Humpback whale research – Acoustic and Photographic

In 2016, Ilka Beith from Germany joined the Sea Search team in Cape Town for a 2 month internship. During her time here she helped us get going with the data processing on on some of the acoustic and photographic data we’d collected from supergroups of humpback whales in 2015.  Her words below:

 The goal of the study was to collect sounds of animals known to be feeding in the large aggregations of whales, which occur off the west coast in late winter and early summer. This data will then be used to help us identify sounds made on moored hydrophones as part of the E3C project. The data was collected around Hout Bay in November 2015 over 6 days in collaboration with Steve Benjamin of Animal Ocean who took us out to sea when we didn’t have our own boat.

Photo-Identification (photo ID):

Photo-identification is the practice of identifying animals from their natural marks (fin shapes, scars, injuries, colouration etc) from photographs of them. Important for photo-ID of whales and dolphins are shots of the dorsal fin from both left and right sides and for humpback whales, the underside of tail fluke, which has individually distinctive black and white patterning.

My task was identifying all the individuals photographed over the 6 days by pulling out all the left dorsal fins (LD), the right dorsal fins (RD) and the tail flukes (TF). I identified every single individual and gave everyone a number and identified the ‘best’ image each side (and tail) of each whale for each day, essentially making three catalogues a LD, RD and TF catalogue. I drew the different dorsal fins and tail flukes of the whales on paper and I also named a few of them to remember them better, which is pretty helpful during the identifying process. On the basis of the best pictures I matched the left and right dorsal fin together to one whale where possible. Matching the tail fluke to the right and left dorsal fin was the hardest part. The main identifying feature used is the under-side but by using the many different angles photographed it is often possible to match a ‘side shot’ to both a dorsal fin and a good underside from scarring on the edges or trailing edge shape.

There are now over 120 individuals in the photo-ID catalogue. I found 33 matches between days of the right and left dorsal fin, 17 matches all (LD, RD & TF) and 37 matches of the dorsal and tail fluke.  Once complete, this catalogue will be compared to those from other research groups to contribute to a national level project.

I also did field work and it was pretty cool that I identified one whale which I saw on my first research trip, as a member of the catalogue. This whale was also seen in November and it has been hanging around the Hout Bay area for several months.

Acoustics:

Humpback whales are known as the best singers in the ocean, but only the male whales sing. Most of the time they sing during mating season to attract female whales. But there are also social vocalizations produced by both male and female humpback whales which are heard on the feeding and breeding grounds and even surface-generated percussive sounds as breaches, pectoral flipper slaps and tail slaps (Dunlop R. A. et al., 2007). [ this work has been taken further in 2017 as part of the MSc thesis of Mariana Silva – updates to follow ]

During my internship, I did the first part of the acoustic analysis Adobe Audition. I converted the spectrograms to the right settings for viewing, noted the start and end time of ea ch noise and quantified, classified and categorized the noises (mostly following the categories defined by Rebecca Dunlop and colleagues in Australia – Dunlop et al. 2007). Most of the sounds are between 100 Hz and 4 kHz and can be divided into low-, mid- and high-frequency sounds. Low frequency sounds are the most common, especially the “wop”, “grumbles” and “barks”. The most common mid-frequency sound is the “modulated cry”.

 

The whales are here!

  The whales are here! By Monique Laubscher The season for spectacular whale sightings is upon us! Every year the southern right whales migrate from Antarctica – their icy cold feeding grounds – to the warmer waters off South Africa. The warmer climates off our coastline provide the perfect habitat for breeding, calving and rearing of […]

Occurrence and distribution of cetaceans in Namibian waters

Occurrence and distribution of cetaceans in Namibian waters

A summary of Pauline Glotin’s MSc thesis, 2016

 

The Benguela upwelling, situated in the west coast of Angola, Namibia and South Africa, is a region highly productive and biologically diverse. Namibia was one of the world’s largest whaling areas in the 20th century and with at least 25 species known to occur here, hosts more than 60% of the world’s whale and dolphin species (Best, 2007). Despite this – knowledge about cetacean fauna is remarkably poor.

Figure 1: Map of the Benguela current upwelling system (Kirkman et al., 2015)

Figure 1: Map of the Benguela current upwelling system (Kirkman et al., 2015)


The main aims of my study were to provide an updated description of cetacean diversity within Namibian waters, especially within and adjacent to the Namibian Islands Marine Protected Area (NIMPA), and to predict the spatial and seasonal distribution patterns of the cetaceans in coastal and offshore Namibia.

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The representations of cetaceans in ancient Greek culture

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Marthe Sandra Ango

The representations of cetaceans in ancient Greek culture

From Canada to China passing by Australia, dolphins and whales are portrayed in so many ways that denote the beliefs and representations of each society. Most of the time, they are described as divine, having supernatural powers. Thus, in Australia, Aboriginals offered food to big cetaceans as they believed them to be the reincarnation of dead warriors. In Canada, Inuit have their own explanation of the narwhal’s unusual tooth form. Furthermore, both the Bible and the Coran contain strong references to cetaceans.

The word “cetacean” comes from the Greek word “Ketos” which means sea monster. Ketos in ancient Greek mythology was an ancient goddess and the daughter of Gaia (the earth) and of Pontos (the wave).  The word is now used to refer to dolphins and whales.

In this article, we focus on the representations of cetaceans in ancient Greek culture. The Greeks left us with plenty of data to work with, helping us to better understand their culture. Greece is composed of several small islands, making the ocean the hub of Greek culture. Therefore,  it is no surprise that the inhabitants were use to frequent encounters of sea creatures.

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The importance of Citizen Science

   

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Author: Marthe Sandra Ango

What does citizen science mean?                                            

For centuries, amateurs have participated and contributed to scientific research, mainly in the areas of astronomy and ornithology. Nowadays this practice, named citizen science or crowd-sourcing, is defined as the collaboration of non-specialist volunteers (“amateurs”) in both thinking and data collection for scientific purposes. This practice is different from the traditional help of undergraduate field assistants as it requires scientists and researchers to work with the public. Citizen science projects follow one of three patterns:

  • The initiators of projects are community-based groups and engage with scientists for advice/supervision.
  • Both scientists and amateurs gather for a mutual project. In this case, the pattern closely follows that of the “learned societies” back in the enlightenment era.
  • Scientists need public involvement to conduct a survey.

Citizen science has many benefits. The first benefit observed is to advance the knowledge and understanding of the world. In 1874, the British government funded a citizen project named the Transit of Venus. This project aimed to measure the distance from the Earth to the sun. Thus, citizen science is also a powerful tool for education and conservation purposes. In 1900, the most famous project started, the Christmas Bird Count, as an alternative to bird hunting around the Christmas holidays. Another benefit of this practice is to provide a bridge between science and the public.

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Let’s meet our new PhD Candidate, Megan Slack, from the United States

Sea Search hosts several interns, volunteers and students (Hons, MSc, PhD). This month we welcomed a young lady,  Megan Slack, who will be doing her Phd research with Sea Search. We are very happy as each newcomer brings a new breath to the team, we can’t wait to get to know her. Here is some background information about Megan.

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Megan Slack

Where do you come from?

I’m originally from a suburb of Baltimore, Maryland in the US. I moved to San Diego, California about 3 years ago to work on my Master’s in Marine Science at the University of San Diego, and just moved to South Africa to start my PhD with Sea Search through the University of Pretoria.

-What is your PhD about?

My PhD project is part of a larger project looking at the effects of climate change on cetaceans. Specifically, I will be looking at temporal patterns of distributions of dolphins in False Bay. I will be using acoustic data from underwater hydrophones around the bay to determine what species are present there, their abundances, and changes in their distributions over time- all through acoustics! By describing their distributions, we can track changes over time to determine if climate change is impacting their ranges.

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The 4th African Marine Mammal Colloquium

All marine mammal scientists of southern Africa are more  than welcome to join us at the African Marine Mammal Colloquium. It is an opportunity to present your work, share and collaborate with others scientists. All abstracts are accepted, so feel free to submit yours!

Whatever your expectations are, they will be fulfilled.

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Tricks to recognize a common dolphin

Long-beaked common dolphin

 

Adult Length:

Long-beaked common dolphins in the subregion reach maximun lengths of 2.5 m in males and 2.2 m in females.

Appearance

Common dolphins are relatively easy to distinguish from other small dolphins at sea from the distinctive criss-cross marking on the side.

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Colour

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When comunity and science meet, wonders occur

Leo Berninsone is a part-time volunteer with Sea Search and Sousa Project. We asked him to share his testimony on how local communities can help science.

 “You cannot defend what you do not love and you can not love what is not known” 

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I remember reading that quote on the back of a t-shirt when I was fifteen years old. The link between those 3 powerful words (Defend-Love-Know) shocked me at first sight. Somehow, that saying lingered in my thoughts through the years and still remains being one of the cornerstones of my work on conservation of marine mammals. It changed my whole perspective about what conservation was; I used to think that working with endangered species would prevent them from becoming extinct, but I was wrong. Working with  people would do so.

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Tricks to recognize a Heaviside’s dolphin

CHARACTERISTICS  OF A HEAVISIDE’S DOLPHIN

Length adult

A small animal, reaching a maximum body length of only 1.75m. There is little obvious difference in size between the sexes.

Appearance

Heaviside’s dolphin can be readily distinguished by its low, almost triangular dorsal fin.

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Colour

The coloration of Heaviside’s dolphin is unmistakable: largely grey with blackish cape, white trident-shaped ventral patch with finger-shaped marks on both sides of lower rear body.

Dorsal fin

Triangular and pointed, dark.

The dorsal fin has an overall triangular shape, but the leading edge tend to be slightly convex and longer than the trailing edge, which may be slightly concave.

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Head

Cone shaped head with indistinct beak

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Group Size

Typical group size up to 10

Behaviour

Shy and rarely active or boisterous, though sometimes porpoises at high speed.

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Aerial activity and social interactions are more prevalent in the larger groups.  While inshore in the early morning, these dolphins seem to favour areas with high surf activity, where they may spend time riding the waves inshore and leaping out of the back as they break.

Seasonality

Present year round