The African penguin is classified as Endangered and its population has crashed (>50% decrease) since 2004. One of the major threats to penguins is a lack of food. Penguins feed predominantly on small pelagic fish (pilchard/sardine and anchovy). Following overfishing in the 1970s, fish stocks crashed off Namibia, leading to a regime shift in the northern Benguela and greatly reduced penguin numbers in this region. Off South Africa, there has been a shift in distribution of the fish from the west coast (where most penguin breeding colonies occur) to the south coast, leading to a spatial mismatch between the distributions of penguins and their prey. The reason for this range shift is thought to be a combination of environmental change coupled with regional concentration of fishing effort.
Currently, penguin foraging areas have been studied only for breeding birds. Data on adults’ foraging areas during the critical pre-moulting and pre-breeding phases, when their survival depends on acquiring large fat reserves, remains unknown. Knowledge of where adult penguins go to feed before moulting and breeding is crucial to understanding why their numbers have collapsed over the last decade. If they roam over large areas, they should be able to find sufficient food to moult and prepare for breeding. However, if they remain close to their colonies, where prey densities are depressed by ongoing fishing effort, this would explain why the body mass of breeding adults continue to fall, and provide a plausible explanation for their reduced survival. This study allows us to identify the threats facing penguins outside the breeding season and whether competition with the fishery is the major factor driving the penguin population decrease. This information can then lead to better management of the fishery and enhanced conservation of the African penguin.
Our project got underway in 2012 and represents a ground-breaking step in African Penguin research. This is the first time that adult African Penguins have been tracked outside the breeding season. We tracked 20 adult African Penguins from two islands, Dassen Island on the west coast and Bird Island on the south coast, from September to December 2012. The satellite transmitters, which weigh only 40 g and are about the size of a matchbox, are attached to the backs of the penguins using special tape and strong superglue. The battery is expected to last for about 100 days.
The results of this first round of tracking have shown interesting regional differences, with penguins from the west coast colony travelling much further than those from the south coast colony. Penguins from Dassen Island travelled up to 1000 km from their colony, sometimes travelling us much as 50 km per day! The penguins stayed at sea for varying periods, with the longest staying out for more than 70 days. The data collected so far suggest that there is a consistent supply of fish around Bird Island, whereas penguins from Dassen Island had a harder time finding food. Penguins from Dassen Island that returned to moult in the shortest time also went to areas with low fishing pressure, but it is too soon to know if this is significant or coincidental.
We need to continue tracking the penguins for several more years and relate their movements to the abundance of fish and the activities of fishing vessels. With these results we will be able to see if the birds and fishermen use similar areas, and with a few more years this project should provide critical and robust insights into potential fisheries-penguin competition.
Please visit BirdLife South Africa's website for more information.
This project is funded by the Charl van der Merwe Trust, Mohammed bin Zayed Species Conservation Fund and the Percy FitzPatrick Institute of African Ornithology.
Project 11252199 location - South Africa, Africa