Featured Research

from universities, journals, and other organizations

Plenty more fish in the sea? New method for measuring biomass reveals fish stocks are more stable than widely believed

Date:
April 28, 2011
Source:
Wiley-Blackwell
Summary:
Fish and marine species are among the most threatened wildlife on earth, due partly to over exploitation by fishing fleets. Yet there are differences in assessing trends in worldwide fishing stocks which, researchers argue, stem from inappropriate use of time trends in catches.

Fishing ships in harbor. Fish and marine species are among the most threatened wildlife on earth, due partly to over exploitation by fishing fleets. Yet there are differences in assessing trends in worldwide fishing stocks which, researchers writing in Conservation Biology argue, stem from inappropriate use of time trends in catches.
Credit: Eric Gevaert / Fotolia

Fish and marine species are among the most threatened wildlife on earth, due partly to over exploitation by fishing fleets. Yet there are differences in assessing trends in worldwide fishing stocks which, researchers writing in Conservation Biology argue, stem from inappropriate use of time trends in catches.

Related Articles


"Estimates of fishery status based on catches suggest that around 30% of fisheries are collapsed and 70% are overexploited or collapsed," said lead author Dr Trevor Branch from the University of Washington in Seattle. "Our assessment shows that the data are seriously biased, and that instead we should be looking at biomass data."

Biomass data from scientific stock assessments indicated a much smaller proportion in these categories (12% collapsed, 26% overexploited or collapsed), and that status trends are stable. Dr Branch's analysis suggests that in most regions fisheries management has led to stabilization, and even recovery, of fished populations.

"Species which are targeted by fishing fleets are divided into stocks, a division of species into units based on political boundaries, genetic divergence, and biological characteristics," said Branch. "The depletion of these stocks has important implications for ecosystem biodiversity; however methods of measuring depletion vary greatly."

Dr Branch's team considered stocks being "collapsed" or "overexploited" on the basis of catch and biomass data. Collapse is defined as biomass of less than 10% of unfished levels while over exploitation is defined by the governments of the United States and Australia as biomass below 50% of biomass that would produce maximum sustained catches. These reference points are widely used in fisheries management, either as management targets or as limits not to be exceeded.

"Our study found the status of stocks worldwide based on catch trends to be almost identical to what would be expected if catches were randomly generated with no trend at all," said Branch, "and that most classifications of collapse on the basis of catch data are not true collapses but are due to taxonomic reclassification, regulatory changes in fisheries, and market changes."

Dr Branch's team argue that where available, biomass data can be used to ground truth catch trends, revealing that catch data greatly overestimates the percentage of stocks collapsed and overexploited.

Although the team's biomass data was primarily from industrial fisheries in developed countries, the status of these stocks estimated from catch data is similar to the status of stocks in the rest of the world estimated from catch data.

"Instead of focusing on what we take out of the oceans (catches), we should be examining the actual state of the ecosystem (biomass data)," concludes Branch. "Catch data produce seriously biased estimates of what is going on in ocean ecosystems, and we need more effort expended on scientific surveys and stock assessments, especially in areas that are currently poorly assessed."


Story Source:

The above story is based on materials provided by Wiley-Blackwell. Note: Materials may be edited for content and length.


Journal Reference:

  1. Trevor A. Branch, Olaf P. Jensen, Daniel Ricard, Yimin Ye, Ray Hilborn. Contrasting Global Trends in Marine Fishery Status Obtained from Catches and from Stock Assessments. Conservation Biology, 2011; DOI: 10.1111/j.1523-1739.2011.01687.x

Cite This Page:

Wiley-Blackwell. "Plenty more fish in the sea? New method for measuring biomass reveals fish stocks are more stable than widely believed." ScienceDaily. ScienceDaily, 28 April 2011. <www.sciencedaily.com/releases/2011/04/110428101754.htm>.
Wiley-Blackwell. (2011, April 28). Plenty more fish in the sea? New method for measuring biomass reveals fish stocks are more stable than widely believed. ScienceDaily. Retrieved December 21, 2014 from www.sciencedaily.com/releases/2011/04/110428101754.htm
Wiley-Blackwell. "Plenty more fish in the sea? New method for measuring biomass reveals fish stocks are more stable than widely believed." ScienceDaily. www.sciencedaily.com/releases/2011/04/110428101754.htm (accessed December 21, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Sunday, December 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Researchers Test Colombian Village With High Alzheimer's Rates

Researchers Test Colombian Village With High Alzheimer's Rates

AFP (Dec. 19, 2014) In Yarumal, a village in N. Colombia, Alzheimer's has ravaged a disproportionately large number of families. A genetic "curse" that may pave the way for research on how to treat the disease that claims a new victim every four seconds. Duration: 02:42 Video provided by AFP
Powered by NewsLook.com
Monarch Butterflies Descend Upon Mexican Forest During Annual Migration

Monarch Butterflies Descend Upon Mexican Forest During Annual Migration

Reuters - Light News Video Online (Dec. 19, 2014) Millions of monarch butterflies begin to descend onto Mexico as part of their annual migration south. Rough Cut (no reporter narration) Video provided by Reuters
Powered by NewsLook.com
The Best Protein-Filled Foods to Energize You for the New Year

The Best Protein-Filled Foods to Energize You for the New Year

Buzz60 (Dec. 19, 2014) The new year is coming and nothing will energize you more for 2015 than protein-filled foods. Fitness and nutrition expert John Basedow (@JohnBasedow) gives his favorite high protein foods that will help you build muscle, lose fat and have endless energy. Video provided by Buzz60
Powered by NewsLook.com
Birds Might Be Better Meteorologists Than Us

Birds Might Be Better Meteorologists Than Us

Newsy (Dec. 19, 2014) A new study suggests a certain type of bird was able to sense a tornado outbreak that moved through the U.S. a day before it hit. Video provided by Newsy
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