Climate change may force Arctic predators to eat more junk

Here is something you don't hear every day – climate change may force Arctic predators to eat more junk food. Of course, their junk food is not the same as ours, but the truth is that food for ringed seals and other Arctic marine predators is shrinking. That's a grim prognosis, but scientists at the University of British Columbia say that the problem is becoming deeper due to unchecked climate change.

Ringed seals, common Arctic marine predators, will suffer from declining fatty cod populations. Image credit: Estormiz via Wikimedia

Predators, just like humans, need a diverse diet. Of course, marine predators eat a lot of fish, but the quality of fish matters as well. Researchers looked at the transformations to the makeup and distribution of fish species in Hudson bay. They created computer models to have a better look into the future. Finally, they wanted to know how these transformations, which include the number of fish in the area as well as their size, will affect such common marine Arctic predators as ringed seals. And the results are not great.

Computer models revealed that by the end of the 21st century the population of Arctic cod, which is a great source of fat for the seals, will decline. Not only will there be less cod available for seals, but the fish will also be smaller. In other words, food for Arctic predators is literally shrinking in size and number. Furthermore, researchers found that if nothing is done to stop them, these transformations of the makeup and distribution of fish species will start accelerating by 2025 and the situation will become worse and worse over time.

So what about that junk food mentioned in the introduction? Well, these computer models revealed that while cod populations will continue to shrink, smaller fish, like capelin and sand lance, may become much more prevalent. Seals do eat them, but because that kind of fish is smaller foraging will require more energy for calories gained. In fact, fish population in Arctic regions may even increase, but the quality will decrease dramatically. Katie Florko, lead author of the study, explained: "It costs energy to forage. Does that mean the seals will need to spend more energy to get a larger number of these smaller fish for the same amount of energy as capturing a bigger fish? It's not unlike how the burgers in fast food restaurants seem to get smaller and smaller every year, and you're getting less bang for your buck".

These changes, if left unchecked, will affect Arctic communities that rely on seals for food as well. On one hand, the change may be positive, because seals will consume fewer contaminants that are more common in larger fish. But on the other hand, the seal population may decline as well and their meat is likely to be less fat. Meanwhile beluga whales could benefit from these predicted changes, because in warmer seasons they rely on smaller fish like capelin. 

 

Source: UBC