Imminent Risk of Extirpation for Two Bottlenose Dolphin Communities in the Gulf of Guayaquil, Ecuador

Abstract

A long-term study of a common bottlenose dolphin (Tursiops truncatus) population inhabiting the Gulf of Guayaquil, Ecuador (2 • 33 S, 79 • 20 W), has been carried out for almost 30 years. Similarly, as in other parts of the world, this population is structured socially and spatially in well-defined subunits or communities. Two of these communities, referred to as Posorja and El Morro, have been studied with major intensity in the last 10 years in the western inner estuary, among others to calculate population parameters that allow assessing their viability in time. Calculated parameters include annual abundance, age and sex composition, annual crude birth rate, calf survival, calf production interval, and average annual mortality/emigration. With these parameters and others derived from other better-studied populations, the trend of both subunits was modeled using the software Vortex. Results show that even under an optimistic scenery both communities will be extinct in the short (Posorja) and mid-term (El Morro), if current stressors continue. Most population parameters calculated in both communities show similar values as in populations elsewhere, but a very low calf survival in Posorja and high mortality/emigration ratios in adults, and probably in juveniles in both communities, contribute to this trend. Population deterioration seems to be the result of different human-induced threats such as fisheries, maritime traffic and others still not well assessed, as well as stochastic demographic events. We recommend taking actions in the short term to halt population decline addressing the major causes of mortality affecting these dolphin communities.

Advocacy, Ecotourism, and Biopolitics of Whale Conservation in Ecuador

“…Does the humpback whale, as a flagship species, lead to improved conservation? In interviews, Fernando Felix [47] and Ben Haase [48] indicated that the whale-watching regulation is only useful to the extent that it will be enforced by the authorities. In other words, they believe that conservation ultimately depends on the state's capacity to intervene and implement protective policies.…”

“…The tourism operators collaborated by allowing the researchers to record their data while aboard the tourist vessels, which made the relationship mutually beneficial [45,46]. Félix noted that when whale-watching began in the early 1990s, it was the only form of nature-related tourism available on the mainland coast of Ecuador [47]. Ben Haase recalled, "Twenty-five years ago, all the attention was on the Galápagos, nobody knew anything about the [mainland] coast" [48].…”

“…As the tourism operators have cooperated with the researchers by offering the use of whale-watching boats for observing and photographing the whales, it has increased the capacity for data collection. In addition to facilitating research, the alliance between the scientists and the tourism operators also provided opportunities for raising public awareness of the value of whales and the urgency of conserving their habitat [53].…”

“…He also claimed that despite their undeniable scientific expertise, the conservation NGOs provide information that is inconsistent and of limited use to government planners and managers [67]. A different perspective was provided by marine biologist Fernando Félix, who suggested that the problem lies not with the fishing communities of Ecuador, but with the government's unwillingness to recognize the magnitude of the threat that fisheries represent for whales [47].…”

“…As an event that fortifies the community identity of Puerto López, the festival serves to solidify the human community's identification with the whales. It has been suggested that the tradition will endure as long as the humpbacks continue their migrations [53].…”