Aquatic Zoos - Captive Animals Protection Society

significantly change most of their procedures in the few years that have passed). If something this view
of the inner working of public aquaria shows us that there are many animal health problems to
encounter when running public aquaria, and death and disease occurs on a regular basis in them. Quite
far from the image that visitors can experience when moving slowly under the underwater tunnel at the
sound of a relaxing soft tune.
Despite most of the health problems of captive fish going unnoticed by the general public, on some
occasions the problems of a high profile aquarium inhabitant do make it to the press. For instance, in the
year 2001, ozone problems in the main aquarium tank caused by equipment failure made the National
Marine Aquarium in Plymouth loose four of their valuable sandbar sharks (Anonymous, 2001a), which
was widely publicised.
Sometimes the health problems do not originate in the public aquarium display, but in any of the other
activities the aquarium is involved, such as during fish capture and transport. For instance, a previous
batch of another four sandbar shark at the National Marine Aquarium also died in 1998 soon after arrival,
probably killed by hypothermia after their flight to the aquarium was delayed (Anonymous, 2001a). This
was not only an animal welfare tragedy, but had conservation implications since sandbar sharks in the
wild travel from the Atlantic Ocean where they are obliterated by one fishery, to the Gulf of Mexico
where they are caught by another. This means that, in addition to the captures for public aquarium
displays, these shark populations are being hit twice, and because they grow very slowly (a 17 year old
sandbar was found to be still immature, and it is considered that females do not mature until they are
nearly 30 years old) their populations are slow to regain numbers and are therefore vulnerable to overfishing
(Bright, 1999). In fact, the survival rate of sharks during transport is often not very impressive.
Young et. al (2002) found that for the scalloped hammerhead shark it was 83% for Beijing aquarium,
83% for the Oceanarium of Lisboa and 33% for the Rotterdam Zoo Oceanarium.
The safe capture and transport of sharks present several challenges due to key features of shark
anatomy and physiology. Important issues include risk of trauma, overexertion, hypoxia, circulatory
compromise/collapse, hypoglycemia, metabolic acidosis, hyperkalemia, and environmental accumulation
of toxic metabolites leading to declining water quality. In addition to capture techniques, some of the
factors contribute directly to a fatal exertional rhabdomyolysis syndrome or ‘capture myopathy’
(Greenwell, 2003), also known as “over standing disease” for terrestrial animals (one of the most
important causes of death in wild ungulates that are captured for translocation).
Once in the aquarium many sharks do not survive for long, since they are very susceptible to bacteria
and fungi infections (Bright, 1999; Grimes et al, 1884). For instance, 69% of the sharks kept at the
National Aquarium of Baltimore between 1981 and 1988 died within a year, which was attributed to their
inability to acclimatise. 103 mortalities occurred, and from the 71 sharks with a definite cause of death,
51% died due to infections, 31% to trauma and 18% were euthanised (Hecker et al.1989).
In other cases disease suffered in public aquaria may contribute to the extinction of threatened species.
An example of this is the captive breeding programme to save the Charco Palma pupfish Cyprinodon
longidorsalis, which was discovered in the early 1980’s and it is considered extinct in the wild since 1991.
A captive population exists in one US institution, London zoo and in the London aquarium. However, fish
tuberculosis (Mycobacterium) was discovered in the British captive population which led to the
euthanasia of all the symptomatic fish, which in turn threatened the success of the captive breeding
programme (Spinks, 2003). This is not an isolated case, because the presence of Mycobacterium
infection in marine and freshwater fish kept in aquaria has been a continual problem for zoological
collections (Nyaoke et al., 2000).
Some species are more susceptible than others to the shortcomings of captive life, and therefore are
more prone to illness and death. Cephalopods (octopuses, squid, cuttlefish and nautiluses), as seen in
the reports above, seem to be a group of animals particularly affected by captivity. Octopuses are very
sensitive to water quality and the tropical ones cannot survive without reef-quality water conditions
(Haywood & Wells, 1989). Most are nocturnal and prefer subdued light, not always available in public
aquaria for the visitors’ sake. Elevated concentrations of heavy metals, especially copper, are especially
deadly to invertebrates. Octopuses are also extremely sensitive to low concentration of dissolved oxygen.
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