Half a century of global decline in oceanic sharks and rays

  • Thread starter Greg Bernhardt
  • Start date
  • Tags
    Global Rays
In summary, 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 seas.
  • #1
Greg Bernhardt
Admin
Insights Author
19,437
10,006
TL;DR Summary
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
 
  • Sad
  • Like
Likes bhobba, Evo and BillTre
Biology news on Phys.org
  • #2
Similar to the decline in insects we have been hearing about for several years.
 
  • Sad
Likes Evo and Greg Bernhardt
  • #3
Last edited:
  • Sad
  • Like
Likes Evo, 256bits and BillTre
  • #4
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:
 
  • #5
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.
 
  • Sad
  • Like
Likes BillTre and Evo

1. What is the main cause of the decline in oceanic sharks and rays?

The main cause of the decline in oceanic sharks and rays is overfishing. These species are often caught as bycatch in fisheries targeting other species, and are also targeted for their fins, meat, and other body parts.

2. How much have oceanic shark and ray populations declined in the past 50 years?

According to a recent study, oceanic shark and ray populations have declined by 71% in the past 50 years. This is a significant decrease and is cause for concern for the health of our oceans.

3. Are all species of sharks and rays declining?

No, not all species of sharks and rays are declining. Some species, such as the great white shark and manta ray, have stable or increasing populations. However, the overall trend for oceanic sharks and rays is a decline.

4. How does the decline of oceanic sharks and rays impact marine ecosystems?

Oceanic sharks and rays play important roles in maintaining the balance of marine ecosystems. As top predators, they help regulate the populations of their prey and contribute to the health and diversity of the ocean. Their decline can lead to imbalances and potentially harmful effects on other species and the overall ecosystem.

5. What can be done to help reverse the decline of oceanic sharks and rays?

There are several actions that can be taken to help reverse the decline of oceanic sharks and rays. These include implementing sustainable fishing practices, reducing bycatch, and protecting critical habitats. Additionally, consumer awareness and support for sustainable seafood choices can also make a positive impact on these species.

Hot Threads

Recent Insights

Back
Top