Featured Research

from universities, journals, and other organizations

Boom in jellyfish: Overfishing called into question

Date:
May 3, 2013
Source:
Institut de Recherche pour le Développement (IRD)
Summary:
Will we soon be forced to eat jellyfish? Since the beginning of the 2000s, these gelatinous creatures have invaded many of the world's seas, like the Japan Sea, the Black Sea, the Mediterranean Sea, etc. Is it a cyclic phenomenon, caused by changes in marine currents or even global warming? Until now, the causes remained unknown. A new study exposes overfishing as the main factor.

Jellyfish food chain.
Credit: © IRD / L. Corsini

Will we soon be forced to eat jellyfish? Since the beginning of the 2000s, these gelatinous creatures have invaded many of the world's seas, like the Japan Sea, the Black Sea, the Mediterranean Sea, etc. Is it a cyclic phenomenon, caused by changes in marine currents or even global warming? Until now, the causes remained unknown. A new study conducted by IRD researchers and its partners, published in Bulletin of Marine Science, exposes overfishing as the main factor.

Related Articles


Jellyfish have free rein

Jellyfish predators, such as tuna and sea turtles, are disappearing due to overfishing. However, jellyfish are primarily taking advantage of the overfishing of small pelagic fish. Just like these cnidarians, sardines, herring, anchovies and more feed off zooplankton. Thus, they represent their main competition for food. In areas where too many of these fish are caught, they free up an ecological niche. Jellyfish now have free rein and can thrive. Furthermore, small fish eat the eggs and larvae of jellyfish. Therefore, under normal conditions, they regulate the population. In their absence, there is nothing to stop the proliferation of these gelatinous creatures.

Comparison as proof

In order to demonstrate the major role played by overfishing, researchers compared two ecosystems belonging to the same ocean current, the Benguela, which flows along the south of Africa. The first ecosystem is located off the coast of Namibia. Here, fish stock management measures are not very restrictive. The stocks are barely restored before fishing activities start up again. Jellyfish are currently colonising these coastal waters. The second ecosystem is located 1,000 km further south, off the coast of South Africa. Here, the opposite is true: fishing has been tightly controlled for 60 years. The jellyfish population has not increased.

Fisheries suffer the effects

A vicious circle is developing in affected areas. Under the water, the links in the food chain are much more flexible than on Earth: prey species can feed off their predators. As such, jellyfish devour larval fish. Their proliferation prevents the renewal of fishery resources. This invasive species in turn threatens fisheries. In Namibia, some 10 million tonnes of sardines in the 1960s made way for 12 million tonnes of jellyfish.

Jellyfish are the pet peeve of tourists. The sting of their poisonous filaments -- although seldom deadly -- is very urticant. Therefore, they put economic activities in many regions across the world at risk. This is particularly true in countries which depend on these resources, such as several developing countries.

This research work underlines the necessity of an ecosystemic approach towards the exploitation of the sea. In other words, the implementation of management measures which take into account all levels of the trophic network. According to scientists, this is the only way to prevent jellyfish from landing on our plates in the near future.

Did you know?

Jellyfish are made up of 98% water. They have neither a brain, nor a heart or teeth… And yet, they are fierce predators! They immobilise their prey with their poisonous tentacles.

The boom in jellyfish is observed across the entire planet. To date, however, there is no hard data on the increase in their global population.

There are hundreds of species of jellyfish which come in a great variety of colours, shapes and sizes, ranging from a few millimetres to several metres in diameter. The majority of them are carnivorous.


Story Source:

The above story is based on materials provided by Institut de Recherche pour le Développement (IRD). Note: Materials may be edited for content and length.


Journal Reference:

  1. Jean-Paul Roux, Carl D van der Lingen, Mark J Gibbons, Nadine E Moroff, Lynne J Shannon, Anthony DM Smith, Philippe M Cury. Jellyfication of Marine Ecosystems as a Likely Consequence of Overfishing Small Pelagic Fishes: Lessons from the Benguela. Bulletin of Marine Science, 2013; 89 (1): 249 DOI: 10.5343/bms.2011.1145

Cite This Page:

Institut de Recherche pour le Développement (IRD). "Boom in jellyfish: Overfishing called into question." ScienceDaily. ScienceDaily, 3 May 2013. <www.sciencedaily.com/releases/2013/05/130503094700.htm>.
Institut de Recherche pour le Développement (IRD). (2013, May 3). Boom in jellyfish: Overfishing called into question. ScienceDaily. Retrieved November 28, 2014 from www.sciencedaily.com/releases/2013/05/130503094700.htm
Institut de Recherche pour le Développement (IRD). "Boom in jellyfish: Overfishing called into question." ScienceDaily. www.sciencedaily.com/releases/2013/05/130503094700.htm (accessed November 28, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Friday, November 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Research on Bats Could Help Develop Drugs Against Ebola

Research on Bats Could Help Develop Drugs Against Ebola

AFP (Nov. 28, 2014) — In Africa's only biosafety level 4 laboratory, scientists have been carrying out experiments on bats to understand how virus like Ebola are being transmitted, and how some of them resist to it. Duration: 01:18 Video provided by AFP
Powered by NewsLook.com
New Dinosaur Species Found in Museum Collection

New Dinosaur Species Found in Museum Collection

Reuters - Innovations Video Online (Nov. 27, 2014) — A British palaeontologist has discovered a new species of dinosaur while studying fossils in a Canadian museum. Pentaceratops aquilonius was related to Triceratops and lived at the end of the Cretaceous Period, around 75 million years ago. Jim Drury has more. Video provided by Reuters
Powered by NewsLook.com
Tryptophan Isn't Making You Sleepy On Thanksgiving

Tryptophan Isn't Making You Sleepy On Thanksgiving

Newsy (Nov. 27, 2014) — Tryptophan, a chemical found naturally in turkey meat, gets blamed for sleepiness after Thanksgiving meals. But science points to other culprits. Video provided by Newsy
Powered by NewsLook.com
Classic Hollywood Memorabilia Goes Under the Hammer

Classic Hollywood Memorabilia Goes Under the Hammer

Reuters - Entertainment Video Online (Nov. 26, 2014) — The iconic piano from "Casablanca" and the Cowardly Lion suit from "The Wizard of Oz" fetch millions at auction. Sara Hemrajani reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins