New study: Unusual occurrences of marine mammals outside their natural habitat

Out of habitat marine mammals – Identification, causes, and management recommendations

A new scientific publication titled Out of habitat marine mammals: Identification, causes and management recommendations, published in the renowned journal Marine Policy, examines the increasingly frequent cases of marine mammals appearing outside their usual habitats. The study involved the participation of Morigenos, which has long been actively engaged in international projects dedicated to the research and conservation of marine mammals. The research was led by colleagues from OceanCare, a long-standing partner organisation with which Morigenos maintains close and productive collaboration.

These so-called out-of-habitat (OOH) cases refer to individual animals appearing far from their natural range or in environments that are no longer suitable for them – often as a result of food scarcity, habitat degradation, pollution, or frequent human interaction. The study emphasises that such events are becoming increasingly common, with primary causes including climate change, the loss of Arctic sea ice, changes in prey availability, underwater noise, disease, and the escape or release of animals from captivity.

The publication presents a wide range of documented cases, including belugas in the Thames and Seine rivers and walruses resting along European coastlines. Similar occurrences have also been recorded in Slovenia – such as a humpback whale observed in Slovenia in 2009, two striped dolphins sighted in the Port of Koper in 2012, and the recent appearances of the common dolphin Ciao.

The authors stress that each situation requires careful, case-specific evaluation. In some instances, monitoring and public communication may suffice; in others, intervention such as relocation is needed. In rare and extreme cases, euthanasia may be considered. All decisions must be based on a thorough assessment of the animal’s welfare, its health condition, and the broader environmental context.

The study also underscores the importance of clear and responsible communication with the public. High levels of human interaction can cause stress, behavioural disturbance, or even danger to both animals and people. In one such case, a female walrus had to be euthanised after repeated failures by members of the public to respect safety guidance. The authors therefore call for stronger institutional coordination, well-defined response protocols, and an appropriate legal framework to enable timely, science-based, and welfare-oriented responses to such events – which are expected to become increasingly frequent in the face of ongoing environmental change.

Read the full study HERE