SAMBAH II – Spatio-temporal Monitoring of the Baltic Proper Harbour Porpoise

The porpoise (Phocoena phocoena) is the only cetacean species regularly found in the Baltic Sea. The number of harbour porpoises in the Baltic Sea declined dramatically after the mid-20th century due to a number of factors. The decline was at least due to deliberate fishing in the 19^th century, environmental toxins, unintentional by-catch in fisheries and severe ice ages.

Based on genetic and morphological studies and temporal and spatial distribution, the animals of the main basin of the Baltic Sea form their own population. In 2016, the population in the main basin of the Baltic Sea was estimated to be only around 500 individuals and is separately classified as critically endangered (IUCN and HELCOM). Acoustic monitoring carried out in 2011-2013 as part of the SAMBAH LIFE+ project and national monitoring continued in 2016 as part of the marine monitoring programme show that the distribution extends northwards to the south-western offshore area of Finland and, based on current knowledge, the occurrence is year-round and regular. The previous population estimate is based on data from 2011-2013, and is therefore already partly outdated. The SAMBAH stock assessment was also the first of its kind, so there is currently no information on possible trends.

OBJECTIVES AND IMPLEMENTATION
The project will prepare nationally and carry out, together with other EU Baltic Sea countries, acoustic monitoring of the entire range of the population, which will be used to assess the size of the population, the priority areas of occurrence and possible changes in these areas, and in the light of this information to assess the risk areas for anthropogenic threats. In the case of a low abundance and highly mobile species, national spatially limited monitoring programmes alone are not sufficient, but monitoring efforts must be coordinated, using the same methodology and at the same time.

The project will also test new and innovative methods for monitoring. One of the possible methods is the use of eDNA. The project will also test the suitability of different types of hydrophones for low density monitoring. Project activities and dissemination of results will be carried out in an efficient way in direct contact with national authorities and international partners.