In 2019, Alaska saw an exponential increase in marine mammal strandings, according to a National Oceanic and Atmospheric Administration report released last month.
Of the 442 strandings reported throughout the state, 51 occurred in the Gulf of Alaska. Of those, 25 occurred around Kodiak and 151 occurred in the Bering Sea.
Stranded animals include those that are found dead (floating and beached), live stranded, mass stranded, abandoned, sick or injured.
Stranded species found in Kodiak included harbor seals, elephant seals, Steller sea lions, gray whales and humpback whales, as well as a number of unidentified species.
Marine mammal stranding reports have been increasing over the last 30 years around the state. June had the most reports, with 140 strandings in 2019 compared to about 40 in June the previous year.
In addition to stranding reports, there were also 88 human interaction reports of animals becoming entangled in fishing gear, ingesting fishing gear or coming into contact with marine debris. Other human interactions include ship strikes, where vessels collide with animals, and firearm injuries, where harmful interaction is intentional.
Kate Savage, a health specialist and data manager with the National Oceanic and Atmospheric Administration, said they were “pretty certain” the numbers jumped in 2019 “because we had two mortality events. Three of the ice seal species and grey whales. Those drove the increase.”
While Savage said part of the increase could be related to more public input than in previous years, the cause could also be related to environmental changes.
Among these changes are a rise in sea surface temperatures, changes in algal bloom locations and increases in some of the harmful algal toxins, she said.
In 2018, NOAA declared an unexpected mortality event, or a stranding where there is significant die-off that requires immediate response, because of the changing ocean conditions and the lack of sea ice.
According to Sarah Wilkin, a national stranding and emergency response coordinator with NOAA, the lack of sea ice could impact animals that need to rest on the ice, and also affect prey availability.
“Changes in ice would impact lots of things in the food web,” Wilkin said.
Savage said that malnutrition and emaciation has been the most common cause of death among grey whale strandings this year, and could be because of melting ice.
With melting glaciers, grey whales have had to switch from their typical diet of arthropods, which are found near ice, to alternate food sources, which could be lower in calories than their typical food, she said.
Around Kodiak, this new source was herring in Ugak Bay. Because herring are closer to the shore, whales began to feed closer to the coast than normal, she said. “Maybe there is not enough prey out there, or they are overwhelming their prey,’’ she said. “You’ve got to eat something. If what you want to eat is gone, then you find something else, and hopefully it works. That’s the bottom line.”
Strandings are typically reported by the public to NOAA’s Alaska Region Marine Mammal Stranding Network, and verified by photos, videos or scientists. Reports should be made to the NOAA Fisheries Statewide 24-hour stranding hotline (877-925-7773 or 877-9-AKR-PRD), or the Alaska SeaLife Center Stranding Hotline (888-774-7325).
“We are trying to keep data so that we have at least a baseline to look at trends and patterns that are happening,” Wilkins said. “We are trying to do examinations of the animals and see what we can do about causes of stranding. We are also trying to look at human interactions.”