Historical versus recent trends in the tropicalization of fisheries catches along a latitudinal temperature gradient

Climate change is reshaping marine ecosystems by altering the abundance, distribution, and productivity of fish and invertebrate stocks that support economically significant fisheries. The mean temperature of the catch (MTC) index is a well-established metric that has been developed to detect the signature of ocean warming in fisheries catches. Here, we used up-to-date catch data sets to analyze long-term historical (1950-2022) and recent accelerated (2000-2022) MTC trends over a latitudinal temperature gradient along the east and Gulf coast of the USA. Analyses revealed regional heterogeneity, with New England and the US South Atlantic region exhibiting the highest long-term MTC increases (0.12 and 0.39°C decade -1 , respectively) that were even more pronounced in recent decades (0.79 and 0.66°C decade -1 , respectively). This northward shift in the intensity of catch tropicalization aligns with accelerated warming in the Northeast US Atlantic shelf. The upward MTC trends were associated with increased prevalence of warm-water species and decreased occurrence of cold-water species in the catches and were predominantly explained by rising sea surface temperatures and the Atlantic Multidecadal Oscillation. Our analyses comprehensively covered >80% of catches in all regions, confirming that observed trends are not driven by single species and supporting the MTC index as a robust tool for detecting fisheries’ responses to warming. This study provides a nuanced understanding of how marine communities and fisheries are responding to climate change across oceanographic regimes. The distinct regional responses challenge simple latitudinal assumptions, highlighting the need for region-specific management adaptations in a warming environment.