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 Nanoparticle Exposure Can Awaken Dormant Viruses in the Lungs
16.01.2017 | Helmholtz Zentrum München - Deutsches Forschungszentrum für Gesundheit und Umwelt

nachricht Cholera bacteria infect more effectively with a simple twist of shape
13.01.2017 | Princeton University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Water - as the underlying driver of the Earth’s carbon cycle

17.01.2017 | Earth Sciences

Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

17.01.2017 | Materials Sciences

Smart homes will “LISTEN” to your voice

17.01.2017 | Architecture and Construction

VideoLinks
B2B-VideoLinks
More VideoLinks >>>