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Keynote speakers

Frederic Cry

Frederic Cyr

Climate and fisheries: Decadal-scale bottom-up controls of the Newfoundland and Labrador ecosystem

The Newfoundland and Labrador (NL) shelf (which includes the Grand Banks of Newfoundland) has been known as an iconic fishing ground for centuries. Being located at the confluence of arctic, subarctic and subtropical currents, the region is especially affected by large-scale ocean circulation changes. Such circulation changes impact not only the regional ocean climate, but also the overall water masses composition and the immediate habitat of numerous commercial and non-commercial fish species.

Systematic hydrographic observations on NL shelf have been carried out by Canada and other countries since the late 1940's. The observational program was reinforced in 1999 with the creation of the Atlantic Zone Monitoring Program (AZMP), ensuring enhanced seasonal coverage and new biogeochemical observations. The creation of the AZMP occurred in the wake of the collapse of the Atlantic Canada groundfish fisheries in the early 1990’s – a period marked by rapid environmental changes – with the general consensus that “changes in climate cannot be ignored as an explanation for fluctuations in marine resources.”

Here we review 7 decades of ocean climate and physical-biogeochemical interactions on the NL shelf, with an emphasis on low frequency variability and cycles. Results suggest, for example, that winter conditions above the North Atlantic largely set the stage for the ocean physical and biogeochemical conditions on the NL shelf during the rest of the year. It is also shown that decadal changes of the sea-level pressure above the North Atlantic influences the subpolar gyre, and thus the interactions between the Labrador and the North Atlantic currents, two major contributors to the NL shelf climate variability. This variability has in turn important consequences on the biogeochemistry and the overall productivity of the NL ecosystem.

Keywords: Ocean climate, Newfoundland and Labrador ecosystem, Atlantic Zone Monitoring Program, physical-biological interactions, Fisheries

Biography

Dr. Frédéric Cyr is a multi-disciplinary physical oceanographer with strong research interests in physical-biogeochemical interactions, ocean climate and fisheries. He works as a research scientist for Fisheries and Oceans Canada (DFO), based at the Northwest Atlantic Fisheries Centre in St. John’s, Newfoundland. He holds a B.Eng. degree in Engineering Physics (Montreal Polytechnic, Canada, 2008), a MSc in Climate Sciences (UVSQ, France, 2008) and a PhD in Oceanography (ISMER-UQAR, Canada, 2014). After postdocs in the Netherlands (NIOZ) and France (MIO-AMU), where he explored topics as broad as Turbulent Mixing and Ocean Chemistry, he joined DFO in 2017 and now mainly focuses on the Northwest Atlantic ocean climate. His research activities are strongly related to DFO’s Atlantic Zone Monitoring Program (AZMP) which aims to provide environmental considerations in support of fisheries sciences and management.

Twitter handle: @cyrf0006

Personal webpage

 

 

Gail Davoren

Gail Davoren 

Post-collapse variability in capelin abundance, phenology and habitat use: impacts on stock recovery and food web dynamics in Newfoundland, Canada

On the Newfoundland and Labrador Shelf, capelin (Mallotus villosus) experienced a population collapse in the early 1990s and have shown minimal recovery. Although Newfoundland capelin are primarily thought to spawn intertidally on beaches in coastal regions, they also spawn in subtidal habitats (15-40 m). Subtidal habitat use is predicted to increase as beaches become warmer under current climate change scenarios, and reports of subtidal spawning are already increasing. The population-level consequences of this habitat shift, however, are unknown, as subtidal habitat is often considered low quality. To quantify the relative contribution of intertidal and subtidal habitats, we began assessing whether chemical signatures in the pre-hatch region of capelin otoliths can act as a natural tag of natal origin. Since 2009, field- and lab-based experiments revealed that despite distinct maternally-derived chemical signatures in the pre-hatch otolith region, otolith chemical signatures differed between habitats and among bays, primarily due to varying site-specific water chemistry and temperature. We now plan to use this technique to investigate whether subtidal habitat represents an ecological trap and, thus, may be limiting population recovery.

Despite the stock collapse, capelin continue to act as a pulsed resource when they migrate from offshore to inshore spawning sites, providing locally abundant prey aggregations for marine predators. Since 2009, we investigated responses of many predator species to inter-annual variation in capelin abundance and phenology. To do this, we integrated predator foraging behaviour, derived from animal-borne data loggers, and dietary metrics, derived from stable isotope analysis, with regular monitoring of the timing of spawning and spawning capelin biomass. Capelin biomass and shoal characteristics changed dramatically with the inshore arrival of spawning capelin each summer, resulting in decreased foraging effort and isotopic niche shifts of predators, including humpback whales, Atlantic cod, and seabirds (e.g., murres, razorbills, gulls). High inter-annual variation in the timing of spawning and biomass, resulted in dietary/isotopic niche shifts, along with higher foraging effort and lowered breeding success of multiple predator species in years of lower capelin availability. Although findings reveal plasticity in predator foraging behaviour, species-specific reliance on capelin suggest that ongoing recruitment dynamics will continue to result in altered species interactions and food web dynamics.

Biography

Dr. Gail Davoren has been a Professor at the University of Manitoba in the Department of Biological Sciences since 2003. Her research investigates the recruitment dynamics of key marine forage fish and how these dynamics shape food web interactions in northern marine ecosystems. She has sustained a long-term interest in the ecology of capelin and capelin-predator interactions in coastal Newfoundland. Although her long-term research program is focused on the northeast coast of Newfoundland, she has also studied capelin ecology in the eastern and western Canadian Arctic. Her predator research focuses on seabirds, but she has also studied Atlantic cod and humpback whales. Dr. Davoren’s team integrates a number of techniques, including hydroacoustics and animal-borne telemetry, with stable isotope analysis and otolith chemistry to reconstruct predator diet and natal origin of capelin.

   
Anna Frank

Anna Frank

Mathematics as an Instrument to New Biological Insights – Two Examples of the Barents Sea Capelin

In this talk, I shall illustrate how mathematical models and their analyses can provide new insights into our understanding of the Barents Sea capelin stock dynamics. The first example demonstrates the effect of time-delay in the overlap between capelin and its prey. In the second example, I examine the stock recruitment relationship using a compact model description of the life-cycle process, aided by functional motifs. These examples showcase mathematical modelling as an instrument in knowledge generation and hypothesis testing.

Biography

Dr. Anna-Simone Frank is a postdoctoral research fellow at the Computational Biology Unit (CBU), Department of Informatics, University of Bergen, Norway. Dr. Frank’s research expertise is in the application of mathematical models to biological systems, perinatal pharmacoepidemiology, and causal inference methodology. Her current projects deal with developing mathematical model frameworks to explain dynamics of empirical predator-prey systems, and macrophage polarization processes. She holds B.Sc. and M.Sc. degrees in mathematics from the Technical University of Munich, Germany, and a PhD from the University of Oslo, Norway.

   

Tom Langbehn

Tom Langbehn 

The Arctic lightscape and its role in pelagic interactions and species distributions

Light has a twofold fundamental impact on life in the ocean. It acts at the very bottom off the food web through photosynthesis that forms the energetic base for all higher trophic levels, but it also affects top-down control through vision. Many higher trophic level predators, from birds, to fish and to some degree even baleen whales, depend on vision, and therefore light to successfully find their prey. Photoperiod becomes increasingly seasonal at high latitudes. In polar ecosystems, organisms have adapted to long periods of winter darkness with low productivity and constant daylight during a short but productive growing season. However, species that extent or shift their ranges poleward as temperatures increase might be unable to adapt to extremes in duration and annual transition in photoperiod. Hence, extreme photoperiod may cap the poleward range-shift of species. While photoperiod is unaffected by climate change, sea-ice loss is bound to change the underwater lightscape of an entire ocean basin, at least during the summer month. Less ice will mean more light entering the water column. This has potentially profound effects on the seasonal cycle of primary production but also the efficiency of visually hunting organisms with ecological and evolutionary knock-on effects.

In this presentation I will synthesize what we know about the role of light in shaping pelagic species interactions and distributions in sub-polar and polar marine ecosystems and attempt an outlook on the consequences of a changing lightscape for a future Arctic Ocean.  

Biography

Tom Langbehn is a marine ecologist interested in evolution and the ecology and biogeography of environmental change, with a particular fascination for polar ecosystems and the ocean twilight zone. In his work, Tom links theory and modelling with observations and field experiments to uncover the mechanics of life in the ocean: what creates, what drives, and what maintains diversity in traits, functions, species, and strategies across different dimensions i.e., along gradients of latitude, seasons, or depth. Tom has a PhD from the University of Bergen, where he is a postdoc in the Theoretical Ecology Group at the Department of Biological Sciences. At present, Tom is a visiting researcher at the British Antarctic Survey in Cambridge where he works on macroecological patterns of Southern Ocean myctophids.

 

 

Hanna Murphy

Mayumi Arimitsu

Hannah Murphy and Mayumi Arimitsu 

Marine heatwaves and cold-spells: Persistent collapse of capelin in two oceans at opposite ends of the thermal optima

Capelin are subject to population collapses that appear to be regulated by environmental conditions when temperatures exceed the boundaries of their thermal optima. For example, in Newfoundland, Canada, the capelin stock in Northwest Atlantic Fisheries Organization (NAFO) Divisions 2J3KL collapsed in 1991 during an anomalous cold spell (1990-1992) and has not recovered in 30 years despite a warming period from 1996-2013, suggesting a change in ecosystem structure (i.e. regime shift). A regime shift was also associated with an abrupt decline of capelin in the North Pacific when ocean temperatures warmed (1977-1978). Although capelin stocks recovered in the Gulf of Alaska, particularly during a cool period (2008-2013), an abrupt collapse was again observed following a prolonged marine heatwave (2014-2016). Ecological responses of capelin to variation in oceanic temperature include population collapses, changes in distribution, phenology, maturation rates, size, feeding conditions, and demography. To explore the drivers of persistent collapses of capelin at the edges of their thermal optima, we compare and contrast capelin responses to marine cold-spells in Newfoundland, marine heatwaves in Gulf of Alaska, and regime shifts in both oceans.

Biographies

Dr. Mayumi Arimitsu is a research ecologist with the US Geological Survey Alaska Science Center in Juneau, Alaska. She completed her masters and PhD degrees in fisheries at University of Alaska Fairbanks School of Fisheries and Ocean Sciences. Dr. Arimitsu’s research interests focus broadly on seabird and forage fish ecology, detecting change in predator and prey populations, and understanding the impacts of climate change on marine food webs in Alaska. She is currently a principal investigator and pelagic component lead for the Gulf Watch Alaska Long-term Marine Ecosystem Monitoring Program. Her recent work has focused on the impacts of the 2014-2016 Pacific marine heatwave on capelin and other small pelagic fish in the Gulf of Alaska.

Dr. Hannah Murphy is a research scientist at the Northwest Atlantic Fisheries Centre, Fisheries and Oceans Canada (St. John’s, Newfoundland and Labrador). Dr. Murphy completed her BSc (Hons) and PhD degrees at the University of Melbourne. Dr. Murphy’s research interests are primarily focused on identifying the drivers of recruitment variability in fishes. Her current research program is on capelin recruitment dynamics with a particular interest on identifying the bottom-up and top-down drivers of survival of the early life history stages. Dr. Murphy’s research is used in the assessment of the Newfoundland capelin stock.

   
Mariano Koen-Alonso

Mariano Koen-Alonso

Capelin-cod dynamics: A comparison between the Newfoundland-Labrador and Barents Sea ecosystems, and what it may tell us about ecosystem regulation.

Capelin is a key forage species in many Northern hemisphere high latitude marine ecosystems. The fluctuations in capelin stocks have often been associated to the performance of top predators in these systems, and Atlantic cod is a frequent example for this connection between capelin and top predators. One useful aspect of considering Atlantic cod, beyond its important role as predator, is the contrast provided by the exploitation histories and stock trajectories from different cod populations. For example, the cod stocks in the Barents Sea (BS) and the Newfoundland-Labrador Shelves (NL) ecosystems have shown divergent trajectories over the last 40 years. These stocks experienced an important decline (BS) or a collapse (NL) in the mid-1980s and early 1990s respectively, but while BS cod quickly rebounded and reached record high levels in recent years, the NL cod has yet to recover, and only started to show some improvements since the mid-2000s. In addition to the impacts of fishing, these contrasting cod trajectories occurred against a backdrop of broader ecosystem changes, including several capelin declines and recoveries in BS, and a collapse with only a marginal improvement in NL. How these differences in capelin and fishing history impacted the cod trajectories in BS and NL was evaluated using an series of modelling exercises, and including an integrated model architecture which allowed estimating common parameters for the two cod stocks. The results indicated that despite their contrasting trajectories, the dynamics of both cod stocks could be explained by the combined impacts of fishing and capelin availability. Furthermore, model parameters that encapsulate intrinsic vital rates for cod were not significantly different between stocks, indicating that NL and BS cod are biologically similar. This implies that the differences in cod trajectories were driven by the ecosystem context in which these stocks were embedded, more than intrinsic differences in their biological traits. This finding highlights not only the relevance of considering capelin within the management of cod stocks, but also emphasizes the role of food availability and bottom-up control in regulating cod dynamics in particular, and top predators more broadly. Better understanding of these mechanisms can be of particular importance given the expectation of future reductions in ocean productivity due to climate change.

Biography

Mariano Koen-Alonso is a marine and fisheries scientist. His research interests include predator-prey and food web dynamics, marine community ecology, and ecosystem-based management. He joined Fisheries and Oceans Canada (DFO) in 2002, where he has been trying to understand the interactions among top marine predators, their prey, benthic habitats, the ocean climate, and fisheries in the Northwest Atlantic, while contributing whatever little understanding he manages to get for the generation of science advice, and to give his best shot at developing and implementing ecosystem-based management frameworks. He is also Adjunct Professor at Memorial University of Newfoundland and Labrador. Mariano holds a PhD in Biology from the University of Buenos Aires, and a Licentiate in Biology from the University of Patagonia, both in Argentina.