This blog was written by the Alaska summer intern, Skye Sunderhauf.
Cook Inlet ranges from the Gulf of Alaska to north of Anchorage. Its blue, sediment-filled waters – a result of surrounding glacial valleys - are home to many marine animals that often go unseen. With the right timing and tides, onlookers may spot a bright white hump breaching the water’s surface as a beluga whale emerges for air!
Cook Inlet is home to a small, isolated population of beluga whales. This population is listed under the Endangered Species Act as endangered, with less than 330 individuals left. Noise pollution from ships and the nearby airport, water pollution and reduction in prey availability are some of the human-caused threats inhibiting these large, slow-reproducing marine mammals from recovering. Let’s dive into two threats this population faces: water pollution and reduction in prey.
Threat 1: A Contaminated Home
Contaminated waterways are a growing global concern due to the amount of human-created and used chemicals. Oil spills have devasting impacts on the marine environment, including harming thousands of animals. Fertilizers, pesticides and salts from agriculture can pollute surrounding water systems. Toxic pollutants from products, such as plastics, cosmetics and cleaning detergents, enter water streams via stormwater runoff or wastewater. Even caffeine can disrupt the natural bodily processes of aquatic organisms, including growth and metabolic activity.
Contaminants such as caffeine and pharmaceuticals have been found in Cook Inlet and are known to affect the marine species calling the waters home. For belugas, there are three pollutant exposure pathways: ingestion of tainted water, proximity to contaminated sediment and consumption of prey.
Some of these chemicals also undergo biomagnification, meaning the concentration of contaminants multiplies as they are consumed up the food chain. In other words: the larger the organism, the higher the concentration of contaminants within them. Warm-blooded mammals must consume more food to maintain their body temperature compared to cold-blooded animals – like sharks – which is why marine mammals are often the most contaminated species in the water.
A whale’s blubber stores energy for times of food scarcity. This, unfortunately, also means it holds contaminants. If food availability becomes low and the whales need to rely on their blubber for energy, they can be at an increased risk of chemical exposure and harm. Even young whales have been found to have high concentrations of chemicals in them. These chemicals were likely passed down from the mother through pregnancy or nursing. Additionally, there have been multiple beluga whales found with birth defects including congenital deformities, such as lack of a tail, which could be a result of toxic contamination.
Threat 2: Limited Fish Food
Access to food is crucial to any living organism, but for large mammals like belugas, getting enough energy to survive can be a challenge. Although belugas are opportunistic feeders eating whatever is around them, the most common and important prey are eulachon (a species of smelt) and salmon.
Both fish are anadromous, meaning they migrate from the sea to river to spawn, but reproduce at different times. The eulachon runs usually range from April to May, while the salmon runs often last from June to September. Because eulachon arrives slightly before salmon, they are essential in providing belugas with a high-lipid food source after a long winter. Throughout the summer until the early fall, salmon are the beluga’s main prey. In the winter, Upper Cook Inlet freezes and belugas move south towards mid-inlet. Here, benthic creatures and more obscure fish, such as gadid, flounder and other smelt species, are presumed to be the prey of choice.
These prey fish are also eaten by other predators like seals, porpoises, other fish and humans. More studies are needed to better understand the health and abundance of salmon and eulachon in Cook Inlet. Improving our understanding of these fish species’ condition would allow for more sustainable fishing and consumption practices, ensuring enough prey for all animals in the inlet, including endangered beluga whales. Without enough food, malnourishment can reduce the beluga’s ability to perform essential life-cycle functions or increase their susceptibility to disease.
You Can Help Belugas
The Cook Inlet beluga whale population needs our help to avoid extinction. That starts with cleaning up the home where they reside. You can help by:
- Properly disposing of medicine, cleaning supplies and plastic products. Be aware of what you put down the drain.
- Choose non-toxic cleaning products when possible.
- Practice sustainable fishing by following state regulations.
- Become involved in Cook Inlet Beluga advocacy! Anyone living or visiting this region of Alaska can attend the Belugas Count! event on September 21, 2024.
Wildlife & Wild Places
Follow Defenders of Wildlife
facebook twitter instagram youtube tiktok threads