Common Bottlenose Dolphins are typically found in coastal waters, over the continental shelf, in archipelagos and around offshore islands, but they also inhabit offshore waters (Bearzi et al. 2009, Hammond et al. 2013, ACCOBAMS 2021, Hammond et al. 2021). They occur in both nearshore and offshore waters over continental shelves and can also be found in highly enclosed bays (Bearzi et al. 2008, 2016, Gonzalvo et al. 2016), in river estuaries and even several kilometers up rivers (Sackl et al. 2007, Genov, unpublished data). While many local populations demonstrate strong and long-term site fidelity, long-distance movements have been documented in several areas (reviewed in Genov et al. 2022).

Diet is highly varied, including demersal species such as European hake (Merluccius merluccius), European conger (Conger conger), Red mullet (Mullus barbatus), Saithe (Pollachius virens), Striped red mullet (Mullus surmuletus), Haddock (Melanogrammus aeglefinus), Common cuttlefish (Sepia officinalis), Common octopus (Octopus vulgaris), Sand steenbras (Lithognathus mormyrus), Rubberlip grunt (Plectorhinchus mediterraneus), Common pandora (Pagellus erythrinus), Snake blenny (Ophidion barbatum) and Gobius sp., bentho-pelagic or semi-pelagic species like the Atlantic horse mackerel (Trachurus trachurus), Whiting (Merlangius merlangus), blue whiting (Micromesistius poutassou), Annular sea bream (Diplodus annularis), Bogue (Boops boops), Cod (Gadus morhua) and epipelagic species such as European pilchard (Sardina pilchardus), Round sardinella (Sardinella aurita) and European anchovy (Engraulis encrasicolus), as well as Salmon (Salmo salar) (Santos et al. 2001, 2007, Bearzi et al. 2009, Giménez et al. 2017, Milani et al. 2019, Borrell et al. 2020).

The Common Bottlenose Dolphin is known to be a behaviourally highly plastic species (Lewis and Schroeder 2003, Daura-Jorge et al. 2012), which is also the case in several European areas (Wilson et al. 2004, Piroddi et al. 2011, Genov et al. 2019a, Díaz López et al. 2019, Bonizzoni et al. 2022). This potentially makes it more resilient to any human-induced changes in its ecosystem, but also makes it more likely to interact with human activities, particularly fisheries. Bottlenose Dolphins appear to be strongly attracted to trawlers and fish farms as observed in several coastal areas of the Mediterranean, where they have adapted to opportunistic foraging near these human activities (Piroddi et al. 2011, Bonizzoni et al. 2014, Genov et al. 2019a, Bonizzoni et al. 2022).

Common Bottlenose Dolphins are widely distributed throughout most of European waters, including the North Atlantic Ocean, the North Sea, Mediterranean Sea, and the Macaronesian archipelagos. They have been reported in the waters of Albania, Belgium, Croatia, Cyprus, Denmark, Finland, France, Germany, Gibraltar, Greece, Ireland, Italy, Malta, Monaco, Montenegro, Netherlands, Norway, Portugal, Slovenia, Spain, Sweden, Türkiye and the United Kingdom, while the Black Sea subspecies T. t. ponticus has been recorded in countries along the Black Sea. Sightings in Finland, Sweden and Poland are considered extralimital and therefore not mapped.

Common Bottlenose Dolphins typically occur in inshore and coastal waters, in archipelagos and around offshore islands, but can also be found in offshore waters (Bearzi et al. 2009, Hammond et al. 2013, ACCOBAMS 2021, Hammond et al. 2021). Local distribution appears to be driven by a number of factors, including bathymetry and physiographic habitat characteristics (Cañadas et al. 2002, Cañadas et al. 2005), prey distribution (Giannoulaki et al. 2017) and anthropogenic factors such as fisheries and aquaculture (Piroddi et al. 2011; Genov et al. 2019a, Bonizzoni et al. 2022) or seasonal recreational boat traffic and underwater noise (Fortuna 2006, Rako et al. 2013).

Resident or semi-resident populations have been documented in various parts of the Mediterranean Sea (Bearzi et al. 1997, Bearzi et al. 2008, Díaz López and Shirai 2008, Genov et al. 2008, Gnone et al. 2011, Pace et al. 2012, Gonzalvo et al. 2014), along the Atlantic coasts (Augusto et al. 2012, Giménez et al. 2018, Methion and López 2018), in the English Channel (Louis et al. 2015), around U.K. and Ireland (Ingram and Rogan 2002, Pierpoint et al. 2009, O'Brien et al. 2010, Cheney et al. 2013), and around Macaronesian archipelagos (Silva et al. 2008, Tobeña et al. 2014, Dinis et al. 2021).

Existing conservation actions
The Common Bottlenose Dolphin in Europe is protected under a number of treaties, including the EU Habitats Directive, ACCOBAMS, ASCOBANS, CITES Appendix II, CMS Appendix II and Barcelona Convention SPA/BD protocol Annex II. As a priority species listed in Appendix II of the EU Habitat Directive, several Special Areas of Conservation have been declared in EU waters for the protection of Common Bottlenose Dolphins. Management units have been identified in most EU countries for the monitoring of Descriptor 1 of the Good Environmental Status for the Marine Strategy Framework Directive. Important Marine Mammal Areas (IMMAs) have been identified in the Mediterranean Sea.

Conservation actions needed to mitigate major threats
This species: (a) is mainly (but not only) found coastal areas and over the continental shelf), (b) its distribution range overlaps substantially with areas subjected to very high levels of anthropogenic activities; (c) exhibits a population substructure, with social and cultural differences, high-site fidelity, natal philopatry and apparently limited genetic exchange across the European region. The following concrete conservation actions are deemed necessary to finally implement already existing conservation measures (Natoli et al. 2021):

1) Monitor impact of measurable threats (in particular, fishery bycatch, seismic surveys, chemical and plastic pollution, boat traffic and underwater noise) and, simultaneously, mitigate pressures by actually regulating these human-activities. In practice, this would imply:
a) Implement a fishery related mortality mitigation framework
b) Develop and implement standardized assessment protocols to address habitat degradation and harassment (including displacement caused by boat traffic, acoustic pollution, marine constrictions) to guide stakeholders in EIAs procedures.

2) Improve the knowledge on the overall European population structure and assess the status of putative resident populations and their trends. This knowledge feeds into all above listed processes. In particular:
a) To better define the genetic populations structure of this species, it is necessary to increase sampling in offshore areas and non-sampled sub-regions.
b) To stimulate photo-identification, acoustic and behavioural data comparisons.
c) To carry out the large-scale surveys (e.g. SCANS, ACCOBAMS ASI, etc.) on a regular basis, including in so-far poorly surveyed regions, such as Macaronesia. Such surveys would allow comparisons to assess temporal trends in distribution and abundance across Europe.