New Frog Rearing Practices at Cedar Creek

New Frog Rearing Practices at Cedar Creek
By Graduate Research Associate Andrea Martin

Frog season has arrived in Western Washington! Cedar Creek Corrections Center is now home to 315 tadpoles.  Oregon spotted frog eggs were brought into the prison from Black River and Conboy Lake Wildlife Refuge by Washington Department of Fish and Wildlife biologists.  There was a significant die-off initially of the Black River eggs; we lost 54 of the initial 158.  Happily, the organisms from Conboy have had a much higher success rate; only four of the original eggs never hatched.

Cedar Creek is undergoing several significant changes in rearing protocol this season.  These changes are designed to provide consistency amongst all of the institutions raising Oregon Spotted Frogs, of which SPP and Cedar Creek are only one of four.

The most significant change is the implementation of net pens to raise the eggs and tadpoles.  In the last 3 years, the eggs have been raised in shoebox-sized plastic bins until they were big enough to be moved to tubs large enough to hold up to 200 growing frogs.

The net pens are a square foot in area, and provide floating habitats for the growing tadpoles.  SPP staff made 20 of the pens using PVC piping to create the enclosure.  The nets were clipped onto the pipes so that they would hang through the middle, and floating mats were cut into strips and secured with zip ties to give the pens extra buoyancy.  Between 15 and 20 tadpoles live in each net pen.

The shoeboxes required much more attention to water quality than the nets.  In the net pens, fecal matter and most extra uneaten food falls through the nets and into the larger tubs, making water changing a less demanding and less frequent chore.  The shoeboxes require multiple water changes every day.  Our rearing partners switched to the net pens last year.

While frequent water changing wasn’t a problem for Cedar Creek, water temperature was problematic.  The shoeboxes were kept inside the shed where the inmates raise crickets.  Because of the small space and the multiple heat lamps, the room is usually at least 70 degrees, and sometimes would get much hotter.  It was nearly impossible to get the water temperature below 70 for the tadpoles, when 65 would be a more preferable.

In the net pens submersible water heaters can keep the large outdoor tubs regulated at 65 degrees, which provides a more realistic environment, and also has a higher oxygen concentration for the growing tadpoles.

So far the transition has been a success, with no tadpole mortalities.  It has been a fun learning process for all parties to record the successes and drawbacks of this new rearing protocol.  We all hope this is the beginning to another successful frog season!

A Cedar Creek frog technician inmate cleans out the net pens with a turkey baster. Photo by A. Martin.

The net pens float in the larger tubs, making water changes less frequent, and water temperature more consistent..JPG The net pens float in the larger tubs, making water changes less frequent, and water temperature more consistent.

The net pens float in the larger tubs, making water changes less frequent, and water temperature more consistent..JPG The net pens float in the larger tubs, making water changes less frequent, and water temperature more consistent. Photo by A. Martin.

To donate to SPP and support the rearing of Oregon spotted frogs in Washington state, click here.

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