During the last decades the number of grey seals Halichoerus grypus has increased more than tenfold in the Baltic Sea, having reached 38 000 in 2019, which has created increasing problems to the coastal fisheries. In the current study, 151 Estonian coastal fishermen were interviewed to sum all direct and indirect monetary losses. The total cost of the damage caused by seals to the Estonian fisheries was around 0.9 million euros in 2009. With the aim of mitigating seal impact, Acoustic Harassment Devices (AHDs, Lofitech) were tested. This study presents quantitative data on seal damage in Estonian trap-net fisheries and analyses the results of the attempts made to mitigate the damage by means of AHDs. It can be concluded that AHDs provided sufficient protection against the seal attacks.
Fjälling, A. 2005. The estimation of hidden seal-inflicted losses in the Baltic Sea set-trap salmon fisheries. ICES J. Mar. Sci., 62(8), 1630–1635.
https://doi.org/10.1016/j.icesjms.2005.02.015
Fjälling, A., Wahlberg, M. and Westerberg, H. 2006. Acoustic harassment devices reduce seal interaction in the Baltic salmon-trap, net fishery. ICES J. Mar. Sci., 63(9), 1751–1758.
https://doi.org/10.1016/j.icesjms.2006.06.015
Graham, I. M., Harris, R. N., Denny, B., Fowden D. and Pullan, D. 2009. Testing the effectiveness of an acoustic deterrent device for excluding seals from Atlantic salmon rivers in Scotland. ICES J. Mar. Sci., 66(5), 860–864.
https://doi.org/10.1093/icesjms/fsp111
Graham, I. M., Harris, R. N., Matejusová, I. and Middlemas, S. J. 2011. Do ‘rogue’ seals exist? Implications for seal conservation in the UK. Anim. Conserv., 14(6), 587–598.
HELCOM 2020.
https://portal.helcom.fi/meetings/EG%20MA MA%2014-2020-774/MeetingDocuments/Outcome%20of%20EG%20MAMA%2014-2020.pdf
https://doi.org/10.1111/j.1469-1795.2011.00469.x
Hemmingsson, M., Fjälling, A. and Lunneryd, S.-G. 2008. The pontoon trap: Description and function of a seal-safe trap-net. Fish. Res., 93(3), 357–359.
https://doi.org/10.1016/j.fishres.2008.06.013
Jacobs, S. R. and Terhune, J. M. 2002. The effectiveness of acoustic harassment devices in the Bay of Fundy, Canada: seal reactions and a noise exposure model. Aquat. Mamm., 28(2), 147–158.
Jounela, P., Suuronen, P., Millar, R. B. and Koljonen, M.-L. 2006. Interactions between grey seals (Halichoerus grypus), Atlantic salmon (Salmo salar), and harvest controls on the salmon fishery in the Gulf of Bothnia. ICES J. Mar. Sci., 63(5), 936– 945.
https://doi.org/10.1016/j.icesjms.2006.02.005
Kauhala, K., Kurkilahti, M., Ahola, M., Herrero. A., Karlsson, O., Kunnasranta, M. et al. 2015. Age, sex and body condition of Baltic grey seals: Are problem seals a random sample of the population? Ann. Zool. Fenn., 52(1–2), 103–114.
https://doi.org/10.5735/086.052.0209
Kreivi, P., Siira, A., Ikonen, E., Suuronen, P., Helle, E. and Riikonen, R. 2002. Seal-induced damage to salmon trap net fishery in the year 2001. Kalatutkimuksia, 185 (in Finnish).
Königson, S., Fjälling, A. and Lunneryd. S.-G. 2007. Grey seal induced catch losses in the herring gillnet fisheries in the northern Baltic. NAMMCO Sci. Publ., 6, 203–213.
https://doi.org/10.7557/3.2735
Königson, S., Lunneryd, S.-G., Stridh, H. and Sundqvist, F. 2009. Grey seal predation in cod gillnet fisheries in the Central Baltic Sea. J. Northwest Atl. Fish. Sci., 42, 41–47.
https://doi.org/10.2960/J.v42.m654
Königson, S., Fjälling, A., Berglind, M. and Lunneryd, S.-G. 2013. Male gray seals specialize in raiding salmon traps. Fish. Res., 2013, 148, 117–123.
https://doi.org/10.1016/j.fishres.2013.07.014
Lehtonen, E. and Suuronen, P. 2004. Mitigation of seal-induced damage in salmon and whitefish trapnet fisheries by modification of the fish bag. ICES J. Mar. Sci., 61(7), 1195–1200.
https://doi.org/10.1016/j.icesjms.2004.06.012
Lunneryd, S. G., Fjälling, A. and Westerberg, H. 2003. A large-mesh salmon trap: a way of mitigating seal impact on a coastal fishery. ICES J. Mar. Sci., 60(6), 1194–1199.
https://doi.org/10.1016/S1054-3139(03)00145-0
Mate, B. R. and Harvey, J. T. 1986. Acoustical deterrents in marine mammal conflicts with fisheries. In Proceedings of Workshop, Newport, OR, USA, February 17–18, 1986. Oregon Sea Grant, ORESU-W-86-001.
Oksanen, S. M., Ahola, M. P., Lehtonen, E. and Kunnasranta, M. Using movement data of Baltic grey seals to examine foraging-site fidelity: implications for seal-fishery conflict mitigation. Mar. Ecol. Prog. Ser., 2014, 507, 297–308.
https://doi.org/10.3354/meps10846
Sainsbury, J. C. 1996. Commercial Fishing Methods: an Introduction to Vessels and Gears. 3rd ed. Wiley, Hoboken, NJ.
Suuronen, P. and Lehtonen, E. 2012. The role of salmonids in the diet of grey and ringed seals in the Bothnian Bay, northern Baltic Sea. Fish. Res., 125–126, 283–288.
https://doi.org/10.1016/j.fishres.2012.03.007
Svels, K., Salmi, P., Mellanoura, J. and Niukko, J. The impacts of seals and cormorants experienced by Baltic Sea commercial fishers. Natural resources and bioeconomy studies 77/2019.
https://jukuri.luke.fi/bitstream/handle/10024/544854/luke_luobio_77_2019.pdf?sequence=1&isAllowed=y
Vanhatalo, J., Vetemaa, M., Herrero, A., Aho, T. and Tiilikainen, R. 2014. By-catch of grey seals (Halichoerus grypus) in Baltic fisheries – A Bayesian analysis of interview survey. PLoS One, 9(11), e113836.
https://doi.org/10.1371/journal.pone.0113836
Varjopuro, R. 2003. Conflicts between protected species and fisheries: social science research and policy approaches. TemaNord, 525.
Varjopuro, R. 2011. Co-existence of seals and fisheries? Adaptation of a coastal fishery for recovery of the Baltic grey seal. Mar. Policy, 35(4), 450–456.
https://doi.org/10.1016/j.marpol.2010.10.023
Vetemaa, M., Eschbaum, R. and Saat, T. 2006. The transition from the Soviet system to a market economy as a cause of instability in the Estonian coastal fisheries sector. Mar. Policy, 30(6), 635–640.
https://doi.org/10.1016/j.marpol.2005.08.001
Waldo, Å., Johansson, M., Blomquist, J., Jansson, T., Königson, S., Lunneryd, S-G. et al. 2020. Local attitudes towards management measures for the co-existence of seals and coastal fishery – A Swedish case study. Mar. Policy, 118, 104018.
https://doi.org/10.1016/j.marpol.2020.104018
Westerberg, H., Fjälling, A. and Martinsson, A. 2000. Seal-induced damage in Swedish fishery. Description and cost calculation based on logbook statistics and journal keeping in 1996–1997. Fiskeriverket rapport, 3, 3–38 (in Swedish).
Westerberg, H., Lunneryd, S.-G., Wahlberg, M. and Fjälling, A. 2006. Reconciling fisheries activities with the conservation of seals through the development of new fishing gear: a case study from the Baltic fishery – grey seal conflict. In Proceedings of the American Fisheries Society Symposium, 2006, pp. 587–597.
