Spatial Distribution Within Different Age Of Two Anguilla Species In Peninsular Malaysia

Abstract

Freshwater eels are divided into tropical and temperate species based on their geographical distribution. Spatial distribution of tropical eels in Malaysia can be revealed through the analysis of migratory pattern. There are studies emphasize on the diversity data of Anguilla species in Malaysia but not their migratory patterns. The objectives of this study were to determine age by otolith annuli examination and to determine the migratory pattern of tropical eels by examining otolith strontium (Sr) to calcium (Ca) ratios using an electron probe microanalyzer (EPMA). Present study provides an insight of tropical eel migratory history and habitat preferences in Peninsular Malaysia, In this study, age of tropical eels was determined by the annual rings of otolith while their migratory patterns were determined by the Sr: Ca ratio of their otoliths that reflect eel movements among various saline environments. A total of 164 eel individuals composed of 126 Anguilla bicolor bicolor and 38 A. bengalensis bengalensis were collected from ten rivers in the states of Penang, Perak and Kedah in the northwestern Peninsular Malaysia. Migratory patterns observed among species and were divided into four contingent types: 1) Type 1, freshwater, 2) Type 2a, freshwater-favoring, 3) Type 2b, seawater-favoring and 4) Type 3, shift type.