Assessing indirect biodiversity conservation benefits of fisheries closures in the Gulf of St. Lawrence, Canada

the highest/lowest value within 1.5 times the interquartile range; horizontal lines within boxes correspond to the median; diamonds represent the mean; outlier dots represent data beyond the end of the whiskers. (B) Preferred temperature ranges for spawning and non-spawning adults of redfish (RH; Sebastes mentella, Sebastes fasciatus), Greenland halibut (GH; Reinhard- tius hippoglossoides), and Atlantic halibut (AH; Hippoglossus hippoglossus). Analysis for changes for 2050–59 are in Fig 2. (PDF) S3 Fig. Baseline and end-century, future bottom sea temperature (˚C), bottom oxygen con- centration (mmol m3), and pH; (A) across the Gulf of St. Lawrence and (B) within individ- ual Other Effective area-based Conservation Measures (OECMs). Baseline values include the years 2010–2019; future projections include the time frame 2090–2099 under two shared socioeconomic pathways (SSPs). Dark grey shading indicates the preferred temperature range for adult non-spawning (grey) and spawning (darkgrey) Atlantic halibut (Hippoglossus hippo- glossus), Greenland halibut (Reinhardtius hippoglossoides), and redfish (Sebastes mentella). Light grey shading indicates oxygen concentration below 60 mmol m3, the threshold for a marine ecosystem to be considered hypoxic [20]. Dashed black line indicates today’s average ocean pH [59]. Boxplots: upper and lower hinges correspond to the first and third quartiles; upper/lower whiskers extend to the highest/lowest value within 1.5 times the interquartile range; horizontal lines within boxes correspond to the median; diamonds represent the mean;

outlier dots represent data beyond the end of the whiskers. (TIF) S4 Fig. End-century percent change in bottom sea temperature, bottom oxygen concentra- tion, and pH for individual Other Effective area-based Conservation Measures (OECMs) and associated average depth (m) of each OECM. Changes represent values in 2090–2099 relative to the baseline time frame 2010–2019. Labels indicate whether an OECM is overlap- ping with potential spawning habitat of AH = Atlantic halibut, GH = Greenland halibut, and RF = redfish. Error bars indicate one standard deviation of the mean. (TIF) S5 Fig. Projected percent changes for sea bottom temperature, bottom oxygen concentra- tion, and pH by mid-, and end-century (2050–2059 and 2090–99) under SSP2-45 in the Gulf of St. Lawrence. All changes are relative to the baseline condition in 2010–2019. Red out- lines denote established Other Effective Conservation Measures (OECMs), retrieved from [45]. Data from Bio-ORACLE v.3.0 [58]. Land shapefiles retrieved from http://www. naturalearthdata.com/. (TIF) S6 Fig. Projected percent changes for sea bottom temperature, bottom oxygen concentra- tion, and pH by mid-, and end-century (2050–2059 and 2090–99) under SSP5-85 in the Gulf of St. Lawrence. All changes are relative to the baseline condition in 2010–2019. Red out- lines denote established Other Effective Conservation Measures (OECMs), retrieved from [45]. Data from Bio-ORACLE v.3.0 [58]. Land shapefiles retrieved from http://www. naturalearthdata.com/. (TIF) Acknowledgments

We thank Paul Gatti for generously sharing data on Atlantic spawning likelihood in the Gulf of St. Lawrence. Thanks to Jorge Assis for helping to navigate the Bio-ORACLE database. PLOS ONE Indirect biodiversity conservation in the Gulf of St. Lawrence PLOS ONE | https://doi.org/10.1371/journal.pone.0316754 January 9, 2025 15 / 20