Research shows the properties that make tuna fish prey

A cross-border science collaboration has yielded a global database that will help researchers understand how climate change is affecting ocean predators like albacore tuna—which also happen to be an important food source for humans in the whole world.

“Climate change is changing where species can live, and the pace of change is most intense in the ocean,” said Stephanie Green, associate professor in the Department of Biological Sciences and Canada Research Chair in Aquatic Global Change Ecology and Conservation.

“Our big questions are where are marine species going, and what does that mean for the communities that depend on the fisheries they support?”

To address these questions, researchers at the University of Alberta are working with colleagues in the United States to discover how top predators will respond to climate extremes and prey changes in the coming decades.

Winds and currents in the Pacific Ocean make the west coast of Canada and the United States an attractive feeding ground for migrating predators such as tuna, where they support beneficial fisheries and also nest. of climate impacts.

The team honed in on albacore tuna, a torpedo-shaped predator known to eat hundreds of different species around the world and whose harvest is regulated by an agreement between the United States and Canada.

Different foods—but similar characteristics

The buffet of prey albacore consume makes it difficult for scientists to predict where their populations will end up as climate change worsens. To meet this challenge, the science team shed a unique light on the snacking habits of this ocean predator by looking at the common characteristics or characteristics of the foods they eat.

“Just as we choose foods based on what we want—whether it’s a salty pretzel or a sweet, crunchy apple—ocean predators make decisions based on the characteristics of the prey they’re facing, ” said Green.

To find out what traits are important to ocean predators, the researchers created a database that categorized more than 30 traits including fat and protein content, shape, color, size, and behaviors that could ocean species become palatable to predators, including albacore tuna.

“Our goal is to better understand when and where the most desirable prey will be found as the climate changes,” Green said.

“What we found is that albacore tuna are quite adaptable; from the hundreds of species that they can eat, they look for prey that have all the characteristics that they want and that they are committed to,” explained the research associate and study lead. author Miram Gleiber.

By using trait-based studies, the group hopes to create a new way to understand how ocean predators are adapting to the effects of climate change.

Big data, open for ocean discovery

Oceans cover more than 70 percent of the planet but are less explored than space. The research team, including seven U of A students, put in more than 10,000 hours to generate 155,000 unique pieces of information on the characteristics of 521 species of fish, crustaceans, squid, octopus, and more found in ocean environments.

While many species are important prey for top predators such as tunas, sharks, salmon and many others in ocean systems around the world, the other animals the team documented are only known from a small number of specimens.

The attribute database is also available for international scientists to support learning about how systems change, Green notes.

“Large datasets like this are created to support statistical models that look at the distribution of ocean species and how interactions between ocean species, such as between predators and their victim, can look to the future.”

“We’re getting a lot of interest from scientists elsewhere who are using the information we’ve gathered, which is really exciting and rewarding for us to see,” said Natasha Hardy, a research associate who led the global diet synthesis.

Outlook for the oceans

The influence of climate change on ecosystems is complex, including more extreme weather events such as heat waves that dramatically alter marine environments. Marine heat waves are masses of superheated water, many degrees warmer than normal, that form in the ocean, disrupting the natural cycle that species rely on in the ocean for tracking their food, spawning, and transfer.

“Scientists have found some species that are hundreds of miles from where we’ve seen them before, and that’s probably causing confusion in the system,” said project co-lead Larry Crowder, a professor at Stanford University’s Hopkins Marine Science Center.

Some species are mobile and can adapt to changing environments, but many live near the edges of the ranges of temperature, acidity, and other stressors they can tolerate, causing some species to lose entire residence, Crowder said.

The findings were published in the journal Scientific Data.