The German scientist E-J.Fittkau hypothesized in 1970 that the decline of fish in the mouths of some tributaries of the Amazon River was a consequence of the massive decline of crocodilians (caimans) due to the high demand for their hides.
Fittkau attributed the decline to lack of nutrients in the aquatic environment that serve as basis for primary productivity. High primary productivity in the past prior to his 1970 study resulted in the high production of both fish and crocodilians as representatives of the various trophic levels ranging from consumers to predators.
Without delving into the various aspects of primary and secondary productivity in aquatic ecosystems, I would like to underscore the direct relationship of crocodilians and fish; where there are many individuals of crocodilians, there are also more fish biomass.
However, this relationship has not been demonstrated through research studies, and Fittkau’s hypothesis has remained a hypothesis.
Workers on Philippine crocodiles have not tried to confirm it. One probable reason is because crocodiles have dwindled to very low numbers in most parts of the country.
Now is the time to ask the question, how important are crocodilians (crocodiles in the Philippines)to ecosystem function?
Many people in the country if asked whether they want crocodiles to be part of their environment would probably answer in the negative because of the public perception that crocodiles are dangerous to humans.
But this perceived notion is common because of the failure of people (including the educated ones) to understand the rightful place and ecological service of crocodiles in nature, not to mention the fact that crocodiles harm humans because the latter have been encroaching into crocodilian habitats in the wild.
The time is ripe for studies on the ecological role of the two species of crocodiles in the Philippines.
Some Philippine communities such as the local government units in Siargao Island have introduced, with the help of DENR and two organizations (Crocodylus Porosus Philippines Inc. and Coral Agriventure Farms, Inc.), young individuals of Philippine Crocodile in a small wetland on the island to boost the tourism industry, making a contribution to the economic life of the island.
There are now two species of crocodiles on this island: the native Estuarine Crocodile and the introduced Philippine Crocodile.
The Estuarine Crocodile most likely has increased the fish production in the mangroves of Siargao Island through their function of nutrient cycling in coastal waters.
Crocodiles, because of their large sizes, are very effective in the production and cycling of nutrients needed by fish of various trophic levels.
This natural service will soon be demonstrated through our controlled ecological experiments in crocodile natural habitats.
We at Silliman University aim to breed our Philippine crocodiles for the purpose of returning their offspring back to the wild in southern Negros, where we got our female in the late 1970s.
The Pagatban River system, their original home, should once more become more productive of fish after more than three decades of very poor fishery yields following the pollution of the river system with mine tailings in the 1970s.
