Mary river turtle, article from The Guardian

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The Mary River turtle - Elusor macrurus was removed from the IUCN redlist of top 25 most threatened turtle species thanks to conservative efforts by AFT breeding, head-starting and releasing over 500 captive bred specimens over a decade long project. Latest population surveys show the turtles are breeding successfully in the wild and surviving with good recruitment numbers of individulas recorded across all stages from hatchlings, juveniles, sub adults and adults. The biggest win for the Mary River turtle was the prevention of the Traverston dam project. That would have sealed and stamped their extinction.

Captive bred Mary River Turtle hatchy.
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The biggest win for the Mary River turtle was the prevention of the Traverston dam project. That would have sealed and stamped their extinction.


What about the turtles in Lake Borumba and upstream of that dam? Aren't they a viable population or are they animals which pre-date the building of the dam? (For those playing at home, Lake Borumba is on a tributary of the Mary called Yabba creek, it joins the Mary river near Imbil.) First version of the dam was built in 1963.

While fishing in that lake I have seen plenty of those long tailed units there. I'm guessing they were Marys.

Cheers,
Dave.
 
Mary's may well be present in Lake Borumba but being a species that relies heavily on riffle zones and highly oxygenated water for cloacal respiration, like Rheodytes leukops - (up to 80%) and staying submerged without surfacing to breathe for 30 days at a time, they would be ageing animals not contributing to the population. Also, unlike many other native species of turtles that will excavate nest chambers in anything from clay, dirt, gravel, in grass in the middle of a field, Mary's will only nest in steep sloping north facing sand banks absent of vegetation adjacent to riffle zones (essential for hatchlings), like those found throughout various stretches of the Mary river. The average nest site is located 2.3m above water level with a straight line average distance of 11m from the water. Nesting females will use the same location every season, returning to within a few feet of the exact location they nested previously. They are true river divers and have evolved and adapted to thrive in a specific habitat, they're not pond or dam turtles like Chelodina longicollis.
With the Mary's specialised biology, it wouldn't cope with any dramatic changes to the river. Are you familiar with the documented disaster for turtles in the late 80's?? Man made lake Mokoan in northern Victoria caused turtles to stop breeding, the aquatic vegetation and aquatic life died when the lake filled to capacity and some 620+ turtles died from starvation.

Mary's naturally occur throughout the Mary from the salt restriction wall 4km north-east of Mungar to Kenilworth. They're also known to be in Tinana creek, Yabba creek and Obi Obi creek.
Myself with a Wild caught Mary River turtle from Obi Obi creek in AFT's 2013 population survey.
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As a freshwater fisho, I'm no fan of man made barriers either.
I know what you mean, I'm an avid angler of the local stocked freshwater impoundments, I regularly chase Murray Cod and Golden Perch at Lake Cooby and Australian Bass at Lake Cressbrook. Unfortunately none of these species will breed and spawn in a closed dam or lake situation and regular stocking of fingerlings is necessary.

Good plate sized golden perch from Lake Cooby.
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And even though I wasn't targeting jew, they're always a sure-catch in Cooby when fishing live earthworms. These eel-tailed catfish are also superb table fish. Great eating.
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The Mary River turtle - Elusor macrurus was removed from the IUCN redlist of top 25 most threatened turtle species thanks to conservative efforts by AFT breeding, head-starting and releasing over 500 captive bred specimens over a decade long project. Latest population surveys show the turtles are breeding successfully in the wild and surviving with good recruitment numbers of individulas recorded across all stages from hatchlings, juveniles, sub adults and adults. The biggest win for the Mary River turtle was the prevention of the Traverston dam project. That would have sealed and stamped their extinction.

Captive bred Mary River Turtle hatchy.
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I have a couple of questions for you Kev if you don't mind. First question is, how much of the Mary River turtles' existential problems actually relate to wild collecting in the 50's and 60's as suggested in the "Guardian" article versus the not reported or glossed over issues of land degradation and clearing, predation by feral animals and so on. I am betting wild collecting even in a population with such a restricted range was not the quintessential factor that actually pushed this species to the edge.

The fact is that, individuals taken into captivity have actually been instrumental in providing a rescue and recovery population that has virtually ensured the survival of this turtle species. That and the prevention of the Traverston dam project as you said. I love this sort of success. It totally vindicates what I have been saying to our wildlife authorities down here for the last several months as part of our wildlife licensing and management systems review being conducted by OEH currently. As far as I am concerned captive bred animals can where needed and should be when needed used to reintroduce and reestablish wild populations where they have disappeared or face serious disappearance risks and that wildlife authorities should see this potential as part of their review process into public and private keeping of native animals.

I hope there is one particular biodiversity officer from OEH that I sat next to in a species list meeting a couple of months ago who reads this because I can see a big fat egg all over her screwed up angry face. This particular woman had the shortsightedness to actually state in an open forum in front of 20 odd people many of whom were PHD qualified scientists and experts, that once an animal is taken from the wild it has no further ecological value as far as wild populations are concerned. The venom in her statement was palpable. Talk about an idiot. This is the sort of nutter that would rather see millions of animals die in land clearing and being eaten by feral cats then be taken into captivity with a view to saving their lives and potentially their species. She would rather leave them at the mercy of the bulldozers and feral cats. She justifies this by the old quality of life argument that is allegedly taken away from them in captivity. As we all know most animals bought into captivity actually enjoy a far superior (and usually considerably longer) quality of life then their wild counterparts. Every time I think of that encounter with that OEH employee I just shake my head in absolute dejection, dejection for the fact that these people are actually influencing and impacting on policy making and decisions regarding the keeping of native animals and the collection of wildlife for captive breeding programs including by private keepers and organisations such as AFT.

Second question or probably more an observation actually is, if the Mary River Turtle has been taken off the IUCN Red list of top 25 turtles facing extinction, then what is the zoological society of London doing placing it at number 30 on their Evolutionary Distinct and Globally Endangered List for Reptiles in April of this year. Surely there is some sort of a problem with respect to their information or reporting of information perhaps. How can a species that is not even in the top 25 in its own family for extinction risk according to the universally accepted and respected IUCN Red list be at number 30 for extinction risk for the whole order of reptiles GLOBALLY in the Zoological Society of London's list.

I know both lists are subjective but I think something is not right here. Be interested in your thoughts.

Mark Hawker
 
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Hello Mark, as for question #1 you are spot on. The modification of the river catchment and predation on eggs and hatchlings by introduced predators must bear the responsibility for the extent of decline that has persisted, particularly over the last 40 years since egg collection ceased. Management actions to protect known high density nesting sites from predators and trampling by stock have resulted in hundreds of hatchies entering the system in recent times.

For some "paper pushing self proclaimed expert" to say that an animal once removed from the wild has zero ecological value as far as wild populations are concerned is RIDICULOUS. Look at what captive specimens are doing right now for the Bell's turtle, Bellinger River snapper and soon, the Manning River turtle! That woman is an absolute twit and her views and opinions have no value or importance whatsoever to someone like myself.

Captive animals do enjoy a better quality of life and their breeding success and survival rate (with turtles in particular) is dramatically increased in captivity. Less than 1% survive in the wild to reach adulthood. Take the Jardine river turtle for example, was thought to be extinct in the wild for years... until their rediscovery in 2013. Whilst thought to be extinct, AFT was busy breeding them and holds a world record for the most successive clutches from a single trio, 15 clutches in 15 consecutive months with 100% success rate. The story was published in Scales&Tails volume 1. No wild turtles would ever breed with that frequency and success.

The Zoological society of London's listing I assume would be taking into account the fact that the Mary with its specialised biology and very limited natural range is at a high risk of extinction if any further major changes occur to the river system and it's tributaries and increasing pressures of land degradation by clearing and farming practices. Whilst the current population numbers are increasing and signs are positive, (reflected in the IUCN red list removal) they'll always be at risk as their range is highly restricted and they're habitat specialists unable to adapt to drastic change which is likely to occur at some point as the human population and urban sprawl creeps ever further. All studies carried out on Elusor macrurus indicate a complex biology that's tied intimately to the structure and flow of the river. Upset the river and interfere with land use practices and this species will simply vanish forever.
 
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