Modeling links between climate-driven three-dimensional habitat compression and fishing effort in the Eastern Tropical Pacific

The Eastern Tropical Pacific Marine Corridor (CMAR) is a crucial environmental initiative formed by Colombia, Costa Rica, Ecuador, and Panama. This collaboration aims to protect and sustainably manage the marine biodiversity in the Eastern Tropical Pacific Ocean, an area known for its high productivity and biological diversity. A key challenge for CMAR is enhancing surveillance, monitoring, and enforcement within its Marine Protected Areas (MPAs). Climate change adds to this challenge by shifting fish distribution and spatial fishing patterns. Specifically, ocean warming and expanding oxygen minimum zones are expected to compress the vertical habitats of large pelagic fishes and their prey, creating high density patches of fish close to the surface that may attract high levels of fishing effort. Understanding how climate-driven shifts in fish and fishing distributions impact MPAs is essential for developing targeted enforcement strategies that adapt to these changes and support sustainable resource management. Here, we use a three-dimensional global database of oxygen data to elucidate how the oxygen minimum zone in the CMAR has expanded in the last few decades, and how this impacts large pelagic fish distribution in the 3-dimensional space of the ocean, along with its implications for tuna fishing effort. We then examine how fish and fishing effort may shift during marine heatwaves and under climate change (2040-2051 relative to 2004-2016 under SSP 1-2.6 and 5-8.5). Our study reveals that climate change is exerting significant pressure on large pelagic fish populations in the ETP by compressing their vertical habitats due to ocean warming and the expansion of oxygen minimum zones. This compression towards the ocean surface is contributing to an increase in catchability, raising concerns about the sustainability of these fish stocks within and around MPAs. The direct correlation between the shoaling of oxygen minimum zones and heightened fishing efforts indicates an urgent need for adaptive management strategies in fisheries.