Investigation into Bryde's whale deaths underway

Image source: www.thesardinerun.info

“Both departments would like to ensure members of the public that they share the concerns and a full investigation on the death of these whales will be undertaken. The situation will be monitored and measures will be put in place to address identified causes,” the departments said in a joint statement.

Experimental octopus fishery

The departments said that currently, there is a perception that the experimental octopus fishery may have contributed to the deaths of whales. However, this must still be confirmed.

“Other potential causes of death might include ship strikes, other types of fishing gear or natural [causes]. However, as the octopus fishery makes use of lines and buoys that have the potential to entangle whales, ongoing attention is being given to the octopus fishery’s gear design to limit possible whale entanglements,” the departments said.

They said concerns around the octopus fishery, including gear designs, were discussed at a stakeholder workshop coordinated by Agriculture, Forestry and Fisheries in June 2017.

The octopus fishing gear is designed to limit entanglement of large whales, and the designs have demonstrated success in reducing entanglement incidents in False Bay. According to both departments, no entanglement was reported in octopus fishing gear since January 2018.

Octopus fishing gear

“The industry uses a long-line fishing method. Weighted longlines lie flat on the sea floor to prevent bowing of ropes between traps. Anchor lines are made up of polypropylene rope, chain and an anchor and set up such that there is no slack in the buoy line.

“Entanglement probability is therefore reduced, both for bottom and pelagic interactions between the gear and large whales. Interference with this design like cutting of buoy lines, become an entanglement hazard due to the resulting slack or lost gear, a problem known as 'ghost fishing'. These interferences drastically increase the risk of entanglement,” the departments explained.

The DAFF will, with the assistance of the DEA and all role players, continue to monitor this experimental fishery closely, they said.

“The experimental nature of this industry means stakeholder engagements are ongoing and all concerned parties should approach DAFF for further industry specific queries and DEA can be contacted if any whales are observed that are entangled, including in fishing gear.”

Bryde’s whales have two different forms; one that occurs offshore and the other one inshore. The latest assessment of the species by the Endangered Wildlife Trust (EWT), classified the inshore form as “vulnerable” and the offshore form as “data deficient”.

“The total population size remains unknown but a study of the inshore form off Plettenberg Bay on the South Coast of South Africa estimated between 125 and 195 individuals. This indicates that the number of whales are low and the mortality of one individual is therefore one too many,” the departments noted.