Gary:

I concur with one of your points if you are referring to the introduction of non-native pathogens/parasites. But as mentioned earlier, introduction of pathogens/parasites already existing in native populations is a non-issue for the reasons I stated.



As you probably am aware, I am a 'nuts and bolts' type of person and adhere to the position that one should stick to facts or application of basic scientific principles. To rely on unsupported, anecdotal information, perceptions, impressions, and the like is classical junk-science. The need to take the 'precautionary approach' is invariably based of speculative conjecture without supporting evidence and is yet another example of junk-scence.



Let me comment on the following quote: "It is commonly reported that upper respiratory tract disease in wild desert tortoises was spread due to the release of infected captives:"



You are correct in that it is "commonly reported" but when you examine this issue, the original reports I have viewed were stated as speculation. Subsequent citations repeat that speculation with the difference being that changes sometimes occur in word usage to indicate that the original position was stated as fact. This scenario is an example of how certain aspects of scientific endeavors (citing previous reports) goes amok.



A similar example of which you might be aware deals with reports on the diet of the Sharp-tailed Snake (Contia tenuis). A scientific note by Darling (1946) mentioned that of the 20 odd Contia he captured near Corvallis, Oregon, a number of these specimens regurgitated slugs. Not long after, another researcher reported that the Sharp-tailed Snakes contain unusually long teeth suitable for grasping and holding onto slugs. If you read subsequent citations concerning Contia, you will note that some indicate that slugs are reported to be the exclusive prey of Contia. When I read some of those subsequent reports, from a biological perspective that did not make sense. I have demonstrated that Contia consume other prey besides slugs and thus those that mentioned Contia as preying only on slugs were sloppy in their referencing the original information.



This same situation is what also has occurred with the tortoise situation only the extent of the 'overkill' in this situation suggests that vested interests are also at play. Last year I looked into tortoise disease situation and found no hard evidence to indicate the disease originated in captive specimens and then was tranmitted to wild populations. Some of the individuals that have mentioned that point lack objectivity in that they do not mention the more likely, opposite scenario that the disease in captive populations came from infected specimens taken from the wild.



To propose (openly advocate) that captive specimens are the original source of the disease and infected wild populations is tantamount to stating that the disease organisms were created under captive conditions. It doesn't seem to dawn on these alarmists that all existing pathogens and parasites already exist in the natural world and get into captive populations when wild specimens with the disease organisms are brought into captivity.



Another way of viewing this issue is to examine what has occurred when the non-native species, Starling, Nutria, parrots, lizards, snakes, innumerable plant species, invertebrates, etc., were introduced into N. America. Such exotic species were subjected to pathogens to which they had never been exposed. That such pathogens and parasites could have held them in check for some time may have occurred. However, suseptable individuals succumbed and left populations of disease tolerant individuals.



Even the scenario of the release of exotic disease organisms

is likely to be blown out of proportion to existing evidence. When exotic pathogens are introduced, they have the possibility of causing immediate problems as has been the case with the West Nile virus. But eventually, instead of extinction occuring amongst our native species of wildlife (or plants), it is far more likely that natural resistance factors in our native species will eventually produce populations that are tolerant or resistance to the introduced desease organisms.



Richard F. Hoyer

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