Phenotypic Divergences in Growth and Reproduction Underpin The Invasion of Suckermouth-Amored Catfishes to Lotic and Limnic Habitats in Vietnam

Abstract

Suckermouth-amored catfishes (Pterygoplichthys spp.) is one of the most widespread invasive species in Vietnam. However, it is relatively unknown how these species have evolved in divergent adaptations to local conditions varying in habitat types, which is essential for managing their invasion in Vietnam. We addressed this by analyzing a large number of fish (766 phenotypes) collected in lotic (Dinh River) and limnic (Suoi Trau Resevoir) habitats in southern Vietnam during one year. Allometric growth patterns estimated by von Bertalanffy growth functions were \({L}_{t}= 500\left(1-{e}^{-0.71(t-0.44)}\right)\) in Dinh River and \({L}_{t}= 346\left(1-{e}^{-1.01(t-0.62)}\right)\) in Suoi Trau Resevoir. Estimated fish age was 2.9 to 4.2 years old. The percentage of fish with matured ovaries peaked in August (100%) and was lowest in February (< 10%), indicating that these fish breed all year round. The main reproductive season is April-October, with a peak in July-August as indicated by gonado-somatic indices index and monthly changes in the percentage of matured fish. The length at 50% maturity 22.93 and 17.51 cm for females from lotic and limnic habitats, respectively. Lotic fish had the fecundity (5830 ± 546 oocytes/ind.) which was five times larger than that of limnic fish (1042 ± 107 oocytes/ind.). This result was consistent with the larger oocytes of females: 2.94 ± 0.03 and 2.58 ± 0.01 mm for fish from Dinh River and Suoi Trau Resevoir, respectively. The faster growth and bigger fish with higher fecundity in the lotic habitats suggest they can accelerate greater population growth, potentially affecting local communities more than those from limnic habitats. Our study sheds light on substantial phenotypic divergences in reproduction and growth of the armored catfish between lotic and limnetic habitats in Vietnam, which is fundament for arriving at an effective management plan.