Fish Shortages Might Cause Penguin Decline

For years, African penguin populations have faced difficulties. Years ago, guano harvesting destroyed nesting areas, while egg collections up to 1930 robbed colonies of 13 million eggs over just 30 years. Today, threats might have changed, but numbers are still on the decline.

Words by René de Klerk. Originally published in SANParks Times. 

A recent University of Cape Town study and a SANParks report shows that today’s penguin declines are likely a result of a number of factors, one being low fish numbers.  Already listed as endangered by the International Union for Conservation of Nature, the African penguin’s chance of extinction is likely if circumstances don’t change.

From the mid-1900s to 2000, population numbers fell by 90%. This trend continued and numbers plummeted from 43 000 breeding pairs in 1999 to about 19 000 pairs from 2012-2015.

The African penguin has a very high risk of going extinct in the wild,” says Dr Ané Oosthuizen, national marine coordinator for Park Planning and Development at SANParks. “Environmental and anthropogenic impacts (fishing and others) on sardines are hard to disentangle, but penguin populations are known to follow the trend in prey, so less fish less penguins. That is something very hard to manage for.”

She says there has been a change in the abundance of sardine and anchovy which has led to a mismatch between fish availability and breeding colonies.  It is assumed that climate related changes drove sardines and anchovies to move in a south-easterly direction, leaving penguins to swim further to find food. This is particularly true along the West Coast, where one of three national parks hosting penguin colonies is situated.

The islands around the West Coast National Park only had 174 breeding pairs recorded in 2016. Ten years prior, pair numbers were as high as 503, says Oosthuizen. However, this trend is not restricted to certain colonies or areas.

The Boulders Penguin colony in Table Mountain National Park had its first count in 1993. While only 241 pairs bred that year, these numbers went up to 1,075 in 2006. After this, fewer penguins at this colony attempted breeding, with only 444 pairs counted in 2011. The last count in 2016 showed a slight recovery with 893 pairs.

The largest South African colony is situated in Algoa Bay within the Addo Elephant National Park. SANParks manage approximately 60% of the African penguin population, while 55% of these birds are found on the islands around Addo. This colony has already experienced a fair share of tribulations. A count in 2000 revealed 20,331 breeding pairs, but this declined to only 6,003 pairs in 2006. While numbers have picked up again (to 9,129 pairs in 2016), this population faces more risks, according to Oosthuizen.

These penguins not only face food shortages. Numbers also declined after the construction of the Coega Harbour in 1999. “It is speculated that the construction of the harbour wall impacted on water quality and hence impacted on the prey fish,” Oosthuizen says.

In 2016, a license was awarded for the transfer of fuel from one ship to another anchored outside the Coega harbour. “This happens within 5km of St Croix. There was already a spill last year, but one big spill can mean the loss of 50% of the world population of African penguins as de-oiled, rehabilitated birds have a lower productivity rate,” says Oosthuizen.

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