Effects of Shipping Noise on Migrating Ringed Seals

The emergence of ambient sound due to ship noise has adverse effects on pinnipeds. This chapter is focused on analyzing potential disturbance behavior of inhabitant animals when exposed to sound from ferry vessels. Three adult free-ranging ringed seals were tagged with GPS tracking devices to reveal their transiting tracks in the Gulf of Riga. Analysis of the telemetry data demonstrates their regular routes are between the Gulf of Riga and Väinameri to forage and rest. During transiting, the seals are likely being exposed to underwater anthropogenic noise emitted from the ferry vessels. Impact of loud continuous anthropogenic noise and very close presence of fast-moving vessels on the seals are possibly predicted from the disruption patterns on regular dive profiles. Disturbed behaviors can be noticed when the seals dive deeper or perform multiple short dives and surfacing coincide to close encounters with the ferries. Received levels (RLs) that cause reactions on the seals are estimated from modeled underwater sound propagation.