Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Overfishing Pushes Baltic Cod to Brink of Economic Extinction

28.08.2008
An ancient fishery collapses as human intervention pushes a valuable species to evolve into a smaller fish

A study of Stone Age fish unearthed on an island in the Baltic Sea suggests overfishing by humans is causing fish populations to evolve and driving commercially valuable species like cod to the brink of economic extinction.

In a report published today (Aug. 27, 2008) in the British scientific journal, Proceedings of the Royal Society B, an international team of scientists reports that 4,500-year-old earstones, known scientifically as otoliths, and vertebrae from Baltic cod found in a pre-Viking settlement on the Swedish island of Gotland indicate the fish harvested by Neolithic fishers were older and larger than those hauled in by 21st century trawlers.

Dr. Karin (pronounced CAR-in) Limburg, a fisheries ecologist at the SUNY College of Environmental Science and Forestry (ESF) in Syracuse, N.Y., who is the paper’s lead author, described the status of the cod fishery in the Baltic as “dire.”

“It’s such an overfished system,” Limburg said. “The big concern is that overexploitation is causing the fish to evolve. The finding that humans can actually cause evolution of fish populations, which in turn can drive their degradation, is relatively new and is drawing a lot of attention.

“Some fisheries, including that for cod, are now known to cause ‘juvenescence,’ or the evolution of younger, smaller adult fish. The ecological and economic consequences both appear to be negative,” she said.

The findings were reported in one of two scientific journals published by the Royal Society, the United Kingdom’s national academy of science. Proceedings B publishes articles about the biological sciences.

Limburg collaborated on the study with Yvonne Walther of Sweden’s National Board of Fisheries; Bongghi Hong, an ESF research associate; Carina Olson, a doctoral student at the University of Stockholm; and Jan Storå, an archaeologist at the University of Stockholm.

“With cod populations at historic lows and challenges to rebuild them mounting, it is important to explore the past for clues about characteristics such as stock sizes, exploitation rates, age and size structure, etc. and what ecological roles cod would have played when their populations were larger,” the paper states.

Limburg said the research will provide baseline information so modern managers can better assess the fishery and plan for its future.

Extrapolating size, age, growth and mortality rates based on examination of the fish remains, the researchers concluded that Stone Age fisheries produced cod that were harvested at an average length of 56 centimeters, or a little more than 22 inches. By contrast, today’s catch averages 49 centimeters, a difference of about three-and-a-half inches.

The difference becomes more significant, Limburg said, when comparing the difference in fishing practices between Neolithic times and the modern era. Neolithic fishers worked from the shore and in simple boats that did not stray far out to sea. Today’s trawlers, by contrast, operate in the deepest waters, where the largest and oldest cod would typically live. Even so, the Stone Age fishers gathered bigger fish in the near-shore waters than today’s commercial ships collect much farther off shore, she said.

Modern fishing techniques, which target the largest fish, remove the older females from the seas. Older females produce the greatest number of viable eggs, Limburg said, and they likely have the most knowledge about how to find productive spawning grounds. In their absence, the fish left in the ecosystem are less likely to spawn productively.

In addition to the physical remains of the fish, the scientists used information gleaned from a collection of fish hooks found on Gotland. They replicated the bone hooks, measured their strength, and drew conclusions about the size of the fish they were designed to catch.

Vertebrae make up the spinal column of a fish. Earstones, known to scientists as otoliths, are made of calcium carbonate and are found in the heads of fishes. They play a role in the hearing and balance system of the fish. Earstones grow with the fish, developing rings much as a tree does. They provide a wealth of information about the age and growth of a fish.

Claire B. Dunn | Newswise Science News
Further information:
http://www.esf.edu

More articles from Studies and Analyses:

nachricht First form of therapy for childhood dementia CLN2 developed
25.04.2018 | Universitätsklinikum Hamburg-Eppendorf

nachricht Do microplastics harbour additional risks by colonization with harmful bacteria?
05.04.2018 | Leibniz-Institut für Ostseeforschung Warnemünde

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: BAM@Hannover Messe: innovative 3D printing method for space flight

At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.

Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
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

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Getting electrons to move in a semiconductor

25.04.2018 | Physics and Astronomy

Reconstructing what makes us tick

25.04.2018 | Physics and Astronomy

Cheap 3-D printer can produce self-folding materials

25.04.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>