By Mark Dixon
Friday 29th June 2018
Today, in the Garden Route, we witnessed the indifference of natural selection. Yet for those present, there was an empathy for one of the giants of the ocean.
One year ago I swam with Humpback Whales during the Sardine run in the Eastern Cape. Today I watched one die.
The scientist in me took notes.
- The bloodshot eyes from stress.
- The loosening of the lower jaw at the approach of death.
- The anguished song at 13h51.
- The last struggle at 13h53.
- The closing of the eyes and last exhalation at 13h54.
Yet it was with heavy feet that I left the sea.
Not all can survive, but it was frustrating being powerless to assist a lonely whale in need.
You can watch a video of the whale attempting to swim to open water and then finally dying from this link : Humpback Whale stranding
I look forward to swimming with them in the future and to hear their song again, in more pleasant circumstances.
You can watch a video of the Sardine run from this link : Sardine Run
Saturday 30th June 2018
Blood flows into the sea.
Along with researchers from SANParks and Cape Nature, at 10h00 we conducted biometric measurements and biopsy sampling on the juvenile Humpback Whale that washed up on the Swartvlei beach yesterday.
Skin, blubber and muscle samples were taken from the back, tail and wound area. Baleen samples were taken from the upper jaw and various length measurements were made with the overall length at 8.83m.
The wound, which was covered in lice when it washed up yesterday, was more clearly visible this morning and from the shape and groove marks appears to indicate either shark or orca attack.
The degree of healing of the wound would indicate it is not recent. Though the rate of would do healing in Humpback Whales is currently unknown to us.
What was remarkable was the variation in temperature of the skin and the internal temperature beneath the 25cm of blubber.
There was blood loss from the sample areas on the tail and the upper jaw.
Public Interest :
This evening I have been contacted by numerous people asking why we didn’t disect the whale to check for stomach contents. Here are some aspects that need to be considered for such a disection.
While there is a pressing need to check if plastic ingestion contributed to the death of the whale, there are some barriers in the way.
Firstly permissions from DEA, the South African authority which has jurisdiction over marine mammals. As an individual it will be almost impossible to get a permit. That leaves getting an organization to submit a permit request.
Unfortunately with the incident occurring on Friday the weekend became a bureaucratic obstacle, to say the least.
Secondly, of the experienced personnel in the region that could have done the disection, one was overseas at an international conference and the other wasn’t available.
Next, a disection of an 8.8m whale is not the same as a lab disection of a rat. The whale was lying on her stomach, slightly on her right side and partially submerged in sand below the water table. It would have required a machine (TLB or bulldozer) to roll her over.
The next obstacle, as she lay at the time of sampling, was the lack of a large enough sharp blade.
First a cut through more than 22cm of blubber. Next, the removal of hundreds of kilograms of liver and hoping that the dorsal part of her didn’t then collapse down. Next would have been dragging from underneath the carcass the substantially heavy stomach and digestive tract.
Hopefully after the weekend permissions will be granted, equipment is sourced and more info is made available to science.
Preliminary sampling and measurements :
Length : the whale measured 8.83m in length.
Sex : Due to the genital slit being buried at the time of sampling it was impossible to make a definite call on the whales sex on the beach.
Using a series of screen grabs from the video I filmed on Friday it was possible to confirm that the whale is/was a female.
Determining the sex of a whale is not as simple as looking for reproduction organs as in terrestrial mammals. Both male and female Whales have a genital groove which is posterior of the umbilcus (the site of attachment of the umbilical chord while in the uterus) and anterior of the anus.
Humpback Whales swim at about 14 knots, so for a male to have exterior genitalia would be a problem and rather painful at that speed. Thus the genital groove contains the penis in males and the vagina in females.
What distinguishes the female whale from a male during an external examination is a pair of mammary slits, one on either side of the groove and a bump called the hemispherical lobe just behind the groove. In the photo below the mammary slits can be seen, as can the lobe.
Skin : for an animal this size, it is surprisingly thin, about 3 or 4 mm.
Blubber : From the samples it was between 22cm and 25cm thick.
Baleen : this is used for feeding. The whale will scoop up a large mouthful of water with krill. It then closes it’s mouth and forces the water out through the baleen which acts like a sieve and traps the krill in the mouth.
Ecto parasites :
Initially while assisting her in the water I observed a heavy infestation of ‘Whale Lice’ on the prominent wound. While investigating her carcass on the beach we noted lice on the wound, tail, lower jaw and on the head forward of the eyes.
A whale louse is a commensal crustacean of the family Cyamidae. Despite the name, they are not true lice, but rather are related to the better-known skeleton shrimp, most species of which are found in shallower waters.
They grip tightly to the skin and have a strong bite as experienced by Wayne Meyer from Cape Nature. Sections of skin had small indentations where the lice had gripped.
We recorded barnacles on the tail, lower jaw and head.
Whale barnacles are barnacles belonging to the family Coronulidae. Whale barnacles attach themselves to the bodies of baleen whales during the barnacles’ free-swimming larval stage.
What is remarkable about the lice and barnacles is that while attached to the whale they have to tolerate subzero temperatures in the Antarctic and warm temperatures in the tropics when the Humpback Whales migrate between these two regions .
There were two wounds, only one of which could be seen during the sampling.
The larger wound was about 45cm across and about 50cm at the widest point. There were a series of evenly spaced grooves well seen on the medial side of the wound which could be from either a shark or Orca, though this would need to be confirmed from more accurate forensics.
Two people have suggested that it could be from a propeller – again a more authoritative forensic assessment would be required.
The second wound I observed while in the water with the whale and managed to film it. From the screen grabs it is circular and approximately 5cm to 7cm in diameter. The wound was still raw though there wasn’t visible evidence of lice.
From the photo below it is an interesting alignment of the two wounds and begs more concise forensic.
Sunday 1st July 2018.
This afternoon I noted (using binoculars) that the whale had rolled over and that the right side was now exposed, but unfortunately I couldn’t do a follow-up visit to get close up photos of the genital groove and accurate measurements of the circular wound. Hopefully tomorrow.