watamura later testified that a trap fisherman he knows has documented a seal repeatedly turning over his traps. Also, seals have been found caught in abandoned nets.
To prevent an increase in such interactions, Walters says he’s made outreach his main priority. NOAA has a new paper on how much monk seals really eat and their impact, as well as a four-page long document on how to reduce and prevent fishery interactions, he said.
“We need to simplify those messages, make them more accessible,” he continued.
“If there was one message I could get out to fishermen, or anybody: please do not feed monk seals,” Walters said. He’s heard of some spearfishers giving a monk seal a fish or two while they’re spearfishing so the seal will leave them alone.
“That’s the worst thing you could do,” Walters said, adding that it only habituates the seals to being fed by humans.
“Seal behavior modification is a growing concern for us,” he said. He added that NOAA is compiling “problem seal” histories of seals that have been fed by or otherwise interact with humans and may need to be captured.
Council member McGrew Rice said some fishermen may not be reporting monk seal interactions out of fear of being more strictly regulated.
“[Seals] learn how to pull the bottomfish off the line … they get used to it. They do it regularly. … The fishermen are going to be the ones regulated because the monk seal decided to get smart. … That’s my fear,” he said.
Walters said he was aware of only three instances of monk seals taking bottomfish off lines and that his records show that fishermen who report interactions are not being prosecuted.
“My point is, get the information so we can start documenting. We have to find a way to coexist,” Walters said.
Wespac executive director Kitty Simonds recommended that Walters work with Watamura on reaching out to fishermen.
“Ed talks to the fishermen on every island,” she said of Watamura, who chairs the council’s advisory panel.
Council member Julie Leialoha suggested that Walters continue outreach on the Big Island, particularly regarding NOAA’s now-shelved proposal to temporarily translocate young seals from the NWHI to the MHI .
“It’s pretty clear some people thought translocation was happening all this time. … That misconception needs to be better explained,” she said.
Walters admitted that when his agency announced it would postpone that program, it got into the O`ahu newspapers, but not those on the outer islands.
Walters said NOAA plans to expand its critter cam research to Moloka`i, Kaua`i, and O`ahu and will continue to study fecal DNA and fisheries interactions.
A draft plan for management of seals in the MHI is expected to be issued later this year and the monk seal recovery team, which has been dormant for some time, is expected to reconvene in October, he said.
The two-stage translocation program has been postponed until more management tools are developed in the MHI, he said. For one thing, NOAA wants to be able to track any translocated seals to keep them out of trouble.
In the meantime, NOAA has filed a permit application with the Papahanaumokuakea Marine National Monument to allow it to take MHI seals to the Northwestern Hawaiian Islands to see how they fare.
State and federal agencies have also discussed the possibility of establishing a protected area around Ni`ihau. That effort is “largely in the hands of the [National Marine] Sanctuary program,” said NMFS Pacific Island Regional Office director Mike Tosatto.
“There are a lot of moving parts regarding Ni`ihau. … Do they affect each other? Sure,” he said.
Council member Alton Miyasaka, a biologist with of the state Department of Land and Natural Resources’ Division of Aquatic Resources, said his director, William Aila, “would like to see some monitoring of resources in the area to base his decision on whether or not it should be included in the sanctuary.”
Dettling, Cabos Lawsuit
A few months ago, the U.S. District Court dismissed without prejudice a case brought against NOAA by Hawai`i fishermen Joe Dettling and Robert Cabos. The two alleged that they lost their fishing grounds with the establishment of the Papahanaumokuakea Marine National Monument and the Pacific Remote Island Areas monument. What’s more, they argued that they should have been compensated along with federally permitted NWHI bottomfish and lobster fishers who benefitted from not one but two rounds of congressional appropriations totaling several million dollars.
Dettling sought $1.2 million in compensation; Cabos sought $900,000.
On May 31, U.S. District Judge Alan Kay found that the men failed to show that they were entitled to fish in the NWHI monument area and thus were entitled to compensation. Neither had obtained a federal fishing permit, although they fished in federal waters.
“Indeed, plaintiffs’ factual allegations appear to show that plaintiffs were not eligible for compensation,” Kay wrote in his decision.
Kay also found that Dettling and Cabos failed to exhaust their administrative remedies.
The two had until June 30 to file an amended complaint, which they did. In it, Dettling is seeking the same amount of compensation, but Cabos now wants $1,260,000.
“$6.7 million dollars of Congressional funds were used to … compensate the federally permitted lobster fishermen who had their quotas set at zero approximately 15 years prior and who had already previously received compensation for being displaced,” they attorneys wrote in their amended complaint. “NOAA employees initially told both Dettling and Cabos that they were accidentally excluded when they disbursed the compensation funds [and] assured both Dettling and Cabos, however, that they would ask Congress to allocate additional funds to compensate Plaintiffs.”
(For more background on this story, see our August 2012 cover story, “Fishermen Seek Belated Compensation for Exclusion from Marine Monuments.”)