Modeling the Migrations of the Capelin, an Indicator Species for Climate Change

The capelin is a species of pelagic fish that lives in the Arctic and subarctic environments. In the seas around Iceland, the capelin plays the role of a biological pump, migrating North to feed on the plankton blooms and then returning South to spawn. It is an important source of nutrition for many commercially and ecologically prominent species such as the cod and haddock. Because of the key role that it plays in the trophic chain, understanding the capelin's migration route and life cycle is key to understanding the impact of the changing oceanic environment on the wider marine ecosystem. Recently, the capelin's migration routes have been changing. Here, we present an interacting particle model for the migrations of the Icelandic capelin. The particles interact using a three-zone model, aligning their direction and speed with neighbors while being repelled by those that are too close and attracted by those that are farther away. The particles also respond to environmental cues. They balance the interactions with temperature gradients, avoiding areas that are too hot or too cold. Particles are translated by the oceanic currents. Using this model, we were able to successfully simulate the spawning migration for three representative years. However, more must be included to capture the feeding migration. The feeding migration is key to understanding the current changes in the capelin's migration routes, since the extent determines how far the fish have to swim as well as their condition upon arrival at their spawning grounds. We will discuss the challenges of modeling this portion of the life of the capelin, as well as identifying the necessary information to meet these challenges.