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.

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 July 30, 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 July 30, 2014).

Share This




More Plants & Animals News

Wednesday, July 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Concern Grows Over Worsening Ebola Crisis

Concern Grows Over Worsening Ebola Crisis

AFP (July 30, 2014) — Pan-African airline ASKY has suspended all flights to and from the capitals of Liberia and Sierra Leone amid the worsening Ebola health crisis, which has so far caused 672 deaths in Guinea, Liberia and Sierra Leone. Duration: 00:43 Video provided by AFP
Powered by NewsLook.com
Raw: Otters Enjoy Water Slides at Japan Zoo

Raw: Otters Enjoy Water Slides at Japan Zoo

AP (July 30, 2014) — River otters were hitting the water slides to beat the summer heatwave on Wednesday at Ichikawa City's Zoological and Botanical Garden. (July 30) Video provided by AP
Powered by NewsLook.com
In Virginia, the Rise of a New Space Coast

In Virginia, the Rise of a New Space Coast

AP (July 30, 2014) — Every summer, tourists make the pilgrimage to Chincoteague Island, Va. to see wild ponies cross the Assateague Channel. But, it's the rockets sending to supplies to the International Space Station that are making this a year-round destination. (July 30) Video provided by AP
Powered by NewsLook.com
Rodents Rampant in Gardens Around Louvre

Rodents Rampant in Gardens Around Louvre

AP (July 29, 2014) — Food scraps and other items left on the grounds by picnickers brings unwelcome visitors to the grounds of the world famous and popular Louvre Museum in Paris. (July 29) Video provided by AP
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:
from the past week

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