November 3, 2016

Everyone deals with change in their own way, and Atlantic salmon are no different. But how is their behavior and health affected by a major change in their surroundings?

The town of Holyrood, Newfoundland is involved in a research project to get a better understanding of how juvenile Atlantic salmon adapt to long-term habitat alterations.

Lead by Jim McCarthy, a part-time UNB PhD candidate, the two-year project has been granted a total of $19,200 in funding from the Atlantic Salmon Conservation Foundation.

The town is supporting the research in Holy Cross Park (Mahers River) which allows an entire river reach to be converted from flowing river habitat to a large pool for extended periods. The reaction of juvenile salmon to these fluctuations will be researched using a variety of innovative methods.

“The project generally entails the use of a small park in Holyrood that has a pool that’s created every summer as a ‘natural’ laboratory to investigate how salmon juveniles react to rapid and permanent changes in habitat,” said McCarthy. “The pool that’s in the park is actually part of a small stream that has a salmon run every year.”

“Each summer, a small dam is closed on the stream to create a pool in a section of the stream in a matter of hours. The dam generally remains closed until early September when it is opened and the pool rapidly drains and becomes a small stream again. Researchers are able to easily look at how young salmon react to storm events which occur over a relatively short timespan but it is difficult to investigate long-term (an entire growing season) habitat changes of this magnitude.”

McCarthy said his team is gathering information from juvenile salmon using a number of techniques such as population estimates – electrofishing – to look at potential changes in fish density and Passive Integrated Transponder (PIT) tagging of young salmon.

“PIT tagging allows us to track the movements of individual salmon as they move in and out of the pool habitat.  We’ve also collected small fin samples to be used in stable isotope (carbon and nitrogen) analysis – this can tell us if the fish change feeding patterns because of the changes in their habitat.”

“We’re hoping that the information gathered from the young salmon that live in the stream can teach us about how they react to these habitat changes that can be associated with human development such as hydroelectric developments. It will allow us to use the information to develop better assessment methods as well as more effective offsetting measures.”

McCarthy said the project is progressing as expected with a full year of PIT tagging data almost collected.

“We’ve also gathered population information both before (in June) and after (late August) the pool was created and have isotope samples ready to be shipped to the lab.  We have also collected environmental data such as water temperatures, flows, and food (invertebrates) throughout the summer months.”