Cape seals impacted by pollution
WHILE the population numbers of Cape fur seals are considered healthy, plastic pollution and particularly fishing line and nets, are causing horrific injuries and can result in a slow, painful death.
These are the first results from a project, initiated in 2018, to investigate the impact of pollution on Cape fur seals in Namibia. The project involves researchers and conservationists from Stellenbosch University (SU), Sea Search-Namibian Dolphin Project and Ocean Conservation Namibia, who have been monitoring the entanglement rates of seals.
Ocean Conservation Namibia has been disentangling many of the animals affected, and since the start of this year said they have already disentangled over 600 fur seals in only two colonies. The study demonstrated that a high number of affected animals were pups and juveniles, which were mainly entangled around the neck by fishing line.
Rates of entanglement were roughly 1 per 500 animals and was similar between the two colonies investigated at Walvis Bay and Cape Cross. Of the 347 entangled animals documented, the disentanglement team, led by Naudé Dreyer of Ocean Conservation Namibia, were able to successfully disentangled 191 individuals between 2018 and March last year.
The team also compared low-cost methods of data collection and found that photographic scans of the colonies were a fast and accurate method to collect data on entangled individuals and the materials they are trapped in.
Dreyer said the project is continuing. “This is the tip of the iceberg. It is imperative that studies such as this highlight the consequences of plastic waste on marine animals, and bring around change for the better.”
Dr Tess Gridley, co-director of the Namibia Dolphin Project and an extraordinary senior lecturer in the Department of Botany and Zoology at SU, said: “Once entangled, these seals face a very painful and uncertain future: finding food becomes harder and wounds can become deep and debilitating, and likely cause death in many cases. Changes to policy could help, such as financial incentives to recover lines, safe disposal of nets and sustainable alternatives to plastics.”