and they smell bad, too
Montana Fish, Wildlife and Parks
Our only finless participants in the Missouri-Yellowstone Adopt-A-Fish Program have been even more anxious than us for ice to recede from the river and water temperatures to warm.
Spiny softshell turtles, a newcomer to the program, had been burrowed in the river bottom hibernating throughout the cold winter months. But as air and water temperatures begin to rise, they’re slowly being lured out from hibernation to start looking for a meal after a long winter’s rest.
Water temperature is the primary factor that determines when spiny softshell turtles emerge from their hibernation sites. Although it’s unknown exactly when our turtles will emerge from hibernation, in other parts of their range turtles do not become active until water temperatures rise above 50oF, which the Yellowstone River has just reached.
Once spiny softshell turtles do become active for the year, it seems that most of them wake up on the wrong side of the bed (or river?). These turtles generally have a disposition that matches their odor, which can be foul!
Even though it makes dealing with them a little tricky, their hostile mood is part of what makes capturing these turtles to attach radio transmitters exciting.
To catch our turtles, we set hoop nets baited with chunks of rotting fish – the smellier the better.
Spiny softshell turtles are considered “generalist carnivores,” which means they’ll eat just about anything the can get a hold of including crayfish, aquatic insects, mollusks, worms, isopods, amphibians, and live fish.
However, over a third of their diet can be comprised of dead fish similar to those we use in our traps, which they can smell from long distances in muddy streams and rivers.
We’ve captured turtles in habitat types ranging from swift riffles to stagnant sloughs but our highest catch rates are in the kind of muddy back waters where you sink up to your waist while slipping and sliding through with a turtle trap.
When we return the next day to check our traps we often know how succuessful we were even before we pull the net from the water. If we chose a good location there can be more than a dozen long necks of angry turtles reaching out from the trap in out in all directions.
Although biologists trying to attach transmitters to bears and mountain lions are certainly dealing with much more dangerous caged animals, considerable care must be taken when confronting a net full of angry spiny softshell turtles.
As we drag our nets up onto the riverbank it’s important to keep it at arms length. Many of the captured turtles once again outstretch their long necks, this time straining towards the biologists carrying the nets in hopes of delivering a sharp and lightning-quick bite.
One unlucky graduate student working with our crews walked too close to a net containing several turtles and received a deep, bleeding wound from a bite to the leg. This ability to strike quickly serves turtles well as they hunt for or ambush prey and try to defend themselves from predators.
Once turtles are successfully captured and radio tagged one might think they live up to their stereotype of being slow moving and lethargic at first glance when comparing their movements to those of other species in the Adopt-A-Fish program. While some of our fish species migrate over 500 miles each year most turtles have home ranges of only a few miles.
However, when they want to, these turtles are capable of making movements that would gain the respect of even the most migratory of our fish species; one turtle near the Big Horn River moved over 20 miles between summer and winter habitats in just a few weeks.
To learn more about Missouri-Yellowstone Adopt-A-Fish and follow radio-implanted fish and turtles, just go to www.pikemasters.com and click on the Adopt-A-Fish link. Teachers can sign up their classes for the program, name their two adopted fish and join in on the fun.
Matthew Jaeger is a fisheries biologist with Montana Fish, Wildlife and Parks at Glendive.