Wild vs Captured Cetaceans
The stress of captivity induces many differences in captive and wild cetacean species. One of the biggest differences between them is their behaviours. Wild cetaceans are highly social animals that form complex social networks. Within these networks many cetacean species such as Orcas have highly unique traditions and rituals which include hunting behaviours, tactics, and unique signature calls (Animal Welfare Institute, 2024). Captive cetaceans can exhibit many abnormal and stereotypic behaviours such as hyper aggression, self-harm, oral stereotypies, calf rejection and failure to nurse (Marino et al., 2020).
Stereotypic behaviour can be described as a pattern of movement... that is performed repeatedly, relatively invariant in form, and has no apparent function or goal - Vaz 2017
Common Stereotypic Behaviours seen in Captive Cetaceans
Hyper Aggression
Hyper aggression can be directed towards humans, conspecifics, or both. This is thought to be in part due to the artificial groups that these animals find themselves in (Marino et al., 2020).
Self - Harming
Self-harm can be performed by ramming their heads on the sides of their concrete tanks or separation gates, actively exiting the tanks onto ledges for sustained periods (suspected method of conflict avoidance), and refusal to eat (Marino et al., 2020).
Oral Stereotypies
Oral stereotypies are the most prominent stereotypy observed which consists of biting and chewing on hard tank surfaces, hard toys, and steel separation gates. This behaviour is recognized as the cause of many chronic dental pathologies in captive cetaceans (Marino et al., 2020).
These stereotypic behaviours can be attributed to the cetaceans not meeting their behavioural needs and experiencing stress in their environment.
Another difference between wild and captive cetaceans is their pathologies. While disease exists among wild populations, animals in captivity have higher instances of infectious viral, bacterial and fungal disease, including but not limited to pneumonia, encephalitis, bacteremia, and leptomeningitis (Marino et al., 2020).
Many instances of disease in captive cetaceans are regarded as opportunistic infections, which are normally harmless but will infect animals under compromised conditions. Some of these diseases are endemic to their populations, however, there have been reported cases of diseases not normally found in cetacean populations.
Fungal pneumonia is the greatest cause of disease-related death in both captive and wild Orcas. However, there is an increased incidence of this disease in captivity due to excessive use of anti-fungal agents and the compromised immune systems of orcas due to poor welfare (Marino et al., 2020).
Because Captive cetaceans spend more time "logging", which is referred to as periods where the animal floats at the surface of the water motionless, they are at risk of vector-borne illnesses such as those carried by mosquitoes. In fact, there have been reports of orcas contracting and dying of St. Louis Encephalitis and West Nile (Marino et al., 2020).
Bent Dorsal Fins
In addition to behavioural and pathological changes in captive cetaceans, the most notable change in them is the folded dorsal fin, primarily seen in captive orcas. This condition has been reported in wild orcas but individuals with this condition make up less than 1% of the population (Alves et al., 2018). Bent dorsal fins is a condition seen in mostly captive orcas, with there being a greater instance of this occurring in males than females (Marino et al., 2020).
Though the exact cause of this issue remains unclear, there have been many rationales made for its occurrence such as increased gravity acting on the dorsal fin due to the whales spending more time at the surface, insufficient movement having an effect on the cartilaginous tissue structure, breakdown of cartilaginous tissue due to long exposure to warm air, or due to nutritional deficiencies (Alves et al., 2018).
