Arms aching sinews straining, as a battling 200 pound catfish makes one last run to avoid capture, the stuff of dreams for big specimen fishermen who travel to the River Ebro, to pit their wits against these aquatic monsters.

These fish grow at a phenomenal rate of ten to fifteen pounds a year. This is achievable by the catfish feeding on a large population of carp, and other endemic species.

The River Ebro is regarded by most specimen hunters to be the premier destination in Europe to catch catfish. The river makes the long 910km (565 miles) journey eastwards to Amposta before reaching the sea. The catfish in the Ebro have an almost perfect environment, an abundance of food, very few predators, and a long growing season due to relatively short Spanish winters.

It has become clear from surveys, that following the controlled introduction of the non-native catfish, there has been a rapid decline in other fish species. For example, the Iberian barbel, (once abundant in the Ebro River), completely disappeared in the middle channel around 1990, due to competition and the predatory nature of the catfish. The plight of the Iberian barbell is blamed on the catfish due to the fact that barbel species from mountain stream tributaries of the River Ebro where catfish have not colonized, have not been affected.

The original catfish introduction was for experimental and sport-fishing purposes, with under-controlled populations. It is believed that the resultant increase in the catfish population is due to improper and uncontrolled introductions by sport fishermen.

In 2007 a law was introduced (Spanish Law 42/2007) for the control or eradication of “illegally introduced” non-native fishes, the basic rules are that an “illegally introduced” species has to have had an adverse effect on native species, and must be supported by documented surveys. In the Ebro basin, 238 surveys were carried out in a period of 9 years, from 2000 to 2009.

Prevention measures need to be implemented to control the spread of non native fish to other rivers and also prevent new introductions. It appears public administrators who have a duty to uphold the law, are slow to do so.

Invasive species are acknowledged as the principal cause of animal extinctions. You only have to look at the devastation caused by the release of mink. On the British waterways, zander are classed as an invasive threat to local species, and “British Waterways” openly encourage anglers to dispatch and eat this predator. Fish stocks have been decimated by this invasive predator. Ebro beware!