Trout will become extinct in the Iberian Peninsula in less than 100 years: study

Sep 05, 2012
In the best of cases, which would involve just slight climate changes, the situation for the trout is "disastrous." Credit: Robeposse

Climate change, pollution, the extraction of water for irrigation and overfishing all threaten the survival of the common trout. This fish is very sensitive to changes in its environment and, according to the Spanish study, its habitat will have reduced by half by the year 2040 and will have completely disappeared from Iberian rivers by 2100, so its population will become extinct.

Global warming is threatening the existence of many , especially those in the salmonid family, which are sensitive to as they require clear and fresh water to live. According to the calculations of a study carried out at the Complutense University of Madrid (UCM), the habitat of the common (Salmo trutta) in the Iberian Peninsula will have practically disappeared by the year 2100.

Ana Almodóvar is a researcher and the lead author of the study published in the journal. It deals with how variations in affect trout population both now and in the future. "This fish has very narrow physiological margins in which it can live and is therefore a good indicator of the highest stretches of our rivers," as explained to SINC by the expert.

The scientists analysed the temperature records of Navarra between 1975 and 2007 and using a they calculated the temperature of the region's rivers. "We saw a clear tendency of temperature increases, which was particularly marked around 1986," outlined Almodóvar. In addition, the team monitored the trout populations of 12 rivers in the Ebro basin and saw that an increase in temperature was associated with a decrease in trout populations.

The biologist points out that "measurements are exact and temperature records are for long periods of time." Therefore, thanks to the collected data, the scientists have been able to create their forecast of the state of the trout in the future.

"In the best of cases, which would involve just slight climate changes, the situation for the trout is disastrous," confirms Almodóvar. The study states that the temperature increases in Spanish rivers will cause the trout to lose half of its habitat by 2040 and become practically extinct by the year 2100.

According to the research team, these results can be extrapolated to other regions of the Iberian Peninsula and the Mediterranean, such as the Italian, Balkan and Anatolian Peninsulas. "The Mediterranean region is very vulnerable to climatic variations and to the decrease in water availability," she adds.

An unrecoverable loss

"It has always been thought that due to climate change trout populations in Southern European countries would be more affected than those in the North. But, a specific study was needed to confirm this notion," points out Almodóvar.

Trout in the displays great genetic variability and it is considered a hot point of biodiversity in the whole continent for this species. The expert explains that "the Hispanic river basins are very ancient and acted as a refuge for Europe's fauna during the Pleistocene ice ages."

Scientists report that this variability is not only under threat by but also because "over the years Spain's rivers have been repopulated with genetically different types of trout."

"There is much allochthonous gene contamination amongst the native population of these fish since over time eggs have been imported from fish farms instead of developing the specific and pure lineage of each basin," adds the researcher with much regret.

One of the greatest threats: fishing

The scientists confirm that due to pollution, the use of fresh water for irrigation and an increase in temperature, "the ecologic state of rivers is more and more precarious and nowadays there are only trouts at the river sources."

Furthermore, trout is a priority species in recreational fishing in Spain and represents a "very important" socioeconomic resource. Almodóvar outlines that there is more and more demand for trout fishing and studies have been warning of the problems of overfishing for years.

"A common characteristic of populations subject to recreational fishing is that there has been a decrease in the oldest specimens since they are captured for being the largest," concludes the expert.

Explore further: Former Iron Curtain still barrier for deer

More information: Almodóvar, A.; Nicola, G.G.; Ayllón, D.; Elvira, B. "Global warming threatens the persistence of Mediterranean brown trout," Global Change Biology, 18: 1549. DOI: 10.1111/j.1365-2486.2011.02608.x 2012

add to favorites email to friend print save as pdf

Related Stories

River flow and temperature limit trout numbers

Sep 09, 2009

Over a 23-year study, Javier Lobón-Cerviá has found the mechanism that controls the number of salmonids found each year in Cantabrian rivers. His method has been to monitor population numbers ...

Climate threatens trout and salmon

May 17, 2010

Trout and salmon are among the world's most familiar freshwater fishes, but numbers have fallen over recent decades - in some areas, dramatically.

Recommended for you

Former Iron Curtain still barrier for deer

4 hours ago

The Iron Curtain was traced by an electrified barbed-wire fence that isolated the communist world from the West. It was an impenetrable Cold War barrier—and for some inhabitants of the Czech Republic it ...

Humpback protections downgrade clears way for pipeline

14 hours ago

Environmentalist activists on Tuesday decried Canada's downgrading of humpback whale protections, suggesting the decision was fast-tracked to clear a major hurdle to constructing a pipeline to the Pacific ...

Maine baby lobster decline could end high catches

14 hours ago

Scientists say the number of baby lobsters settling off the rocky coast of Maine continues to steadily decline—possibly foreshadowing an end to the recent record catches that have boosted New England's lobster fishery.

User comments : 0

More news stories

In the 'slime jungle' height matters

( —In communities of microbes, akin to 'slime jungles', cells evolve not just to grow faster than their rivals but also to push themselves to the surface of colonies where they gain the best access ...

New alfalfa variety resists ravenous local pest

( —Cornell plant breeders have released a new alfalfa variety with some resistance against the alfalfa snout beetle, which has ravaged alfalfa fields in nine northern New York counties and across ...

Former Iron Curtain still barrier for deer

The Iron Curtain was traced by an electrified barbed-wire fence that isolated the communist world from the West. It was an impenetrable Cold War barrier—and for some inhabitants of the Czech Republic it ...

Rainbow trout genome sequenced

Using fish bred at Washington State University, an international team of researchers has mapped the genetic profile of the rainbow trout, a versatile salmonid whose relatively recent genetic history opens ...

Robot scouts rooms people can't enter

( —Firefighters, police officers and military personnel are often required to enter rooms with little information about what dangers might lie behind the door. A group of engineering students at ...