Tracking global environmental conditions, the movements of aquatic animals, the growth of the Network, members of the Network and their successes.
Modelling the Big Blue
Beyond Animal Tracking
Picturing the future of vast and dynamic oceans is challenging. Examining the environmental conditions that animals encounter is a critical aspect of understanding what drives their movements and survival and, in turn, helps us manage our use of the oceans for a sustainable future.
Today’s Information, Tomorrow’s Ocean
Modelling helps us see into the future. Experts can answer big questions about changes in our underwater world by tracking oxygen decline, plankton biomass, temperature and shifting sea ice in relation to animal movements. We’re not just tracking animals—we’re tracking oceans.
An Atlantic wolffish photographed in the waters around Nova Scotia.
Photograph by lloyd bond
Lives of Atlantic Salmon
Atlantic salmon have been a large focus of OTN research due to their ecological, cultural and socioeconomic importance. A network of tracking stations in the Cape Breton Bras d’Or Lake Biosphere Reserve is assessing mortality and survival strategies along migratory journeys and across tremendous spatial scales.
What has telemetry taught you about salmon movements in the Bras d’Or Lakes?
Our findings suggest that following spawning in late fall, salmon in poor condition with depleted energy reserves either died or left the river shortly thereafter, while salmon in better condition spent the entire winter in the river before migrating out to sea in the spring. It seems that this decision about when to leave the river may have a large influence on their longer-term survival.
What’s been the most surprising discovery?
Atlantic salmon are remarkable animals, often undertaking indirect, long-distance migrations to the coasts of Greenland to feed, and subsequently returning to spawn in the exact river in which they were born.
Why are Atlantic salmon important?
Atlantic salmon are very important ecologically, culturally and economically, but are declining throughout their global range, largely because of people. Here in Nova Scotia, most Atlantic salmon populations are now endangered and I feel that we have the responsibility to care for and protect them. This starts with gaining scientific knowledge on the factors contributing to mortality, especially at sea. What’s happening to salmon in the marine environment has largely remained a mystery.
What is the legacy of this research?
Our research has led to a better understanding of some of the factors contributing to differences in the mortality and habitat use of Atlantic salmon in the Bras d’Or Lakes after they spawn. We have also documented some of the consequences associated with current management practices on post-spawners, which has led to new questions about how these practices could be improved to minimize their impact on repeat-spawning rates, as well as on the role that repeat spawners play in population maintenance.
Xavier Bordeleau • HOMETOWN: Gatineau, QC • PhD Candidate (Dalhousie University)
Xavier Bordeleau prepares to release an externally tagged sea trout into the waters of the Kerguelen Archipelago.
Photograph by Clément Rio
A salmon kelt ready for release after being tagged in Cape Breton’s Middle River.
Photograph by Leah Strople
Mysterious Migrations of American Eels
Bordered by four ocean currents and unbounded by land, the Sargasso Sea in the North Atlantic Ocean is where the story of the American eel begins—and, if they’re lucky, ends.
One of North America’s most endangered fish, eels migrate thousands of kilometres to protective inland waters along North America’s eastern seaboard and mature for 10 to 25 years before beginning a perilous migration back to the Sargasso Sea, where adults die after spawning a new generation. Prior to OTN studies, over a century of research had failed to document the journey of American eels; electronic tags recorded the first formal observations of eels entering the Sargasso Sea, and revealed a two-phase migration. This is an important step in understanding routes and migration cues, which will help with conservation planning for this species.
An American eel slithers into an open spot in an underwater meadow of estuarine eel grass.
Photograph by Sean Landsman
Located 300 kilometres southeast of Halifax, surrounded by the mighty waters of the North Atlantic, lies a crescent-shaped sandbar called Sable Island. A sliver of iconic Canadian landscape, the island teems year-round with birds, wild horses and the world’s largest breeding colony of grey seals.
Novel Tags, Novel Data
OTN researchers outfitted grey seals with innovative tracking tags that enhance ocean monitoring by going where humans and robots can’t. Tags tracked the seals, but also collected oceanographic data and recorded interactions between seals and other tagged animals. These unwitting seal scientists revealed ocean “hotspots,” areas of high productivity or importance, which determine biodiversity in the Northwest Atlantic and Gulf of St. Lawrence.
A grey seal outfitted with tracking tags rests on the beaches of Sable Island.
Photograph by Damian Lidgard
Surviving the Journey
The longest river in British Columbia, the Fraser River flows almost 1,500 kilometres from the Rocky Mountains, through Vancouver’s bustling port and into the open ocean. The multitude of waterways that feed into the Fraser River are among the most ecologically rich in the world and are a nursery for Pacific salmon populations. Recently, survival of salmon at sea has changed for the worse.
More than 2,500 sockeye salmon, at all life stages, were tagged in a seven-year OTN study to capture information on their movements and survival. Documenting the movements of juvenile salmon, especially as they prepare to transition to life in saltwater, is crucial due to the high mortality they experience and what role this mortality plays in subsequent generations.