Cape fur seals have tragically appeared in the news recently after thousands of these quirky animals have been washing up on the shores of Shelly Beach, Elands Bay and Lamberts Bay. But another painful and devastating reality is increasingly affecting these beloved seals: plastic pollution.
The curious nature of Cape fur seals means that they are prone to becoming tangled in loops of plastic pollution, or discarded fishing lines, and over time, these nooses can inflict severe damage as it works its way down their necks, resulting in infections or even death.
According to the Two Oceans Aquarium, sea rescuers have wanted to utilise safe tranquiliser darts that can be used on hard-to-reach seals in order to approach them, and help disentangle these seals. And until recently, little information existed to assist rescuers in their pursuit to help Cape fur seals.
Over the past two years, the Two Oceans Aquarium Education Foundation has worked closely with veterinarian Brett Gardner of Zoos Victoria, and the Department of Forestry, Fisheries and Environment to trial a protocol for the use of sedative darts and stimulants on high-risk Cape fur seals.
This is more evident in the paper titled Disentanglement of Cape fur seals (Arctocephalus pusillus pusillus) with reversible medetomidine-midazolam-butorphanol, which was published in the Journal of the South African Veterinary Association.
The study was done on eight Cape fur seals identified by the seal patrol in the V&A Waterfront and by members of the public in the Hout Bay harbour. This is how it works: when a seal was darted, two boats were kept in the area.
The smaller boat would follow the seal to confirm that the dart hit, while the larger boat would allow a veterinary support team and scuba divers to enter the water to recover the seal should the sedation kick in while it was swimming. They would then free the seal of entanglement, and thereafter administer the reversal agent.
These were the results of the study, as per the Two Oceans Aquarium: the sedative took around four minutes to work through on the seal, while the average time from darting to the handling of the seal was 20 minutes. It took the seals around 27 minutes to fully wake up after being administered the reversal agent.
Of the eight seals that were part of the study, six of the, were successfully retrieved and disentangled, while one couldn’t be sufficiently sedated, but was able to fully recover without needing the reversal agent. The last seal was able to hide after being given the sedative and couldn’t be found by the divers deployed to recover it.
This seal, unfortunately, was found dead days later, but an independent necropsy could not determine the cause of death. “Despite this unfortunate death, these initial findings do suggest that the use of MMB has a lower mortality rate than other drug combinations used in previous Cape fur seal studies, and it’s important to keep in mind that these seals would not be able to survive without an attempt to free them of their entanglements,” the Two Oceans Aquarium expressed.