Memorial University – Dr. Craig Purchase

July 7, 2016


What technology is the most useful when it comes to restocking efforts?

Research underway at Memorial University is hoping to gain some insight with a project designed to look at the offspring quality of virgin/repeat spawning grilse salmon and the success of Jordan-Scotty incubators in conjunction with salmon reintroduction to Rennie’s River.

The ASCF has provided the university with $15,000 in funding; the research is being supervised by Dr. Craig Purchase, an Associate Professor of Biology & Ocean Sciences.

“Salmon conservation regularly requires restocking,” says Purchase. “Research has shown the method used to produce juveniles influences long term outcomes. Instream incubation provides natural conditions for fry and exposes embryos to ambient environmental conditions. Scotty-Jordan incubators provide one option for instream incubation, but are difficult to install in areas that lack gravel substrate. This project addresses how installation methods affect silt accumulation, and therefore hatch success in these incubators.”

He says this project builds on top of a restoration program in a St. John’s watershed and uses eggs from the Exploits River. Egg quality from two spawner types is also being compared through this effort.

“We broke the incubator installation comparison into 2 phases. Phase 1 was completed in November (2015), and Phase 2 began in December, but it will be late spring before they are removed from the river.”

“Starting in 2014, we have been comparing offspring quality of virgin versus repeat spawning salmon. We get 10-15% repeat spawning females each year in our samples (five fish in 2014, six fish in 2015) so this research needs to be repeated in multiple years to get a clear conclusion.”

Purchase said the grant for this research helped pay for the work on the 2015 spawners.

“We already know virgin/repeat status of females, we know egg sizes of each female and will shortly have information on egg colour. It will be a few months before we know egg chemistry and hatching/fry performance.”

This project has already achieved a number of goals – 100 sites were set up in Rennie’s River for restocking efforts; experimental incubation sites were set up as well for incubator installation comparisons.

Twenty-five volunteers helped stock the Rennie’s River watershed with 86,000 eggs at 86 sites.

The hatch success of the incubator sites will be determined in the summer of 2016.