What does the seal eat?
VOTO supports a project to increase the knowledge about what seals eat. There is a shortage of knowledge about how seals feed in archipelagoes. An important part of the project is to collect fresh data. This is done by analysis of seal excrement collected from various sites in the Stockholm archipelago.
The gray seal shows a yearly population increase of about 5% in the Baltic Sea. Little is known about how this affects the populations of fish along the coast. Knowledge about the impact of seals on the coastal ecosystem is vital for the management of the gray seal.
By combining data from the composition of seal food with population data, it is possible to calculate the impact of gray seal on littoral fish stocks. The food data can further be combined with estimations of gray seal abundance and its effect on the populations of various fish species.
Littoral fish stocks are already low and under pressure from fishing, exploitation of the habitat, and predators, such as stickleback fish and cormorants. Increased predation pressure from gray seal can lead to a depletion of such fish stocks as pike, perch, and pikeperch. Part of the project is focused specifically on the impact of gray seal on pike, considering that there has been a noticeable decrease of pike in the archipelago.
(The video is only in Swedish.)