Population Dynamics Reveal a Core Community of the Common Bottlenose Dolphin (Tursiops truncatus) in Open Waters of the South-Western Gulf of Mexico

• DOI: 10.3389/fmars.2021.753484
• Publication Date: 2021-12-01T13:59:17Z
• Authors: Jaime Bolaños-Jim...; Eduardo Morteo; Christian A. Delf...; Pedro F. Fruet; Eduardo R. Secchi; Javier Bello-Pineda
• Keywords: Bottlenose dolphin; Closure (psychology); Mark and recapture

The presence of transient and temporary individuals in capture-mark-recapture studies may violate the assumption on equal catchability, thus yield biased estimates. We investigated effects residency patterns population parameters bottlenose dolphins inhabiting coastal waters off Alvarado Lagoon System (ALS), Veracruz, Mexico. hypothesized that this is open but there exists a “core community” behaves as closed population. Between 2006 2010, we conducted 75 photo-identification surveys recorded 263 dolphin group encounters, which 231 were identified. Individuals present during only one season, classified transients ( n = 85), excluded from study, standardized index (IH 4 ) was computed for each remained sample 146). used K-means clustering method to split into groups based individual (seasonal, annual) IH values. These clusters named regular residents (RR, 55), occasional (OR, 45), visitors (OV, 46). cumulative frequency newly identified displayed an asymptotic trend whole all clusters, indicating most study area period demographic closure tested define core community, rejected OV cluster p < 0.001 both cases), open. not RR OR (χ 2 6.88, DF 13, 0.91, χ 17.8, 16, 0.33, respectively), these demographically over 5-year period. Thus, defined aggregation community”. model M th indicated total abundance community 123 (95% CI: 114–133). Our results provide quantitative evidence existence Gulf Mexico, points toward pattern main driver dynamics. highlight importance considering when dealing with heterogeneity highly mobile species.