Project

Cetacean Conservation Project of Nicaragua

Goal: Study of the presence, distribution and habitat use of cetaceans in Nicaragua

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Project log

Joëlle De Weerdt
added 3 research items
South America hosts two stocks of humpback whales (Megaptera novaeangliae), stock A occupying southwest waters of the Atlantic, and stock G, located in the Southeast Pacific. After breeding in these locations in the austral winter and spring, both stocks travel in the austral summer to the feeding areas located in the Magellan Strait, Corcovado Gulf and Antarctic waters. As being physically accessible to one another, feeding areas are the only possible meeting point of two stocks. ·Male humpback whales use complex vocal displays to communicate throughout the year. These are known as songs, subjected to constant evolution. Here, to assess changes in South American humpback whale song, we have analyzed units as its simplest elements. Units were used to build the first ever unit dictionary of these stocks and compare their songs. Unit dictionary is a common method in studying bird song, while rarely used in humpback whales. To build the dictionaries, multiple years of songs from both stocks were recorded on their breeding grounds, feeding grounds and during migration, by various researchers. Using units as the basis highly enlarged the amount of usable data from this diverse dataset. Additional advantage of this methodology is its simplicity, while likely potent to help uncover stock dynamics and interactions. Comparing dictionaries of these two stocks revealed high level of difference in song complexity, specifically stock G song units appear much more diverse. Further, stability in the number of different units varied between stocks, as stock A had a more stable number of different units used over the seasons. These findings highlight the importance of feeding grounds for cultural exchange and stock interactions, possibly upholding the dynamics of humpback whale culture altogether. Used dataset is the outcome of the largest collaboration effort in humpback whale acoustics in South America to date.
We report the northernmost records to date of Southern Hemisphere humpback whales migrating from the Antarctica Peninsula to the Pacific coast of Nicaragua during the austral winter. From 2015 to 2018, data from opportunistic sightings of humpback whales were gathered during boat trips in Nicaragua, crowd-sourced through local citizen science efforts in the region and matched with a whale photographed in Antarctica through the citizen science program Happywhale. Sightings were made between July and October, coinciding with the occurrence of Southern Hemisphere humpback whales in their breeding areas. Whale sightings were lowest in July (6.3%), peaked in August (59.4%,), and declined in September (22.0%) and October (12.5%). The photographic recapture of one whale in Antarctica confirmed that whales migrating from the Southern Hemisphere enter Nicaraguan waters. These findings indicate either a previously unknown migratory pattern of Southern Hemisphere humpback whales, and/or a potential northward extension of their breeding grounds.
Joëlle De Weerdt
added 2 research items
False Killer whales are listed as nearthreatened on IUCN red list, Lack of knowledgecon distribution and occurrence along the Pacific coast of Central America,
The discovery of Nicaragua as a feeding stopover for migrating humpback whales could indicate it represents a previously undocumented feeding site or that whales are seeking new feeding sites.
Joëlle De Weerdt
added a research item
The cetacean conservation project of Nicaragua is a science-based conservation project that aims to combine scientific research and education activities to make conservation actions effective in collaboration with decision makers.
Joëlle De Weerdt
added a research item
The North-East Pacific humpback whale population migrates to warm breeding grounds to give birth and reproduce. Although a lot of research effort has been put in place to understand general humpback whale migration behavior, little is known on the distribution of Mother-calf (MC) pairs in breeding grounds. The objective is to understand MC spatio-temporal distribution during wintering months in Central America. Data was gathered on temperature, distribution, group composition and behavior between January and April on four different sites in Central America: Padre Ramos (PR) and San Juan del Sur (SJDS), Nicaragua (2016-2018) and Drake Bay (DB) and Golfo Dulce (GD), Costa Rica (2001-2017). Preliminary observations on group composition reveals that MC pairs represents 43% in of the groups PR (n=15), 7% (n=9) in SJDS, 58% in DB (n=67) and 48% in GD (n=7). MC pairs displayed a higher percentage of Travelling (78%) in SJDS compared to PR (46.7%), DB (50%) and GD (57.1%). Higher proportions of MC were observed in February North (PR) and South (DB) of SJDS (upwelling site). MC were present close to the coast (0.8-4.8km) in shallow waters (0-80m) in all study sites, excluding these parameters as explaining the remarkable difference in MC presence between sites. Measured Sea Surface Temperatures in Nicaragua (range 17-31°C) were lower than the breeding range temperature (21.1-28.3°C) suggested by Rasmussen et al (2007), which might be unfavorable conditions for calf development. Our results suggest that MC pairs likely searches for warmer waters to nurse their calves to avoid the cold upwelling waters of the South-West Coast of Nicaragua. These results can have important implications for future management strategies of the endangered Central America Subpopulation. Surveys should be conducted in other Central-American countries to accurately determine mother-calf humpback whale seasonal occurrence and behavior in the whole breeding area, including Guatemala and Panama.
Joëlle De Weerdt
added a research item
Coastal anthropogenic activities such as ecotourism are going to increase in the coming years and understanding habitat use patterns and underlying factors of dolphin distribution is therefore very important for their conservation. The pantropical spotted dolphins have an offshore and a coastal form and very little is known on the occurrence of the coastal form: Stenella attenuata graffmani. In the present study, an examination of the spatio-temporal distribution in the coastal waters of San Juan del Sur (SJDS, Southwest Nicaragua) was effectuated between January and April 2016-2018. Boat based surveys were carried out during 449 hours of effort and the pantropical spotted dolphin was the most commonly sighted dolphin species in San Juan del Sur with 75.5% in 2016; 43.2% in 2017 and 23.2% in 2018 of the sightings. Temporal and spatial distributional variations have been looked for. From 2016 to 2018 there was a clear decrease in encounter rates, while the group size was increasing with the years. This pattern could be explained by two hypotheses. The first hypothesis includes habitat exclusion with bottlenose dolphins. the encounter rate of bottlenose dolphins is increasing exponentially with the years while the pantropical spotted dolphins are presenting the reversed tendency. Both species might be in competition for the same habitat. The second hypothesis represent the feeding strategy of spotted dolphins. When prey availability is low they tend to form numerous smaller groups to enhance their chances to find food but will form on the contrary a lower number of big groups to increase their efficiency in feeding activities. Both hypothesis could be equally influencing pantropical spotted dolphin distribution. More research is needed to unravel the underlying factors of this distribution and understand the impact of the seasons on the general distribution patterns.
Joëlle De Weerdt
added a research item
Pantropical spotted dolphins (Stenella attenuata) are a widespread species in the Pacific Ocean. Recent genetic studies have confirmed that two subspecies (coastal and offshore) were identified along the Pacific coast from Mexico to Nicaragua. Studies using mark-recapture methods on pantropical spotted dolphins are scarce. This study offers a comparison on mark-recapture between two coastal populations of pantropical spotted dolphins in Nicaragua. Two study sites have been included: Padre Ramos (PR) lying in the North-West coast of Nicaragua and San Juan del Sur (SJDS) in the South-West coast of Nicaragua. Spotted dolphins have been studied within the cetacean conservation project in Nicaragua over a total effort time of 346h in August 2015, in January to March 2016 and in July 2016. Photo-identification data has been collected and thanks to the mark-recapture technique resightings of individual spotted dolphins have been inferred. Resighting rates in SJDS are higher during February and March compared to in PR during the same period. The animals were seen most of the time feeding in SJDS which could be explained by the presence of the Costa Rican Dome (CRD), an upwelling zone, that comes toward the coastal area of SJDS from February to April. More research is needed that include more specific data in the analysis in order to confirm the hypothesis. Understanding cetacean distribution in function of natural currents in tropical ecosystems have important implications for the management and safeguard of this cetacean species occurring in Nicaragua.
Joëlle De Weerdt
added a project reference
Joëlle De Weerdt
added a research item
In the light of environmental conservation and management it is important to get insights into movement patterns of animals, especially for migrating animals such as the humpback whales. Humpback whales in the South Pacific (G stock) migrate to Costa Rica which is the most Northern part of their breeding ground according to the IWC. Humpback whales haven’t been studied in Nicaragua until now. A pioneer project is in progress and in this context a feasibility assessment has been done from 17 to 21 of August 2015, both North of Nicaragua in Padre Ramos and South of Nicaragua in San Juan del Sur with a total effort time of 21,5h. Several recent observations of humpback whales occurrences in San Juan del Sur in August 2015 suggests an extension of the breeding ground of the breeding stock G. Several sightings were reported by touristic operators during august 2015 with mentioning of time, location and group type. On the 17th of august, a mother-calf pair was observed during a scientific boat survey in San Juan del Sur and behavioral data, geographic position, distance to the coast, depth, water temperature and photo-identification of dorsal fins were taken. The 5 sightings suggest a potential extension of the actual breeding ground for the Southern Pacific humpback whale population (Stock G).
Joëlle De Weerdt
added a research item
This is the first study that has been conducted in the waters of Nicaragua (Central America) along the Pacific Ocean to assess the diversity and occurrence of cetaceans. Boat based surveys were carried out in San Juan del Sur (South-Western Nicaragua) and in Padre Ramos (North-Western Nicaragua) in August 2015 and January -March 2016. Boat based surveys were also effectuated in San Juan del Sur in July 2016 as well as Land based surveys from January-March 2016 (93h of effort). During this period 166 hours and 189 hours of boat based effort has been spent in San Juan del Sur and Padre Ramos respectively. 104 Sightings were recorded during the surveys and 6 cetacean species were identified: one mysticete (Megaptera novaeangliae (n=13)) and five odontocetes (Stenella attenuata (n=70), Stenella longirostris (n=1), Tursiops truncatus (n=17), Steno bredanensis (n=1), Pseudorca crassidens (n=2)). For each sighting: species, groups size, geographic position and primary behavior was recorded. These results will have important implications for future spatial management in the frame of the construction of the canal of Nicaragua.
Joëlle De Weerdt
added a project goal
Study of the presence, distribution and habitat use of cetaceans in Nicaragua