Long-term field studies are critical for safeguarding biodiversity: a new concept and concern

The data file associated with Figure 1b provides population data from the Kattegat-Skagerack harbour seal (Phoca vitulina). Historical data are reconstructed based on bounty statistics (1). Data from 1970 are based on systematic annual surveys (2,3,4). Projections beyond 2023 are hypothetical illustrations of potential population developments inspired by a population projection model (3).

1 Heide-Jørgensen, M.-P., and Härkönen, T. J. (1988). Rebuilding seal stocks in the kattegat-skagerrak. Mar. Mammal Sci. 4, 231–246. doi: 10.1111/j.1748-7692.1988.tb00204.x.

2 Härkönen, T., Dietz, R., Reijnders, P., Teilmann, J., Harding, K., Hall, A., et al. (2006). The 1988 and 2002 phocine distemper virus epidemics in European harbour seals. Dis. Aquat. Organ. 68, 115–130. doi: 10.3354/dao068115.

3 Silva, W. T. A. F., Bottagisio, E., Härkönen, T., Galatius, A., Olsen, M. T., and Harding, K. C. (2021). Risk for overexploiting a seemingly stable seal population: influence of multiple stressors and hunting. Ecosphere 12. doi: 10.1002/ecs2.3343.

4 SMHI (2020). SharkWeb. Available at: https://sharkweb.smhi.se/hamta-data/ [Accessed March 6, 2023].