Time-variant bioeconomic risks on a gastropod fishery affected by uncertain ocean acidification trajectories

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Introduction In the north-eastern Pacific, high-value abalone fisheries, which are sensitive to pH variations, require in situ pH data to properly assess the bioeconomic effects of their possible dynamic trajectories under alternative fishing mortalities. Methods In situ pH data were collected every 15 min using a HOBO® MX2501 sensor in the La Bocana pink abalone fishing grounds and compared them with Argo float and Copernicus Marine Service observations. The observed pH distribution was fitted to the Extreme Value Minimum distribution based on the Anderson–Darling goodness-of-fit statistic. Stochastic pH trajectories were generated through 10,000 Monte Carlo replications under three IPCC ocean acidification scenarios (SSP1-2.6, SSP2-4.5, and SSP5-8.5) and three fishing mortalities ( F D = 0.02, 0.04, and 0.06). These trajectories were incorporated into a dynamic age-structured bioeconomic model by making individual growth and age-specific natural mortality functions dependent on pH. Biomass and resource rent per boat were projected from 2025 to 2100, and linear mixed-effects models, sensitivity analyses, and 95% confidence intervals were used to evaluate temporal responses and parameter uncertainty. Dynamic risks were estimated as the probability that biomass and resource rent fell below their respective limit reference points (LRPs: 190 t and USD 15,000 yr -1 ) across scenarios and fishing mortalities. Results The results indicate considerable variability in pH measurements between remote and in situ sources, which may introduce a proportional bias into the bioeconomic modeling if local observations are absent. Also, the effects of ocean acidification on H. corrugata biomass, survival, and fishery resource rent increase with time, IPCC pH scenario, and alternative exploitation intensity. Under the current exploitation rate ( F MSY = 0.06), effects were negligible in the short term under SSP1-2.6, whereas by 2100 pH-related growth effects decreased by 4%, 13%, and 26% under SSP1-2.6, SSP2-4.5, and SSP5-8.5, respectively. Over the same period, pH effects on survival rates resulted in a slight increase of 2.14% under SSP1-2.6, but reductions of 6.48% and 22% under SSP2-4.5 and SSP5-8.5, respectively, while age-specific biomass peaks declined by up to 20% and 44% under SSP2-4.5 and SSP5-8.5. Mixed-effects models confirmed significant effects of pH scenario, exploitation rate, and time on biomass and resource rent, including significant interactions (all p < 0.001). By 2100, annual resource rent per small-scale boat was significantly higher under SSP1-2.6 than under SSP2-4.5 and SSP5-8.5 by USD 3,083 and USD 7,482, respectively ( p < 0.0001). Under F MSY , the risk of biomass falling below its LRP was <25% during 2025–2040 but increased to 34% and 54% under SSP2-4.5 and SSP5-8.5, respectively, by 2100; corresponding risks for resource rent increased to 27% and 48%. Discussion These results indicate that ocean acidification may substantially increase the long-term bioeconomic vulnerability of the fishery, particularly under high-emission scenarios. Management actions to mitigate the undesired bioeconomic effects of OA will likely depend on the fishery authority’s risk attitude (i.e., degree of risk aversion) and corresponding exploitation-rate strategy selection.