Half a century of global decline in oceanic sharks and rays

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SUMMARY

The global abundance of oceanic sharks and rays has declined by 71% since 1970, primarily due to an 18-fold increase in fishing pressure. This decline is tracked using the Living Planet Index, which aggregates data from 57 abundance time-series datasets for 18 species, and the Red List Index, which assesses extinction risk for all 31 oceanic species. These findings highlight the urgent need for conservation efforts to address overfishing and protect marine biodiversity, aligning with Aichi Biodiversity Targets and Sustainable Development Goals.

PREREQUISITES
  • Understanding of the Living Planet Index and its application in biodiversity tracking.
  • Familiarity with the Red List Index and its role in assessing extinction risk.
  • Knowledge of marine ecology, particularly concerning oceanic sharks and rays.
  • Awareness of global fishing practices and their impact on marine species.
NEXT STEPS
  • Research the methodologies behind the Living Planet Index and its datasets.
  • Explore conservation strategies for oceanic sharks and rays, focusing on policy changes.
  • Investigate the implications of overfishing on marine ecosystems and biodiversity.
  • Study the concept of mass extinction events and their historical context in relation to current biodiversity loss.
USEFUL FOR

Marine biologists, conservationists, environmental policymakers, and anyone interested in the preservation of oceanic biodiversity and the impact of human activities on marine life.

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TL;DR
We find that, since 1970, the global abundance of oceanic sharks and rays has declined by 71% owing to an 18-fold increase in relative fishing pressure.
Overfishing is the primary cause of marine defaunation, yet declines in and increasing extinction risks of individual species are difficult to measure, particularly for the largest predators found in the high seas1–3. Here we calculate two well-established indicators to track progress towards Aichi Biodiversity Targets and Sustainable Development Goals4,5: the Living Planet Index (a measure of changes in abundance aggregated from 57 abundance time-series datasets for 18 oceanic shark and ray species) and the Red List Index (a measure of change in extinction risk calculated for all 31 oceanic species of sharks and rays). We find that, since 1970, the global abundance of oceanic sharks and rays has declined by 71% owing to an 18-fold increase in relative fishing pressure.

https://www.nature.com/articles/s41586-020-03173-9
 
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Biology news on Phys.org
Similar to the decline in insects we have been hearing about for several years.
 
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jim mcnamara said:
Birds as well. Some like passenger pigeons are extinct. Audubon has a list of once more common species, species that have become rare. Here is one list:

http://focusonnature.com/BirdListRareBirdsNorthAmerica.htm
Any in there that are warm, cuddly and cute?

Besides the sharks and scary insects, that is.:wink:
 
John Terborgh 'Where have all the birds gone' 1989 -- discusses the impact of deforestation of Cuba and the steep decline of North American songbirds that used to overwinter there.
https://www.amazon.com/dp/0691024286/?tag=pfamazon01-20

It is not like we have been unaware of an impending problem.
 
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