Life history patterns
My laboratory conducts comparative studies on reproduction, foraging ecology, and population dynamics of seals in relation to adult phenotype and environmental variability. Our approach is to integrate physiological, behavioural and morphological studies to gain a better understanding of how life history traits evolve in large marine carnivores.
Foraging ecology, diet and population energetics of pinnipeds
Foraging success determines an organism's intake of nutrients, while life-history patterns result from the expenditure of these nutrients on fitness-related activities. The allocation of limited resources among competing activities links these two such that an understanding of feeding ecology is central to an understanding of the evolution of life-history patterns. Despite its importance, the foraging ecology of most marine mammals is poorly known. To understand the role of apex predators in large marine ecosystems, we need information on what they eat, the scales at which they forage, and how diet changes with changes in prey abundance.
We are using several microprocessor-based data recorders and satellite and VHF telemetry to investigate the spatial and temporal distribution of diving in wild seals. These tools, coupled with isotope dilution studies and quantitative fatty acid signature analysis, provide detailed information on the foraging behaviour, feeding success, diet, and energetic consequences of foraging on seasonal energy storage.
Seals are long-lived mammals which give birth to a single pup each year. We have been monitoring trends in the number of harbour seal and grey seal pups born on Sable Island for many decades. We also also studying long-term changes in reproductive performance and survival based on annual sightings of permanently marked, known age adults. These long-term data are needed to determine how seal populations respond to environmental variability and human activities.
The grey seal population on Sable Island has been growing for the past four decades. The continued growth of this population has raised concerns about the potential impact of grey seal predation on commercially important fish and invertebrate stocks in eastern Canada. Thus, we have been using our data on the population dynamics, distribution of foraging, diets and energy requirements to develop models of the possible impacts of grey seals on prey populations. More generally, we hope this work will provide a useful model for the impact of marine carnivores on prey populations.
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Last updated August 2011