03 August 2015
SOUTH
AFRICA - Survival of endangered African penguin chicks increased by 18
per cent following a trial three-year fishery closure around Robben
Island in South Africa, a new study from the University of Exeter has
found.
The results, which are published in the
Royal Society Journal Biology Letters, indicate that even small 'no-take zones' can dramatically improve the survival chances of endangered species.
The African penguin population is in 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.
Dr Richard Sherley from the University of Exeter said: "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.
"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."
African penguins feed on sardines and anchovies but fishing of these
species off Cape Town is considered to have contributed to a 69 per cent
reduction in penguin numbers between 2001 and 2013.
The species' worsening conservation status led to experimental
fishing closures around four colonies between 2008 and 2014. These were
earlier found to reduce penguin foraging effort but a beneficial impact
on demographic parameters had not been demonstrated before this study
and so the benefits of the closures have been the subject of much
debate.
Although this study has shown that the fishery closure around Robben
Island has improved chick survival, if the current fishing pressure
exerted on sardine in particular continues on the west coast there will
still not be sufficient food to allow the penguin population to recover.
Seabirds will 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.
1501 nests were monitored 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.
Top image credit: © Davide Gaglio
source