Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Abundance of a look-alike species clouds population status of a million dollar fish

New findings cast uncertainty on previous population size assessments for the severely overfished white marlin and call for reassessment of international recovery efforts

The prized white marlin, sought by anglers in million dollar prize tournaments and captured incidentally in commercial fisheries, is among the most overfished marine species under international management and the subject of contentious debate on how to best achieve its recovery.

Now a new study published today in the journal Endangered Species Research casts uncertainty on the accuracy of current knowledge of white marlin biology and previous population assessments, which form the basis of management and conservation policy. The study reports that the white marlin look-alike species, the enigmatic roundscale spearfish – whose very existence was only confirmed three years ago – makes up almost a third (approximately 27%) of the fish historically identified as white marlin.

This previously unrealized, relatively high abundance of roundscale spearfish and their misidentification might have impacted past assessments of white marlin population sizes and concomitant management efforts.

Given considerable concern about its declining populations, petitions to list the white marlin under the U.S. Endangered Species Act were considered in 2002 and 2007. Listing the fish would have undoubtedly put an end to white marlin fishing tournaments, which infuse millions of dollars into the recreational fishing industry as well as local economies.

"This proportion of roundscale spearfish along with its longstanding misidentification as white marlin for decades compromises the accuracy of current biological knowledge on white marlin" said lead author Lawrence Beerkircher of the NOAA Fisheries Service. "These findings illustrate a need for the immediate collection of biological and fishery data such as age and growth, migratory patterns, and fishery catch statistics for both the real white marlin and the roundscale spearfish."

To examine if the high proportion of roundscale spearfish and its misidentification might have impacted past assessments of white marlin population sizes, the research team conducted computer simulation studies which calculated historical population size trends for each species individually. Since the past ratios of roundscale spearfish to white marlin are unknown, the researchers also examined how variations in these ratios would impact the projections of population size trends for each species. The results of these computer simulations illustrated that variations in the ratio of the two species could indeed alter projections of white marlin population sizes, highlighting the influence that species misidentifications could have on the accuracy of past assessments.

For example, the most recent population assessment conducted by the International Convention for the Conservation of Atlantic Tunas (ICCAT) for white marlin in 2006 indicated a slight increasing trend in its population sizes, which was one of several reasons for its removal from the National Oceanic and Atmospheric Administration's (NOAA) Species of Concern List. However, based on the computer simulations conducted in the new study, whether this was, or was not, the right call cannot be determined without a breakdown of the two species ratios over time.

"It's remarkable how a simple case of mistaken identity can muddy what we thought we knew about a species from decades of study. This case points to the importance of making sure we know what species are out there in the first place", said Mahmood Shivji, Director of the Guy Harvey Research Institute at Nova Southeastern University, who co-led the study. "Furthermore, it's important to realize that we are also dealing with the existence of another large oceanic species, the roundscale spearfish, about which we know almost nothing and whose populations may be declining, steady or even on the rise"

"Obtaining a robust picture of white marlin population status will require conducting population assessments with updated roundscale spearfish proportions", said Lawrence Beerkircher. "New species-specific monitoring measures will be essential for achieving this goal and aiding rebuilding of white marlin populations."

NOAA Fisheries Service's Southeast Fisheries Science Center conducts multi-disciplinary research programs to provide management information to support national and regional programs of NMFS; and to respond to the needs of Regional Fishery Management Councils, Interstate and International Fishery Commission, Fishery Development Foundations, government agencies, and the general public. The SEFSC website is:

The Guy Harvey Research Institute at Nova Southeastern University, Florida, conducts basic and applied scientific research needed for effective conservation, biodiversity maintenance and understanding of the world's wild fishes. For more information, please visit

Ken Ma | EurekAlert!
Further information:

More articles from Life Sciences:

nachricht Don't Give the Slightest Chance to Toxic Elements in Medicinal Products
23.03.2018 | Physikalisch-Technische Bundesanstalt (PTB)

nachricht North and South Cooperation to Combat Tuberculosis
22.03.2018 | Universität Zürich

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Space observation with radar to secure Germany's space infrastructure

Satellites in near-Earth orbit are at risk due to the steady increase in space debris. But their mission in the areas of telecommunications, navigation or weather forecasts is essential for society. Fraunhofer FHR therefore develops radar-based systems which allow the detection, tracking and cataloging of even the smallest particles of debris. Satellite operators who have access to our data are in a better position to plan evasive maneuvers and prevent destructive collisions. From April, 25-29 2018, Fraunhofer FHR and its partners will exhibit the complementary radar systems TIRA and GESTRA as well as the latest radar techniques for space observation across three stands at the ILA Berlin.

The "traffic situation" in space is very tense: the Earth is currently being orbited not only by countless satellites but also by a large volume of space...

Im Focus: Researchers Discover New Anti-Cancer Protein

An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.

The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...

Im Focus: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

New solar solutions for sustainable buildings and cities

23.03.2018 | Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

Latest News

For graphite pellets, just add elbow grease

23.03.2018 | Materials Sciences

Unique communication strategy discovered in stem cell pathway controlling plant growth

23.03.2018 | Agricultural and Forestry Science

Sharpening the X-ray view of the nanocosm

23.03.2018 | Physics and Astronomy

Science & Research
Overview of more VideoLinks >>>