Long-term outlook for African penguins still poor
FRISCO — Biologists say a no-fishing zone around South Africa’s Robben Island has benefited endangered penguins, showing how even small protected marine zones can help conservation efforts.
The study from the University of Exeter says survival of endangered African penguin chicks increased by 18 percent during the three-year trial period, which is important because the African penguin population has been in a “freefall, with adult survival rates over the last decade desperately low.”
Although the ban on commercial fishing off Robben Island has boosted chick survival, the long term prospect for the species remains gloomy.
“One of the major challenges of conserving a mobile species like the African penguin is that once they leave a protected area they are subject to outside pressures and dangers, including poor prey availability,” said University of Exeter researcher Dr. Richard Sherley.
“Our study shows that small no-take zones can aid the survival of African penguin chicks, but ultimately commercial fishing controls must be combined with other management action if we are to reverse the dramatic decline of this charismatic species,” Sherley said.
African penguins feed on sardines and anchovies but fishing of these species off Cape Town is considered to have contributed to a 69 percent reduction in penguin numbers between 2001 and 2013.
The penguin decline spurred experimental fishing closures around four colonies between 2008 and 2014. The new study helps quantify the benefits of the restrictions.
But the researchers said that if widespread sardine fishing continues, the penguins are still likely to run out of food and the population probably won’t recover.
Seabirds often respond to a scarcity of food by skipping or abandoning breeding, opting not to re-lay after losing clutches of eggs, or reducing the amount of food brought to the chicks leading to slow growth, poor chick condition and mortality through starvation. African penguins have shown all of these responses in recent years.
The study monitored 1501 nests at Robben Island between 2001 and 2013 to determine chick survival rates and a hydro-acoustic survey was carried out to estimate sardine and anchovy biomass.
Bottom-up effects of a no-take zone on endangered penguin demographics by Richard Sherley, Henning Winker, Res Altwegg, Carl van der Lingen, Stephen Votier and Robert Crawford is published in the Royal Society journal Biology Letters.