The currents and bathymetry (sea floor) of the seas surrounding South Georgia have resulted in large amounts of nutrients upwelling from the deeper oceans, causing an incredible richness in marine life. As with most rich biological resources around the world, there are great profits to be made from exploiting these. South Georgia has a history of extreme over-exploitation of these resources – especially sealing and later, whaling – from the beginning of the 20th century and Captain Cook first claimed it for Britain in 1775. After this, fish populations were heavily hit by overfishing during the 1970s.
A large proportion of South Georgia’s income is still from fishing with its only other income coming from tourism so they have realised it is in their interest to ensure that that the fish populations are conserved.
Cold water species tend to have very long life cycles, grow slowly, have relatively low fecundity (the ability to produce large numbers of young) and reach sexual maturity very late. This means that fishing irresponsibly for one year could easily result in the loss of the fishery for the next 50 years, with recovery rates being very slow and sometimes irreversible.
In order to prevent this happening, the South Georgia Government have invested large amounts of money and research into the setting up of self-sustaining fishery, where the ecosystem is managed and researched as a whole, and where money made from the fishery is used to invest in the policing of fishing as well as research into the broader effects of fishing on the environment.
Food chains are extremely complex things and hard to fully understand. However, monitoring of key predators within them can give a good indication as to the health of lower levels in the same food chain. This is why, in South Georgia, the fisheries are researched and overseen, as well as the higher predators. This is where I come in: I work intensively with the Antarctic Fur Seals and Gentoo Penguins because they feed almost exclusively on krill, which is at the centre of most Antarctic food chains. I also observe the behaviour of giant petrel and albatross.
The main focus of my job is to work with these top predators at an area of the island called Maiviken. I have to visit my study site every other day during the summer period here and take pictures of the fur seal colonies. The aim of this is to allow us to understand more about the build up of the colonies during the breeding season and also understand how successful the colonies are.
On top of this, we also look closely at the development of the pups and chicks by weighing them at various stages because growth rates relate back to how successfully the adults are fishing, which in turn indicates the health of the ecosystem.
We also study the diet of these predators through analysing their scats (poo) as this gives us a good indication as to what species in the food chain are thriving and which species may be struggling. For example, if we only find adult krill in the seal’s scats then this suggests that there has been no recruitment of young krill into the population and that there could be a problem in the ecosystem.