Traits-Based Lens Shines New Light on Marine Predators Under Climate Change

To better understand how climate variability will impact fish, fisheries management, and fishing communities, the Lenfest Ocean Program has funded a portfolio of work focused on addressing issues around predicting range shifts of fished species, understanding climate-vulnerability of communities, and potential adaptive capacity to these changes. Many of these projects will come to fruition this year. In anticipation of that, we are exploring ways to capture their intricacies, not just by showcasing their results, but also by shedding light on how the research teams have worked with others to better inform fisheries management in the future.

In this blog, we asked Dr. Stephanie Green and Dr. Miram Gleiber of the University of Alberta to share more about their project “Using Predator-Prey Relationships to Predict Shifts in Marine Species Distribution” and how their work can help predict range shifts for albacore tuna in the Pacific Ocean.

Using a traits-based lens to shine new light on marine predators under climate change

In the ocean, climate change is rapidly shifting where species can live, and fisheries managers are looking for ways to predict where they will go as a result. For predators, this is even more challenging because their distributions depend on how their prey are also impacted by climate shifts. To address this challenge, our team is shining a new light on the snacking habits of ocean predators to illuminate the common characteristics, or traits, of the foods they eat. Just like we choose foods based on what we like — be it a salty pretzel or sweet, crunchy apple — ocean predators make decisions based on the characteristics of their prey. The goal of this project is to better understand when and where the most desirable prey will be found in coming decades, so we can better understand how predators will move.

To start, we focus on albacore tuna- a climate-sensitive ocean predator known to eat hundreds of species across the world. Each year, albacore migrate to the northeast Pacific Ocean in search of hearty prey resources created by the rich nutrients from ocean upwelling. In this area, albacore fishing is regulated under a bi-national treaty between the United States and Canada. Fisher access to albacore depends on where the fish have migrated. But as marine heatwaves wreak havoc on temperature and nutrient sources, the migration path becomes increasingly uncertain, leaving potential catch inequities among fishers. A valuable new tool, however, can help predict where albacore will go and how abundant they will be under new climate stressors, potentially improving the livelihoods and well-being of coastal communities across the region.

Pelagic Species Trait Database: An opportunity to expand knowledge and collaboration

To understand which prey characteristics are most important to albacore and other predator species, we created a Pelagic Species Trait Database that categorizes more than 30 traits for over 500 species of fish, crustaceans, squids, and others found in pelagic (i.e., open ocean) environments. To generate such a massive database, dozens of student and staff researchers from several institutions invested more than 10,000 hours to generate 155,000 unique pieces of information from over 1,800 resources. A feat in collaboration already, the database was designed to invite even further expansion.

Currently, 70% of species in the database are found in the Pacific Ocean. Our hope is to expand to more regions, ensuring that all scientists, managers, and others who want to follow a traits-based approach in their work have a reliable resource from which to draw and accelerate the process. To make it easier to access and add information to the database, we include materials and instructions in our paper. This collaborative approach enables our research team and others to develop statistical models that assess the future distribution and interactions of ocean species under climate change.

What do albacore think is yummy?

The buffet of prey that albacore consumes has made it tough for scientists to predict where their populations will go as climate change worsens. But when we looked through a trait lens, we found something hopeful- of the hundreds of species albacore can eat, they consistently target prey with just a handful of key features: silver, counter-shaded, high-energy animals that school in the coastal zone.

Importantly, their preferences stay the same in different years and places. This means that albacore tuna may be quite adaptable and able to seek out different prey species that meet their needs in a range of environmental conditions. Now that we know which traits albacore find the ‘yummiest’ we can use this information to map where prey will go, and how tuna might respond, giving us clues as to where these predators will be found in decades to come.

Applying Traits-based Approaches to Fisheries Management

Traits are frequently used to study ecosystems and species interactions on land for plants, insects, and mammals. But traits-based work is just getting started in open ocean environments. We see it as a valuable tool for understanding the complex marine food web — the landscape on which we build climate-resilient fisheries.

Throughout the project, we’ve worked with collaborators at NOAA Fisheries Science Centers and other universities along the west coast of the United States to ensure that the project’s conceptual frameworks meet the realities of the systems and needs of the scientists and managers working in this space. These conversations and partnerships have been critical to ensuring our outputs are directly relevant to decision-making for albacore tuna and other migratory species. Using information from the Pelagic Species Traits Database, we can now begin the process of mapping projections for the abundance and distribution for albacore prey in the face of anticipated ocean change. These layers have the potential to be used with other modeling tools to infer potential redistribution of the species across jurisdictional boundaries in the years to come.