Invasive alien animal species that have been intentionally or accidentally introduced into freshwater ecosystems are proving to be harmful to the native species and/or the environment in a number of ways.
The reason for this could be the wide tolerance of these species to environmental factors, in contrast to that of endemic species which have adapted to narrow ranges of these factors in their habitats. Endemic species would, therefore, lose out to the invaders because they could not compete or they are preyed upon.
It seems that no government body is in charge of the problem of invasive species. The Protected Areas & Wildlife Bureau of the Department of Environment, and the Bureau of Fisheries have yet to grapple with the problem of introduced alien species, which has been recognized by biodiversity experts as a threat to the native and endemic biodiversity of a country.
This lack of attention is not acceptable at this time when nations of the world are aware of the importance of biodiversity.
Here in the Philippines, we have just celebrated the Year of Biodiversity (2010) with an international conference held on Feb. 1-3, 2011. There is big gap between what government says and what it does.
What seems to make matters worse is that the newspapers are ahead in pointing out to our people the perils of harmful introductions of alien species that most likely will turn out to be invasive.
For example, our authorities have been silent on harmful fish introductions, instead of taking the lead in explaining why these events are happening.
A case in point is the article in the Thursday issue of the Philippine Daily Inquirer (March 10, 2011) which featured the janitor fish from South America that threatens to have a serious ecological impact on our freshwater ecosystems through competition in space and food, as well through predation on the eggs and larvae of our native fishes.
And this is only one of the several harmful alien species in the country.
It will be recalled that the country lost 15 of the 18 species of endemic cyprinids in Lake Lanao during the 20th century, most probably through competition with and predation by two marine gobies introduced into the lake most probably by a government agency.
If true, it indicates a serious lack of understanding of the perils of alien species introduction.
What is needed at this time is a research program to determine the actual occurrence and distribution in the country of the janitor fish, as well as other alien species.
Our recent studies on rivers have shown that this species and eight other species are found in the Bago River in Negros Occidental. Nine alien fish species are also found in the Jalaur river in Iloilo province. Seven of these nine species are common to both rivers. Their effects could be disastrous in the future. It is possible that several alien fish species have invaded many of our rivers and other freshwater ecosystems. We know for example that the janitor fish occurs in Laguna Lake.
The second thing to do is to establish a program to eradicate the janitor fish and other introduced aquatic species (including frogs) found in our natural environment. The PAWB should be responsible for this program in cooperation with other government agencies.
Another action would be to determine who among the aquarium fish dealers (as alleged by the Inquirer) had a hand in its introduction into the wild. Such irresponsible behavior should be sanctioned. Maybe, the Foundation for the Philippine Environment, a funding agency tasked to deal with biodiversity, should lead in this investigation.