Looking ahead: what does climate change have in store for Pacific Coast fish?
From Alaska to California, researchers are looking into the impact of climate change on the distribution of fish that live near the seafloor. Focusing on species such as halibut, pollock, sablefish and rockfishes, which have commercial and environmental importance for the Pacific Coast of the US, these fish are impacted in different ways by shifting ocean temperature and oxygen, resulting in a myriad of knock-on effects.
We spoke with Julia Indivero, a PhD student at SAFS, about what some of these effects could be. Rising temperatures and decreasing oxygen may affect where fish can live, which in turn may change how close they are to boats and ports involved in the fishing industry. “Fishers are used to fish being in a certain area, and if fish move farther away, this may become difficult for fishery operations. Different species responses to ocean conditions may also change the overlap in habitat between species and impact possible bycatch issues,” Julia shared.
Julia’s research is combining data to look at the Pacific Coast in its entirety, versus being separated out by region as is usually done in work on this topic. By combining predictions for multiple regions, researchers can build models which include more sensitivities and reflect broader-scale change in fish distribution.
Conducting her work in Tim Essington’s Marine Conservation and Ecology Group, Julia’s quantitative research involves developing models to predict where fish may be located under future climate change scenarios. By combining data on ocean conditions and on fish abundance from thousands of locations each year from the 1990s through 2023, these models estimate how fish abundances are impacted by temperature and oxygen. Then, these relationships are used to predict fish abundances at these locations if temperature and oxygen change, following what global forecasts of human-caused carbon emissions expect.
Countries and fishery management bodies around the globe are interested in understanding how fish distributions might shift in future climates.
“The possible implications for transboundary governance is especially interesting. Quotas, catch limits, treaties, and protected areas, are all based on geographic locations, but fish ignore these boundaries when big climate change shifts happen,” Julia said.
This makes the ability to predict future fish distributions even more important, so that individuals, regions, and countries, can better anticipate these changes and put in place the required modifications to management structures and boundaries now.
There is an inherent level of uncertainty when making forecasts based on climate change shifts in ocean temperature and oxygen. The models that Julia works on recognize these uncertainties: “There’s uncertainty in the level of carbon emissions that will happen, there’s uncertainty in the exact temperature and oxygen change in the ocean, there’s uncertainty in how fish will respond to a changing environment. But predictions can provide us with plausible scenarios and a range of possible future situations.” One area that needs some work, Julia mentions, is understanding how relationships between fish and ocean conditions that are based on data from the past, may hold up or break down in a warmer world: “We’re developing methods to try to better predict how fish might respond to temperature and oxygen levels that are completely beyond what they’ve experienced before.”
What would pre-emptive action to deal with future changes in fishery distribution look like for those on the ground?
“Fishers could look at these predictions and start investing in different types of vessels and gear needed to catch new fish in their fishing areas,” Julia said. “Being able to share scientific information that informs diversification efforts would be a great benefit,” she added.
On a large scale, ports and cities can start investing in infrastructure that has the ability to process different fish products based on future predictions. Managers can begin developing flexible policies that allow individual vessels and fishers to switch permits between species. It also reaches the highest level of those involved in fisheries management. “At an international level, future predictions of fish distribution mean they can start thinking about how to deal with, and adapt, to species moving in and out of national boundaries,” Julia shared.
Now in her fourth year at SAFS and just getting started on this research, Julia will be focusing on this topic for the remainder of her PhD.