Potential changes in the distribution of suitable habitat for Pacific sardine (Sardinops sagax) under climate change scenarios

The Pacific sardine, Sardinops sagax, is the most important fishery by volume in Mexico; however, this small pelagic species shows fluctuations in catch due to its susceptibility to environmental changes. In turn, this susceptibility leads to variations in distribution, abundance, and recruitment, making the Pacific sardine highly vulnerable to the effects of global climate change. In this study, we analyze the effects of environmental variability on the Pacific sardine distribution through the development of the habitat suitability for the Mexican Pacific. We used bathymetry, sea surface temperature (SST), sea surface salinity (SSS) and net primary productivity (NPP) to develop an ecological niche model to forecast the suitable habitat of the Pacific sardine and reproduce the historical patterns for the 2003-2017 period. We then used this model to make future projections to the year 2100 using the emission scenarios RCP 2.6, 4.5, and 8.5 proposed by the Intergovernmental Panel on Climate Change. Under the RCP models, on average, the greatest impact of climate change was observed inside the Gulf of California, with an increase in SST (+ 1.68 degrees C) and a decrease in 25% of NPP (-256 mg C m(-2) d(-1)) reducing habitat availability for this species by 95. Stocks on the Pacific coast are projected to fluctuate substantially, similar to past events driven by environmental variability. At the regional level, a loss of suitable habitat of up to 50% is expected by the end of this century for the Pacific sardine.