Another beached whale found
Marine biologists are worried about unexplained strandings by humpback whales and other sea animals in the last two months.
It's been quite a busy few days for the Namibian Dolphin Project (NDP) in Walvis Bay and for Lüderitz Marine Research (LMR) crews.
With four confirmed strandings (and counting) reported along the Namibian coastline and four possible strandings reported for the west coast of South Africa, something awfully wrong is going on at the moment.
The emaciated state of the first humpback discovered at Paaltjies seemed to rule out the algal toxin hypothesis after some potentially toxic algal blooms were detected earlier this month off Lüderitz.
“The high number of strandings of humpback whales over the past two months in Namibia at this time of year is very unusual. No clear cause is yet known,” said Dr Simon Elwen of the NDP.
“We currently do not have any data yet from South Africa but the Namibian Dolphin Project is coordinating with colleagues in Lüderitz (Ministry of Fisheries and Marine Resources) and South Africa (Department of Environmental Affairs) to ensure we collect all the data we can.”
Elwen pointed out that a similar event occurred off the coasts of South America and Australia in 2010 and was thought to be associated primarily with malnutrition.
He said the humpback whale population off West Africa was generally regarded as large and healthy and had been growing at between 7 and 10% per year.
“This is likely to result in increased competition for food within and between species for resources, all of which are being affected at all levels of the ecosystem by human overfishing and climate-change effects.”
In addition to the two dead humpback whales discovered at Paaltjies on 26 and 29 March, after the two had been discovered near Oranjemund earlier, reports were received of a dead Heaviside's dolphin and a dead leatherback turtle between Windpomp 14 and Swakopmund on 24 March.
LMR also reported the successful rescue of an adult female Risso's dolphin in distress within the perimeters of the Lüderitz harbour on 28 March.
According to Dr Jean Paul Roux, a marine biologist with the Ministry of Fisheries and Marine Resources, the Risso's dolphin rescued in Lüderitz harbour appeared healthy. It is very rare to Namibian waters and the three-metre-long animal is capable of reaching a weight of 300 to 500 kg.
“We didn't manage to find the dolphin but found the turtle. Our strandings network team also visited the site where the first humpback whale stranded at Paaltjies on 26 March and took a range of standard measures and samples for further analysis.
The animal was a 15.3m-long male humpback whale. Unfortunately it was already well decomposed, suggesting it had died at sea several days earlier, but a skin sample was taken for inclusion in long-term databases and comparisons.
“No cause of death or human interference was evident. The second animal was discovered in the same vicinity and is of smaller size,” commented Elwen.
Leatherback turtles are endangered globally and very little is known of these elusive turtle giants in Namibia. Although in recent years whales have been recorded in all months of the year at some point, strandings at this time of year are usually rare.
Humpback whales are the most common large whale species along the Namibian coast and are usually observed between June and October during their northward and southward migration from Southern Ocean feeding grounds to breeding grounds in the tropical waters of Angola and West Africa.
“Some whales stay around on the west coast of southern Africa well into summer where they feed in the rich waters of the Benguela Ecosystem and this result in an additional summer peak in numbers.
“The feeding whales have been known to form into 'supergroups' of ten to hundreds of animals and although summer feeding has been observed in Namibia no supergroups have been seen yet,” Elwen pointed out.
The NDP advises people who come across a live stranded whale or dolphin not to touch the animal but to rather cover its body with a towel or blanket to prevent sunburn and keep the animal wet using fresh or saltwater.
The blowholes on the top of the head, which are the animals' 'nostrils', should be kept uncovered. Noise should be kept to a minimum and crowds must be kept away from the animal.
OTIS FINCK
With four confirmed strandings (and counting) reported along the Namibian coastline and four possible strandings reported for the west coast of South Africa, something awfully wrong is going on at the moment.
The emaciated state of the first humpback discovered at Paaltjies seemed to rule out the algal toxin hypothesis after some potentially toxic algal blooms were detected earlier this month off Lüderitz.
“The high number of strandings of humpback whales over the past two months in Namibia at this time of year is very unusual. No clear cause is yet known,” said Dr Simon Elwen of the NDP.
“We currently do not have any data yet from South Africa but the Namibian Dolphin Project is coordinating with colleagues in Lüderitz (Ministry of Fisheries and Marine Resources) and South Africa (Department of Environmental Affairs) to ensure we collect all the data we can.”
Elwen pointed out that a similar event occurred off the coasts of South America and Australia in 2010 and was thought to be associated primarily with malnutrition.
He said the humpback whale population off West Africa was generally regarded as large and healthy and had been growing at between 7 and 10% per year.
“This is likely to result in increased competition for food within and between species for resources, all of which are being affected at all levels of the ecosystem by human overfishing and climate-change effects.”
In addition to the two dead humpback whales discovered at Paaltjies on 26 and 29 March, after the two had been discovered near Oranjemund earlier, reports were received of a dead Heaviside's dolphin and a dead leatherback turtle between Windpomp 14 and Swakopmund on 24 March.
LMR also reported the successful rescue of an adult female Risso's dolphin in distress within the perimeters of the Lüderitz harbour on 28 March.
According to Dr Jean Paul Roux, a marine biologist with the Ministry of Fisheries and Marine Resources, the Risso's dolphin rescued in Lüderitz harbour appeared healthy. It is very rare to Namibian waters and the three-metre-long animal is capable of reaching a weight of 300 to 500 kg.
“We didn't manage to find the dolphin but found the turtle. Our strandings network team also visited the site where the first humpback whale stranded at Paaltjies on 26 March and took a range of standard measures and samples for further analysis.
The animal was a 15.3m-long male humpback whale. Unfortunately it was already well decomposed, suggesting it had died at sea several days earlier, but a skin sample was taken for inclusion in long-term databases and comparisons.
“No cause of death or human interference was evident. The second animal was discovered in the same vicinity and is of smaller size,” commented Elwen.
Leatherback turtles are endangered globally and very little is known of these elusive turtle giants in Namibia. Although in recent years whales have been recorded in all months of the year at some point, strandings at this time of year are usually rare.
Humpback whales are the most common large whale species along the Namibian coast and are usually observed between June and October during their northward and southward migration from Southern Ocean feeding grounds to breeding grounds in the tropical waters of Angola and West Africa.
“Some whales stay around on the west coast of southern Africa well into summer where they feed in the rich waters of the Benguela Ecosystem and this result in an additional summer peak in numbers.
“The feeding whales have been known to form into 'supergroups' of ten to hundreds of animals and although summer feeding has been observed in Namibia no supergroups have been seen yet,” Elwen pointed out.
The NDP advises people who come across a live stranded whale or dolphin not to touch the animal but to rather cover its body with a towel or blanket to prevent sunburn and keep the animal wet using fresh or saltwater.
The blowholes on the top of the head, which are the animals' 'nostrils', should be kept uncovered. Noise should be kept to a minimum and crowds must be kept away from the animal.
OTIS FINCK
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