Pectoral Fin Morphology as a Reliable Field Sexing Characteristic in Populations of the Invasive Oriental Weatherfish (Misgurnus anguillicaudatus)

Abstract

Invasive Oriental Weatherfish (Misgurnus anguillicaudatus) populations have become established in many countries worldwide. To understand the invasive potential of this non-indigenous species, information about its demography and life history within these novel habitats is needed. Here we present data supporting the use of pectoral fin morphology for determining sex within a population of weatherfish in and around Boise, Idaho, USA. Enlargement of the second pectoral-fin ray and presence of a lamina circularis was seen in males both mature and immature. No such morphology was seen in females. Examination of gonadal tissue confirmed external sex determination in 99% of mature females, 97% of mature males, and 70% of juveniles less than 10 cm total length. This study is the first to verify use of sexually dimorphic fin characteristics as a field diagnostic in an invasive population of Oriental Weatherfish.