Phoca hispida botnica (GMELIN 1788), Baltic Ringed Seal (Phocidae)

Compiled by: Dieter Boedeker & Wolfgang Dinter, Germany

1. Description of the habitat/autecology of the species

 Ringed seals are mainly found in the Arctic. The Baltic sub-populations are “land-locked” and exist as geographically isolated postglacial relicts, not only in the Baltic Sea itself, but also in the lakes Ladoga (P.h. ladogensis) and Saimaa (P.h. saimensis). They grow to an average length of 1.5 – 1.75  meters and a mass of less than 120 kilograms, and can reach a maximum age of 48 years[1]. Females become sexually mature between 3 and 6 years after which they normally generate one pup every year.  The moulting season is from mid April to early May[2]. Ringed seals feed on a wide variety of fish and invertebrates.

2. Distribution (past and present)

The most recent estimates from 2006 suggest that there are about 7,100 ringed seals in the Gulf of Bothnia (Härkönen, T. personal communication), with a actual count of 4748 in 2004 (ICES Advisory Report 2005). Counted numbers in the Gulf of Finland are below 200, and about 1,400 –1,500 in the Gulf of Riga (Mart Jüssi, personal communication). The subspecies is also found in the Archipelago Sea (with a minimum of 150 specimens, Miettinen et al 2005) and in the eastern Baltic Proper (ICES 2005). Population models (based on bounty statistics from Finland and Sweden, and data from Estonia) suggest a population size of roughly 180,000-220,000 at the beginning of the century (Harding and Härkönen 1999). However, it should be noted that bounty statistics may contain sources of error, decreasing reliability of the estimates.

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

The Baltic Sea population is considered to be of sub-regional importance in the HELCOM area. In EU waters, this species is protected by the Habitats Directive and listed in its Annexes II and V.

4. Status of threat/decline

The Baltic ringed seal sub-species was classified as Vulnerable by the IUCN in 2009. While the HELCOM List of threatened and/or declining species uses HELCOM sub-regions, HELCOM Recommendation 27-28/2 identifies two management units for the Baltic ringed seals: Gulf of Bothnia on one hand and the Southwestern Archipelago Sea, Gulf of Finland and Gulf of Riga ringed seals on the other hand. According to ICES WGMME Report (2005) ringed seals in the Gulf of Bothnia, where the main part of the Baltic population occurs, is increasing steadily. Nevertheless, based on data from 1988-2006, the annual rate of increase for the ringed seal population in the Bothnian Bay has been only 4.3%, which is less than half the intrinsic capacity (Karlsson et al. 2007). In Gulf of Riga and the Gulf of Finland the rate of increase was zero between 1996 and 2003 (Karlsson et al. 2007). According to the 2005 ICES report, the southern sub-population has a worse conservation status. There is no sign of recovery and there is indication of a recent decline. HELCOM ad hoc SEAL Expert Group has expressed its concern about the situation in the southern management unit. According to the EU’s Habitats Directive Art. 17 reporting, the population and conservation status in the whole Baltic Sea is assessed as unfavorable.

5. Threat/decline factors

By the 1970s, hunting and pollution had reduced the total population drastically. The sub-population of the Gulf of Bothnia is currently increasing by about 5% annually, where uterine occlusions still affect roughly 20% of the adult females (Helle et al. 2005). The trend of occurrence is however decreasing. The main threats ringed seals are facing are the contamination of the Baltic Sea and climate change (Management plans for Baltic seals in Finland 2007).  Although the contaminant levels in Baltic seals have decreased since the end of the 1970’s, the levels in ringed seals are still high (ICES 2005). Climate change is of particular concern for the southern distribution range (Gulf of Riga, Gulf of Finland and Archipelago Sea), where mild winters might have already significantly affected the reproductive success of these populations (ICES WGMME Report 2005) which are adapted to ice breeding. Other threats include entanglement in fishing gear (by-catch), a wide range of disturbances and increasing shipping, such as ice breaking vessels destroying the pack ice habitat (Stenman et al. 2005).

6. Options for improvement

National seal conservation and management plans should be developed in order to ensure a proper conservation and management of all sub-populations during all life stages (ICES 2005). According to ICES WGMME Report (2005), it is important to address possible impacts on ringed seals when planning the use and exploitation of marine areas such as infrastructure development (e.g. shipping, oil transit, fixed links and wind parks). Regulations for shipping should in particular be implemented for ice breaking vessels during winter time. Further improvement of long-term monitoring and research programmes is needed. Ringed seals in the southern distribution range require more attention because current knowledge about vital population parameters is missing (ICES 2005). Further, the responsible national authorities should develop and coordinate their monitoring strategies regarding shared seal populations with neighbouring countries. HELCOM Recommendation 27-28/2 further recommends the Contracting Parties to collaborate within the HELCOM seal expert group to identify and establish a network of protected areas for important actual and potential seal habitats across the Baltic Sea area (re. the EU Habitat Directive, Annex II), and attempt to harmonise the regulations and monitoring of these conservation areas.

7. References

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

ICES 2005. Advice to HELCOM on seal and harbour porpoise populations in the Baltic marine area. http://sea.helcom.fi/dps/docs/documents/Nature%20Protection%20and%20Biodiversity%20Group%20(HABITAT)/HELCOM_ICES_EU%20Seal%20Workshop,%202005/3-1.pdf

Helle, E., Nyman, M & Stenman, O. 2005. Reproductive capacity of grey and ringed seal females in Finland. International conference on Baltic seals, 15–18 February Helsinki, Finland.

Härkönen, T. 2005. General principles for management of Baltic Seals. Presentation 1. HELCOM/ICES/EU Seal Workshop 2005. http://meeting.helcom.fi/web/habitat/1?p_p_id=110_INSTANCE_Yd0I&p_p_action=0&p_p_state=maximized&p_p_mode=view&_110_INSTANCE_Yd0I_struts_action=%2Fdocument_library_display%2Fview&_110_INSTANCE_Yd0I_folderId=73472

Harding, K.C. and T.J. Härkönen 1999. Development in the Baltic grey seal (Halichoerus grypus) and ringed seal (Phoca hispida) populations during the 20th century. Ambio. 28: 619-627.

Karlsson, O., Härkönen, T. and Bäcklin, B-M. 2007. Havet 2007. Avaliable from the Swedish Environmental Protection Agency.

Miettinen, M, Halkka, A., Högmander, J., Keränen, S., Mäkinen, A., Nordström, M., Nummelin, J. & Soikkeli, M. 2005. The ringed seal in the Archipelago Sea, SW Finland: population size and surveys techniques. International conference on Baltic seals, 15–18 February Helsinki, Finland.

Stenman O., Pöyhönen O. 2005. Food remains in the alimentary tracts of Baltic grey and ringed seals. Symposium on Biology and management of seals in the Baltic area, 15-18 February 2005 Helsinki, Riista- ja kalatalouden tutkimuslaitos 51-53.

Stenman O., Verevkin M., Dmitrieva L., Sagitov R. 2005. Numbers and occurrence of ringed seals in the Gulf of Finland in the years 1997-2004". "Symposium on Biology and Management of Seals in the Baltic area, 15 –18 February 2005 Helsinki, Riistaja kalatalouden tutkimuslaitos: 55-57

[1] http://marinebio.org/species.asp?id=185 and Härnkönen, T (personal communication)

[2] http://marinebio.org/species.asp?id=185