Seasonal population parameters reveal sex-related dynamics of common bottlenose dolphins in open waters of the southwestern Gulf of Mexico

In coastal populations of the common bottlenose dolphin, resident females are usually more abundant and have more restricted home ranges than males. Here, we studied sex-specific population dynamics of bottlenose dolphins off the Alvarado Lagoon System, southwestern Gulf of Mexico. We used standard photo-identification and capture-mark-recapture methods to determine population parameters under the superpopulation approach. Seasonal survival fluctuated around 0.96 (range: 0.80-1.00) and was equal for the sexes; recruitment of putative females (PF) and males (PM) was low, asynchronous, and reached 0.14 (range: 0.04-0.10) and 0.09 (range: 0.09-0.09), respectively, indicating high residency. PF abundance ranged from 60, 95% CI [48, 74] in the northern winds' season of 2008 to a low of 38, 95% CI [31, 47] in the dry season of 2010. PM abundance ranged from a high of 14, 95% CI [12, 16] in the northern winds' season of 2008 to a low of 9, 95% CI [7, 11] in the dry season of 2010. A regression analysis showed significant autocorrelation, and a pattern in the residuals of abundance, indicating no trends as well as temporal fluctuations that suggest a possible carrying capacity effect. Accordingly, high site fidelity, restricted ranging patterns, and low sporadic recruitment from the superpopulation are likely driving population parameters for this population.