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Importance of long-term research



 

 

Cetaceans are long-lived animals with low reproductive rates. As such, conservation efforts require long-term studies spanning decades to understand how populations are doing in the wake of our rapidly changing world.

Since 1991, we have been collecting data annually to contribute to on-going studies of resident coastal bottlenose dolphins, Blainville’s beaked whales and sperm whales, and more recently West Indian manatees as well as more transient species like short-finned pilot whales. BMMRO dedicates six months of field work each year, collecting information on the individuals present in each group which allows us to track them over their lifetimes.

This on-going effort has resulted in an unprecedented longitudinal dataset for cetaceans in the region which is providing increasingly valuable information on the ecology and conservation of species both locally and globally.


Marine mammal conservation

 

 

Marine mammals in The Bahamas face many of the same threats from human activities as they do elsewhere in the world. These include ocean pollution including man-made noise and marine debris, habitat alteration and coastal development, impacts of over-fishing and entanglement in fishing gear, and vessel collisions.

All marine mammals are protected species in The Bahamas which provides the basis for developing conservation directives for local populations. The recent establishment of 15 new marine protected areas will advance the protection of marine mammal habitats in The Bahamas. BMMRO’s scientists continue to work closely with the Government of The Bahamas and local environmental groups as well as our regional counterparts to ensure that marine mammal conservation needs, both current and future, are addressed.

 

 
Conservation of local populations
 
 

 

Our on-going studies enable us to learn if local populations are stable or declining and what threats these populations face as their habitat continues to change because of human activities. Our studies of population trends and the effects of noise pollution address these conservation concerns. Our results suggest that in areas where human disturbance is greater, some local populations may be in trouble while others inhabiting more pristine environments appear to be doing well.

For example, bottlenose dolphins in the Sea of Abaco have declined by nearly 50% since the 1990’s which is likely the result of cumulative effects of development, over-fishing, and marine pollution as this area has experienced economic growth during the same time period. However, the dolphin population off Sandy Point, an area that hasn't experienced a lot of development, has remained stable over the same time period. Blainville’s beaked whales on the U.S. Navy’s Atlantic Undersea Test and Evaluation Center (AUTEC) in Andros are regularly disturbed by sonar use during Navy tests and appear to have lower reproductive success and abundance compared to a nearby population in Abaco that is not disturbed. Our challenge now is to work with policy makers to lessen and where possible eliminate these impacts.

 
 
Marine mammal ecology studies
 
 

 

Ecology is the study of how animals function in their environment; what do they eat, what eats them, what habitats are important, how they behave, etc. An understanding of species’ ecological roles, especially top predators like marine mammals, is critical to marine conservation.

BMMRO’s observations of other non-resident species sighted in the Bahamas are more opportunistic in nature but have allowed us to amass some of the only information available about the ecology of marine mammals in the Wider Caribbean region.

Check out our publications to learn more about studies of ranging patterns, occurrence (biodiversity), communication, diving and foraging behaviour, and other research that we have contributed to over the years. Also have a look at our Guide to Marine Mammals to learn more about the ecology of species that occur regularly in The Bahamas.
 

 
Funding challenges of long-term research
 
 

 

Despite the importance of this work, it is often difficult to secure funding for long-term studies. Much of this work has been carried out through partnerships with universities and funding agencies, but funding cycles tend to be short. The truth is without the dedicated efforts of BMMRO’s scientists and volunteers over the past 25 years, these studies would have ended long ago. We are continually challenged to ensure this work continues by training young Bahamians to carry this effort forward into the future.

If you recognise the importance of this work, and wish to make a contribution to support its continuation, please contribute.

 

 
Featured highlights from the field
 
 

 

Watch a video to see how we did it!
 
 
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Are Abaco's Whales Stressed Out?

In a collaborative study with the New England Aquarium and funding from the U.S. Office of Naval Research, we set out to answer this question. The goal of this project was to develop faecal hormone assays to measure stress levels in two species of deep-diving whale that occur regularly on U.S. Navy ranges: Blainville’s beaked whales (Mesoplodon densirostris) and sperm whales (Physeter macrocephalus). But we first wanted to field test the methods in Abaco.

Based from Sandy Point, we used small rigid-hulled inflatable boats (RHIBs) to locate whales during summer months from 2011 – 2014. When whales were sighted, one or two swimmers would tow alongside the RHIB and when a whale pooped the swimmer would dive down and gather the faeces in a custom-made net. Once back onshore, each poop sample was centrifuged to remove the seawater and later shipped to the research lab at the New England Aquarium for analyses. In total, sixty-nine faecal samples were collected.

Hormone concentrations showed some expected patterns with varying sex and age–class providing evidence of the biological validity of this approach. The physiologic data generated by this project has provided baseline levels of stress and metabolic hormones in free-swimming beaked and sperm whales for comparison with conspecifics experiencing known acoustic disturbances, such as at the nearby U.S. Navy Atlantic Undersea Test and Evaluation Center (AUTEC).

Look for our upcoming publications about this work.

 
 


 

Comparing the foraging efficiency of beaked whales on and off naval ranges.

 
Mass strandings and behavioural responses of beaked whales have been associated with naval sonar exercises. Recent studies at the US Navy’s Underwater Test and Evaluation Center (AUTEC) off Andros Island revealed that when sonar is used beaked whales stop feeding and move away from the area, returning only once sonar operations have ceased. By comparing feeding behaviour of beaked whales on and off naval ranges in The Bahamas, this study will help us understand the potential disruption these human-induced disturbances may have to key life functions, such as reproduction. If reproductive females are not getting enough to eat because their feeding is interrupted, they will fail at raising their young. DTAGs, digital acoustic tags, deployed on Blainville's beaked whales (Mesoplodon densirostris) at AUTEC and Abaco are collecting detailed energetics and diving data to evaluate foraging efficiency and performance. DTAGs are equipped with four silicon suction cups for attachment and are deployed using a 7 m carbon fibre hand-pole (see photo on left). Once deployed, the tagged whale is tracked visually and via a VHF radio beacon built into the tag. After a pre-programmed recording duration, the tag automatically detaches from the whale and is collected. Since this study began in 2015, we have deployed 9 DTAGs which have revealed the extraordinary depths of greater than 1,300 metres (almost 4,000 feet) at which this species feeds (see dive profile on left). Stay tuned for updates on the results.


 

Photogrammetry with an unmanned aerial system to assess body condition and growth of Blainville's beaked whales.

 
During June 2016 we ran the first field trial using aerial photogrammetry to directly measure the body condition and growth of beaked whales in the world! Specifically, we demonstrated the utility of the NOAA APH-22 marine hexacopter as an Unmanned Aerial System (UAS) for obtaining vertical images of whale lengths and width profiles. We launched the hexacopter from our 22-foot boat (see photo) to fly short missions over Blainville’s beaked whales when they are sighted close-by at the surface, obtaining high resolution digital images from a height of approximately 30 metres (100 feet). Southwest Abaco was an excellent site to validate this system because BMMRO has been conducted a photo-identification study over the past 17 years that has demonstrated high site-fidelity of beaked whales. Aerial images can readily be matched to photo-identifications to link measurements to whales we know well and have been tracking for over a decade, to obtain metrics for all age/sex classes. The analysis is currently underway but specific measurements will include:

1.     Width profiles for adult females, specifically comparing those with (lactating) and without dependent young, to validate the ability to assess differences in body condition and detect pregnancy.

2.     Lengths for dependent young of different ages, to validate the ability to measure growth.

Based on the success of our field trial, we are hoping to apply this new technology to compare the body condition of beaked whales and reproductive success at AUTEC, where whales are regularly disturbed by navy sonar (see above) and Abaco where disturbance is rare. This approach provides a promising means of monitoring the health of beaked whales on Navy testing ranges around the world.