Stock Assessment of the Benthic Macroinvertebrates and Fish Resource of Mestizo River in Vigan, and Caoayan, Ilocos Sur

Abstract

This study aimed to list down the edible benthic macroinvertebrates and fish resource of Mestizo River in Metro Vgan, Ilocos Sur and assess their natural stocks from January to October 1999. This study also sought to find out the variation of three physical factors of the river, namely: pH, temperature, and salinity. Five sampling stations were established along the entire length of the river. Data on the benthic macroinvertebrates and fish resource were based on the weekly average catch per fishing effort of the fisher-respondents of this study. A representative sample of each species caught was taken for identification as to its common name, phylum,family, class, and gemus. Fifteen edible benthic macroinvertebrates were caught in Mestizo River. The twelve known species were distributed in two phyla, namely, Arthropoda and Mollusca, in three classes (Crustacea, Pelecypoda, and Gastropoda), and in eleven genera. Three macrobenthic species were still unknown as to their gemus classification. These macrobenthos were distributed in the river as follows: six species in Amianance, Vigan; three species in Pagpartian, Vigan; five species in Beddeng Laud, Vigan; six species in Cal-laguip, Caoayan; and nine species in Pandan, Caoayan. All the 23 edible fish species caught from Mestizo River belong to Phylum Chordata, Class Osteichthyes. Seventeen of them were distributed in general. The general of six species were still undetermined. Of
the 23 fish species, none was caught at Amianance; 10 species at Pagpartian; nine species at Beddeng Laud; 13 species at Cal-lagip; and 11 species at Pandan. The water in the Mestizo River is basic as shown by a mean pH ranging from 7.1 to 7.39. The mean temperature readings of the surface water ranged from 26.76°C to 28.50C and the mean water salinity readings ranged from 1.0/oo to 4.1/oo. Data gathered indicate that the edible benthic macroinvertebrates and fish resource of the river are habitat-specific. Some are considered persistent species; others are seasonal.