Shell Dimension-Weight Relationship and Condition Index of the Invasive Mussel Mytella strigata in Sasmuan, Pampanga, Philippines

Abstract

A total of 300 Mytella strigata were collected at three sampling points in the mussel coastal demonstration farm in Sasmuan, Pampanga, and subjected to morphometric and gravimetric measurements for the evaluation of its growth pattern and condition index. Designated sampling sites were based on the distances to the river mouth (200 m, 400 m, and 600 m) with varying water quality parameters (temperature, salinity, pH, water velocity, and chlorophyll-a). Mussels in Site 2 had significantly larger shell dimensions (SL = 2.862 cm, SW = 1.458 cm, SH = 0.926 cm), shell weight (0.640 g), and total live weight (1.150 g). Significantly higher (p < 0.05) soft-tissue dry weight (0.083 g), however, was obtained in Site 3, while comparable (p >0.05) soft tissue weight was observed in Site 2 (0.364 g) and Site 3 (0.413 g). Nevertheless, mussels in all sites demonstrated negative allometric growth (b < 3). The length-weight relationship revealed a weak to moderate, positive correlation. A significantly higher (p < 0.05) condition index was obtained in Site 3, which could have been influenced by higher chlorophyll-a and substantially lower water velocity. As such, this signifies its potential to have a well-established population in this spatial distance (600 m) from the river mouth. Hence, regular harvest and product development is recommended as strategic options to control its proliferation.