Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Predator fish populations recover with fishing away its prey

26.06.2007
The recovery of large predator fish populations can benefit from fishing away its prey.

This can be more effective than releasing large numbers of artificially cultivated predator fish. This is the conclusion of research from the Institute for Biodiversity and Ecosystem Dynamics (IBED) of the Universiteit van Amsterdam (UvA), the Swedish Umeå University, and the University of Tromsø (Norway). A joint publication appeared in the 22 June issue of Science.

The majority of populations of large predator fish such as cod and salmon have been strongly diminished over the last decades because of overfishing, bringing these species to the brink of extinction. The problem is so severe that even a complete embargo on the fishing for these species would appear to provide little remedy. In 2002 Prof. dr. André de Roos from the Institute for Biodiversity and Ecosystem Dynamics (IBED) of the UvA published a theoretical study proposing an explanation for the lack of recovery of the cod population in the northwestern part of the Atlantic Ocean.

This population suffered a dramatic collapse at the end of the 1980’s from which it has failed to recover to date, in spite of the fact that the fishing for this species has been suspended. In the study a controversial solution to the lack of recovery was proposed: by diminishing the capelin population, the main preyfish of cod in the area, the size distribution of capelin could change in such a way that it would promote the recovery of the cod population. In other words, to stimulate the recovery of the cod population, we should fish away its main prey. Using experimental data from the Norwegian lake Takvatn, the current publication in Science shows that this is not just a wild theory.

Better growth possibilities

Since the 1930’s the brown trout had almost completely disappeared from lake Takvatn, leaving its preyfish, the arctic char, as its sole inhabitant. This arctic char population consisted of large numbers of individuals of intermediate size (15-20 cm) and hardly any truly large fish (35-50 cm). In an attempt to increase the number of large individuals, which are a favorite game for recreational fishermen, the University of Tromsø removed a large proportion of the arctic char from the lake at the end of the 1980’s. Thinning the population indeed increased the chances for the remaining individuals to grow to above average proportions, and resulted in an increased number of larger arctic chars in the lake. As a side effect, the brown trout population recovered as well to the point where this species of fish now makes up 15% of the total fish population in the lake.

In the current publication in Science, it is shown that the increased number of large arctic char individuals in the lake led to a significant increase in the production of offspring, even though the total number of arctic char that is reproducing has decreased. As a result, the availability of young char that serve as prey for the brown trout has grown as well. Even more important is that the brown trout is now maintaining the favorable situation itself: by their own preying on small arctic char they are themselves producing a stable population of large arctic char that in turn produce more offspring for the brown trout to eat. As a result the system has remained stable even though the human fishing program for arctic char was stopped in 1989. The strange paradox is that apparently a predator fish can increase the availability of its favorite preyfish by preying on it.

The experimental results from the Norwegian lake together with the model calculations indicate that fishing for preyfish of large predator fish may well be the most effective way of restoring the predator fish population. More effective than releasing large numbers of artificially cultivated predator fish.

Josje Spinhoven | alfa
Further information:
http://www.uva.nl

More articles from Ecology, The Environment and Conservation:

nachricht Understanding animal social networks can aid wildlife conservation
23.06.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

nachricht Making Oceans Plastic Free - Project tackles the problem of plastic pollution in the oceans
31.05.2017 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Individualized fiber components for the world market

23.06.2017 | Physics and Astronomy

How brains surrender to sleep

23.06.2017 | Life Sciences

Can we see monkeys from space? Emerging technologies to map biodiversity

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>