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 How fires are changing the tundra’s face
12.12.2017 | Gesellschaft für Ökologie e.V.

nachricht Using drones to estimate crop damage by wild boars
12.12.2017 | Gesellschaft für Ökologie e.V.

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: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

Im Focus: Successful Mechanical Testing of Nanowires

With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong

Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

A whole-body approach to understanding chemosensory cells

13.12.2017 | Health and Medicine

Water without windows: Capturing water vapor inside an electron microscope

13.12.2017 | Physics and Astronomy

Cellular Self-Digestion Process Triggers Autoimmune Disease

13.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>