How does the middle of the Pacific Ocean, an area that’s practically a desert when it comes to the nutrients that lie at the very heart of the marine food chain, manage to support some of the largest life forms on Earth?
“It’s an enigma,” says Jeff Polovina, who, though recently retired, was for years chief of the Ecosystem and Oceanography Division at the Pacific Islands Fisheries Science Center in Honolulu, an agency of the National Oceanic and Atmospheric Administration (NOAA).
“Even though there’s little productivity, some foraging hotspots allow deep nutrients to come to the surface,” supporting whales, sharks, dolphins, and large bony fish, including those species targeted by the Honolulu-based fleet of longline ves- sels, with revenues of around $100 million a year, he said.
But that critical link in the trophic chain is weakening. Modeling done by Polovina and his colleagues predicts dire changes in ocean productivity by the end of the century, he said in a talk that opened
the annual meeting of the federal Marine Mammal Commission, held in May at the Keauhou Sheraton.
“Zooplankton densities will decline by 20 to 40 percent. There will be fewer nutrients and lower productivity of zooplankton. The carrying capacities of many organisms will decline 40 to 50 percent around the subtropical gyre by the end of the century,” he said.
Ten years ago, Polovina addressed the same body when it held its annual meeting in Honolulu. At the time, he warned that areas of extremely low productivity in the ocean – called oligotrophic zones – were expanding, with the zone in the North Pacific having expanded at an average annual rate of around 2.2 percent over the previous nine years. Should the trend continue, he said, it could significantly affect populations of important commercial fish, but also disrupt the oceanic food chain, affecting everything from seabirds to sea turtles to marine mammals.
In the decade since, the trend has neither slowed nor reversed.
“What is the biggest change since 2009?”
The question was the first one lobbed to Polovina after he had concluded his talk.
“We have another decade of data, of continuing trends – and we’re more aware that climate impacts are happening earlier than we thought,” he answered.
And, he said, “We’re more aware of the impacts of the longline fishery,” he said.
“The fishery started in the core area” – around the Main Hawaiian islands – “in the late 1980s,” Polovina said. “Around 2005, its effort increased and expanded to the north and the east,” to the point where now some 13 million square kilometers are commercially fished around Hawai‘i.
With that increasing effort has come declining catch rates, between 2 and 7 percent a year. The size of the fish caught is shrinking as well, while the proportion of smaller fish in the catch shows substantial increases, he told the commission members, its scientific advisors, staff, and the several dozen interested members of the public in attendance.
“The catch rates of small fish” – those with a mean weight of less than 15 kilograms – “have increased 25 percent since 1996,” Polovina said, while those for the larger fish have declined more than 50 percent. More and more of the catch is made up of fish having no commercial value, such as lancetfish and snake mackerel.
Overall, “the fisheries yield is expected to decline by as much as 50 percent, and the size structure of the catch will also decline,” he said.
The change does seem to be a “top-down response: as you remove large animals, the population of smaller animals increases,” he said. While this may be bad news for commercial fishers, he added, “there may be some benefit for marine mammals. Maybe more mahi and ono for false killer whales.”
But the benefit may be fleeting.
“Marine mammals and fisheries will be impacted,” he said, with insular popula- tions, such as Hawai‘i’s insular false killer whale population, being hard hit, while pelagic stocks may be able to find areas of higher productivity.
The average rate of annual decline in fishery yields that he had observed in 2009 now is predicted to be as high as 5 percent. “As fishing and climate change impacts combine to shift the size and trophic structure to smaller sizes and lower trophic levels, the subtropics will lose resources that migrate out,” Polovina said. “And it’s not clear anything will migrate in.”
So while the rate of change in the central Pacific Ocean north of the equator may not be as fast as that predicted for northern latitudes, “the impact to ecosystem services may be much greater,” he said.
He cautioned, however, “there are so many caveats when we try to project climate impacts. We’re unsure how parts of the ecosystem will change as chemistry changes. … We have more tools, and we’re making more projections, but we’re also aware there’s so much uncertainty. There’ll be surprises.”
But probably not pleasant ones.
Swim-With-Dolphin Rule Still a Work in Progress
Dolphin tours are big business – very big business in Hawaii. Along the Kona Coast of the Big Island and off Wai‘anae, on O‘ahu, dozens of companies hold out to their paying guests the prospect of swimming with pods of spinner dolphins.
Lars Bejder, director of marine mammal research at the University of Hawai‘i’s Hawai‘i Institute of Marine Biology, told the commissioners that on O‘ahu alone, the annual revenue of dolphin tours amounted to $58 million, while the figure for Kona- based tours came to $44 million a year.
But while snorkelers may pay a premium to enjoy getting up close and personal with the animals, the price the dolphins pay is to their health. The animals feed in the open ocean at night and come in to protected bays during the day to rest. When their rest is interrupted by human activity, their ability to forage, to protect their young, and to successfully reproduce suffers.
Nearly three years ago, in August 2016, NOAA proposed a rule intended to beef up protections for the spinner dolphins. Under the federal Marine Mammal Protection Act, it is already illegal to harass, injure, or kill all dolphins, seals, whales, and other marine mammals without specific authority to do so. But in the absence of rules, enforcement of the MMPA is difficult and uncertain.
The rule would bar vessels or individuals approaching closer than 50 yards to spinner dolphins, would prohibit swimming with the dolphins, and would also ban the practice of “leapfrogging,” or placing a boat or person in the path of a dolphin.
Ann Garrett, supervisor for protected resources in the Pacific Islands Regional Office of the National Marine Fisheries Service, said that NMFS was “still in the process of finalizing the rule” and had only recently completed its review of all 2,294 unique comments. A final rule was still months away at the earliest, she said.
But at the MMC meeting, several of those present voiced their concerns that the proposed rule did not do enough to protect dolphins.
Prominent among them was Bejder, who cited research that emphasized the importance of the sheltered bays where the spinner dolphins rest. Sites along the Kona Coast were studied by an Australian researcher, Julian Tyne, who, Bejder said, determined that the spinner dolphins there had “the highest human exposure rates of anywhere in the world.”
“Eighty-three percent of the time the dolphins spent in resting bays had humans within 100 meters,” Bejder said, referring to Tyne’s work. “That’s 25 percent higher than what has been reported for any other cetacean species. And the average time between exposure events was just 9.6 minutes.”
Up until 2015, he said, NOAA’s preferred approach to managing human-dolphin interactions was through time-and-area closures. But in 2016, that changed to the 50-yard standoff. That, he said, “is a good start … but the resting bays need greater protection.”
“Also, the 50-yard rule doesn’t consider vessel noise,” he added, noting, “Acoustic exposure propagates over hundreds to thousands of yards.”
“It’s clear that if you have a vessel just outside 50 yards, it will be audible,” he said. “A 50-yard approach limit is good outside bays, but in the bays, it’s very inadequate. I’m afraid that we’ve spent 25 years to get a rule in place, but if we put a rule in place now that we already know is not protective, we’ll spend another 25 years to get another rule, while we know that the pressure on dolphins is increasing.”
Addressing Bejder’s concerns, Garrett said that NOAA had “considered closed areas, but we got feedback from our partners that that wasn’t a preferred option.”
In any case, she noted that her agency was already working with operators and others in the affected communities: “As the rule hasn’t been in place, we have been doing other things to help the spinner dolphins. We’ve engaged in outreach with commer- cial operators and the tourism industry to help them understand the issues. And as far as recreational viewing goes, we’ve engaged in outreach on beaches and bays. And we have a growing social media presence.”
When the public attending the meeting was invited to comment, the testimony was scathing.
Rick Wilson of Kona, identifying himself as a “50-year user of oceans,” said, “First, I suggest each of you here go down to Kailua Bay at 7:30, 8 in the morning. Watch what happens. It’s absurd. We will have between 10 and 15 tour boats in the bay, following the dolphins. They surround them. I live right above Lymans. I watch every day as they’re just harassing the hell out of the dolphins. … You need to get this under control. It’s a joke, and it’s been going on for 25 years.”
The tour operators themselves weighed in with complaints about their own indus- try’s behaviors. One captain said that for years, the company he worked for resisted, but, “we ended up swimming with dolphins five years ago. You can’t beat ‘em, so join ‘em.” Another tour operator, whose boat carries just six passengers, complained about the other 56 operators who can drop “up to 60 people in the water at a time.”
Whatever the final rule is, it might not be coming anytime soon. Timing, Garrett said, “is difficult to predict, especially as we move across administrations. Certain rules that aren’t administratively required have been slowed down.”
Monk Seal Recovery Threatened by Disease
“Under the Endangered Species Act, we have downlisting criteria,” Jason Baker, a marine biologist with NOAA’s Pacific Islands Fisheries Science Center, reminded the MMC members. “For the Hawaiian monk seal to be listed as threatened instead of endangered, it will take 31 years at the current rate of growth for the population to meet downlisting criteria.” That current growth rate is about 2 percent a year.
“And I can tell you, the population won’t grow at current rates for 31 years in a row.”
Still, Baker did report that throughout the range of the species, monk seal counts were increasing. “There’s a lot of variation over time,” he said, “but at most sites, we’re seeing stable or rising populations.”
Past threats – especially predation on seal pups from Galapagos sharks – remain. Last year, he said, at French Frigate Shoals, deaths of pups due to shark predation was the worst ever seen.
And the population is still suffering from low pup survival rates at French Frigate Shoals. Overall, though, Baker said, “we’re happy to see the population is growing.”
“In 1998, I was pretty depressed,” Baker said. “From the time I took over” as head of the monk seal research group, “the population kept going down and down.”
“But, despite the fact that we have a long way to go, we’re seeing positive trends since 2013, and myself and others in the program are pretty excited about it.”
Angela Amlin, the monk seal recovery team coordinator for NMFS’ Pacific Islands Region Office (PIRO), had a more sobering assessment in her overview of threats to the species.
Seals in the Northwestern Hawaiian Islands face multiple threats, including food limitation, entanglement and entrapment in abandoned facilities, male aggression, and habitat loss – in addition to the shark predation mentioned by Baker.
In the Main Hawaiian Islands, there’s the ever-present threat of interaction with fishing gear (and sometimes fishermen): “As of 2017,” Amlin said, “there have been 18 seal mortalities from fishery interaction. Seven from hook ingestion, with the rest suspected of dying in nets. All but one of the confirmed cases involved laynet gear, which is illegal.” One mortality, she noted, was associated with an aquaculture pen.
There have been 14 intentional killings of monk seals in the Main Hawaiian Islands, with another four or five deaths from trauma where the intent could not be determined, she said.
To mitigate the threats in the North- western Hawaiian Islands, juveniles that are malnourished – especially females – are translocated or transferred to the seal rehab hospital in Kona.
Entanglement with nets remains a seri- ous threat, with the NWHI seeing one of the highest entanglement rates for seals anywhere, Amlin reported, as a result of ocean currents dumping debris on the beaches of the archipelago. “We have dis- entangled 379 seals since 1982,” she said. As for entrapment: “Since 2015, we’ve released 23 monk seals from behind the Tern Island sea wall.”
Male aggression occurs when a male or group of males mobs female or juvenile monk seals, which can lead to death or serious injury and the skewing of the population’s sex ratio. This, Amlin said, “was a significant cause of mortality in the 1980s and 1990s, but because of mitigation – hazing, wound treatment, translocation, or permanent captivity for males only – it has gone down.”
About one third of the monk seals today, Amlin said, “are alive because of direct interventions. Either they were saved directly, or they’re descendants of seals that were saved in the past.”
Yet even as past actions have helped the population recover, new threats have arisen. There’s the loss of habitat due to a changing climate. Whale-Skate Island, in the French Frigate Shoals, sank out of sight in the 1990s. More recently, East Island, the second-largest land mass in the same atoll, disappeared after Hurricane Walaka tore through the area last fall, while Trig Island was overrun by wave action. French Frigate Shoals is one of the most important nesting areas for green sea turtles as well as a haul-out for the seals.
“After Whale-Skate,” Amlin said, “the seals relocated on their own. It remains to be seen what happens when you lose one after another island. It could be significantly more damaging.”
In addition to losing land, the seals also face the threat of disease.
Starting last summer, hundreds of harbor seals and gray seals along the eastern seaboard of the United States began to die in what NOAA called an “unusual mortality event.” The cause of most deaths was eventually determined to be a morbillivirus – phocine distemper virus, much like canine distemper.
To protect against this, NMFS has launched a vaccination program, now in its fourth year. Michelle Barbiere, a veterinarian with the Pacific Islands Fisheries Science Center, said the seals are vaccinated with a syringe at the end of a hand-held pole. Two injections are needed, three to five weeks apart.
So far, in the Main Hawaiian Islands, 63 seals have been vaccinated to date accounting for about a fifth of the population. In the Northwestern Hawaiian Islands, the percentage is 57 percent, or 634 seals out of a total of roughly 1,100.
“We’re not aiming to vaccinate every seal,” she said, “but enough to establish herd immunity.”
The virus itself, she said, has never been detected in a Hawaiian monk seal, but to prepare for a day when an animal is suspected of having the disease, “we’ve been identifying sites where quarantined seals could be held.”
No vaccine is available to prevent toxoplasmosis, however, which Barbiere described as the leading disease-related cause of mortality in Hawaiian monk seals.
“Cats are the only definitive hosts,” shedding the oocysts in their feces. Those oocysts can survive for months and do not die even when they are washed into the ocean.
Toxoplasmosis was first detected in monk seals in 2011, and since then, a total of 11 seal deaths have been attributed to the disease. “It mostly hits females, including many of productive age,” Barbiere said.
Further strengthening the linkage between the disease and cat populations is the fact that almost all the seal deaths from toxoplasmosis have occurred in the Main Hawaiian Islands. Just one seal outside the MHI is known to have died from toxoplas- mosis – a seal at Laysan Island.
“There’s no way to easily prevent expo- sure,” Barbiere said. “Most seals found with this disease end up dead.”
Dramatic Fluctuations In Humpback Numbers
In 2012, Phil Fernandez was named volunteer of the year by the Hawai‘i Humpback Whale National Marine Sanctuary. Less than a year later, he was one of the organizers of a group called Hawai‘i Fishermen’s Alliance for Conservation and Tradition (HIFACT), many of whose directors are closely allied with the Western Pacific Fisheries Management Council. Within two weeks of HIFACT’s official founding, it petitioned the National Oceanic and Atmospheric Administration, asking that it define the North Pacific humpback whale population as a distinct population segment and then remove it from the list of federal endangered and threatened species.
That year, as it turned out, marked the high point for the humpbacks that winter in Hawai‘i and summer in Alaska. In 2016, based on population growth estimates of 6 to 7 percent a year, the humpback whales that frequent Hawai‘i waters in winter were found to be so abundant that they lost their status as endangered. The Hawai‘i distinct population segment of the Northern Pacific population was taken off the list of ani- mals protected by the Endangered Species Act – although it still enjoys more limited protection under the Marine Mammal Protection Act.
Was it too soon?
“Three to four years ago,” says Marc Lammers, researcher coordinator at the Hawaiian Islands Humpback Whale National Marine Sanctuary, “something unusual began to happen here and in Alaska.
“The 2015-2016 whale season started normally enough, with the first sighting off Molokini in October. But in January, people started to notice the whales were slow to arrive… People got worried. Headlines read: ‘Whales have gone missing.’”
The annual whale count conducted by the Pacific Whale Foundation in 2016 counted just 732 animals, less than half the number seen the year before (1,488), Lammers said.
Also, acoustic monitoring of whale activity showed a decrease. “In December 2015, the sounds were about the same as the previous year. But then, for the rest of the year, they never reached the level of the year before. Also, there was an earlier departure” from the islands, Lammers noted.
“A change of six decibels is equal to a 50 percent drop in acoustic energy,” he said, adding that there was a difference of between six and seven decibels over the three seasons from 2014-15 to 2017-18.
Other evidence of change, Lammers said, came in from the sanctuary’s ocean count, which takes place on Kaua‘i, Oahu, and the Big Island. “It’s held three times in the whale season” (January-March), and at all locations, we’ve seen a steady decrease in the number of whales people see and count.”
The alarming trends led Lammers and others to hold a workshop last November that brought together more than 30 experts and resource managers from 17 different agencies and institutions in both Hawai‘i and Alaska.
At the end of the workshop, there was general agreement that whale counts from Southeast Alaska, Prince William Sound, Hawai‘i island, and Maui “all show strong decreases in sighting rates over the last four-to-five years,” Lammers said. And this included both adults and calves.
The consensus of those at the workshop was that changes in prey abundance and distribution played a role. But they also identified “unknowns:”
Do the decreasing numbers reflect changes in habitat use or an actual decline in the population?
Is this limited to the Hawai‘i population or does it reflect a broader trend across all Central North Pacific humpback populations?
And are these changes linked to declines in other species or changes in the ocean itself?
As an outcome of the gathering, eight different working groups were formed to pursue a number of different research efforts. But in addition, Lammers said, “some interesting information has come out” since the workshop.
“In the time period beginning in 2013 to 2016, some really major ecosystem-wide changes took place in the North Pacific,” he said. This included “ocean heat waves” that led to the collapse of the cod fishery and seabird die-offs.
In the 2018-19 whale season, Lammers said, whale numbers in Hawai‘i jumped up. “This season, actually, was a pretty good whale season, by most accounts. Operators were happy,” he noted.
Acoustic data confirmed the increase, with levels that were almost up to those of 2015 at one site, Lammers said, with a “definite improvement” at a second site.
One of the benefits of the government shutdown in January was that a NOAA research cruise was reprogrammed to look for humpbacks in the Northwestern Hawai- ian Islands.
“We only had a week to spend in the [Papahanaumokuakea Marine National] monument,” Lammers said. “The cruise hit a number of islands about halfway up the chain. We all were quite surprised that we found whales everywhere we looked.
“In total, we saw approximately 180 whales, including at least 13 calves. The area appears to be quite important for humpbacks. They’re breeding there.”
Christine Gabriele, with Glacier Bay National Park in Alaska, described the decline of humpbacks in Glacier Bay, one of the areas where the Hawai‘i humpbacks spend summer months.
From 2014 through 2015, she said, “a huge patch of unusually warm water” spread over the North Pacific. The “blob,” as it came to be called, was characterized by water that was up to 2.5 degrees C higher than average, resulting in “lots of ecological consequences,” she said.
From 1985 to 2013, the humpback popu- lation in Southeast Alaska increased at a rate of 5 percent a year, with a peak in 2013 of 239 whales.
“Then the downhill slide began,” she said. By 2017, the number of humpbacks dropped by more than 40 percent.
“Eleven whales were seen every year for 30 years,” she said. “From 2013 on, all were missing.” In 2018, finally, three were resighted – though just one of them was seen in Glacier Bay.
The number of missing “regulars” has been increasing every year, with the fate of most of these unknown, she added.
Calving success also declined dramatically. In 2013, the birth rate was 9.3 percent. “After 2014, it was 2.8 percent. The first thing we knew was wrong was in 2014. Half of the calves were missing from their mothers after the end of summer in 2014. The calves were presumed dead, since they were not old enough to be weaned.
“In 2018, there was just one calf, which died. It was total reproductive failure – the first time in the 34 years we’ve been studying the whales,” she said.
Many of the whales that make it back to Glacier Bay are in poor shape. In 2016, 13 percent were judged to be “skinny,” while in 2017, that had increased to 24 percent, she reported.
Gabriele noted that strandings had also increased after 2014, with many of the stranded whales being emaciated. Also, she and her colleagues were noticing an increas- ing prevalence of unusual skin conditions, including bleeding from flippers, patchy dermatitis, blotchy, rough skin, and bumps, or nodular dermatitis.
What had happened?
“The carrying capacity of the ocean had changed in a heartbeat,” she said. The herring fishery had collapsed, with none harvested at all in 2018 and no harvest in 2019. “These fish are not of marketable size – and these are prey for the humpbacks,” she noted. The same held true for other fish species, including capelin, lampfish, and pollock. Not least, the zooplankton itself had become “skinny,” with a reduced lipid content.
As to whether the delisting decision was premature, Angela Somma, chief of NMFS’s Protected Resources Division at its headquarters in Silver Spring, Maryland, said this:
“When NMFS makes a listing decision under the Endangered Species Act it makes that determination, as it did in 2016 with respect to the Hawai‘i DPS of humpback whales, based upon the best available scientific and commercial data available. We can’t speculate, without conducting a full analysis of the data available and assessing all of the listing factors what the outcome of an ESA status review for this DPS would be today.”