The 2014-2016 Pacific ocean heat wave (also dubbed “The Blob”” caused havoc to the Alaskan marine ecosystem.
It transformed seastars into goo in the process and resulted in dead seabirds being able to be swept up onto beaches. Researchers believe that it killed nearly half of the whales that reside at Glacier Bay and Icy Strait.
However, animal biologist Janet Neilson with Glacier Bay National Park says that things are improving for the humpback whales of Southeast Alaska.
“The positive side lies in the fact that whales have proven to be resistant,” Neilson said. “They can really be adept at rebounding.”
Glacier Bay and Icy Strait are the primary feeding grounds for Humpback whales. They replenish their energy before migrating to winter breeding areas within Hawaii or Mexico. In the heat wave, cold-water fish and plankton species decreased and caused what Neilson refers to as an “underwater food shortage.”
In the time since nearly 50% of the humpbacks within Glacier Bay and Icy Strait are missing and they’ve not been seen in any other location. Many are believed to have died due to the heat waves.
Although temperatures have cooled off since 2019 Neilson claims that for several seasons, the team continued witnessing devastating results of the survey.
“We think of it as the aftermath that came with the heat” Neilson said. “Things actually were worse after the heat wave had ended before they got better.”
However, this update for 2022, that was announced this week, is sure to show indications of improvement. Whales are gaining weight again and spending more time on Glacier Bay and Icy Strait more than they did during the heat wave. This indicates a need for improvement in the conditions for feeding.
“We’re witnessing less obese whales. We’re seeing less skinny whales” Neilson said.
Southeast humpbacks also reproduce more efficiently, and with fewer sudden deaths of calf. However, birth rates have not returned to pre-heat-wave levels. Scientists don’t know the precise reason for this however Neilson suggests that it could be because female whales haven’t recovered enough nourishment to support pregnancy.
“A majority of females we’d expect to be pregnant. They’re not coming back to us with calves” Neilson said. “We’re not certain what’s the issue here.”
For adult whales the possibility of vessel collisions remains. The survey of 2022 found at most one death among adult female whale in the vicinity of Angoon. The survey only found an adult humpback population of 165 within Glacier Bay and Icy Strait and Icy Strait, which means that one loss could have a significant impact.
Since the number of whale-watching boats to individual whales in the Southeast is rising, researchers fear the threat of disturbances are increasing as well. A lot of boat activity can cause humpbacks to become stressed, making the process of feeding much more difficult.
Neilson believes that avoiding further stress and death for the humpbacks is crucial since climate change is increasing the likelihood of future marine heat waves. However, for the moment she believes that Southeast’s humpbacks are on the right track.
“Things certainly aren’t returning to the way they were,”” Neilson. “But there are positive indicators.”
