Example of recent evidence of propeller scar on humpback whale calf. Fortunately, this scar appears superficial and will not permanently injure this whale. Photo obtained under NMFS ESA/MMPA Permit No. 2702. Photo captured July 23, 2024/NPS Photo, J. Neilson
National Park Service Working To Reduce Whale Collisions At Glacier Bay National Park and Preserve
By Matthew Cahill, Glacier Bay National Park and Preserve
Scientists from the National Park Service and NOAA Fisheries recently engaged in the somber task of necropsy on a dead humpback whale near Point Adolphus in Icy Strait, south of Glacier Bay National Park and Preserve.
The necropsy team, led by a veterinary pathologist from Alaska Veterinary Pathology Services, found that the 48-foot female was pregnant, and while they found evidence that suggested blunt force trauma, it was not possible to confirm the cause of death. The adult female whale is the second whale found dead in the area within the past month. In early July, a juvenile humpback necropsied near Elfin Cove, southwest of the park, was found to have skull and spinal injuries, strong evidence that the whale died as a result of a vessel collision.
There have been a number of self-reported collisions this summer in Icy Strait – whales hitting stationary boats and boats underway hitting whales, but there appear to be additional strikes occurring as well. Just this week, during routine population monitoring that the NPS conducts every summer, whale biologist Janet Neilson found evidence of yet another instance of vessel whale collision in the area, fresh propeller scars on a humpback whale calf in Glacier Bay. While this injury does not appear life threatening, it illustrates that whale-vessel collisions can go unreported.
Humpback whales come to Glacier Bay, Icy Strait, and elsewhere in Southeast Alaska in the summer to feed on the forage fish and krill that congregate in these rich waters. Concentrations of whales attract sightseeing vessels large and small that inevitably affects whales’ behavior, specifically, their ability to feed and communicate. Vessels can collide with whales, often injuring or killing the whale. There is also a serious boater safety concern, because hitting a whale is like hitting a brick wall, and people can be injured or thrown into the water by the impact.
Whale researchers, such as NPS whale biologist Christine Gabriele, are concerned about the effect that elevated vessel strikes are having on the whale population, “which has recently come through very rough times after the Northeast Pacific Marine Heatwave” (PMH). During and after the PMH 2014-2016 marine heatwave, humpback whales were among many marine species (seabirds, cod, salmon, fin whales) that were strongly impacted by the resulting lengthy and widespread ecological collapse.
Data from NPS whale population monitoring demonstrated that the whale population in Glacier Bay and Icy Strait, decreased by 56 percent in four years, and has remained at a lower level since then. Humpback whales demonstrated very low reproduction for several years afterward. From 2015-2019, very few calves were born, and the calf survival rate was extremely low. Across the North Pacific, a broad collaborative study concluded that the abundance of humpback whales wintering in Hawai‘i had declined by 34 percent (roughly 7,000 whales) by 2021 after reaching a peak in 2013, just prior to the PMH.
Gabriele is concerned about disturbance and collisions because the population is already under stress from marine heatwaves and general ocean warming. “The ocean is much less predictable, and the whales are taking the brunt of that — it's harder for them to find food in some years.”
”Losing a juvenile and a pregnant female this month is a big setback. We lost 30 percent of our whale population in the last marine heatwave, and if the next heatwave takes another 30 percent, the whales are in deep trouble,” Gabriele added.
The good news is that Glacier Bay’s whale monitoring has documented a record number of calves this year, following on high numbers reported in the Hawaii wintering area in early 2024.
“We’re thrilled to see so many calves around this year, but this also may be why we are seeing a spike in collisions," says Neilson. "Calves are not experienced around boats and often get too close. They can easily stray from their mom and get hit. It’s no surprise that in our study of Alaska whale-vessel collisions, calves and juveniles were at higher risk of collisions. Mothers and calves need extra consideration; limiting whale watching time and watching them from a greater distance can help.”
Reducing speed and avoiding high-speed transits in known whale habitats are two ways that boaters can reduce the risk of whale strikes/NPS, C. Gabriele
In all Alaska waters, a 2001 NOAA Fisheries federal regulation that requires vessels to maintain a “slow, safe speed” near humpbacks is designed to protect whales from disturbance and possible collision. In addition to operating at “slow, safe speed,” vessels shall not approach within 100 yards of humpback whales or be positioned in the path of oncoming humpback whales such that they will surface within 100 yards. Vessel operations shall not disrupt the normal behavior or prior activity of a whale. This regulation is especially helpful for whale watching boats, but vessels in transit for other purposes may not be aware of the presence of whales, or have a different idea of a “slow, safe speed.”
Along with federal requirements, there are things that boaters can do proactively to reduce their risk of colliding with a whale.
In Glacier Bay National Park waters, the NPS protects whale habitat and reduces the potential for whale strikes by limiting the number of vessels and how they travel within Glacier Bay. Hot spots where whales congregate predictably to feed are identified by NPS biologists and “whale waters” speed and course restrictions are implemented by the park superintendent to reduce the disruption of feeding humpback whales and to lower the risk of whale/vessel collisions.
In whale waters, the NPS requires vessels to travel at less than 13 knots (nautical miles per hour) and in the lower bay where whales predominantly feed near shore vessels are prohibited from operating within one mile of shore. Separating whales from vessel traffic and requiring vessels to travel slowly are important parts of the park’s whale protection strategy. Vessels in park waters are prohibited from approaching within one-quarter nautical mile of a humpback whale, and if they find themselves within that distance of a whale they must decrease speed to 10 knots or less. The NPS also has worked closely with cruise ship captains and marine pilots to develop a whale sighting network, Whale Alert Alaska, to give ships advance warning of whale distribution so the navigation bridge can be prepared to post an extra lookout or reduce speed.
All types of vessels are responsible for avoiding whale strikes. Part of the problem is that whales surface in unexpected locations and may be underwater for quite a long time. When whales are on longer dives, fast moving vessels may have little to no warning that a whale is in the area.
The best course of action is to avoid transiting through known whale hot spots and reduce speed if avoiding the area is not possible. Some areas, like Point Adolphus, are predictable places to see humpback whales in the spring, summer, and fall. Vessels should always assume that several humpback whales are present in these areas.
Reducing speed gives the vessel operator more time to spot whales in the area, which can help prevent surprise close encounters. Slowing down also gives the whales more time to react and move away to avoid vessels.
If you’re anchored or drifting in an area where whales are feeding, make some noise onboard so the whales can hear where you are. That means leaving your engine or echo-sounder running or thumping on the hull periodically to be audible to the whales. Neilson said that “[M]any people don’t realize that humpback whales do not have active sonar like toothed whales, instead they rely on underwater sound to hear vessels. So, when a vessel is anchored or drifting silently, the whale may not realize that the vessel is there and may hit it on their way up to breathe or during lunge-feeding.”
This has happened many times in Alaska waters, and the consequences for small boats are serious, as demonstrated again recently off New Hampshire.
Gabriele noted: “Everybody loves whales — they are culturally and economically valuable — but we all need to do more to protect them if we want to have them around in 20 or 50 years. Fortunately, there are a lot of things that every boater can do to avoid collisions.”
Helpful guidance and information about whale behavior may be found on the “Five Ways to Avoid a Whale Strike: Behavioral Cues You Can Use” flyer.
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