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.
