Seal Group receives major financial boost from the NRF

Posted on February 03, 2009

The grant was made available for a five year period (2009 – 2013) and will be used to launch the group’s new research programme entitled: Population Ecology of Pinnipeds at the Prince Edward Islands.

“This allocation will allow me to complete much of the research that I have been dreaming about within the next five years,” he says.

According to him, the administrative support he received from the DRS played a major role in the success of his application. “On the same day that the outcome of the application was made known, staff members in the DRS made sure that the acceptance form was processed, signed and hand delivered to the NRF – just in case they decided to change their minds,” he jokingly added.

Prof Bester, who heads the Seal Group, launched the Pinniped Monitoring Programme in 1983 and has led it ever since. The research effort is focused around the sub-Antarctic Prince Edward Islands and the three kinds of seals found there: the southern elephant seal, Antarctic fur seal and Subantarctic fur seal.  These islands and the marine resources in the exclusive economic zone around them belong to South Africa. Such long-term ecosystem studies are important components of understanding and protecting the fragile marine environment.

Much of the research focuses on trophodynamics, that is, detailed studies of the seals’ food in quality and quantity. Pup growth and survival rates reflect the availability of food in the marine foraging range of their mothers. The attendance status of the fur seal females – how long they leave their pups alone when they go to sea to feed – is another important indicator of the availability of prey.

The researchers collect and analyse seal faeces to get further evidence of their diet. Fish remnants in the faeces, in particular fish ear bones and squid beaks, can be used to identify the species and size of prey. Data on the seals’ numbers, condition, diet and foraging habits translate into information that is important to the management of the region and future fish stocks.

In addition to these feeding studies, the researchers are also trying to unravel the population genetics of the two species of fur seals breeding and hybridising at these islands.

The elephant seal mark-recapture programme has been maintained for close to 25 years, making it one of the longest marine mammal monitoring programmes worldwide. So far, more than 10 000 elephant seals have been tagged and monitored.

“At times, we had to fight to keep the programme going, but it was worth it,” says Prof Bester. “We now have an irreplaceable and sought-after database that is also invaluable in the training of future researchers. It provides fascinating insights into the dynamics of a small population of a long-lived marine mammal in a changing environment.”

There was a dramatic decline in elephant seal numbers until around 1994. At Marion Island alone, the elephant seal numbers plummeted from nearly 13 000 in 1951, to just 1 350 in 1994. Now the population has stabilised and there are indications that their numbers are increasing again.

“From 1983, we have tagged virtually every elephant seal pup at about three weeks of age,” Prof Bester explains. “We know them all and we will detect any further changes in the population through this pool of known-age seals.” 

The age and sex specific body size and growth of the large southern elephant seals are also being investigated through sophisticated photogrammetry (making measurements from photographic images of the seals).

Prof Bester’s research team collaborates with polar researchers around the globe. The Alfred Wegener Institute for Polar and Marine Research in Germany, the Australian Antarctic Division and the Hubbs-Sea World Research Institute in San Diego, USA, are key partners in their elephant seal research efforts.

Research also includes satellite tracking of both elephant seals (long-range foragers) and fur seals (intermediate range foragers) through international collaboration, and with a view to contributing to the International Polar Year 2007 research initiative. The tracking data on elephant seals contributed substantially to the first attempt to delineate a Marine Protected Area around the Prince Edward Islands.

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