Effects of climate‐change‐driven gradual and acute temperature changes on shark and ray species

Abstract

1. Climate change is altering distributions and abundances of marine species through both gradual and acute changes in temperature and productivity. Due to their high mobility and metabolic rates, elasmobranchs (sharks and rays) are likely to redistribute across latitudes and depths as they thermoregulate, but little is known about their responses to these climatic changes, which could vary widely across this diverse group of species.2. Here, we assessed how species with differing mobility and ecology responded to gradual changes in daily sea surface temperature (SST) and acute temperature anomalies, caused by the El Niño-Southern Oscillation (ENSO), at Cocos Island, Costa Rica, the site of multiple marine heatwaves.3. We used generalized linear mixed models to analyse 34,342 records of relative abundance or frequency of occurrence for seven shark and ray species collected in 27 years ) by a dive company. We compared effect sizes for SST and the Oceanic Niño Index across the different species, which vary widely in body size and mobility.4. Large, mobile species responded strongly but inconsistently to temperature. For scalloped hammerhead sharks Sphyrna lewini, a 1℃ rise in SST reduced counts by over 14%, and dropped the occurrence of their large schools by almost onefifth (19.4%). Mobula ray occurrence also declined substantially with a few degrees rise in SST, whereas tiger shark Galeocerdo cuvier occurrence sharply increased.These species also had divergent responses to the ENSO: S. lewini and G. cuvier were sighted with greater frequency during La Niña events, and their abundance dropped considerably during El Niño events-over a twofold decline between a strong La Niña and strong El Niño for S. lewini. In contrast, Mobula rays showed little response to ENSO. The smaller and sedentary Triaenodon obesus exhibited the weakest response of all species to both SST and the ENSO, reflecting its lower metabolic rates and mobility. 5. Climate change will continue to impact elasmobranchs, even for smaller and more localized species, with the potential to impact the effectiveness of marine protected areas (MPAs). Our results compel further work on the diversity of elasmobranch responses to environmental change.

A Risk-Based Assessment to Advise the Responsible Consumption of Invertebrates, Elasmobranch, and Fishes of Commercial Interest in Mexico

“…Most of the elasmobranchs in this analysis resulted with moderate RV to fishing activities in Mexico. However, future analysis should consider that species may be subject to other sources of pressure (e.g., overlapping with fishing fleets from other countries, oil spills, climate change, and habitat loss) (Calich et al, 2018;Osgood et al, 2021;Yan et al, 2021;Romo-Curiel et al, 2022). Moreover, half of the evaluated elasmobranchs in this study belong to extinction risk categories of the Red List of Threatened Species of the International Union for Conservation of Nature (IUCN) of Critically Endangered, Endangered, and Vulnerable (Supplementary Table S3).…”

Determining the Role of Environmental Covariates on Planktivorous Elasmobranch Population Trends within an Isolated Marine Protected Area

“…Another possibility is that whale sharks are responding to changes in zooplankton community composition (i.e., specific species present), rather than the concentrations of species. Neither White et al 2015 or Osgood et al 2021 included Chlorophyll A in their models; however, in our models we included this parameter, and it was one of the most influential covariates in our whale shark models.…”

“…Using the same methods as a previous study on the same system, ONI data was obtained from NOAA at their website https://www.cpc.ncep.noaa.gov/data/indices/oni.ascii.txt (Osgood et al 2021). We adapted the methods from Osgood et al 2021 and included temperature of dive, mean monthly sea surface temperature, and ONI index. We selected these because they each represent a different type of temperature change: ONI represents the running 3 month mean of SST anomalies in the Niño-3.4 region of the east-central Pacific and correlates with more general oceanographic features of the eastern tropical Pacific, temperature of dive captures the immediate responses of species at depth, and sea surface temperature captures the immediate responses of species at the surface.…”

“…The specific aims of this study are threefold. First, we expand on past studies on the same system (White et al 2015, Osgood et al 2021) to examine the role of food availability (e.g., primary productivity), acute climate changes (e.g., sea surface temperature, temperature at depth), long term climate trends (e.g., Ocean Niño Index), oceanographic conditions (e.g., current, salinity), and lunar cycle (e.g., lunar phase, lunar distance) on the population trends of planktivorous elasmobranchs. Second, we examine how accounting for environmental covariates shifts predictions about population trends when compared with models which examined population trends over time without accounting for environmental variability.…”

Distant water industrial fishing in developing countries: A case study of Madagascar

“…Past work on the drivers of fluctuations in fishing effort over time (Stephenson et al, 2018), has demonstrated the importance of global oil prices and seafood prices as two important predictors of global fishing effort (Cheilari et al, 2013;Dahl & Oglend, 2014;Guillotreau et al, 2017;Kroodsma et al, 2018). In addition, biological productivity, large scale climate oscillations (e.g., El Niño, Indian Dipole Index), and extreme weather events have all been shown to be important predictors of commonly-fished pelagic species occurrence (Osgood et al, 2021) and fishing effort (Belhabib et al, 2018;Kroodsma et al, 2018;Kumar et al, 2014). However, this past work has typically focused on regional and global data sets, with implications for specific countries less clear (Kumar et al, 2014).…”