Seventy years of tunas, billfishes, and sharks as sentinels of global ocean health

Abstract

Fishing activity is closely monitored to an increasing degree, but its effects on biodiversity have not received such attention. Using iconic and well-studied fish species such as tunas, billfishes, and sharks, we calculate a continuous Red List Index of yearly changes in extinction risk over 70 years to track progress toward global sustainability and biodiversity targets. We show that this well-established biodiversity indicator is highly sensitive and responsive to fishing mortality. After ~58 years of increasing risk of extinction, effective fisheries management has shifted the biodiversity loss curve for tunas and billfishes, whereas the curve continues to worsen for sharks, which are highly undermanaged. While populations of highly valuable commercial species are being rebuilt, the next management challenge is to halt and reverse the harm afflicted by these same fisheries to broad oceanic biodiversity.

Seascape Genomics and Phylogeography of the Sailfish (Istiophorus platypterus)

“…However, given the uncertainties about its fishery stock assessments and the lack of continuous time series of genome-wide heterozygosity measurements, fishing activity's effects on its populations are unclear because fisheries-induced evolution would be relevant to fisheries management if it happens across time ( Law 2007 ). Nevertheless, even marine species severely affected by overfishing for extended periods, such as the ATL cod ( Gadus morhua ), may sustain healthy levels of genetic diversity if management strategies were adopted to strengthen the efforts to cease overfishing and reduce fishing pressure within the maximum sustainable yield ( Pinsky et al 2021 ; Juan-Jordá et al 2022 ). In order to promote straightforward and affordable genomic approaches for future fishery stock evaluations, we provided a subset of 200 highly informative SNPs that can be applied for future sailfish fishery stock assessments with the same accuracy as the whole data set from this study, democratizing access to these techniques.…”

“…Currently, most fishery stocks are fully exploited, overexploited, depleted, or need recovery ( McCauley et al 2015 ; Pauly and Zeller 2016 ), and overfishing is a major threat that can reduce biomass and genetic diversity ( Pinsky and Palumbi 2014 ). However, implementing effective fisheries management has decreased mortality rates for tunas and billfishes ( Juan-Jordá et al 2022 ). Therefore, improving management measures is required to rebuild fishery stocks, ensure a sustainable fishery, and decrease extinction risks of fishery resources.…”

Transient demographic dynamics of recovering fish populations shaped by past climate variability, harvest, and management

“…Excessive human exploitation continued through the twentieth century has depleted marine living resources worldwide, threatening biodiversity, food and nutrient security, and other ecosystem services that the oceans provide (Pauly, Watson & Alder 2005;Crowder et al 2008;Worm et al 2009). Long-lived, late-maturing vertebrate predators are disproportionately depleted by industrial fishing as target or incidental catch (Christensen et al 2003;Juan-Jordá et al 2022). As part of the efforts to halt and reverse the losses, national government and intergovernmental organizations began applying the precautionary principle to the management of marine fisheries (Hilborn et al 2001;Punt 2006), following international agreements, including the Code of Conduct for Responsible Fisheries adopted by the Food and Agriculture Organization of the United Nations (FAO 1995;Melnychuk et al 2021).…”

Patterns and drivers of the diving behavior of large pelagic predators

“…A mechanistic understanding of the drivers of LPP vertical migration could help in anticipating changes in the behavior of key species in a warming ocean (Hazen et al 2019), in particular in the poorly observed mesopelagic ecosystem (Hidalgo and Browman 2019). LPP include closely monitored species of economic value for fisheries and recreation (Arostegui et al 2022; Juan-Jordá et al 2022), protected species, and species threatened by bycatch (Scales et al 2018). Understanding their vertical behavior could thus help management of valuable stocks.…”