Rainbow Trout, An Invasive Species for Nova Scotia?

When I was buying my fishing license this week I ran into Larry Short. He told me that two Rainbow Trout were caught in the Sackville River on opening day.

Why is this significant?

Well, they are not a native spices here. Back in November, a hurricane crashed into Nova Scotia.


There was an amazing amount of rain, screaming winds and waves of over 12 meters, that is about 40 feet, were reported in the ocean off the coast of Nova Scotia.

Hurricane Noel destroyed an aquaculture facility in the waters of Liverpool Bay. They lost about $1,000,000.00 in equipment and stock. The stock in this case was big Rainbow Trout that escaped.

Between Liverpool where this happened and the Sackville River are several salmon streams. I call them salmon streams but all of our Nova Scotia rivers have been severely damaged by acid rain and other human activities. The naturally breeding salmon stocks are extinct in many and endangered in all.





The Sackville Rivers Association has been working for years to rehabilitate these urban waters and re-establish a breeding population of Atlantic salmon in them. With some success, I might add. Nevertheless, it is a fragile victory.

These two Rainbow Trout could disrupt the whole program if they were carrying a pen-born disease. It could be a disaster if they are the harbingers of breeding pairs pioneering local waters.




I asked Larry if these fish were not triploid as much fish farm stock is.

Triploid fish are sterile because of a genetic manipulation. They have three sets of chromosomes instead of two (diploid) which is normal.

The advantage to fish farmers of using triploid fish in aquaculture is their rapid growth and weight gain. The disadvantage is their susceptibility to deformities and disease. It also means that escapees cannot reproduce and become an invasive species.

Larry told me that the problem is that even though triploid fish are being raised, not all of them are in fact sterilized. As in anything, there is a margin of error.

What does it all really mean?

Well, in talking to my fishing friends not all of them are unhappy about the fish escaping and entering our rivers. About half of the guys are looking forward to catching them if they can.

They point to Cape Breton, which has Rainbows and Steelhead in the rivers now, apparently from aquaculture escapees getting into the Bras D’Or Lake over the last twenty years or so. I have gone fishing for Steelhead there myself. (I did not get any so went salmon fishing instead).

Others fear the big picture. A new invasive species that just might be the straw that breaks the Salmon’s back.

The Rainbows are out of the cage now so only time will tell. It is too late for our opinions on the subject to have an effect but I would still be interested in hearing what you think.


Image of fish after storm on Beach Meadows Beach from the Queens County Times