Phocoena phocoena (LINNAEUS 1758), Harbour porpoise (Phocoenidae)

Compiled by: Dieter Boedeker, Stefan Bräger & Wolfgang Dinter, Germany

Updated by: Anders Galatius, Denmark, and Iwona Pawliczka, Poland 

1. Description of the habitat/autecology of the species

The harbour porpoise is one of the smallest cetacean species. It inhabits temperate and cold coastal and shelf waters throughout the northern hemisphere. In the Northeast Atlantic and Baltic Sea, adult males reach average lengths of 1.45 meters, while females average 1.60 meters. Age at sexual maturity is 3-4 years, after which females can potentially produce a calf each year (Lockyer 2003). Maximum recorded longevity is 24 years, but few porpoises live beyond 12 years (Lockyer 2003). Harbour porpoises primarily feed on fish, in the Baltic Sea mainly on cod, herring, sprat and gobies (Santos and Pierce 2003, Malinga et al. 1996).

2. Distribution (past and present)

Different studies indicate that there are two populations in the Baltic Sea, one in the western Baltic Sea incompassing the southern Kattegat, the Belt Sea, the Sound and the German Baltic and a second one in the proper Baltic Sea (Huggenberger et al. 2002; Wiemann et al. 2010; Galatius et al. 2012). In the 19^th and early 20^th centuries harbour porpoises were widespread throughout the entire Baltic, as far northeast as the Aaland Islands and the Gulf of Finland [1]. Today, harbour porpoise observations in the proper Baltic are very rare and it is estimated that the number of remaining individuals) is at most few hundreds (Berggren et al. 2004). The two populations inhabiting the Baltic Sea differ significantly in genetic composition from that in the North Sea.

3. Importance (sub-regional, Baltic-wide, global)

The Baltic Sea populations of the harbour porpoise are considered to be of Baltic-wide importance in the HELCOM area. In the EU marine area harbour porpoises are under strict protection, because they are not only listed in Annex II, but also in Annex IV of the EU Habitats Directive. The species is also part of the “Agreement on the Conservation of Small Cetaceans of the Baltic, North East Atlantic, Irish and North Seas (ASCOBANS)” under the Bonn Convention. ASCOBANS has specifically focused on the recovery of the proper Baltic Sea population with the enactment of the Jastarnia Plan (ASCOBANS 2009). The ASCOBANS recovery plan for the western Baltic Sea population has been developed and presented in 2012. Further, the Baltic Sea States have agreed in HELCOM Recommendation 17/2 to protect the harbour porpoise in the Baltic marine Area.

4. Status of threat/decline

The harbour porpoise population in the Baltic proper has declined dramatically over the past 100 years and there are indications that this population is facing extinction (classified as Critically Endangered (CR C2a(ii)) under the IUCN Red List 2008). In the southern Baltic Proper, a mean abundance of 599 porpoise groups was estimated in June 1995 (Hiby & Lovell 1996, cited in Berggren et al. 2004). This survey was repeated in 2002 resulting in a mean estimate of 93 porpoise groups (Berggren et al. 2004). These survey results confirm the extremely low and probably decreasing population abundance in the Baltic Proper. Calculations based on a subset of the data from the SCANS surveys (SCANS II 2008) covering the distribution of the western Baltic population yield a drop in point estimates from 28,000 to 11,000 between 1994 and 2005 with 96% support for a decline in abundance from 1994 to 2005 (Teilmann et al. in prep.).

5. Threat/decline factors

Porpoises are threatened by a variety of anthropogenic activities and impacts. Among these, by-catch in fisheries is of greatest concern (Vinther 1999, ASCOBANS 2000, Skóra and Kuklik 2003). Other threats in the Baltic Marine Area include pollution, acoustic disturbances, shipping and prey depletion due to over-fishing.

6. Options for improvement

All EU Member States are obliged according to the Habitats Directive to protect harbour porpoises in its entire range as well as to designate Special Areas of Conservation (SACs) for the species by 2012. ASCOBANS obliges its Contracting Parties to engage in habitat conservation and management, surveys and research, pollution mitigation and public information. With the Jastarnia Plan (ASCOBANS 2009), ASCOBANS has set an interim goal of restoring the population of harbour porpoises in the Baltic Sea to at least 80% of its carrying-capacity. In order to fulfil this aim, by-catch reduction is the highest priority, and measures to achieve such reduction should begin immediately. Further, the EU asks for the deployment of observers in certain fisheries to record by-catch and validate the use of pingers.as well [2]. A mechanism for the elimination of bycatch in set net fishery is still needed.

7. References

 

ASCOBANS 2000. Agreement on the Conservation of Small Cetaceans of the Baltic and North Seas. Proceedings of the third meeting of parties to ASCOBANS. Bristol, UK, 26–28 July 2000.

ASCOBANS 2009. Recovery Plan for Baltic Harbour Porpoises (Jastarnia Plan) (revision). Bonn, Germany, 2009:  48 pp.

Berggren, P., Hiby, L., Lovell, P., Scheidat, M. (2004). Abundance of harbour porpoises in the Baltic Sea from aerial surveys conducted in summer 2002. Paper SC/56/SM7 presented to the IWC Scientific Committee, July 2004, Sorrento, Italy.

Boedeker D., Benke H., Norden Andersen O., Strempel R. 2002. Marine Mammals. Environment of the Baltic Sea Area 1994-98). BSEP 82b: 171-173.

Castensen J., Henriksen O.D., Teilmann J. 2006. Impacts of offshore windfarm construction on harbour porpoises: acoustic monitoring of echolocation activity using porpoise detectors (T-PODs). Marine Ecology Progress Series 321: 295-308.

Galatius, A., Kinze, C.C., Teilmann, J. 2012. Population structure of harbour porpoises in the Baltic region: Evidence of separation based on geometric morphometric comparisons. Journal of the Marine Biological Association of the United Kingdom, in press.

Huggenberger S., Benke H., Kinze C.C. 2002. Geographical variation in harbour porpoise (Phocoena phocoena) skulls: support for a separate non-migratory population in the Baltic Proper. Ophelia 56 (1):1–12.

Lockyer, C. 2003. Harbour porpoises (Phocoena phocoena) in the North Atlantic: Biological parameters. NAMMCO Scientific Publications 5: 71-89.

Malinga, M., Kuklik, I., Skóra.,K.E.  1996. Food consumption of harbour porpoises (Phocoena phocoena) in Polish waters of the Baltic Sea. In European research on cetaceans – 10, P. G. H. Evans (ed.). Cambridge: European Cetacean Society, 260

Santos, M.B., Pierce, G.J. 2003. The diet of the harbour porpoise (Phocoena phocoena) in the Northeast Atlantic. Oceanography and Marine Biology: an Annual Review 41: 355-390.

SCANS II. 2008. Small Cetaceans in the European Atlantic and North Sea (SCANS-II). Final report to the European Commission under project LIFE04NAT/GB/000245. University of St Andrews, Fife, Scotland, U.K. Available at http://biology.st-andrews.ac.uk/scans2/.

Skóra, K.E., Kuklik, I. 2003. Bycatch as a potencial threat to harbour porpoises (Phocoena phocoena) in Polish Baltic waters. NAMCCO Scientific Publications 5: 303-315

Teilmann, J., Sveegaard, S., Dietz, R., Galatius, A. in prep. Integrating abundance movements, genetics and morphology in population management of harbour porpoises.

Vinther M. 1999. Bycatches of harbour porpoises (Phocoena phocoena L.) in Danish set-net fisheries. Journal of Cetacean Research and Management 1 (2):123–135.

Wiemann A., Andersen L.W., Berggren P., Siebert U., Benke H., Teilmann J., Lockyer C., Pawliczka I., Skóra K., Roos A., Lyrholm T., Paulus K.B., Ketmaier V., Tiedemann R. 2010. Mitochondrial control region and microsatellite analyses on harbour porpoise (Phocoena phocoena) unravel population differentiation in the Baltic Sea and adjacent waters. Conservation Genetics 11: 195-211.

[1] http://www.ascobans.org/index0201.html

[2] EU:regulation 812/2004 states: "Member States shall design and implement monitoring schemes for incidental catches of cetaceans using observers on board the vessels flying their flag and with an overall length of 15 m or over, for the fisheries and under the conditions defined in Annex III."