Feeding ecology of Pangasianodon hypophthalmus (Sauvage) and its impacts on Taal Lake Ecosystem, Philippines.

Date

2011

Abstract

Another introduced species of unknown character was found in Taal Lake hence its feeding ecology was examined using a new method for stomach content analysis in order to verify its impacts on the lake ecosystem. Twenty nine wild caught adult samples of Pangasianodon hypophthalmus were collected in different landing centers around the lake from March 2011 to July 2011 to know its food preference. The adequacy of collected samples for stomach content analysis was determined through a Cumulative Prey Curve. The spatial distribution of the species in the lake was also established using secondary data from eleven major landing centers. Likewise, water quality of the lake where the species were caught was also determined. Structured interview with fishermen who had caught P. hypophthalmus was undertaken to know their perceptions about its introduction in the lake. Phytoplankton was the most predominant food of the adult fish. Macrophytes and zooplankton ranked second and third respectively. The least preferred food items were crustaceans, commercial fish feeds and fish. Apparently, P. hypophthalmus largely adopted the environmental conditions of the lake as it surpassed the range of temperature, pH and hardness (CaCO3) where it was known to thrive. During the period of study, the species had been caught in different fishing grounds except in Mataas na Kahoy, Balete and Lipa City where the deep portions of the lake were located. In almost three years of existence of P. hypophthalmus in Taal Lake, more than half of the fishermen respondents who had caught the species earned by selling the fish but admitted difficulty in marketing the initial catch in the lake for it was then an unknown food fish in the area. Majority of them believed that the fish had no harsh effects on the lake ecosystem despite being an introduced species.

Document Type

Master Thesis

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 995 2011 E8 H84

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