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A diverse team of Canadian experts is studying the movement and habitat of young salmon as they migrate through the St. Jean, Dartmouth and York rivers in Quebec and across the Bay of Gaspé. The knowledge could help governments mitigate the effects of a worldwide decline in wild Atlantic salmon.

How do juvenile salmon move through rivers and estuaries to make their way to the sea? What is the best freshwater habitat for increasing their chances of survival during the first years of life? A first-of-its kind geomatics project – called Geosalar – is looking for answers.

With funding from the GEOIDE Network of Centres of Excellence (NCE), researchers and graduate students from Université Laval, the Institut national de la recherche scientifique (INRS), McGill University, Université de Montréal, University of British Columbia and the University of Durham in the U.K. are working with industry, government and conservation groups to develop new tools for tracking young salmon and constructing detailed maps of their habitats.

"We're developing one of the clearest geographic pictures ever taken of what's going on over the entire river landscape," explains Dr. Julian Dodson a biologist at Laval. "Our goal is to understand how fish exploit this mosaic of habitats across changing seasons as they grow, and if changes in the habitat are contributing to a decline in the salmon stocks. If so, we can look at what actions can be taken to ensure those nursery grounds continue to be viable."

First, the team needed an efficient and effective way to track young salmon while measuring the fluvial environment around them, including substrate size, water current speed and salinity levels. Until Geosalar, little was known about how much territory fish covered in a day, what conditions influenced their survival during the winter or what impact floods have on their mortality.

The challenges were far too complex for any one researcher, or single scientific discipline. Finding a solution would require the collective skill of experts from geomorphology (the study of landforms), fish ecology, oceanography, geomatics, resource management, telemetry and software programming, all working in close collaboration with industry, government, NGOs and conservation groups.

"Internationally, I think we're well out in front in taking such a multidisciplinary approach to these challenges," adds Dr. Dodson. "And the NCE, with its focus on networking and collaboration, makes this type of solutions-oriented research possible."

Dr. Dodson and Dr. Normand Bergeron of the INRS are the principal investigators of the Geosalar project, which began five years ago. The multidisciplinary team existed prior to Geosalar, but it lacked the necessary tools to take their research to the next level. They found their opportunity with GEOIDE.

"With the tools we had, we couldn't characterize the habitat over long river reaches or effectively track fish throughout their lifecycle," explains Dr. Bergeron, an expert in fluvial geomorphology (landforms created by running water) at the Centre Eau, Terre et Environment of INRS. "It was at this time that we heard of the GEOIDE Network and the fit seemed perfect because we needed to use or develop geomatic approaches to help us rapidly characterize the habitat over long river reaches and to track fish."

One of the project's first breakthroughs was by a post-doctoral student now working as a professor at the University of Durham. Dr. Patrice Carbonneau developed computer software that automatically translates high resolution aerial photos into maps that provide detailed measurements of the physical environment below, including water depth and even the size of pebbles on the riverbed. The maps can cover over 80 kilometres of river. "We were amazed at how precise we could get with this technology," says Dr. Bergeron. "This was the first time these types of maps had ever been generated. They provide a much better handle on habitat quality and the distribution of habitat quality over the riverscape."

The next challenge was to determine how juvenile salmon move through this physical environment during different periods of their life cycle and in real-time. With conventional tagging, researchers only knew where the fish was released and later caught – where it travelled in between was a mystery.

Research Participants - * Université Laval - * Institut national de la recherche scientifique - McGill University - University of British Columbia - University of Durham - Université de Montréal - ALCAN - Aquasalmo R&D Inc. - Atlantic Salmon Federation - Fisheries and Oceans Canada - Fondation pour le saumon du Grand Gaspé - GENIVAR - Hydro-Québec - Ministry of Natural Resources and Wildlife, Quebec * Lead institutions

The Geosalar team used acoustic transmitters to track young salmon as they abandon their freshwater nursery streams and venture out to sea. They also moored instruments to measure current, salinity and temperature. The data were then plugged into a hydrodynamic model, which government agencies and environmental consulting companies will be able to use to predict fish migration patterns and sediment movement.

Passive Integrated Transponder (PIT) technology was used to track even younger salmon, called parr. Dr. Bergeron's team developed a portable antenna to increase the detection range of parr from about 30 centimetres to about 1 metre, and a new 5-metre long portable antenna that can more rapidly scan large stream areas. They also modified the design of commercially available transponders in order to be able to mark fish as small as 8.5 cm.

The team is currently burying a wired network of 256 PIT antennas in the substrate of a small river in eastern Quebec. "This will provide continuous coverage of where the tagged fish are and when they move, over a 100-metre section of the river. This will be our major breakthrough for the year," says Dr. Bergeron.

The tools developed in the Geosalar project will help Canada and other countries to manage salmon stocks more effectively through better habitat management.

www.geoide.ulaval.ca