Experts wonder how warmer oceans will further impact whale sightings
Humpback numbers have declined in recent years, but last season saw uptick in counts
KIHEI — While there has been a slight increase in humpback whale sightings this past year, officials said they “do see some trouble on the horizon” from a potential ocean heat wave in the Pacific and changing trends in marine wildlife behavior.
“What we’ve been hearing this past summer is that there’s a new ocean heat wave, but what that means is that we don’t know yet,” said Marc Lammers, research coordinator at the Hawaiian Islands Humpback Whale National Marine Sanctuary in Kihei. “It could mean that there will be a strong winter with a lot of storms and churn everything up and this blob will just go away, so that’s kind of what we’re hoping for, but if it doesn’t and it persists, well we’ll just have to see what that means in terms of how it affects our humpback whales.”
Lammers said that whale numbers have improved and that “this past season we saw more whales that were here, so some encouraging news there.” However, experts are still searching for answers as to why sightings have declined in Hawaii in recent years — and how it could be connected to changing ocean conditions.
On Wednesday night, about 150 people squeezed into the sanctuary building to learn about whale trends, surveys and research results as the 2019-20 humpback whale season gets underway in Hawaii. The season generally runs from November to May, though the first whales are often spotted earlier. The first reported sighting in Hawaii this season was on Oct. 1 off the coast of Kauai; the first in Maui County was reported by a Pacific Whale Foundation boat in the Auau Channel on Oct. 9.
A whale of a mystery
Hawaii is the principal winter breeding grounds for the North Pacific humpback whale population, with about half coming to Maui, Lammers said. In 2016, federal authorities decided that most categories of humpback whales had recovered enough to be removed from the endangered species list.
“Coincidentally, right around that time, people started to observe and note that fewer whales seemed to be coming to Hawaii. . . . This has received a fair bit of media attention over the past several years and it’s a trend that has continued,” Lammers said.
The sanctuary was “very concerned about this trend” and researched reasons for the decline by using acoustic monitoring at six long-term Maui Nui sites, such as Olowalu, Kahekili and Molokini, to document changes in chorusing levels.
It also began conducting weekly shore station surveys off Olowalu for visual counts, and collecting Ocean Count data in partnership with the Pacific Whale Foundation to calculate whale abundance trends across the state.
“The reason we monitor acoustically is because as more and more whales come into an area, the song volume gets louder and louder, and that’s something we can measure, record and quantify,” he said.
For example, from November through March, song volumes typically increase, but during the months of April and May, charts show a natural steady decline.
However, from 2014 to the 2018-19 season, humpback chorusing has been lower overall than in the past, both acoustically and visually, Lammers said.
After comparing two studies that involved 30-minute interval scans on the west side, there were 46 percent fewer whales counted in 2018 (an average of eight whales per scan) when compared to a 2015 count (15 whales) in the same location.
To compare, the same study on Hawaii island demonstrated a 49 percent decrease in whale abundance during the same timeframe, Lammers added.
Changes in “prey abundance” in Alaska is likely an influencing trend, he said.
Not only is there a slight decline in individual whale visits, but in the last couple years, the overall frequency of large groups has reduced and the average size of those groups has also dropped, said Ed Lyman, sanctuary natural resource specialist.
However, last season “we see a slight bounce-back,” he said.
The Hawaiian Islands Entanglement Response Network also found that about 1 in 5 whales has tangle scars from wounds caused by entanglement or boat collisions, and that calves and sub-adult whales make up 65 percent of vessel contacts, Lyman said. But these statistics also saw a slight improvement last season.
The response team, which is led by the sanctuary and partners with the National Oceanic and Atmospheric Administration’s regional office, the state Department of Land and Natural Resources, the U.S. Coast Guard, whale researchers, Hawaii’s tour boat industry and others, also monitors the abundance of separated calves, floaters, out-of-habitat whales and injured whales.
“That’s where the data is coming from. A big part of it is people on the water,” Lyman said. “About 80 percent of it is coming from that source.”
About 50 percent of reported large whale entanglements have been confirmed to be caused by fishing gear, with a rise in overall reports in 2018, he said.
“I think what was happening is we started getting more from British Columbia, getting more entanglements up there, and we got some of those animals down here,” he said.
So what was happening to the whales?
Last year, a group of experts gathered for a two-day workshop in Honolulu where they examined the trend of humpback whales in Hawaii and Alaska, principal locations where whale presence has dropped in the past three to four years.
From 2013 to 2016, the Pacific Ocean heat wave, also known as the “Blob,” caused about 4 million square miles of relatively warmer temperatures.
In 2017, El Nino occurred, a large-scale periodic warming in sea surface temperatures across the Central and East-Central Pacific Ocean, as well as a “warming period” called Pacific Decadal Oscillation, which is a long-term ocean warming cycle that occurs primarily in the North Pacific, Lammers said.
“All those things basically combined created this really warm water anomaly in the Northeast Pacific,” Lammers said. “So what did that do? The warm water basically resulted in major changes in ocean circulation. The warm water kind of turned off the winds, which led to the water not getting mixed.”
This then led to “major disruptions in nutrient flow” and “alterations in the food chain,” resulting in collapses in humpback whale feeding and productivity.
“There were some mass die-offs of some pretty hardy seabirds that come in the areas, so it pretty much affected the whole ecosystem,” he said. “We do know that there was some mortality. We do know that there were some reported cases of whale carcasses. We also know that there were multiple reports of thinned whales, so we know that they were having a hard time finding food, and likely this led to them having to go somewhere to go find food in places where they normally wouldn’t go.
“We also suspect that this led to them, or a portion of the whales, maybe deciding to skip the migration to the breeding grounds,” he added.
Lyman later tagged on to Lammers’ comments by saying that “maybe mothers aren’t getting enough energy and aren’t producing as much, so there are few calves out there.”
“A lot of what we do is visual based,” Lyman said. “Looking at indices, things like emaciation, rough skin, dark skin, whale mites and wounds. . . . They can be indices at both the population level and the individual level.”
More than 140 whales have been confirmed entangled in marine debris or fishing gear in Hawaii since the response team was started in 2002, Lyman said. But interestingly enough, overall risk and threat by entanglement and vessel contact dropped around the islands during times of ocean warming.
Lyman hypothesized that because there are fewer whales in Hawaii during ocean warming events, the risk of entanglement also goes down.
“There are some drops here, like in 2011-12, that was an El Nino year, a big one by the way,” Lyman said while pointing to the charts. “And then you see the drop here more recently as well, so are we surfacing connections with those environmental aspects even with small data set numbers in things like our threat analysis? Maybe we are.”
Additionally, before the “environmental change,” Lyman noticed that entanglement reports by gear from British Columbia was very minimal, but after such heating events, reports quadrupled.
He suggested that one hypothesis is that humpbacks are getting tangled in debris or fishing gear in nearshore areas in search for food in places they usually don’t go.
“Even within region, maybe they’re feeding differently, maybe their core resources have changed and what we’re seeing up in Alaska, in many cases, whales are closer to shore,” he added. “Some potential changes there.”
All hands on deck
In the meantime, local researchers and community members are doing what they can to save the whales, whether by tracking them visually or rescuing them from marine debris.
Saving a 45-foot, 40-ton humpback whale from marine entanglement poses many challenges, but the Hawaiian Islands Entanglement Response Network has freed more than 30 whales since 2002, with more than 12,000 feet of gear removed, Lyman said.
Equipment used during an disentanglement mission includes pole cameras, helmet cameras, drones, VHF antennas and 360-degree cameras to make precise cuts and to collect footage to learn how to approach the next case.
The rescue team also uses cutting grapples, carbon-fiber poles and hooks, as well as buoys and kegs to drag, slow down and free the whale.
Lyman said that they use their past experiences and footage to determine the whales’ chance of survival and create the best game plan to untangle the whales.
Since 2002, they’ve mounted more than 180 responses, and “have a 43 percent success rate from those cases that are warranted and able,” he said.
Federal regulations prohibit anyone from approaching within 100 yards of whales when on the water, but local tour and fishing boats can help to report any potentially injured or entangled animals by calling the NOAA Marine Mammal Hotline at (888) 256-9840.
“We’re getting a lot of help from the community, we’re getting live information, a lot of reports, helping us to monitor and assess the whales out there on the water,” Lyman said.
Those interested in collecting and sharing data to a global database can download The Pacific Whale Foundation Whale and Dolphin Tracker app.
The app collects scientific data about marine wildlife in the regions of Maui, Kahoolawe, Lanai and Molokai.
“We’re basically building an app for your iPhone or a crew’s iPhone, and this is where a lot of volunteers are going to help us as well,” he said. “Help us get a greater scope, more geographic coverage, more effort out there, expand what we’re doing.”
While the future is unclear, organizations continue to follow humpback whale trends and look to history to learn how to protect them.
Starting last season, the Pacific Whale Foundation’s Great Whale Count survey joined efforts with NOAA’s Ocean Count to create a three-year project under the Office of National Marine Sanctuaries. The annual whale counts are a way to get volunteers involved as well.
To monitor whale activities, the sanctuary also deployed ecological acoustic recorders across Maui Nui’s seven sanctuary sites and one at the Papahanaumokuakea Marine National Monument, as well as three sites on the U.S. East Coast and West Coast.
“This will allow us to do acoustic comparison, not just in Maui but now start to expand our acoustic perspective to the archipelago to answer such questions,” he said. “We know that whales are actually up there, but that’s a different story that needs to be told. . . . Things like acoustic monitoring are really our best bet in the time being to know what’s going on up there.”
Lammers added that five SoundTraps were also deployed off Maui, Molokai, Oahu and Kauai.
Both the recorder and sound trap can sit between 15 to 200 meters (about 49 to 656 feet) underwater.
There are also plans to use a wave glider to conduct acoustic research along the banks of Papahanaumokuakea for the presence of songs between January and March of next year. The marine drone uses the ocean’s waves to propel itself forward.
“We’re being optimistic, but it’s done some very interesting missions from Mexico and back,” he said. “This is a really cool project we’re excited about.”
The sanctuary also began using vessel transects and shore-based surveys to sample whale densities using distance and acoustics. Lammers said they plan on doing about 10 to 12 transects during whale season, starting next month through April.
Lastly, as a long-term effort with the Hawaii Institute of Marine Biology at Manoa and UH-Hilo, the sanctuary is tagging whales with suction cup sensors to study the humpbacks’ behavior, communication patterns and movement, and “study how they are affected by changes in their environment.”
“It’s a very useful tool, we’re looking at their behavior when they’re under the water and out of our view,” he said. “The suction cups last anywhere from a couple minutes, but we’ve had one stay on as long as 36 hours.”
The Hawaiian Islands Entanglement Response Network also will conduct drone test flights for future aerial assessments.
For more information, visit the sanctuary website at hawaiihumpbackwhale.noaa.gov.
“That’s what the sanctuary is going to do, we’re going to do our best,” Lyman concluded. “Working with the community and keep being as prepared as we can and get new tools and techniques as much as can, and we’ll do our best.”
* Dakota Grossman can be reached at firstname.lastname@example.org.