Modelling the big blue (4.1)

Using observations and mathematical ocean models, this project examined the effects of physical and biogeochemical ocean changes on OTN study species such as American eel, Atlantic sturgeon and Atlantic salmon. Models contributed to understanding the underlying mechanisms of observed movement patterns. Use of these models in several studies had direct implications for more effective management. For example, by combining observations and model-simulated projections of oxygen decline on the Scotian Shelf with known habitat requirements of endangered Atlantic wolffish, researchers showed that oxygen depletion is likely reducing wolffish habitat. Additionally, these models are a) helping in the analysis and interpretation of data from ocean sensors (OTN project 4.1), b) helping determine environmental conditions and their effects upon the swimming ability of adult Atlantic salmon (OTN project 4.4), c) have helped elucidate the effect of currents and oceanographic conditions on American eel migration (OTN project 4.5), and d) are allowing the characterization and prediction of winter aggregation sites of Atlantic sturgeon in the Bay of Fundy (OTN project 4.6).

Roboprobes (4.2)

In 2010, the OTN ocean-observing (glider) component launched one of the first glider-based oceanographic observation programs in Canada. In collaboration with MEOPAR, the glider program currently operates seven gliders: one Liquid Robotics Wave Glider, and six Slocum Gliders. One of the major questions framed by OTN Canada is how oceanographic and environmental features affect animal habitat use, movement and migrations. Gliders collect an array of physical, biological and chemical data and describe key ocean processes relevant to both animal-tracking research and weather and sea-state forecasting. Combined, OTN’s gliders have spent more than 2,000 days at sea, traversing a distance of more than 48,000 kilometres and collecting 70 million data points along the way. OTN and its industrial partners pioneered the autonomous offload of data by the Wave Glider from bottom-mounted acoustic receivers (first achieved in 2014), and the Wave Glider is now a regular, cost-effective alternative to expensive manual data retrieval using ships. Gliders have been deployed on missions in support of the WHaLE project, which passively listens for whales in the rich feeding habitats of the North Atlantic in order to understand critical habitat use and provide real-time monitoring to mitigate ship strikes. Gliders are also used in other OTN studies to track tagged salmon, cod, eels, snow crab, sharks and seals throughout the Atlantic, Pacific and Arctic.

Fitbits for animals (4.3)

OTN accelerometry research has led to significant advancements in biologging tag design. Maritime bioLoggers, a spin-off company created and led by two OTN students, has emerged as a leader in Canadian biologging technology development. Within OTN, these tags have been used in a suite of studies that first successfully showed the relation of fish acceleration to changing body size, with the potential to estimate fish growth rates in the wild. Studies were then expanded to examine movement ecology in a range of ocean predators, including Atlantic grey seals, Pacific halibut and North Sea flapper skate. A large-scale study involving researchers across the Atlantic region used accelerometer tags to validate at-sea time budgets and prey-capture events in grey seals (OTN project 4.7). In collaboration with the International Pacific Halibut Commission, accelerometer tags deployed on halibut in Alaska allowed determination of their activity levels in the summer months, prediction of habitat use and importance of the area for adults. Accelerometer tags were also used to assess habitat use of endangered flapper skate in a collaboration with the Scottish Government, with the aim to deliver the scientifically based information required for evaluation and renewal of an MPA in Scotland.

The mysterious migrations of American eel (4.5)

The long-distance migrations of endangered American eels have puzzled and fascinated scientists for over a century— no adult has ever been caught in the open ocean or at their putative spawning grounds in the Sargasso Sea. The movement patterns of juvenile (yellow) and adult (silver) eels from the St. Lawrence River to the Sargasso Sea were investigated beginning in 2010. Multiple complementary approaches were used, including acoustic and satellite telemetry, numerical modelling (OTN project 4.1) and chemical analysis. Acoustic receivers were deployed from the upper St. Lawrence River to the mouth of the Gulf of St. Lawrence, where 604 eels were acoustically tagged to determine the timing and pathways of this migration segment. Although detection rates were unexpectedly low, data revealed extensive variability and downstream migrations of more than 200 kilometres over 13 to 67 days using nocturnal ebb-tide transport to leave the Gulf. The oceanic migrations of adult eels were investigated using pop-up satellite archival tags, which recorded eels’ positions over a three-month period before releasing from the eels and transmitting their archived data via satellite. Data from 60 satellite-tagged adult eels revealed substantial predation by porbeagle sharks before exiting the Gulf. The at-sea trajectories were reconstructed for 27 eels, including five tracked all the way to the Sargasso Sea, providing the first formal observation of adult eels entering their spawning grounds. These tags recorded epic oceanic migrations of more than 2,700 kilometres using similar paths and against ocean currents, indicating a degree of consistency but also complexity in the orientation and navigation mechanisms employed throughout the migration. Findings resulted in extensive media coverage, including in National Geographic.

A ‘tail’ of two sturgeon: part I   (4.6)

Sturgeon are long-living, late-maturing animals with a complicated anadromous life cycle (living mostly at sea, and returning to freshwater to spawn). This OTN project primarily studied threatened Atlantic sturgeon in two areas of the Bay of Fundy—Minas Passage, Nova Scotia, and the Saint John River, New Brunswick. This research program has filled critical knowledge gaps on sturgeons’ complex life history and population dynamics, spatial and temporal movement patterns, overwintering areas, growth, diet, survival and abundance. In Minas Passage, data have provided insight into the controversial overlap of the sturgeon population with deployed and proposed in-stream tidal turbines. This is helping researchers and managers assess potential negative impacts of tidal power infrastructure on these and other species of concern. The results are being used directly by DFO and other regulators to improve management regimes for conservation and protection of Atlantic sturgeon. In the Saint John River, studies have revealed the distribution and timing of migrating adult Atlantic sturgeon to and from the river, as well as the timing and location of spawning. In addition, studies of both Atlantic and shortnose sturgeon determined movement and aggregation areas of juveniles within the Saint John River, which offered the first evidence that overwintering juveniles made regular movements among sites and suggested competition for foraging areas and prey existed between the two species. These studies provided the basis to develop the OTN project on Pacific white sturgeon in the Fraser River, British Columbia (OTN project 4.14), and to incorporate accelerometry studies (OTN project 4.3) into sturgeon research.

Seal scientists (4.7)

The bioprobe project advanced the concept of using large aquatic animals to carry tags that collect biological and oceanographic data while tracking interactions between predators and other tagged species in the Northwest Atlantic. This project also helped advance analytical methods, including modelling and visualization tools, for OTN data (OTN project 4.8). Beginning in 2009 and working closely with DFO, researchers equipped seals with satellite-GPS tags (recording transiting and diving), environmental sensors (measuring oceanographic characteristics), VEMCO Mobile Transceivers (transmitting acoustic signals and logging detections from other tagged animals), accelerometers (OTN project 4.3, measuring fine-scale behaviour and jaw movement), and even animalborne cameras for short periods to validate behavioural inferences and consumption of specific prey. In addition, acoustic tags were deployed on more than 1,200 Atlantic cod over the same period. To date, data have been retrieved from 104 seals (85 per cent) tagged on Sable Island and from an additional 18 seals deployed with specially developed bluetooth-enabled tags in the southern Gulf of St. Lawrence. This long-term program documented how seasonal oceanographic features (temperature, phytoplankton biomass) and depth influence seal movement, as well as the links between environmental change and impact on top marine predators. Data have helped elucidate interactions of tagged individuals with other seals, and between seals and other tagged species of potential prey (Atlantic cod, salmon, eel, snow crab, lobster) as well as competing predators (bluefin tuna, sharks). For instance, encounters between seals and tagged cod did not record predation events but suggested co-occurrence in ocean ‘hotspots’—areas of high productivity where many species forage. Better understanding of such relationships between top predators and potential prey is critical for effective policy decisions and resource management.

Connecting species, habitats and people (4.9)

Little is known about the relative habitat use of different species of anadromous salmonids in areas where their distributions overlap, particularly in the North. Predicted effects of climate change, such as reduced anadromy, altered growth and changing species mix, have increased the need for understanding comparative ecology of anadromous species. These species are central to recreational and subsistence food fisheries in Newfoundland and Labrador as well as the Arctic. The first component of this OTN project focused primarily on Arctic char and Atlantic salmon, species historically divided by resource and habitat preferences. The work was carried out in several nearshore river systems in northern Newfoundland and Labrador. The distributions of these animals are shifting due to climate change, with the southern salmon pushing north into char habitat. Using acoustic and archival geolocation tag technology, the project characterized overwinter movement and diel (24 hour) activity patterns, thermal habitat use and dispersal rate of Arctic char, which revealed correlations of movement with daylight, temperature and body size. Likewise, in Newfoundland Atlantic salmon, movement patterns, residency, feeding ecology and survival were quantified for the first time in relation to life stage and spawning history. The studies provided insight into how climate change may affect individual fitness and on the relative competitive abilities of these salmonids. The second project component focused on understanding the patterns and consequences of Arctic char dispersal, the most northerly distributed freshwater fish, in the Arctic region of Cambridge Bay, Nunavut. Key findings revealed clear preferences of char for coastal, surface waters when in the marine environment; regular and lengthy forays into estuaries throughout the summer; extensive stock mixing, including in freshwater; and that the largest (and most heavily fished) lake in the region appears to be used as an overwintering area for fish from many rivers in the region. These findings will guide future management for these species in the region.

Arctic interactions (4.10)

The high Arctic is a region that is experiencing increasing stress due to rapid climate change and human activity. Research in the nearshore environment from 2010 to 2015 in Resolute Bay used a combination of acoustic and satellite telemetry, isotope analysis, oceanography and traditional ecological knowledge to study movements and interspecies interactions of key Arctic fish and marine mammals. Underwater acoustic noise and marine mammal vocalizations showed that beluga were only present in periods of low ice concentration, while bearded and ringed seals remained throughout the entire year. Arctic cod, a key prey of seabirds and marine mammals, collectively left nearshore areas when ice formed, changed habitats to avoid invasive jellyfish and vessel traffic, and made long-range migrations of more than 180 kilometres, revealing the first large-scale movements of individual cod. Shorthorn sculpin, a common benthic fish, were shown to have different movement patterns that related to foraging and feeding. Large-scale movements, presumably directed migrations, also occurred, and movement patterns of the fish changed when vessels were present or moving. The data collected on oceanographic characteristics, ocean noise and high-resolution fish movement are among the most intensive ever collected in the Canadian Arctic. This has provided new insight into the relationship between predators and prey and the influence of environmental and anthropogenic disturbance on animal behaviour in a rapidly changing and vulnerable high Arctic ecosystem. This in turn is improving equitable access to local resources for Inuit, as well as guiding sustainable fisheries management and tourism practices. In addition to the natural science conducted, OTN Arctic studies generated innovations in technology that increased acoustic detection in challenging Arctic environments, expanding animal-tracking range in some monitoring areas.

Emerging Arctic fisheries  (4.11)

Nunavut fisheries are rapidly developing, and managers in the region frequently have little biological information to guide their decisions. To address this, OTN researchers conducted novel studies on the population structure, movement ecology and depth preferences of commercially important Greenland halibut (as well as two common commercial bycatch species, Greenland shark and Arctic skate) around the Baffin Island coastal region. Interactions with marine mammals were also studied. In Cumberland Sound, a Greenland halibut fishery had been established, which was divided into northern and southern sectors by an arbitrary management boundary and regulated as if the two sectors had separate fish populations. However, OTN’s telemetry data revealed that the fish were a single population that regularly crossed the boundary and that, overall, the Sound’s halibut population was dwindling. In 2014, OTN Arctic researchers, working with Indigenous communities, successfully influenced the relocation of the management boundary to the entrance of the Cumberland Sound, which has helped guide more sustainable and effective management of the resource and ensured fair access to the fishery by local Inuit. Results also showed extensive migrations of Greenland sharks between Greenland and Canada and produced altered handling practices for bycaught individuals. As in other Arctic projects (OTN project 4.10), marine mammals were tracked by listening for their calls. The data revealed that narwhal and bowhead whales were only present before full ice cover developed in fall, while seals and walruses remained after ice formation. This project provided multiple discoveries about the secret lives of deepwater Arctic species and involved exceptional collaboration with local stakeholders and the government of Nunavut.

Catch 22 (4.13)

Three popular sport fish (Atlantic salmon, Arctic char and coho salmon) served as the models of this OTN study, which investigated stressors associated with recreational catch-and-release fishing. It focused on the impacts of handling of the fish during capture and the influence of environmental characteristics such as water temperature and pathogen presence. This study provided the first post-release data for both Arctic char (Cambridge Bay) and coho salmon (Lower Fraser River). The work collaborated with an OTN Atlantic salmon study (OTN project 4.9) to include fish angled in lower river areas soon after sea entry and those caught in the nearshore coastal environments. This is one of the first studies to link health and pathogen presence to different fisheries stressors. Coho salmon mortality was low and treatment-specific impacts were negligible, presumably reflecting that fish were in a mature state in the final phases of their migration. Arctic char also had high levels of survival. Atlantic salmon had a high survival rate after release (approximately 93 per cent), although higher mortality was associated with warmer waters. Post-release mortality was independent of fishing gear, fish size and fight time. Anglers who used best practices could expect released fish to survive overall, although fly fishing yielded a higher number of survivors than lure fishing. Duration of air exposure was a good predictor of fish mortality after release. No standard for air-exposure maximums exists and many species can tolerate different exposure times. This study has resulted in numerous recommendations for best practices in recreational fisheries.

A ‘tail’ of two sturgeon: part II (4.14)

The Lower Fraser River white sturgeon population is complex and poorly understood, with portions of the population being found at varying times and seasons in the marine environment, in large lakes and in flowing sections of rivers. White sturgeon in the Lower Fraser River are listed as threatened under Canada’s Species at Risk Act, and face various threats such as poaching, habitat destruction and loss of prey. Yet beyond mandatory catch-and-release fishing, there are few regulations on angling activity. This study in collaboration with the British Columbia Ministry of Forests, Lands and Natural Resource Operations filled knowledge gaps about white sturgeon movements and reproductive patterns, and investigated the effects of stress from capture by angling on survival rates. Starting in 2013, researchers tagged 174 adult white sturgeon with long-life acoustic transmitters that will be monitored well beyond 2018. Sturgeon were captured via angling. Blood samples were taken to assess their physiological stress state at the time of capture. Nearly all of the acoustically tagged fish were detected at multiple locations after release, many traveling more than 125 kilometres and at known or suspected spawning channels. Results indicated a high recapture rate in the fishery, but also suggest rapid recovery from stress and high post-release survival. Many fish were recaptured by anglers more than once. The OTN white sturgeon project directly contributed to federal management by gathering data on key aspects of sturgeon biology and movement, advised fishers and fisheries managers on post-angling mortality and identified areas and times of year when sturgeon were most susceptible to disturbance and stress.

Pacific salmon: surviving the journey (4.15)

This project used acoustic transmitters to tag sockeye smolts in British Columbia’s Chilko Lake. OTN researchers examined how environmental and genetic characteristics influenced salmon migration, behaviour and survival as the fish moved from rivers to the open ocean. This was one of the first studies to use new miniaturized transmitters in a large-scale (more than 2,500 tagged salmon) tracking project of juvenile salmon. The project revealed the technical feasibility of tagging the smaller smolts with the new tags; previous models were too big for 98 per cent of the population. Results indicated that more than half of the tagged fish did not survive river movements to enter the open ocean, a distance of more than 1,000 kilometres. Further results showed distinct patterns in both behaviour and survival—in small, clear, upper-river reaches, downstream migration largely occurred at night at speeds of up to 50 kilometres per day and coincided with poor survival. Only 60 to 80 per cent of smolts survived the first 80 kilometres of their downstream journey. A parallel laboratory study of tagged fish documented high short-term survival and unhindered swimming ability, eliminating negative effects of tagging as a mortality cause. This suggested that, in nature, predation was the main source of mortality in smolts. Additional field work documented largescale predation by adult bull trout, which fed almost exclusively on sockeye smolts. Yearly workshops put on by the OTN Pacific salmon group include other academic stakeholders, government, community, and ENGOs. This group has also helped author CSAS reports in order to improve management of Pacific salmon at the federal level.

Summary

The lists below include past and present NSERC research network members, Council, SAC and ISAC members, as well as headquarters staff.