Image: Thomas Bjørkan
You might have heard about oceanic sea pens as the superior alternative to housing marine mammals within marine parks. Many claim them to be the magic solution to end captivity for cetaceans currently living in human care.
Unfortunately, the conversation too often leaves out the smallest details that are the largest problems.
Viruses, pathogenic bacteria and fungi, and parasites.
All are part of the biodiversity that live in our oceans. Seawater is teeming with microorganisms and infectious agents that have existed long before mammals. And they have everything to do with the sea pen debate.
There are 53 orcas known to be in human care and 32 of them have been born in this environment. There are also multiple orcas that are not the first generation but the second or third born in human care. The immune systems of these whales have adapted to the ever-evolving microbes they are naturally exposed to and the same is to be said for wild populations. However, the strains each population experience are different. Each host enables the virus to mutate; as they gain access to the host’s genetic material they evolve and adapt.
Wild populations are bound to be carrying strains of infectious agents that captive populations have no immunity against and vice versa.
If the point of all this is to save orcas, it is reckless and deliberately obtuse not to discuss the dangers of microbial pathogens.
An excellent and relevant example of a virus mutating amongst populations and crossing regions is the cetacean morbillivirus (CeMV).
What exactly is a morbillivirus? It may be more familiar to you than you think.
The National and Oceanic Atmospheric Association (NOAA), describes this pathogen as such:
“Morbilliviruses are in the family Paramyxoviridae. Specific morbilliviruses cause measles (in people), canine distemper (in dogs, coyotes, wolves, and seals), rinderpest (in cattle), and peste-des-petits-ruminants (goats and sheep). Five types of morbilliviruses have been detected in marine mammals in the United States: canine distemper virus (CDV) and phocine distemper virus (PDV) in seals and sea otters, and dolphin morbillivirus (DMV), pilot whale morbillivirus (PWMV), and Longman’s beaked whale morbillivirus (LBWMV), which are collectively referred to as cetacean morbillivirus (CeMV), in porpoises, dolphins and whales.”
Large-scale mortality caused by this virus is not a new occurrence and there have been novel strains that are phylogenetically distinct even within the same body of water. Simply stated, the morbillivirus is mutating and evolving to survive as microbes on Earth have done for billions of years.
One of the first mass mortality events caused by CeMV was recorded during 1987-1988 and affected Bottlenose dolphins along the East Coast from New Jersey to Florida. Over 700 dolphins of all ages were stranded, the majority of them dying within hours of washing ashore over 11 months. Another large-scale event affected thousands of striped dolphins in the Mediterranean Sea from 1990-1992. Since then, strains of CeMV have been found in cetacean mortalities in the Indian Ocean, Indo-Pacific regions, the eastern and western Atlantic, and the eastern and western coasts of Australia.
It has spanned multiple regions and adapted to infect varied marine mammal species over the last few decades. Recent studies hypothesize that current Atlantic/Gulf of Mexico populations are at risk of infection as older individuals that are immune, either from exposure or antibodies received while nursing, begin to die off. It would seem they are on the right track as over 1300 cetaceans in these regions have been found dead or stranded, testing positive for CeMV, from July 1, 2013 to June 29, 2014.
So why are the previous and current outbreaks of this virus relevant to the discussion of sea pens?
Because exposure is the most critical hurdle there is to clear before attempting to expose these two now completely separate populations to each other, even if it is through the walls of a sea pen. Viral transmission happens in varied ways such as blood or body fluids, fecal-oral routes, infectious vectors (ex: mosquitos), and airborne transmission.
Exposing orca populations to any strain of any pathogen is derelict in the ultimate goal to protect ecosystems. On our best day, scientists can’t expect to predict all of the potential pitfalls associated with such exposure or the dangers involved on a microbiological level. This one obstacle alone, cross-contamination and subsequent infection, relegates sea pens to what Dr. Naomi Rose recently accused marine parks of being – an experiment.
However, unlike parks and their staff, sea pens are in their infancy. It is cruel and apathetic to expose captive whales to pathogens they are biologically ill equipped to deal with. Just as it is grossly negligent to endanger wild populations to maladies we are ill equipped to prevent.
If anti-captivity supporters wish to continue to tout oceanic sea pens as the magical solution to the current living conditions of captive orcas, they have quite a bit of work to do.
Would you like to learn more about viruses currently afflicting wild populations of marine mammals? Below are links to help you learn more about morbillivirus, viral pathogens of marine mammals, and what you should do if you should encounter a stranded marine mammal.