Abundance, Residency, and Potential Hazards for Coastal Bottlenose Dolphins (Tursiops truncatus) Off a Productive Lagoon in the Gulf of Mexico

Influence of artisanal fisheries on the behaviour and social structure ofTursiops truncatusin the South-western Gulf of Mexico

“…However, we believe that, as shown by our data, the differences found in dolphin behaviour are more related to the effect of the presence and distance of the survey boat (i.e. a local fishing skiff), possibly due to the anticipation of antagonistic responses by fishers posing risk for the dolphin population, as have been described for the study area (Morteo et al ., 2012, 2017; Rechimont et al ., 2018).…”

“…Locomotion and feeding were the most frequent behaviours regardless of the distance to the fisheries, and their intrinsic relation is explained by the daily and seasonal shifts in the abundance and distribution of prey (Neumann & Orams, 2005), causing the dolphins to move continuously between the locations with available food. The latter also evidences the opportunistic nature of the bottlenose dolphin, since both these activities were especially recorded around fishing gear, which captures fish that are part of their diet (Jaiteh et al ., 2013; Chávez-Martínez, 2017), and also the importance of this site as a feeding ground (Morteo et al ., 2012, 2014, 2017; Rechimont et al ., 2018).…”

“…It is noteworthy that frequencies for socio-sexual and play were low, but they showed significantly higher local rates during the operational interaction (Figure 4A and B, respectively). This may be explained considering that dolphins that are interacting with the fisheries are not categorized as residents, as shown by the occurrence records from the long-term photo-identification programme for this dolphin population since 2002 (Morteo, 2011; Morteo et al ., 2012, 2014, 2017, Garcia-Vital et al ., 2015). Thus intense social and playful contact between dolphins may be indicative of recognition among the individuals involved (Dudzinski, 1998).…”

“…Fishing is another common and worldwide distributed activity with a similar scenario; for instance, non-target species (i.e. accompanying and by-catch fauna such as marine mammals and turtles) are frequently reported as accidentally entangled in nets or even killed by fishers' violent responses; this occurs in both industrial and artisanal fisheries (Bearzi, 2002; Jiménez & Domínguez, 2007; Adimey et al ., 2014; Morteo et al ., 2017). Particularly in the latter, in which various rustically constructed gear are used (Jiménez & Castro, 2007), marine mammals such as dolphins, especially of the species Tursiops truncatus (Montagu, 1821), are the ones with the highest frequency of interaction reports (Reeves et al ., 2001; Lauriano et al ., 2004; Waples et al ., 2013; Morteo et al ., 2014).…”

“…These interactions are commonly reported and widely distributed across the world (Rocklin et al ., 2009; Powell & Wells, 2011; Jaiteh et al ., 2013; Adimey et al ., 2014; Morteo et al ., 2014); however, there are no studies in Mexico that describe in detail the strategies used by these cetaceans, as well as their behavioural changes in relation to the presence of artisanal fishing activities. Therefore, we studied a bottlenose dolphin population in the coastal waters of the western Gulf of Mexico, where the dolphin–fisheries interactions are well known to cause conflict due to depredation on fishing gear (Morteo et al ., 2012, 2014, 2017; Rechimont et al ., 2018). Our main goal was to document behavioural variations in relation to dolphin group size and age structure, using their proximity towards the artisanal fishing as an indicator of the types of interactions.…”