Adopt-A-Fish update – May 11, 2006
 a turtle fitted with a transmitter. |
spiny softshell turtles
By MATT JAEGER
Montana Fish, Wildlife and Parks
GLENDIVE – We’ve learned and written quite a bit about the fish in the Missouri-Yellowstone Adopt-A-Fish program, but there are two other radio-tagged species out there that weren’t included this year – sauger and spiny softshell turtles.
For the last 30 years, much of our research and monitoring effort on the Yellowstone River has been focused on sauger because of declines in numbers and their popularity as a game fish. During that time, we’ve learned quite a bit about sauger biology, including how sensitive this species can be to changes in habitat.
Every year, Yellowstone River sauger migrate up to 500 miles between where they spawn and their home locations. Even more impressive is the ability of individual sauger to successfully return to the same particular habitats.
Like other species in the Missouri-Yellowstone River Adopt-A-Fish program, sauger exhibit remarkable fidelity to certain areas. One particular radio-tagged sauger spent most of the summer, autumn, and winter in a small bay created by a side channel downstream of the Big Horn River. Each spring she migrated 150 miles downstream to spawn below the Powder River, then went back upriver to the exact same bay.
Movements of this sauger are telling us about the factors that may have contributed to declines in some areas. Sauger move long distances on the same routes to very specific habitats, which the presence of dams or other barriers may block.
This particular fish, like most of our radioed sauger, moved to parts of the Yellowstone River with especially muddy water to spawn. Luckily for sauger, the Powder River is usually a reliable source of muddy water and sauger abundance remains high downstream of this tributary.
However, the Big Horn River also used to provide muddy flows and support large spawning runs of sauger. Following the construction of Yellowtail Dam, the Big Horn and Yellowstone became much clearer than they were historically.
As a result, the strong spawning runs in those areas disappeared and sauger became relatively rare in the 60 miles between the Big Horn and Cartersville Diversion Dam at Forsyth.
Fish are currently being followed to learn more about our ability to monitor and predict changes in population levels. Sauger are also being tagged with yellow plastic spaghetti tags to study survival and harvest rates.
If you capture a sauger with a yellow tag, please call Fish, Wildlife and Parks at (406) 234-0900 in Miles City and report the tag number even if you release the fish.
The other fish we’re tracking isn’t a fish at all – it’s a turtle. Wildlife and fisheries biologists are teaming up and radio-tagging spiny softshell turtles to learn more about their distribution, movements, and habitat use in the Yellowstone River. Although this species appears to be doing very well in the Yellowstone, it is rare in the Missouri below Fort Peck Dam. Because little is known about habitat preferences, the causes of this rarity in some areas are unclear.
We’ve only been tracking spiny softshell turtles for a short period but have already made some interesting discoveries. Turtles moved one to 10 miles between the time they were tagged late last summer and the onset of winter conditions.
They became active again about a month ago and are primarily occupying side channel and backwater habitats with muddy bottoms. It is possible that these areas are being used for nesting and will be monitored closely in the coming months.
However, our most interesting finding so far has to do with where turtles aren’t, rather than where they are. Turtles become fewer and fewer in number as you go downriver. In fact, no turtles were captured downstream of Sidney, where the stream bottom transitions from gravel and cobble to sand and silt.
That turtles are absent from this reach, which is similar to the Missouri below Fort Peck Dam, is especially puzzling considering their preference for similar habitats upstream.
As we learn more about habitat needs in coming years we’ll gain a better understanding of why spiny softshell turtles are abundant in some areas but rare in others.
Weekly updates on our radio-implanted fish can be found on the Missouri-Yellowstone Adopt-A-Fish home page with updates posted Thursday mornings in April and May. Just click on the Find your Fish button on the home page.
School classrooms, youth fishing clubs and home schoolers can sign up for the program and adopt and name two fish. Just go to the Web site and click on the How To Adopt Button or send us an e-mail at Missouri-Yellowstone Adopt-A-Fish.
Adopt-A-Fish correspondents Dave Fuller, at Fort Peck, and Matt Jaeger, at Glendive, are fisheries biologists with Montana Fish, Wildlife and Parks. They’ll post weekly updates every Thursday throughout April and May on this site and in the Outdoors section of The Billings Gazette.