Jeffrey Bernus

Project details

Title: Aiming to protect Cetaceans in the Dutch Caribbean across their geographical range

Time: 1 July 2022 – 30 June 2027

Project leaders: Jeffrey Bernus

Project summary:

The Caribbean is an important area where cetaceans feed, rest, and breed. To ensure that the population of cetaceans is stable or increasing, the breeding, feeding, and migratory areas of cetaceans in the Wider Caribbean Region need to be protected. While it is known that at least 33 species of cetacean have been seen in the Wider Caribbean Region, little is known about their population size, distribution, migratory patterns and where they encounter threats. The protection of cetaceans in the Caribbean during their various life stages needs to be improved by identifying and implementing management plans to counteract the various threats they face.

The Caribbean Cetacean Society (CCS) works at the Caribbean scale to improve cetacean conservation through international cooperation, education, and research. Their objective is to improve understanding of, distribute and share the knowledge on cetaceans in the Caribbean, and ultimately to ensure adequate conservation measures are put in place. In this respect, WWF is establishing a strategic partnership with CCS for a multi-year cetacean conservation program. The current partnership targets two overarching strategic goals of WWF:
1.     Reducing man-made threats to cetaceans 
2.     Expanding coverage & improve management of MPAs / cetacean sanctuaries

WWF targets these goals by strengthening regional collaboration by identifying and protecting Blue Corridors in the WCR, to which CCS will actively contribute. 

Abstract

The killer whale (Orcinus orca) is a cosmopolitan cetacean distributed worldwide. Extensive studies have described its ecology and behavior across multiple polar and temperate regions. On the other hand, there is limited information on the distribution, ecological roles, and abundance of killer whales in tropical and subtropical regions. Herein, we build on previous work to update information on the spatiotemporal distribution, exploitation, and natural history of killer whales in the Caribbean Sea. We also document new records on their interaction with other species and human activities. We collated 385 records from the literature, online biodiversity information systems, the Internet (social networks and video-hosting websites), and citizen science-based initiatives. Records included sightings (87.3%), intentional captures (10.6%), bycatch (0.3%), and strandings (1.8%). Data primarily originated from research projects/activities (57%) and citizen-science-based initiatives (43%). Records were distributed in the eastern Caribbean (39.5%), the southern Caribbean (19.7%), the Greater Antilles (19.2%), the Bahamian Region (13.0%), Central America (6.8%), and eastern Florida (1.8%). Killer whales were recorded year-round, but most data were reported between March and August (59.6%). The scarcity of records in Central America could reflect true lower densities in the region, lower observation effort, or a combination of the two. Because of the paucity of data, this study supports the growing importance of citizen-science initiatives to document the occurrence and ecology of this species in the Caribbean. Our dataset also confirms the occasional and widespread occurrence of killer whales throughout the Caribbean Sea. Potential low densities and limited predictability of their occurrence hinder dedicated research on this species.

MSc internship report

The Lesser Antilles hosts a high diversity of cetacean species, which are essential top marine predators whose abundance reflects the overall health of marine ecosystems. Despite the high research interest in cetacean ecology, Fraser’s dolphin (Lagenodelphis Hosei) remains one of the least studied dolphin species, primarily due to its tropical offshore and low-density distribution. However, some Fraser’s dolphin populations particularly frequent the coastal waters of tropical oceanic islands featuring steep topography. The Lesser Antilles has been identified as one of the few places where Fraser’s dolphin is frequently observed, providing a unique opportunity to learn about this mysterious species. Using boat survey data collected all along the Lesser Antilles, we aimed to gain insights into Fraser’s dolphin distribution and habitat preferences. Consequently, we used presence-absence Generalized Additive Models to identify the environmental covariates that best explained its distribution and used them to predict habitat suitability. presence is suspected all year-around and was confirmed during our sampling period from March to October along the Lesser Antilles arc. Covariates such as chlorophyll a concentration, proximity to canyons, sea surface temperature, depth, and eastward current velocity best explained the observed distribution. An amount of 76% of Fraser’s dolphin observations co-occurred with a total of 6 other cetacean species. To understand if this pattern is unique to Fraser’s dolphin, we performed a simple statistical analysis of cetacean co-occurrences to test for its significance. Fraser's dolphin exhibited more frequent associations with other species, and these associations displayed greater strength compared to interactions involving other cetacean species. We hypothesize that the co-occurrence behavior of Fraser's dolphin is likely driven by a versatile and opportunistic foraging strategy. The presence of occasional feeding surface behaviors provides evidence that its diet in the Lesser Antilles may not be confined to mesopelagic prey species.