Prevention, early detection and quick response are key

SAHABAT Alam Malaysia is alarmed over the irreversible damage to the environment caused by the invasion of an alien fish species, the African catfish

Alien species that enter a biological niche where they have never before existed can be difficult to control and predict, resulting in catastrophic economic consequences, but the authorities do not see it that way. As more invaders are accumulating in ecosystems, it can be expected that they will be more disruptive.

The presence of African catfish in our waterways is disturbing as it is a top predator, and a serious threat to native fish. Local fishermen have experienced low catches with some returning home empty-handed.

The African catfish will feed on any fish species. They respond quickly to new food sources and change their feeding patterns to match the organisms available. Young fish feed mostly on small invertebrates in shallow inshore areas.

Various factors make this species difficult to control: omnivorous diet, direct air breathing, ability to walk on land, burrowing capabilities and ability to hide in between vegetation. A 2kg African catfish can produce about 45,000 eggs.

Studies conducted in 1972 in central Africa showed that this species has profound negative ecological effects on aquatic insect communities, as well as amphibian and invertebrate populations. Insect diversity in the Chleoptera order has been reduced by up to 78 per cent and Hemiptera by 66 per cent.

The African catfish could also facilitate the spread of parasites, leading to extinction of indigenous fish species.

The unprecedented pace of introduction of this alien fish is from fish farm breeding, hatcheries for commercial purposes, release of the fish into rivers and ponds by the public, import for the aquarium fish trade and other channels.

The impact of the African catfish or other alien fish species on our environment should be treated with the same concerns as oil spills. It requires intense investigation with emphasis on developing techniques for controlling its dispersal.

Many citizens, key sector groups and governments have a poor appreciation of the magnitude and economic costs of the problem. As a consequence, delay in early detection and poor rapid response efforts give invaders time to reproduce and increase in numbers, making control difficult. Federal and state agencies need to monitor new invasions.

The authorities must realise the ecological costs of biological invasion in terms of irretrievable loss of native biodiversity and degradation of ecosystems. While the underlying causes of invasive species threats are significant and global in nature, these threats can be effectively dealt with through collaborative efforts at the regional and local levels, especially through prevention, early detection and rapid response.

Failing to effectively address the invasion would mean failing to meet the criteria of the International Union for Conservation of Nature.

SAM calls on the Agriculture and Agro-based Industry Ministry and the Fisheries Department to conduct a survey on the waterways where the African catfish are found. There is a need to stop fish farming of this alien catfish and to ban the import of the African catfish and all alien fish species.

S.M. MOHD IDRIS

President, Sahabat Alam Malaysia