390
The Biology of Sea Turtles, Vol. II
of ecosystem and wild population health, it is equally likely that most of the
infectious agents that will cause disease in captivity have their source in the wild
and were introduced into captive collections through inapparently affected animals.
Thus, what is learned from captive animals may become extremely valuable in the
face of an epizootic in the wild population. For example, FP was first described in
captive green turtles at the New York Aquarium in 1938, but was not recognized as
a significant threat (Smith and Coates, 1938). In the mid 1980s, however, when FP
emerged as a worldwide problem in green turtles, these early descriptions became
extremely valuable for clinicians trying to understand the disease (Herbst, 1994).
Similarly, LET disease was first described at Cayman Turtle Farm (Jacobson et al.,
1986). The herpesvirus that was found to be associated with this disease in captivity
has not yet been isolated in wild turtles with similar clinical signs. However, there
is now a body of serologic evidence that wild green and loggerhead turtles are
exposed to this virus (Coberley et al., 2001a; 2001b). Furthermore, marine turtles
may be kept in zoos, aquaria, and rehabilitation centers as educational and tourist
exhibits, and also in large numbers as part of captive breeding, farming, and “headstart” programs. In situations in which captive animals may be released to the wild,
their health problems may directly impact wild populations (Jacobson, 1996).
Captivity provides a number of advantages in the study of marine turtle health
and diseases. First, because diseases are likely to occur, and occur with high incidence,
captivity provides an excellent opportunity for discovery and description of new
diseases and infectious agents if the animal care program involves adequately trained
and observant professional staff, including a consulting veterinary clinician and
pathologist. Captive collections allow for ready access to animals, intensive monitoring with longitudinal observations and repetitive sampling of individual turtles, and
thorough diagnostic workups that include access to sophisticated diagnostic tools.
Thus, the opportunity for detailed investigation is very good. Second, turtles in
captivity may provide access to life stages such as pelagic posthatchlings and juveniles
that are very difficult to observe and sample in the wild. Infectious agents that may
only cause clinical disease and mortality in a specific susceptible life stage may not
be observed among free-ranging animals because of the improbability of recovering
ill and dead animals in the field. Third, captive collections provide a resource for
development and improvements in diagnostic tests and procedures, and improvements
in treatments, either through planned clinical research or empirically through practice.
The study of disease processes occurring in wild marine turtle populations, on
the other hand, is extremely important because conservation efforts are aimed at
protecting and managing viable free-ranging stocks. Certain diseases and infections,
especially parasitic infections, are more likely to be seen in wild populations because
quarantine procedures and prophylactic treatments given to captive turtles may
remove ecto- and endoparasites and disrupt complex parasitic life cycles. The natural
environment also provides the full range of factors and variables that may be
important in diseases that have complex etiologies. It is important for one to appreciate the extent and severity of diseases in sea turtles in their natural environment:
to know what is “out there” as a reality check. One must always be aware, however,
that biased observation and sampling of wild populations may reinforce the perception that primary disease is rare in wild populations.
1123 book.book Page 390 Monday, November 11, 2002 11:11 AM
The Biology of Sea Turtles, Vol. II
of ecosystem and wild population health, it is equally likely that most of the
infectious agents that will cause disease in captivity have their source in the wild
and were introduced into captive collections through inapparently affected animals.
Thus, what is learned from captive animals may become extremely valuable in the
face of an epizootic in the wild population. For example, FP was first described in
captive green turtles at the New York Aquarium in 1938, but was not recognized as
a significant threat (Smith and Coates, 1938). In the mid 1980s, however, when FP
emerged as a worldwide problem in green turtles, these early descriptions became
extremely valuable for clinicians trying to understand the disease (Herbst, 1994).
Similarly, LET disease was first described at Cayman Turtle Farm (Jacobson et al.,
1986). The herpesvirus that was found to be associated with this disease in captivity
has not yet been isolated in wild turtles with similar clinical signs. However, there
is now a body of serologic evidence that wild green and loggerhead turtles are
exposed to this virus (Coberley et al., 2001a; 2001b). Furthermore, marine turtles
may be kept in zoos, aquaria, and rehabilitation centers as educational and tourist
exhibits, and also in large numbers as part of captive breeding, farming, and “headstart” programs. In situations in which captive animals may be released to the wild,
their health problems may directly impact wild populations (Jacobson, 1996).
Captivity provides a number of advantages in the study of marine turtle health
and diseases. First, because diseases are likely to occur, and occur with high incidence,
captivity provides an excellent opportunity for discovery and description of new
diseases and infectious agents if the animal care program involves adequately trained
and observant professional staff, including a consulting veterinary clinician and
pathologist. Captive collections allow for ready access to animals, intensive monitoring with longitudinal observations and repetitive sampling of individual turtles, and
thorough diagnostic workups that include access to sophisticated diagnostic tools.
Thus, the opportunity for detailed investigation is very good. Second, turtles in
captivity may provide access to life stages such as pelagic posthatchlings and juveniles
that are very difficult to observe and sample in the wild. Infectious agents that may
only cause clinical disease and mortality in a specific susceptible life stage may not
be observed among free-ranging animals because of the improbability of recovering
ill and dead animals in the field. Third, captive collections provide a resource for
development and improvements in diagnostic tests and procedures, and improvements
in treatments, either through planned clinical research or empirically through practice.
The study of disease processes occurring in wild marine turtle populations, on
the other hand, is extremely important because conservation efforts are aimed at
protecting and managing viable free-ranging stocks. Certain diseases and infections,
especially parasitic infections, are more likely to be seen in wild populations because
quarantine procedures and prophylactic treatments given to captive turtles may
remove ecto- and endoparasites and disrupt complex parasitic life cycles. The natural
environment also provides the full range of factors and variables that may be
important in diseases that have complex etiologies. It is important for one to appreciate the extent and severity of diseases in sea turtles in their natural environment:
to know what is “out there” as a reality check. One must always be aware, however,
that biased observation and sampling of wild populations may reinforce the perception that primary disease is rare in wild populations.
1123 book.book Page 390 Monday, November 11, 2002 11:11 AM