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 Bioinvasion on the rise
15.02.2017 | Universität Konstanz

nachricht Litter Levels in the Depths of the Arctic are On the Rise
10.02.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

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: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>