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

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Tricks to recognize a Dusky Dolphin

Dusky dolphins are unlikely to be confused with Heaviside’s dolphins but can be easily distinguished from them by their recurved dorsal fin.

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Acoustic and photo-ID research on humpback whales (Megaptera novaeangliae)

Internship @ Sea Search Africa

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Ilka Beith, German intern from the 01.02.2016 to 01.04.2016. She did her Bachelor degree in Geography at the Ruhr-University of Bochum in Germany and is going to do her Masters in Marine Science in Scotland.

During my internship with Sea Search Africa I worked on a set of photographic and acoustic data on humpback whales (Megaptera novaeangliae) collected late last year. 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 (e.g. FIG. 2), RD (e.g. FIG. 1) 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.

Some of the pictures I turned into black and white, because it is easier to see marks and it also highlights the shape.

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FIG. 1: 20151104_RD_001 (date, right dorsal fin, number)  WSAMN_001 (first whale of the catalogue)

20151104_6D_HB-IMG_2035 (SSA - Simon Elwen)

FIG. 2: 20151104_LD_001 (date, left dorsal fin, number)  WSAMN_001 (first whale of the catalogue)

 

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’ as below to both a dorsal fin and a good underside (FIG. 3).

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FIG. 3: pictures of the left dorsal fin, the right dorsal fin, the tail fluke in different perspectives and a “side-shot” of the whale WSAMN_006

 

 There are now over 120 individuals in the photo-ID catalogue. I found over 30 matches of the right and left dorsal fin, nearly 20 matches all together (LD, RD, TF) and nearly 40 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).

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 each noise and quantified, classified and categorized the noises (mostly following the categories defined by Rebecca Dunlop and colleagues in Australia – Dunlop et al. 2007). All in all I found over 1500 sounds in the acoustic data of the first three days of research. 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” (FIG. 4), “grumbles” (FIG. 5) and “barks” (FIG. 6). The most common mid-frequency sound is the “modulated cry” (FIG. 7) and the common high-frequency sound is the “shriek” (FIG. 8). For those who are interested in listening to some social sounds of humpback whales, here are some sound clips you can listen to (above is an example of the associated soundwave).

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FIG. 4: most common low-frequency sound – wop

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FIG. 5: low-frequency sound – grumble

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FIG. 6: low-frequency sound – bark

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FIG. 7: most common mid-frequency sound – modulated cry

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FIG. 8: most common high-frequency sound – shriek

Tricks to recognize a Southern Right Whale

Southern Right Whale

Length adult: 14 -16m (with females larger than males).

Appearance:

Right whales are hard to confuse with other large whales.

20150727_04_MA-RE-I_FB_EV_IMG_0554 (EVermeulen)

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We as Marine Scientists, we deal with marine pollution

Water is Work

 “No water no jobs” is the sentence we can read in the UN World Water Day campaign. This year’s purpose is to highlight the links between water, jobs and sustainable developments. Indeed, water  is essential for life,  but it is also essential for jobs.

 One and a half billion people (half of the world’s workers) work in water related sectors.   According to the report released on the 22th of march, the population in Earth  will grow a 33% between 2011 and 2050 (from 7 billion to 9,3 billion). Due to increasing population,one of  the main issues will be the global food security.

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WORLD WATER DAY

 

A day to celebrate freshwater

Each year since 1993, the United Nations dedicated a day to draw people’s attention to the importance of freshwater and to advocate for the sustainable management of freshwater resources. Water World Day was officially assigned to the 22nd of March with a different theme each year, organized by one of the UN’s Water members.

Better Water and Better Jobs

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Tricks to recognize a Humpback Dolphin

How can we recognize a Humpback dolphin? Read More…

Jean Paul Roux, the man who rescued 33 dusky dolphins in Namibia

On the 3rd of February 2016, Jean Paul Roux managed to rescue 33 stranded dusky dolphins on the Lüderitz coast. The news has been released on his facebook page “Lüderitz Marine Research”. Before reading the interview, it’s good to get to know the man. Read More…

Bottlenose Identification

Tricks to recognize a Bottlenose dolphin

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