Pollution from hydrocarbons can affect marine mammals both:
- directly, causing poisoning and chronic irritation to sensitive tissue,
- indirectly by being ingested over time and asphyxiating species.
Further study into this subject is required.

Persistent organic pollutants such as PCBs (polychlorinated byphenyls), meanwhile, build up in the mammals’ fatty tissue. As predators, the mammals are often at the end of the food chain, so are likely to be more contaminated than other marine animals as a result of the bioaccumulation phenomenon. This large build-up of pollutants can have negative biological effects on cetaceans: physical weakness, reproductive problems.

Pesticides such as DDT also pose problems including malformation, cancer and other issues adversely affecting reproductive and immune systems, which can make animals more vulnerable and cause increased illness (as with morbillivirus infection, for example). Furthermore, these chemical pollutants are transferred through the fat-rich milk that mothers feed to their young when nursing.

Heavy metals (mercury, lead etc.) also cause physiological problems, mainly affecting the nervous system.

We should also note that there are other types of pollutants in the Mediterranean – urban waste and household liquid waste, which is sometimes untreated before disposal.

Management options

• Implementing existing agreements and recommendations to fight marine pollution (RAMOGE Agreement, ACCOBAMS)
• Manage and monitor areas
• Environmental impact studies that include marine mammals
• Water Framework Directive (WFD)
• Marine Strategy Directive Framework (MSDF), etc.