Whales and dolphins in Península Valdés: what are their underwater foraging strategies?

Latest update July 23, 2019 Started on April 15, 2019

The main goal of this investigation is to know and describe the feeding behavior of whales and dolphins in Península Valdés. We are mainly interesting in their diving behavior, including the study of their prey.

April 15, 2019
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ES: Continuamos con la práctica del Trident Open Rov. Estamos casi listos para observar el comportamiento submarino de ballenas y delfines !!!!

EN: We continue with the Trident Open Rov practice. We are almost ready to observed whales and dolphins underwater behavior!!!!

ES: OpenROV Trident al agua!!!

Hicimos nuestra primera prueba con el tridente OpenROV en Puerto Pirámides, Península Valdés. En las fotos, estamos con nuestros amigos de Whales Argentina que nos ayudaron con la expedición. Muchas gracias National Geographic, Open Explorer, OpenROV, S.E.E. Initiative y a todos nuestros seguidores. Nos estamos preparando para ir por más!!

EN: OpenROV Trident to the water!!!

We did our first proof with the OpenROV trident at Puerto Pirámides, Península Valdés. In the photos, we have our friends of Whales Argentina that helped us with the expedition. Many thanks to all involved at National Geographic Open Explorer, OpenROV, the S.E.E. Initiative, and our followers We are getting ready to go for more!

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In The Field

ES: Cada salida turística de avistaje de ballenas o delfines es una oportunidad única para el estudio de estos cetáceos.
Puerto Pirámides es considerado como uno de los mejores lugares del mundo para realizar el avistaje de la ballena franca austral. Es por ello que cada año entre los meses de junio a diciembre nos trasladamos desde la ciudad de Puerto Madryn hacia Puerto Pirámides, (Chubut, Argentina) para embarcarnos junto a turistas que viajaron desde varias partes del mundo para realizar el avistaje de ballenas. Mientras que, para la observación de delfines aprovechamos las salidas turísticas que operan desde la ciudad de Puerto Madryn entre los meses de diciembre a abril. La temporada de delfines también es una excelente oportunidad para estudiar su comportamiento. La principal especie de delfín que se encuentra durante estas salidas es el Delfín Oscuro, que suele verse reunido en grupos que van de unos pocos individuos a cientos de ellos, los cuales son muy sociables con las embarcaciones turísticas. Las empresas de avistajes de ballenas y delfines colaboran con nosotros permitiéndonos subir a sus barcos cada vez que lo necesitamos. En tanto que, los capitanes y guías balleneros nos ayudan en la recolección de muestras fecales de ballenas y principales presas de delfines y ballenas, como así también nos comparten las fotos y vídeos de algún comportamiento interesante a investigar. Es importante destacar que durante estas salidas los turistas interactúan con nosotros y pueden ver el desarrollo de una actividad científica como lo es el estudio del comportamiento de cetáceos en su medio natural.

EN: Every tourist excursion to watch whales or dolphins is a unique opportunity for the study of these cetaceans. Puerto Pirámides have been considered one of the best places in the world to southern right whale watching. Every year, between June and December we move from the city of Puerto Madryn to Puerto Pirámides (Chubut, Argentina) to ship with tourists who traveled from several places of the world to do the whale watching. For dolphins observation we go onboard a tourism vessel from Puerto Madryn, between December and April. The dolphin season is also an excellent opportunity to study dolphins’ behaviors. The main species of dolphin found during the trip is the Dusky dolphin, which is usually seen in groups of a few individuals to hundreds of them, which are very sociable with tourist boats. Whale and dolphin watching companies collaborate with us allowing us to get on their boats every time we need it. Likewise, watching companies staff help us in the collection of fecal samples of whales, and main prey of dolphins and whales, as well as they share with us some photos and videos of interesting behaviors to investigate. Is important to highlight that during the whale and dolphins watching, tourists interact with us and they can see the development of a scientific activity such as the study of the behavior of cetaceans in their natural environment.

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We are applying to the S.E.E. Initiative. We will use OpenROV Tridents to explore the underwater world of Patagonian gulfs. We want to monitor and describe whales and dolphins behavior in the marine protected area of Península Valdés. This tool will allow us to explore what whales and dolphins are eating and how they do it. This cetaceans can dive more than 80mts to reach their prey and we want to know all about this.
We want to explore the frequency that whales feeding at the calving ground of Península Valdés. In the last years we observed an increase in the feeding events in the area that could be due to a decrease in Antarctic Krill abundance in their traditional feeding grounds because of climate changes. The results of this exploration will be communicated to the local authorities, marine mammal-watching operators and public in general, to create awareness about the potential risks of climate changes and conservation issues that affect the species that inhabits the study area.

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Sharing science!!!
Because we believe that knowledge must not be only for a few people, we are doing the diffusion of our research to educate and sensitize firstly young people and local whale watching tourist operators about marine wildlife conservation. We are convinced that conservation strategies must be applied in conjunction with the researchers, the local community and government; and the way to do this is sharing science!!!

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Expedition Background

Península Valdés in Patagonia is a site of global significance for the conservation of marine mammals that has been declared World Heritage Site by UNESCO. It is home to an important breeding population of southern right whale (Eubalaena australis), as well as other cetacean species like dusky dolphins (Lagenorhynchus obscurus) and orcas (Orcinus orca).
Each year, the first whales arrive in May and the whale season extends to December with a peak of whale abundance from August through September. In mid-December almost all individuals of E. australis leave Península Valdés to spend summer in their feeding grounds located at mid and high latitudes of the South Atlantic and Subantarctic regions. However, in Península Valdés the southern right whales feed on surface and subsurface when denser zooplankton patches occur in the area. These whales feeds by swimming with the mouth open at or below the surface and allowing water to flow through the baleen filtering apparatus, trapping organisms too large to pass through the baleen (>335 um). In addition, during the whale’s season often see whales diving deep and then returning to the surface with their snouts covered with mud, probably for feeding. However, the diving feeding behavior in the zone remains unknown. To now, there are not studies about the main prey, the depth and the foraging strategies of these whales. On the other hand, dusky dolphins occur all years in the gulfs of Península Valdés. We are carried out studies about behavioral pattern and social dynamic of this dolphins groups. Dusky dolphins primarily feed on schooling southern anchovy (Engraulis anchoita), which they hunt cooperatively at the surface, during the day. However, other species, such as juvenile common hake (Merluccius hubbsi) and squids (Argentine short-fin squid, Illex argentinus, Patagonian long-fin squid, Loligo gahi, and South American long-fin squid, Loligo sanpaulensis), were also recorded in their diet. Dolphin groups at times join together during foraging, with feeding lasting for several hours. Seasonal variation in activity budgets was observed for dusky dolphins. Dolphins spent a greater proportion of time traveling and feeding at the water surface during the warm season, while they spent a greater proportion of time diving during the cold season. An association between diving and milling behavior was observed during this season suggesting that feeding at depth could be an alternative foraging strategy. We collected hydroacoustic data to try to identify dolphins’ prey but we need to collect visual data on this to validity our findings and to describe the diving behavior. Therefore, the main goal of this investigation is to know and describe the feeding behavior of whales and dolphins in Península Valdés. We are mainly interesting in their diving behavior, including the study of their prey. The result of this project can help to better understand the foraging behaviors of these cetaceans and serve as a starting point for the more complex studies about the functional relationship between predator performance and prey distribution and abundance. This is critical to understanding the dynamics of trophic interactions and pathways of energy flow in pelagic marine ecosystems.

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