Phylogenetic Origins and Age-Based Proportions of Malacho (Elops smithi) Relative to Ladyfish (Elops saurus): Species on the Move in the Western Gulf of Mexico

Abstract

Two species of ladyfish occur in the Gulf of Mexico (GOM), Elops saurus and Elops smithi, that are morphologically indistinguishable except for vertebral counts but can also be identified by mitochondrial DNA haplotypes. Here we expand on previous work, most of which has occurred in Florida, and examine the demography, phylogenetics, geographic distribution, and age—structure of ladyfishes in Texas estuaries. Fishery—independent gill net data demonstrated that ladyfishes increase in abundance from north to south along the Texas coast. The abundance of ladyfishes also increased in Texas waters from 1982–2021, which coincides with recent trends of warmer winters. Genetic data confirmed that both E. saurus and E. smithi occur in Texas waters; however, E. smithi was far less common. Contrary to previous research, we observed higher levels of genetic diversity in E. saurus due to larger sample size and thorough sampling of the western portion of its geographic range. Phylogenetic analysis supported the existence of E. saurus as a distinct species but indicated that E. smithi may be paraphyletic with other species of Elops. Otolith analysis showed that the ages of E. saurus and E. smithi ranged from 0–3 years. The lack of individuals > age—3 suggests that ladyfishes migrate to the offshore GOM at age 3 and do not return to coastal areas. This study enhances knowledge of the biology of ladyfishes in inshore waters of the northwestern GOM. Future management would benefit from expanding this research to the entire geographic range of the genus Elops.

Environmental DNA compliments traditional sampling for monitoring fish communities in a Texas estuary

“…One of the benefits of traditional long‐term fisheries sampling programs is that the data obtained can be used to track single‐species abundance through time. For instance, the TPWD has used long‐term species accounts from both gears deployed in this study to track abundance and distribution of multiple recreationally and commercially important species (e.g., Red Drum, Anderson et al 2023; ladyfishes, Williford et al 2022; Gray Snapper Lutjanus griseus , Anderson et al 2022; Black Drum, Olsen 2014). Regarding eDNA as a comparative method, the relationship between the number of sequence reads that was obtained in a single sample and the numerical presence and recency of taxa that were observed via traditional sampling is often unclear and confounded by either environmental or methodological processes.…”