Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Elver fishing multiplies the accidental capture of other fish by eight

09.05.2008
In the Ebro River delta, the fishing of elver (Anguilla anguilla) leads to the accidental capture of other fish species, with the capture of one ton of elver possibly resulting in the capture of up to 8.2 tons of accompanying species. Researchers from the Institute for Agro-Food Research and Technology (IRTA), who have assessed the effects of this method of fishing and identified the most fragile species, propose improvements in current methodologies.

With the capture of elver, eel (Anguilla anguilla) fry, scientists have identified up to 17 fish species, apart from the eel, which on average die in 36.5% of cases. The “dramatic” situation of accompanying ichthyofauna (fish captured with elver), which represents 43% of the various types of species in the area studied (350 Km²), may lead to ecological imbalances since it is the smallest specimens that are most likely to die when captured.

Enric Gisbert, main researcher of the study to be published in the next edition of the magazine Hydrobiologia, explained to SINC that improvements are necessary in fishing methods to “reduce the mortality of accompanying ichthyofauna associated with capture processes and initial elver selection, as well as increase the sustainability of this activity”.

Fish species accidentally affected by elver fishing in the estuaries and coastal lagoons of the Ebro delta include mullets (fish normally found in ports or estuaries) and, in particular, the fry of Liza ramada, Liza aurata and Mugil cephalus, species which, according to the research, share part or their entire recruitment calendar with the elver fishing season.

In addition, researchers have shown that “the impact of elver fishing is not only on migratory species but might also ultimately affect resident species, as well as other strictly limnetic species”.

According to the data obtained for the two-year project, it has been determined that for every one ton of elver captured, 8.2 tons of other fish species are accidentally fished too, without taking into account illegal fishing which could make up between 20% and 25% of captures.

Gisbert puts the mortality of species captured during the elver manual selection process down to “not very careful or delicate handling by the fishermen, i.e. excessively harmful, worsened by the effects of prolonged immersion that causes lack of oxygen (anoxia) in fish”.

More sustainable fishing methods

The study shows the need to consider the impact of elver fishing at a population, trophic and ecosystem level. The IRTA researcher, together with Miguel Ángel López from the Department of the Environment at the Generalitat de Catalunya (Catalan autonomous government), pointed out to SINC that “actions which promote the reduction of the collateral effects of fishing and the selection of elver must be introduced”.

Among the most relevant actions, “informing fishermen so that they are aware of the impact of their activity appears to be a priority”. Researchers also stress that “methodological and procedural changes should be introduced in elver handling and selection tasks”. In this case, scientists suggest that a reduction in handling time and maximising care in selecting fish could avoid the death of many fish captured by accident.

In addition, an improvement in the design of fishing nets used for “highly” selective fishing might be another solution as this would “only target the species to be fished”, said Gisbert. According to the researcher, this method has been proved “experimentally” in situ, with “very promising” results. A simple alteration was made in the design of the fishing net, which significantly reduced the handling and selection time of elver, accidental captures, number of accidental species rejected during fishing and, naturally, deaths.

This work could “serve as a basis to the administration for implementing measures which guarantee a far more sustainable exploitation of this natural resource”, concluded Gisbert and López.

SINC Team | alfa
Further information:
http://www.plataformasinc.es

More articles from Ecology, The Environment and Conservation:

nachricht Preservation of floodplains is flood protection
27.09.2017 | Technische Universität München

nachricht Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen

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: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Electrode materials from the microwave oven

19.10.2017 | Materials Sciences

New material for digital memories of the future

19.10.2017 | Materials Sciences

Physics boosts artificial intelligence methods

19.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>