Humpback Whale killed in shark nets off Durban

Shark net mortality being reduced by new measures
October 2011. On Monday 10 October 2011 a male humpback whale calf measuring 7.9m washed up on the beach at Umhlanga Rocks, KwaZulu-Natal. From the presence of netting material around the calf it was apparent that it had become entangled in one of the protective shark nets set off this popular bathing beach to reduce the risk of shark attack.

The KwaZulu-Natal Sharks Board (KZNSB) investigates every report of a whale that may be in distress and it has a 100% record of releasing entangled animals found alive. Three specialised and well equipped whale release teams carry out the hazardous task. Unfortunately in this particular case the whale calf was not seen at the time it encountered the nets and hence no release was possible. It is suspected that the entanglement occurred during the hours of darkness because the Umhlanga beach is overlooked by numerous high-rise buildings and a daytime entanglement would have been observed.

Measures to reduce entanglement in shark nets
The KZNSB has implemented various measures that reduce the risk of entanglement of whales and other marine animals that pose no threat to bathers. These measures included:

• The reduction in the total length of netting on the KZN coast from 45 km to 23 km.
• Some nets have been replaced with drumlines, more selective shark fishing devices that catch very few non-shark animals. It is hoped that further replacement will occur.
• Whakle alarms have been attached to a number of the shark nets to alert the animals to their presence and hopefully reduce the risk of entanglement.
• KZNSB lifts the nets during the annual sardine run in June and July to reduce catches of predators accompanying the sardine shoals. Humpback whales are not known to predate on sardines on the KZN coast but the sardine run coincides with the northward migration of the whales.

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