Enrique A. Crespo

Human Interactions with Dusky Dolphins: Harvest, Fisheries, Habitat Alteration, and Tourism

Publisher Summary Dusky dolphins have been hunted off Peru for over three decades, where they are used as fish bait and food for human consumption. During the late 1980s and early 1990s, thousands of dusky dolphins were killed each year in directed hunts using nets and harpoons. In the mid-to-late 1990s, new legislation restricted dolphin harvests, but also made it more difficult to assess the number of dolphins harvested as hunting practices became more clandestine. Direct harvest of dusky dolphins continues today, but it is estimated that the number of dolphins harvested has dropped to less than 1000 per year. Human interactions with dusky dolphins include direct harvest, fisheries, changes to habitat, and tourism. Due to limited population information combined with high levels of direct and indirect mortality from dolphin harvest and fisheries by-catch, dusky dolphins are listed by the IUCN as a species lacking sufficient information to fully assess conservation status. Dusky dolphin tourism has grown substantially over the past two decades. Tourism has the potential to provide conservation benefits by encouraging local communities to preserve healthy dolphin populations and by providing tourists with a greater appreciation for wildlife. Tourism can also affect the daily lives of dolphins, and in extreme cases even impact the health of wild populations. Careful monitoring and regulation of tourism are important to promote development of a truly “dolphin friendly” industry.

Dusky Dolphin Trophic Ecology: Their Role in the Food Web

Publisher Summary Like most top predators, dusky dolphins (Lagenorhynchus obscurus) may play different roles in marine ecosystems, although they are still poorly known. Dusky dolphins are an integral part of several marine ecosystems of the southern hemisphere. Among other cetaceans, pinnipeds, seabirds, and sharks, dusky dolphins represent the near-terminal links in the food webs in which they are embedded. This set of species is also referred to as the “top predators” or “upper trophic level predators” and the study of the trophic role dusky dolphins play in marine ecosystems is driven mostly by the same interests that one has in top predators. The goal of this chapter is to briefly summarize what is known about their trophic ecology and to attempt to develop, within the limitations of the available data, an initial description of the trophic role of dusky dolphins in their ecosystems. To achieve this goal, several topics are presented, including diet and feeding habits, relationships with other top predators, competition and kleptoparasitism, the role in the transmission of parasites, and finally their trophic relationships with fisheries.

Occurrence of South American fur seals Arctocephalus australis in San Matías Gulf, Patagonia, Argentina

Fil: Svendsen, Guillermo. Universidad Nacional del Comahue. Instituto de Biologia Marina y Pesquera Alte.storni;

Chapter 3 – Dusky Dolphin Trophic Ecology: Their Role in the Food Web

Publisher Summary Like most top predators, dusky dolphins (Lagenorhynchus obscurus) may play different roles in marine ecosystems, although they are still poorly known. Dusky dolphins are an integral part of several marine ecosystems of the southern hemisphere. Among other cetaceans, pinnipeds, seabirds, and sharks, dusky dolphins represent the near-terminal links in the food webs in which they are embedded. This set of species is also referred to as the “top predators” or “upper trophic level predators” and the study of the trophic role dusky dolphins play in marine ecosystems is driven mostly by the same interests that one has in top predators. The goal of this chapter is to briefly summarize what is known about their trophic ecology and to attempt to develop, within the limitations of the available data, an initial description of the trophic role of dusky dolphins in their ecosystems. To achieve this goal, several topics are presented, including diet and feeding habits, relationships with other top predators, competition and kleptoparasitism, the role in the transmission of parasites, and finally their trophic relationships with fisheries.

Chapter 11 – Human Interactions with Dusky Dolphins: Harvest, Fisheries, Habitat Alteration, and Tourism

Publisher Summary Dusky dolphins have been hunted off Peru for over three decades, where they are used as fish bait and food for human consumption. During the late 1980s and early 1990s, thousands of dusky dolphins were killed each year in directed hunts using nets and harpoons. In the mid-to-late 1990s, new legislation restricted dolphin harvests, but also made it more difficult to assess the number of dolphins harvested as hunting practices became more clandestine. Direct harvest of dusky dolphins continues today, but it is estimated that the number of dolphins harvested has dropped to less than 1000 per year. Human interactions with dusky dolphins include direct harvest, fisheries, changes to habitat, and tourism. Due to limited population information combined with high levels of direct and indirect mortality from dolphin harvest and fisheries by-catch, dusky dolphins are listed by the IUCN as a species lacking sufficient information to fully assess conservation status. Dusky dolphin tourism has grown substantially over the past two decades. Tourism has the potential to provide conservation benefits by encouraging local communities to preserve healthy dolphin populations and by providing tourists with a greater appreciation for wildlife. Tourism can also affect the daily lives of dolphins, and in extreme cases even impact the health of wild populations. Careful monitoring and regulation of tourism are important to promote development of a truly “dolphin friendly” industry.

Dusky Dolphin Trophic Ecology

Publisher Summary Like most top predators, dusky dolphins (Lagenorhynchus obscurus) may play different roles in marine ecosystems, although they are still poorly known. Dusky dolphins are an integral part of several marine ecosystems of the southern hemisphere. Among other cetaceans, pinnipeds, seabirds, and sharks, dusky dolphins represent the near-terminal links in the food webs in which they are embedded. This set of species is also referred to as the “top predators” or “upper trophic level predators” and the study of the trophic role dusky dolphins play in marine ecosystems is driven mostly by the same interests that one has in top predators. The goal of this chapter is to briefly summarize what is known about their trophic ecology and to attempt to develop, within the limitations of the available data, an initial description of the trophic role of dusky dolphins in their ecosystems. To achieve this goal, several topics are presented, including diet and feeding habits, relationships with other top predators, competition and kleptoparasitism, the role in the transmission of parasites, and finally their trophic relationships with fisheries.

Human Interactions with Dusky Dolphins

Publisher Summary Dusky dolphins have been hunted off Peru for over three decades, where they are used as fish bait and food for human consumption. During the late 1980s and early 1990s, thousands of dusky dolphins were killed each year in directed hunts using nets and harpoons. In the mid-to-late 1990s, new legislation restricted dolphin harvests, but also made it more difficult to assess the number of dolphins harvested as hunting practices became more clandestine. Direct harvest of dusky dolphins continues today, but it is estimated that the number of dolphins harvested has dropped to less than 1000 per year. Human interactions with dusky dolphins include direct harvest, fisheries, changes to habitat, and tourism. Due to limited population information combined with high levels of direct and indirect mortality from dolphin harvest and fisheries by-catch, dusky dolphins are listed by the IUCN as a species lacking sufficient information to fully assess conservation status. Dusky dolphin tourism has grown substantially over the past two decades. Tourism has the potential to provide conservation benefits by encouraging local communities to preserve healthy dolphin populations and by providing tourists with a greater appreciation for wildlife. Tourism can also affect the daily lives of dolphins, and in extreme cases even impact the health of wild populations. Careful monitoring and regulation of tourism are important to promote development of a truly “dolphin friendly” industry.