The control of predators, on land and in the sea, is a complex topic. Both marine and terrestrial mammal predators come into conflict with humans in Europe in many ways and yet their situations are rarely compared. Areas of conflict include the predation of livestock and farmed fish, and the perceived competition for wild prey (for example wolves competing with hunters for deer and seals competing with fishermen for salmon). A lethal method (shooting) and non-lethal methods of conflict reduction (including enclosures, guarding, and aversion) used for terrestrial large carnivores (e.g., bear, wolf, wolverine, lynx) and marine mammals (seals) are discussed. Control measures tend to be species- and habitat-specific, although shooting is a widely used method. Potential impacts on predator welfare are described and welfare assessments which have been developed for other wildlife control scenarios, e.g., control of introduced species, are considered for their potential use in assessing predator control. Such assessments should be applied before control methods are chosen so that decisions prioritizing animal welfare can be made. Further work needs to be carried out to achieve appropriate and widely-accepted animal welfare assessment approaches and these should be included in predator management planning. Future research should include further sharing of approaches and information between terrestrial and marine specialists to help ensure that animal welfare is prioritized.

This study examined the licensing system that permits seal shooting in Scotland, which was established under Part 6 Conservation of Seals of the Marine (Scotland) Act 2010. Four approaches were used: data were collated and analyzed from both the Scottish Government and Scottish Marine Animal Stranding Scheme; a survey was sent to current license holders and informal interviews were conducted with key stakeholder types. Between February 2011 and the end of October 2015, 1229 gray seals, and 275 common seals were reported shot under license to the Scottish Government. The numbers of seals reported as shot has reduced year-on-year since the licensing system was put in place. While some license holders, notably fish farms, were using some non-lethal forms of deterrent to reduce seal-related damage, these were often used alongside seal shooting. Of the seals reported as shot to the Scottish Government, only a small percentage were also reported to the Scottish Marine Animal Stranding Scheme, despite this being a licensing requirement. Only 2.3% of the shot gray seals and 4.5% of the shot common seals were necropsied. There is evidence from these necropsies that some seals had not died instantly or had not been shot in the manner recommended by the Scottish Seal Management Code of Practice. These preliminary results show that more carcasses need to be recovered and necropsied if the welfare implications of current seal shooting practice are to be properly assessed. The current legislation does not specify closed seasons to protect breeding seals and 35% of necropsied seals were pregnant gray seals. Seals have also been shot during their lactation periods when pups are dependent on their mothers. This raises significant welfare concerns. The re-introduction of closed seasons specific to each species of seal is recommended along with greater effort to deploy non-lethal methods. Independent assessment of the number of seals being killed would also improve the credibility of the system.

Predator control is also considered necessary in some places for preventing the escape into the wild of farmed fish (Butler et al., 2005). In Scotland, seal management has also had to take into consideration the required protection of Atlantic salmon (Salmo salar), common seals (Phoca vitulina) and grey seals (Halichoerus grypus) under the European Union (EU) Habitats Directive (Butler et al., 2006; Butler et al., 2015). Some European nations permit seal killing for commercial reasons to sell the skin, blubber and meat for profit (EFSA, 2007). Norway, Greenland and Russia carry out commercial hunts targeting harp seals (Pagophilus groenlandicus), and Greenland's hunters, many of whom are considered traditional subsistence hunters, also target bearded (Erignathus barbatus), hooded (Cystophora cristata) and ringed seals (Pusa hispida) as well as walruses (Odobenus rosmarus) (EFSA, 2007; Ministry of Fisheries, Hunting and Agriculture, 2012). Within the EU, seal products can only be placed on the market if they result from a hunt conducted by Inuit or other indigenous communities, if the hunt has been traditionally carried out by the community, if it contributes to the subsistence of the community and is not carried out for commercial reasons and if it "has due regard to animal welfare" (European Parliament 2009 and 2015). The EU Regulation on the trade in seal products has not prevented seal hunting in some places, for example Finland, but does mean that seal export markets cannot be developed (Meek et al., 2011). Seal hunting is a recreational activity in some regions and seals are regarded as game animals meaning that, even if they are killed for management reasons, the carcase may be collected for the personal use of the hunter. This occurs for example in Åland (an autonomous Swedish-speaking province of Finland),

The conservation of harbor porpoises (Phocoena phocoena) appears to be failing in Europe. There are particular concerns about this species in the Baltic Proper, Black, and Mediterranean Seas, as well as in the Northeast Atlantic, including the Iberian population, off the Spanish and Portuguese coasts. The Baltic Proper porpoise is “critically endangered,” with a population only in the low hundreds, and the Scientific Committee of the International Whaling Commission has repeatedly called for action to ensure its survival. In 2020, the Committee issued a series of recommendations relating to it and the Iberian population. Similarly, the Black Sea harbor porpoise, Phocoena phocoena ssp. relicta, is classified by the IUCN as endangered. Another population which may be genetically distinct is the West Greenland harbor porpoise, which is hunted without quotas or close seasons. European cetaceans and their habitats are covered by a number of international and regional conventions and agreements and, under European Union law, are “highly protected.” In practice, however, these legal protections have failed to generate effective conservation. For example, Special Areas of Conservation (SACs) are required for them and, although sites have been designated in some marine areas/countries, in the absence of appropriate management plans, SACs cannot be expected to help improve the harbor porpoise's conservation status. Compared to many other species, porpoises are relatively long-lived with low reproductive capacity and only poor public recognition. Conservation and management efforts are caught up in a complicated nexus of interactions involving a web of commitments under international conventions and agreements, European environmental laws, and European fisheries policy. However, public disinterest, lack of political will to implement conservation measures, and complicated fishing-related issues hinder any real progress. More positively, recent advice from the International Council for the Exploration of the Seas (ICES) provides a new scientific foundation for conservation action to address fisheries bycatch in the Baltic Proper harbor porpoise population. Populations of other porpoise species (family Phocoenidae) are also threatened, most notably the global population of the critically endangered vaquita, or Gulf of California porpoise (Phocoena sinus). The common threats and factors affecting porpoise populations are discussed and recommendations offered.

Dolphins are typically regarded as highly social animals. However, some individuals live apart from their own species and may come to socialize with people through a recognized series of stages which are presented and expanded on in this paper. The term “solitary-sociable dolphins” has been used to describe these animals and such individuals have been identified from several different species and reported in many parts of the world. In many instances, the interactions with people that may follow their original isolation, and which typically become more intense over time, have created situations where the welfare of the animal has been compromised by disturbance, injury, the feeding of inappropriate items and aggressive human behavior. Several solitary-sociable dolphins have also been deliberately injured and killed by humans. People who interact with these dolphins may also put themselves at risk of injury. This paper reports on recent cases drawing on published and unpublished sources. Since 2008, 32 solitary dolphins have been recorded including 27 bottlenose dolphins (25 Tursiops truncatus and two Tursiops aduncus), two striped dolphins and three common dolphins. Four solitary belugas have also been recorded. There are some ten solitary dolphins and one beluga known at the present time. Laws and guidelines currently in place to protect solitary-sociable dolphins need to be strengthened and interactions with people should be avoided or, at the least, carefully managed to protect both the dolphin and the humans involved in the interaction. Terms, such as disturbance and harassment which are included in laws need to be clearly defined. Additionally, management plans for solitary-sociable dolphins need to be developed and adapted on a case by case basis taking into account the individual dolphin's sex, age, personality, stage of sociability and home range. It is also important that government officials and local stakeholders work together to implement guidelines which set out how the public can observe or interact with the dolphin safely.