ADU postdoc Richard Sherley is presenting a seminar on Monday in the MA-RE/SANCOR seminar series. Richard's topic is Could local and regional prey availability both have roles in influencing the breeding success of African Penguins Spheniscus demersus at Robben Island? The presentation is on Monday 13 February, at 13h00, in the Oceanography Seminar Room, UCT. The Department of Oceanography is on the lowest level of the RW James Building at the north end of University Avenue. Most of this building is occupied by the Department of Physics.

ABSTRACT: Past population trends of African Penguins Spheniscus demersus breeding in the Western Cape, South Africa, as well as their breeding success, have been linked to the abundances of their main prey species, Sardine Sardinops sagax and Anchovy Engraulis encrasicolus. During the late 1990s and the 2000s, the abundance and distribution of both fish species changed markedly and this study re-examines past relationships in this light. The breeding participation and reproductive output of African Penguins was monitored at Robben Island from 2001–2009. The number of pairs breeding in each year and chick-growth rates were influenced by Sardine abundance in the November proceeding each breeding season, while nest success and chick-fledging rates were positively influenced by the annual purse-seine catch of Anchovy within 30 nautical miles of the colony. In addition, chick-fledging rates were depressed in two-chick broods during years when Anchovy contributed less than 75% by mass to the diet of breeding African penguin. Previously reported relationships between the overall abundance of small pelagic fish in the southern Benguela ecosystem and penguin breeding success at Robben Island were not replicated here, possibly as a result of the recent changes in the populations of these fish in South African waters resulting in a decoupling of local and overall prey availability. Taken together, these results highlight the importance of local food availability to African Penguins during the reproductive cycle, but also the importance of adequate prey abundance during the non-breeding season.

Richard is part of the large ADU team doing research trying to understand why the African Penguin is in decline. Two years ago, the IUCN threat classification of the African Penguin was changed from "Vulnerable" to "Endangered", one category closer to "Extinct in the Wild." Uncovering the real issues for penguin decreases is becoming an urgent issue.

Two of the Animal Demography Unit's Honorary Research Associates, Rob Crawford and Jean-Paul Roux, are co-authors of an important paper published in the leading journal Science today. It provides critical guidance on how fish stocks should be managed in such a way that there is enough left over for the seabirds.

"Fishing can have devastating effects on seabirds. Not only do they get snagged on hooks and tangled in nets, but chronic overfishing can deprive the birds of their prey—the same small fish that boats are catching. Now a study has identified what appears to be a universal threshold for danger: when the biomass of so-called forage fish drops below one-third of its maximum, seabirds of many species start to have fewer chicks.

"'This is one of the most important seabird papers to be published in some time,' comments conservation biologist Dee Boersma of the University of Washington, Seattle, who was not involved in the research. The findings demonstrate the widespread reliance of seabirds on small forage fish, she says. To protect the birds, the papers' authors call for lower harvest levels of forage fish. 'The problem remains that most fisheries are not properly managed and controlled,' says co-author Philippe Cury of the Institute of Research for Development in Sète, France. Worldwide, about 25% of forage fish stocks have collapsed, he adds.

These are the first two paragraphs of the report that appears on the website of the journal Science. Read the full report here.

The abstract of the paper reads like this: "Determining the form of key predator-prey relationships is critical for understanding marine ecosystem dynamics. Using a comprehensive global database, we quantified the effect of fluctuations in food abundance on seabird breeding success. We identified a threshold in prey (fish and krill, termed “forage fish”) abundance below which seabirds experience consistently reduced and more variable productivity. This response was common to all seven ecosystems and 14 bird species examined within the Atlantic, Pacific, and Southern Oceans. The threshold approximated one-third of the maximum prey biomass observed in long-term studies. This provides an indicator of the minimal forage fish biomass needed to sustain seabird productivity over the long term." The full reference is Cury PM, Boyd IL, Bonhommeau S, Anker-Nilssen T, Crawford RJM, Furness RW, Mills JA, Murphy EJ, Österblom H, Paleczny M, Piatt JF, Roux J-P, Shannon L.J, Sydeman WJ 2011. Global seabird response to forage fish depletion – one-third for the birds. Science 334: 1703–1706.

After a nice run of almost three months, it seems that Kathy's PTT has stopped transmitting. The update I posted on 9 December (for which the data came from 6 December) was the last transmission received from PTT 105338. Kathy was released at Betty's Bay on 13 September along with her sibling, dubbed Georgie. Unfortunately the PTT Georgie was carrying (105339) only transmitted for 12 days, but Kathy's sent updates on her whereabouts for just under three months. In that time she covered close to 2000 km but, unlike the three chicks that had gone before, she did not head into Namibia waters. Kathy spent most of her time on the West Coast of South Africa, between about 70 and 300 km north of St Helena Bay. She also didn't spend quite as much time far offshore as Lucy (105335 shown in red), Richie (105336, green) and Nicky (105337, yellow) did. Interestingly, we have been hearing from the scientists at the Department of Agriculture, Forestry and Fisheries (DAFF) that this winter has been a relatively poor one for small pelagic fish recruitment and there were apparently very few youg sardine and anchovy found during the annual survey conducted in May. Could that explain why Lucy, Richie and Nicky all headed so far north? At present we can only guess but more deployments are planned for next winter, so perhaps we will be able to shed more light on that question in the future.

I hope to post a more complete summary of these deployments in the New Year, once we have started to undertake the data analysis. For now, just to say thanks again to everyone that helped to make sure the deployments happened, especially Bruce Dyer and Rob Crawford (Department of Environmental Affairs, DEA) for their help obtaining and deploying the PTTs as well as Mike Meyer (DEA) for tirelessly downloading the data every few days. The Chick Bolstering Project is a collaborative project and we are grateful to all the other partners and sponsors: SANCCOB, the Bristol Conservation and Science Foundation, the Animal, the Department of Environmental Affairs (Oceans and Coasts), CapeNature, Robben Island Museum and the International Fund for Animal Welfare (IFAW). The project is made possible by the following sponsors: Zoo Basel; Zoo Leipzig; Living Coasts; Erlebnis Zoo Hannover; Dierenpark Amersfoort; Le Pal Nature Foundation; Allwetterzoo Muenster; ZOOM Torino; La Palmyre Zoo; Burgers Zoo; Georgia Aquarium; Leiden Conservation Foundation; National Aviary; Seaworld Animal Crisis Fund; Little Rock Zoo; Memphis Zoo; Steinhardt Aquarium; Toledo Zoo, Mystic Aquarium; Disney Rapid Relief Fund; Wallace Global Fund; Fort Wayne Kid’s Zoo; and Jenkinson’s Aquarium and Oceana.

You can find the background to this project here.

I guess, as should be expected by now, Kathy didn't do what I suggested that she might in the last post. She has moved back inshore and back north to the area of Brand se Baai and the border with the northern Cape. Clearly, something is keeping her in the area and we hope it is small pelagic fish.

You can find out more about this project here. Thanks to all the partners and sponsors of the Chick Bolstering Project for making this research possible.

This year, MSc student Kate Robinson and postdoc Antje Steinfurth have been responsible for the GPS logger monitoring of African Penguins on Robben and Dassen Islands, respectively. We do this research in close collaboration with the Oceans & Coasts Branch of the Department of Environmental Affairs (DEA) and the Fisheries Branch of the Department of Agriculture, Forestry and Fisheries (DAFF). The GPS loggers (which cost a scary R30 000 each) are bought by DEA, and the ADU helps by doing the deployments of the loggers on the penguins. This fieldwork requires enormous amounts of skill to attach the loggers, and then nerves of steel waiting for the penguins to return. A logger makes one trip on a penguin and then gets removed and the precious data downloaded. The data consists of accurate positions of the penguins at intervals of a few minutes, and detailed data about their dive behaviour.

Kate shares four of the 30 tracks she obtained of penguins from Robben Island: "The red track was made in May, the yellow in June and the green and the blue in July. The penguin with the red track made 430 dives during a 10 hour trip, and the yellow penguin made 349 dives in a 10.8 hour trip. The total length of the green track, the longest one, is 62 km. The penguin that made the blue track got into the sea at 07h15 on the morning of 13 July, at dawn, covered a total distance of 46 km, and got back to Robben Island at 18h00 that evening, at dusk. This is the typical one-day foraging trip of a penguin with chicks in the nest."

Antje made a similar number of deployments on Dassen Island. One of her birds was away for a long time, and when she ultimately got the logger back, she discovered that the bird had made a trip around Cape Point, almost as far as Hermanus!

We are steadily building up an understanding of where penguins feed when they have chicks, and ultimately we aim to get really good insights into where the penguins are feeding in relation to where the fish actually are. In simplified terms, the fish biology runs like this. During the main penguin breeding season, in winter, there is "river" of young anchovy swimming south along the West Coast and passing with penguin foraging range of the two islands. The fish are heading for the Agulhas Bank, where they spawn. We are aiming to do the monitoring on an annual basis, and we want to find out if the penguins are telling us whether they need to go longer and longer distances each year in search of food, and from the diving patterns we can estimate how hard they are working. This information all contributes to a much larger research programme which aims to discover the reasons for the decline in penguin population sizes, and to make recommendations for how to reverse it.

Kate and Antje are currently funded by the Marine Research Institute at UCT, by the Leiden Conservation Trust in the US, and by the National Research Foundation in Pretoria. We are grateful to these organisations for bursaries and we greatly value the support, through equipment and logistics, provided by CapeNature, Robben Island Museum, Earthwatch Institute, DEA and DAFF.