Bottlenose dolphin acoustics - by Mel Ngo

20 June 2011
This past weekend, we were given Saturday and Sunday off to relax and explore the wonders of Namibia. A couple of interns went on a camping trip to Spitzkop, which is about 3 hours away from Walvis Bay. From the stories and pictures they shared, they had a great time seeing the kind of glory Namibia has to offer.

This week has been the most productive by far. After coming back from our two day break, we were all re-energized and eager to get back to work. On Monday, we had an encounter with the bottlenose dolphins, which we haven’t seen much of this month.  This season the NDP has brought in some new technology, a hydrophone to record the sounds made by the bottlenose dolphins (and anything else they encounter), focusing on whistles and other sounds they are able to make which are mostly for communication.

Back in the office, the ‘acoustic team’ uploaded the data on to the computer; from there we are able to look more closely at the data to see (and hear) if we have recorded any whistles.  Unfortunately, there were no whistles from Monday’s encounter, but there were a couple of other interesting sounds such as clicks, buzzes and burst pulses.

The next day, Tuesday, we did our normal routine of launching the boat around 8 am. The boat team for that day was Simon, Heidi, Hannah, Kuan and I. As always, we were on search for whales and dolphins, and heading north just off the fishery docks we spotted bottlenose dolphins again. I was very excited as it was my first time seeing them this season and for some of the others as well. I forgot how massive and big these dolphins are and I was happy I got to see them again. Some were friendly in the beginning, approaching the boat and others were jumping and socializing from a distance. With Tess not being on the boat I’d been ‘promoted’ to run the acoustic recordings. Once we found them, I immediately prepared the equipment, hooking up the hydrophone to the boat, connecting it with the recorder, finding a spot for the recorder, and plugging the headphone to the device. When everything was set up and the hydrophone was placed in the water and the recording was on, I listened to the eerie mysterious sound of the sea for the first time. It was quite an interesting experience, it was very quiet when the engines were off, kind of spooky in a way. Within the first couple of seconds that the recorder was recording and the headphones were on my head I heard these amazing animals whistles. I jumped and shouted “They’re whistling!”. Simon and Heidi just looked at me and laughed as I could not believe what I was hearing. VERY COOL! We did several recordings and most of those files had at least a few whistles and many clicks the bottlenose produced. SO VERY COOL!!!!

At the time of the recording at sea, listening in on the dolphin’s secrets, it seemed like no sound was being made much of the time, but once everything was downloaded on to the computer, I found other whistles in the files that I did not hear when at sea. It’s much easier to pick the whistles out visually on the computer than by ear on a noisy boat! It was one of the coolest experiences I have got to experience again with the NDP team this season. I cannot wait to learn and find out more!!

Intern blog 3 - Kuan Li

Tess's birthday last Friday (17th), so we decided to combine a beach survey following the spring tide with a little beach braai (barbeque) to celebrate the occasion.  Worked the poor car almost to death, apparently a full tank and 8 people on a soft beach is about the limit a Mitsubishi Turbo Diesel can deal with..


Blog entry by Kuan:

June 17th, Friday

We went to Donkey Bay for beach survey today. Donkey Bay is at the south of Walvis Bay. On the way to Donkey Bay, we passed the salt banks and everyone was excited about it. We jumped of the car and had a walk along the muddy road. The pools were red because of algae and the mud around the pool had different layers of color. Then, Simon drove us all the way south to the border of Sandwich Bay. We saw four jackals, probably a big happy family, walking along the sand dunes.

Basically, the survey started from Donkey Bay till Pelican point. We travelled north and tried to find dead animals especially dolphins and whales. There were a lot of dead seals on the beach, some were freshly dead and others had only bones left. We drove to a freshly “dead” seal on the beach and wanted to check it out. As soon as we stopped the car beside it, it opened eyes and started to run away from us. We were so amazed because everyone thought it was dead. The seal looked back at us innocently like saying: “Leave me alone. I am just having a nap”.  We had a big laugh and continued the search. After a while, we discovered a dead leatherback turtle. It had been dead for a long time since only bones were left and buried in the sand. The turtle was about 160cm long and its skull was missing, but we could see its tail, legs and shell. Apart from the turtle, we also found a piece of whale’s bone nearby, which was pretty awesome. It could be a right whale or a humpback whale. After investigated the area, we headed to Pelican point.

At the Pelican point, we set a bonfire and prepared for braai on the beach. At the meanwhile, we explored a wrecked ship. The water was quite shallow but freezing cold. There were some sea anemones, which were fun to touch. It was awesome to have braai on the beach and we all enjoyed the day.

Science...it's not all about pretty pictures of dolphins...

Blog entry by Hannah "Banana" Murphy...

The first day we went out to sea, I did not go out to sea.  When I was informed of this tragedy, I replied, “Oh, okay! That’s great!”  I did not, however, think it was great.  I was dying a little on the inside.  We all woke up at 6 and I waved at everyone as they filed out the door with excitement in their voices.  I locked the door behind them and turned around to face the empty house.  I trudged to the office and plopped down next to the stack of data forms that I was going to enter into an Excel spreadsheet.  There were so many! “Well,” I thought to myself, “someone has to do it… and it might as well be me.”  I prepared myself for the boring task ahead.  Only a few minutes passed before I was intrigued by the information on the data sheets!  The first thing that I leaned was that being on a boat is not conducive to good hand writing.  I now read Simon Hieroglyphics and Tess Hieroglyphics almost fluently.  It was super difficult at first, but got easier as the day went on.  I felt like I was learning more about dolphin behaviour than the people were on the boat! It was so cool! Before long, I could recognise where the dolphins liked to hang out! When I got on the boat the next day, I picked up the data form and knew exactly what I was doing! It was great!! The next week when my office day came around, I was excited to sit in my PJ’s, drink tea, and enter really interesting data about dolphins!

Necropsy Day

While we have interns, we’ve asked them to write the blog entries for us to get across some of the excitement and novelty of doing all this for the first time.  I think that having done this for a few years now I sometimes forget what an impression a whale necropsy makes when you do it for the first time.  I loved Kassler’s contribution so much I’ve left it entirely unedited except for correcting place names.

I think in all the excitement and ‘gore’, some of the interns may have missed the bit where we looked for parasites, obvious signs of death and collected skin and blubber samples for genetic, stable isotope and pollutant analyses.  The skulls of both animals have been collected and are going to the National Museum in Windhoek in due course.

Both animals described below were discovered by Naude Dreyer of Sandwich Harbour tours who is one of the key members of the Walvis Bay Strandings team.  

I've put in some photos below showing the stages from collection on the beach to final remains. Also a photo showing the small hair follicles on the snout, the shark bites on the tail stock (after death) and Tess looking up cranial structure as we tried to look for the sound producing organs

7th June, Tuesday, 2011

By Kassler Peh – Oceans Research Intern from Singapore

Necropsy of killer whale (calf) and Heaviside’s dolphin (calf)

We set off for Swakopmund early in the morning and reached the offices of the Ministry of Fisheries and Marine Resources at about 0900 hrs. Somewhere within fisheries laid our prized possessions, the dead killer whale and Heaviside’s dolphin. The whale was about 2.3m in length while the dolphin was much smaller, only about 80cm long. Excitement could be sensed all across the intern’s faces and everyone was ready for the necropsy. There were even two journalists present, sharing the exciting moment with us. But little did we know that what started off as a pleasant day would soon turn into a day filled with gore and blood.

First up was Mel, who had the task taking off the killer whale’s head. As soon as the knife sliced through the layer of blubber on the whale, blood started oozing out of the slit. Gas from within the whale started escaping as well and soon, the whole room was filled with the foulest smelling stench ever. As soon as the head came off, Simon took over and dismembered the beast like a seasoned butcher. Together with a few other interns, we started tearing and cutting off the blubber and flesh of the whale. Bits of whale flesh and blood started spewing and spurting all across the room, finally exposing the insides of the whale after about an hour. From the oesophagus all the way to the anus, every bit of the whale was pointed out by Simon expertly. It was a really insightful day for the interns albeit the gore and mess. Finally, the whale was chopped into pieces and packed into small bags, ready for disposal.

Next up after lunch was the Heaviside’s dolphin. Relatively easier to butcher due to its size, the insides of the dolphin was exposed in a matter of minutes. The surprising thing was that the lungs of the dolphin actually had dark patches in it and lung worms were present in its lungs. Milk was also discovered in the stomach and intestines of the dolphin. Just like the whale, the dolphin was also chopped up into pieces and packed into bags.

 

The only remains of the two corpses were their skulls, which will be transported to the National Museum in Windhoek. Removing the flesh and brain matter off the skull was the last thing on the agenda that day. Once that was done, signs of relief can be witnessed all over the intern’s faces and all of us gladly left the fishery with a huge sense of achievement. What a bloody Tuesday indeed.

     

 

Namibian Humpback Whales

06 June 2011 - by Simon Elwen

Humpback whales are one of the most well studied large whales in the world and yet there is still  great uncertainty about many aspects of their lives. Even such relatively simple facts such as where exactly they feed and breed can be surprisingly complicated as individuals sometimes mix between these grounds. The International Whaling Commission (the body which governs and controls global whaling) has defined the  stock of humpback whales which breed off the West coast of Africa as 'Breeding Stock B'. This stock is split in a northern (B1) and southern (B2) component based mainly on historic whaling data records.

Most of the work on this population has taken place in Gabon (by the Wildlife Conservation Society), which is a breeding area and in South Africa (by the University of Pretoria), which is largely seen as a migratory corridor, and there is very little information from the thousands of km of coast in between. Genetic analysis of whales from South Africa and Gabon, has shown some evidence of stock separation, supporting the B1/B2 split. However individual animals have been resighted (from photographs and using genetic sampling) in both South Africa and Gabon showing that at least some animals use both areas. However there is still some confusion about how all these stocks, breeding areas and migratory corridors actually fit together.  Data from the areas in between SA and Gabon are particularly valuable right now in trying to help the IWC answer these questions.

In addition to our main dolphin focus, the NDP has been collecting photographs and genetic samples from humpback whales at sea and from strandings as much as possible since we started. We've also been collating photographs and records from tour boat operators in Walvis Bay which has greatly increased our data set of humpback whale photos. Most of these photos have been taken by Mike Lloyd and Orlanda Sardinha who work on the Cataraman Charters vessels (http://www.namibiancharters.com).  Recently, a colleague of mine who did his PhD work on the humpback whales off western South Africa, matched the photographs we've collected in Namibia to his catalogue of known animals from SA. Unfortunately no matches have been found yet between Namibia and South Africa, but we'll keep looking. Although this is a very small sample (only 35 individuals were identified from tail flukes in Namibia), it is still an interesting result and is being presented as paper SC-63-SH21 at the meeting of the Scientific Committee of the International Whaling Commission which is being held right now in Tromso, Norway (www.iwcoffice.org).

Next up is matching our Namibian whales to the catalogue from Gabon. Meanwhile, work continues here in Walvis Bay and we hope to see lots more humpback whales this winter!