I am working on a variety of projects currently addressing different themes, aspects, and scale of the resilience and sustainability of complex social-ecological systems. If you have any thoughts or suggestions on these projects, I’m open to collaborating!
Some projects I am working on currently and some details below:
- Collaborative pathways towards rebuilding Pacific salmon fisheries in the Central Coast
- Managing the consequences of disturbances on spatially structured populations
- Life-history diversity in Canada’s lake trout
- Quantifying spatial and temporal trends in the life histories of Pacific groundfish
- Social-ecological resilience in changing fisheries
Collaborative pathways towards rebuilding Pacific salmon fisheries in the Central Coast
The conservation and management of Pacific salmon in Canada faces an uncertain future. Coinciding with fisheries policy moving into an era of co-governance and reconciliation, many salmon continue to decline owing to climate-driven regime shifts and legacies of overfishing. These declines highlight a key need for risk assessments that can inform precautionary management. Coho salmon along the North and Central Coast (NCC) of British Columbia represent one such example, where recent declines jeopardize conservation and fishing opportunities for a fishery that crosses multiple jurisdictions including U.S., Canadian, and Indigenous governments. We developed a Bayesian time-series model to quantify spatial and temporal patterns in population dynamics for 52 coho salmon populations across the NCC, estimate fisheries reference points, determine population status, and assess conservation risks. We then used forward simulations testing future productivity trends and harvest management scenarios to evaluate future risks and pathways towards recovery.
Overall, we documented widespread coho declines owing to shifting productivity regimes that varied by region and identified conservation concerns for 51% of coho populations in recent years. In general, we found that reducing harvest rates from U.S. and Canada fisheries can improve short-term coho recoveries, but longer-term recoveries depended mostly on future productivity trends. Precautionary management of coho fisheries requires coordinated decision-making that span international and domestic jurisdictions and is informed by forward-thinking monitoring and assessment. Our findings revealed a widespread decline in productivity and abundance among NCC coho that coincided with the onset of marine heatwaves in 2014. While the ability of coho to recover to pre-collapse abundances depends largely on their productivity improving, harvest management remains one of the few tools available to allow coho a safe operating space to adapt to ongoing ecosystem changes.
Understanding and managing the consequences of disturbances on spatially structured populations
Spatially structured populations, like salmon watersheds, are composed of many interconnected local populations – called a ‘metapopulation’. Metapopulations can have strong patchiness in local processes, like dispersal, productivity, or mortality, which are often density-dependent, and these local processes feedback to structure aggregate dynamics. For resource populations, like fish and wildlife, management often works at the scale of the whole metapopulation whereas non-random stressors tend to work on a more local scale causing unpredictable patterns to emerge. This creates a mismatch between the scale of management and the scale of the ecological processes that drive population dynamics. Together with the Salmon Watersheds Lab, we want to explore how spatial structure in local density-dependence drives surprising patterns at the metapopulation-scale ideas using (1) a conceptual model to illustrate this idea, (2) a theoretical model to quantify spatial patterns, and (3) review empirical case studies on a wide-variety of taxa to show how linkages between network structure, local density-dependence, and different stressors can create surprising patterns to emerge at the scale of resource management.
Life-history diversity in Canada’s lake trout
In 2008-2009, BC FLNRO sampled 30 lake trout populations that ranged from larger, exploited lakes to pristine, backcountry, and high-alpine lakes. From this, they collected back-calculated size-at-age from 1,100 lake trout. These fish ranged drastically in maximum body size (several > 100cm in fork length) and age (many were born in the 1950s!). Throughout their range, lake trout are known to have several large- v. small-bodied morphs typically associated with variation in their diet and/or their post-glacial evolution. These “polymorphs” may represent a unique contribution both to fisheries and to biodiversity conservation. We can use this dataset to ask several intriguing questions on the ecology of lake trout:
- Are their polymorphs present in these 30 lakes?
- If so, how many morphs are there?
- Use bioenergetics von Bertalanffy model to ask does a fish belong to one particular morph or another?
- What drives variation in their growth over time?
- Use time-series of climate and fishery infrastructure development to determine when, at age or in years, growth conditions change
Quantifying spatial and temporal trends in the life histories of Pacific groundfish
West Coast groundfish species, including long-lived rockfish species like Yelloweye Sebastes ruberrimus, support culturally vital fisheries for Indigenous communities across the Central Coast of British Columbia. However, many rockfish species are increasingly at-risk of population declines because of ongoing size-selective harvest, overfishing, benthic habitat disturbances, and ocean climate changes – these declines risk the collapse for many food, social, and ceremonial fisheries for Indigenous communities, including the Central Coast First Nations. As large-bodied and long-lived species, many groundfish life histories adapt to changes in their environments, including stressors from fishing and disturbances. In this work, we are working in collaboration with the Central Coast First Nations, academic scientists, and government colleagues to understand and quantify spatial and temporal patterns in the life histories of groundfish along Canada’s Pacific coast. This work will support CCIRA and the Central Coast First Nations in ongoing co-governance and fisheries management plans related to the rebuilding and recovery of West Coast groundfish.
Social-ecological resilience in changing fisheries
Fisheries are complex social-ecological interactions between people and nature, and they provide subsistence, cultural, and leisure opportunities for billions of people. Many fisheries are collapsing from overfishing and ecosystem changes, yet some fisheries remain resilient to these threats. Biodiversity may help foster resilience via the ‘portfolio effect’, analogous to how financial managers select portfolios composed of diverse assets to stabilize their returns. Hence, fisheries with high diversity (some populations ‘boom’ when others ‘bust’) appear more stable than fisheries with low diversity (populations ‘boom’ or ‘bust’ at the same time). However, fisheries are also diverse socio-culturally, yet current research exploring fishery portfolio effects has ignored these human dimensions. This research aims to illuminate the processes that underpin resilience in one complex social-ecological systems by integrating diversity in biological and social processes to understand how interactions between these dimensions contribute to the stability and resilience of fisheries. To answer this, we will first contrast the contributions of diverse people and their behaviours with fish biodiversity in a theoretical model. As not all fisheries have high biodiversity to conserve, these results can be used to determine how social-ecological diversity drives portfolio effects, and whether fishery managers can increase social well-being to manage for resilience.
These concepts will then be applied to British Columbia steelhead: a migratory Pacific salmon recommended for emergency-listing as an at-risk species that supports dozens of fisheries worth $33 million CAD·yr-1 to BC’s economy. This work aims to integrate steelhead life-cycle dynamics with fisher diversity to determine policies that best realize resilience of BC fisheries and beyond, to help manage both existing biodiversity and the vast range of human interactions with that diversity.