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DFO experiment aims to give insight on escapee farm fish movement
Published on October 06, 2014
Where do they go?
What do farmed salmon do if they escape from their sea cages?
An experiment being carried out this fall by the Department of Fisheries and Oceans (DFO) hopes to get the answer to that question.
Geoff Perry, Director of Aquaculture for this province with DFO, told The Advertiser the department will organize a small, controlled release of tagged farmed Atlantic salmon from southern Newfoundland sites over the next three years to learn more about the movement and behavior of fish that escape from aquaculture pens.
The department is conducting the research in collaboration with Northern Harvest Sea Farms, and with the support of the Aboriginal community: Qalipu Mi’kmaq First Nation Band and the Miawpukek First Nation (Conne River).
The project got underway in September with the first group of fish tagged and released from three farm sites in Fortune Bay.
Perry said three groups of fish were released – some in the 100 gram class; some were about one pound while others were in the two to four kilogram weight class.
“We will be releasing fish from different farms and that have a different life history,” Perry said. “Some more fish will be released later this fall while the other three release groups will be set free in 2015.”
Each of the fish released carries a surgically-implanted transmitter device. The transmitter emits a signal, which can be spotted and recorded by electronic receivers.
DFO has a network of receivers in Fortune and Hermitage Bays to listen for the transmissions and help track the movements of escaped fish.
Through this study, DFO aims to determine how far salmon disperse from their cages after an escape; what direction do they go in; what are the environmental conditions that drive them; do they lead the shore as wild salmon tend to do in their movements and what role does wind and water temperature play in their movement.
“If we can understand what escaped fish will do when they get out of cages it will help us understand the potential impact they could have on wild salmonids,” Perry said in an interview.
“It will also help us to develop measures to prevent those interactions with wild salmon populations. We may have a fishery for them or, if we know where they are going, we can direct companies that own them to go get them. We could also have an angling fishery for them, similar to the program now in use in the Bay d’Espoir area.”
While the final results of the release program may not be known until 2016, DFO officials are hoping to have some preliminary information as early as this fall.
“We’ll get to pick up the receivers this winter,” Perry said. The data collected by the receivers is then downloaded to a computer program for assessment and study.
“We’ve heard reports that at least one of the fish was eaten by a tuna or a shark, which is consistent with what we would expect. Farmed fish have a high mortality rate once they escape, as they don’t know how to avoid predators.”
One of the more curious questions the study may answer is how long farmed salmon stay around their cages after an escape. A similar study on rainbow trout about 15 years ago shows this species will stay around the cages for about 10 days in the summer before dispersing. In the fall, however, they tend to leave the cage sites very quickly.
According to Perry, similar studies in Norway showed that escaped salmon leave the cage site area very quickly after an escape.
“This issue of escaping salmon is one that has to be monitored. The main overall concern is do these fish enter fresh water, are they spawning and do they interact with wild fish?
“The aquaculture industry is controversial with many people on the pro and con side of the industry. We are trying to use science to make science-based management decisions to avoid the emotional side of the escapee issue.”