Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Mistaken identity? When a white marlin may not always be a white marlin

28.02.2007
New species creates identity crisis

For years, anglers thinking they were catching the prized white marlin may have caught something quite different, raising concerns about the true remaining numbers of the threatened species, according to an article in the most recent issue of the scientific journal Bulletin of Marine Science.

A team of scientists from the Guy Harvey Research Institute at Nova Southeastern University and NOAA Fisheries Service's Southeast Fisheries Science Center in Miami has confirmed the existence of an enigmatic billfish species closely resembling the heavily-fished, overexploited white marlin.

Known as the roundscale spearfish, the new billfish species has been found in the northwestern Atlantic Ocean, where its distribution overlaps that of the white marlin, a prized game fish of American recreational anglers.

This finding has significant implications to the future of the threatened white marlin, as recent population assessments may have been overestimated since the species is virtually indistinguishable from the previously unrecognized roundscale spearfish. A prior petition to qualify the white marlin for the U.S. Endangered Species List, arguing its declining population size, was unsuccessful.

"The existence of the roundscale spearfish was confirmed by analyzing the shape of its mid-body scales, which are slightly more rounded at one end compared to the scales of all other Atlantic billfish species, and by analyzing its DNA which turns out to be very different from other billfish species," says Mahmood Shivji, Ph.D., the article's lead author and director of the Guy Harvey Research Institute.

Without an expert eye to see the subtle differences between the white marlin and the roundscale spearfish, conservation and management may be difficult. Without DNA analysis, a very close examination of the scales or calculating the ratio of the distance of the animal's urogential opening from the anal fin to the height of that fin are the primary methods of determining the difference between the white marlin and the roundscale spearfish. Shivji says that commercial and recreational fishers without knowledge of these subtle appearance differences may misidentify a "white marlin," when it actually is a roundscale spearfish.

"We don't know much about roundscale spearfish, particularly how abundant they are. If they are abundant and if they have been consistently misidentified as white marlin in the historical landings database of the International Commission for the Conservation of Atlantic Tunas (ICCAT), then white marlin population sizes may have been overestimated in past assessments," said Eric Prince, Ph.D., of NOAA Fisheries Service and a co-author of the study. "This unexpected finding adds an unknown level of uncertainty to our previous estimates of white marlin population size, and certainly suggests that the magnitude of roundscale spearfish misidentification and possible 'contamination' of white marlin landings data need to be examined in greater detail."

Additional roundscale spearfish specimens have subsequently been seen by specially trained fisheries observers, suggesting that encounters with this species may not be uncommon in the northwestern Atlantic, according to Lawrence Beerkircher, manager of the Pelagic Observer Program at NOAA Fisheries and a co-author of the article.

"This finding also raises the possibility of 'mistaken identity' problems in larval billfish surveys that have been conducted throughout the Atlantic Ocean," said co-author Joe Serafy, Ph.D., a NOAA fishery biologist and an associate professor at the University of Miami.

Using fine-mesh nets towed behind research vessels, larval billfish surveys obtain important management information on when and where spawning occurs and the location of nursery grounds for the marlin, sailfish and spearfish species.

Based on a stock assessment performed in 2002 by ICCAT, white marlin populations are already severely overfished and only at about 12 percent of the level necessary to maintain maximum sustainable harvests (i.e., fishing mortality is way too high).

With much international concern about preventing further population declines, the discovery of the roundscale spearfish now adds to this concern by raising the possibility that white marlin populations may be even smaller than previously estimated due to misidentifications. International management and conservation efforts will need to take this new uncertainty into consideration.

Chris Dudley | EurekAlert!
Further information:
http://www.sefsc.noaa.gov/
http://www.iccat.es/assess.htm
http://www.nova.edu/ocean/ghri

Further reports about: Assessment Atlantic Fisheries NOAA roundscale spearfish

More articles from Life Sciences:

nachricht Flow of cerebrospinal fluid regulates neural stem cell division
22.05.2018 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Chemists at FAU successfully demonstrate imine hydrogenation with inexpensive main group metal
22.05.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

Im Focus: Computer-Designed Customized Regenerative Heart Valves

Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.

Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...

Im Focus: Light-induced superconductivity under high pressure

A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.

Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Supersonic waves may help electronics beat the heat

18.05.2018 | Power and Electrical Engineering

Keeping a Close Eye on Ice Loss

18.05.2018 | Information Technology

CrowdWater: An App for Flood Research

18.05.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>