By: Daniel Stanton
Flash back: ‘Sea Cages’ hit the mainstream media with the reintroduction of Keiko.
There are some who believe sea cages are a better alternative for marine mammals in human care – especially killer whales. The idealistic notion that a killer whale would be better off in a sea cage rather than a perfectly controlled and healthy aquarium environment is just that – idealistic.
In fact, there too many variables ignored by the activists in their effort to support and push for sea cages and those variables can result in an almost certain death.
While Keiko is the most famous and unsuccessful reintroduction project, there was another whale in Japan that suffered a similar fate.
Her name was Nami. While her death was caused by various pathogens, it was her location that made her susceptible to such pathogens. Nami was in a sea cage.
Nami was on display in a sea cage located off of Taji Whale Museum for many years before being relocated to the Port of Nagoya Public Aquarium where she died in January of 2011.
During a necropsy, The Port of Nagoya Public Aquarium veterinarians found that Nami had 491 stones weighing a total of 81.4 kilograms (179.5lbs) in her stomach. There are no stones in the pool where Nami was kept at the aquarium in Nagoya, which indicates that the stones were consumed wile she was in the sea cage.
Swallowing stones is well known in birds and large reptiles like crocodiles, but marine mammals can also swallow stones. Scientists don’t know why marine mammals consume stones, but it likely acts as either a digestive aid to break up hard parts of food or they could be used in dealing with intestinal parasite infections.
They also swallow stones when they go through long periods without food so that stones prevent the stomach from shrinking, which is directly linked to a loss of organ function. Essentially, the stones keep the stomach busy when food is not available to digest. Some scientists also believe that whales eat stones to adjust their buoyancy.
When whales are overfed and overweight, the adipose tissue causes problems with their specific gravity and they have a harder time submerging in water. The stones act as ballasts to increase the weight of the whale. Some seals have as much as 11 kilograms of stones in their stomachs to act as a ballast adjustment.
While this necropsy finding was shocking, the most significant finding was that this is the first reported case of zygomycosis caused by Cunninghamella.
Bertholletiae in a marine mammal. C. Bertholletia (Abdo et al. 2012). C. Bertholletia is a zygomycetous (Zygomycete spore forming) fungus that lives in soil in subtropical climates. It can also be found in animal waste along with other sources. C. Bertholletia infections are often highly invasive, and can be more difficult to treat with antifungal drugs than infections with other species. In humans this pathogen is deadly in immunocompromised human patients. There have also been a few cases of endocarditis, epicardial artery thrombosis and at least 17 other cases involving the heart resulting from C. Bertholletia, and other zygomycetes (Abdo et al. 2012).
According to The Orca Project, Nami’s cause of death was Fungal Bacterial Pneumonia, Stomach Ulcers, Myocardial Fibrosis, Heart Failure and Chronic Colitis after swallowing the stones over the course of many years at the Taiji Whale Museum. There are no stones in the pool where Nami was kept at the aquarium in Nagoya, which indicates that the stones were consumed wile she was in the sea cage.
However, the histopathology reports the cause of death was severe bronchopneumonia in conjunction with degenerative changes in the liver and systemic lymphadenitis that may have been the result of opportunistic microflora causing subsequent septicemia. Additional secondary infections of common microflora such as P. miarbilis, P. aeruginosa, and P. oryzihabitans likely resulted from Nami becoming immunocompromised.
While this is the first documented case of zygomycosis associated with C. Bertholletia, one must ask an important question. Would Nami have contracted this fungal infection if she was not in a sea cage and did not have access to the rocks of the sea pen and surrounding area?
Would she have swallowed the stones that were found in the sea pen if she was not immunocompromised? And did the fungal infection lead to her eating more rocks than what how many rocks would have she ingested without the infection? We may ever know the answers to these questions but one thing is certain – Nami acquired the fungal infection from her sea cage, therefore sea cages can kill.
Daniel Stanton has a passion for animals and conservation. He holds a Master’s of Science Degree in Biology from Winthrop University where he did his thesis on the evolution of circadian clock genes in the lower Metazoa. He is a Sr. Biological Scientist and has experience in various areas of biology. Mr. Stanton has presented his research at many scientific meetings and worked on many scientific publications in collaboration with fellow researchers. He believes that one person can make a difference and create a wave of positive change.
Source: Abdo, W., Kakizoe, Y., Ryono, M., Dover, S.R., Fukushi, H., Okuda, H., Kano, R., Shibahara, T., Okada, E., Sakai, H. and Yanai, T., 2012. Pulmonary zygomycosis with Cunninghamella bertholletiae in a killer whale (Orcinus orca). Journal of comparative pathology, 147(1) 94-99.