Geometric morphometric analysis and meristic variations of Philippine populations of the crescent perch Terapon jarbua (Centrarchiformes: Terapontidae)

Abstract

The crescent perch Terapon jarbua is a demersal and catadromous fish that is widespread in the Indo-West Pacific region. It is a commercially important species in the Philippines and other Asian countries. Morphological differentiation among populations of T. jarbua throughout Philippine waters was investigated using morphometric and meristic characters. A total of 609 crescent perch (428 male, 181 female) were collected from nine localities in the Philippines. Meristic analyses showed the highest significant differences among populations in the lateral line scale and gill raker counts. Morphometric analyses revealed significant differences in shape among the nine T. jarbua populations. Allometry was found to be independent of size differences. Morphological differences were detected in the head, lip, and caudal peduncle regions. Specimens from General Santos City and Navotas were the most morphologically distinct from each other, whereas specimens from Sariaya and Balayan had the most similar shape. These can be attributed to the latitudinal gradient of the localities. Sexual dimorphism was also detected as significant differences were found in the specimens' lip positions, anal fin spine positions, caudal peduncle width, lateral line scale counts, gill raker counts, and pectoral fin ray counts. These morphological and meristic variations could be attributed to differences in feeding habits because T. jarbua is an omnivorous fish with a broad diet and can be found across marine, freshwater, and brackish environments. Further investigation of its diversity is recommended through the evaluation of T. jarbua feeding habits and their habitat's physicochemical characteristics. Additional sampling of populations outside of the Philippines is also recommended.