The Southern Cape coastline boasts a dynamic ocean and shoreline driven by strong winds and strong currents and the relatively shallow seabed of the Agulhas Bank which extends up to 100km from the shoreline.
The prevailing current that moves past the Garden Route is the warm Agulhas Current, also referred to as the Mozambican current. As this warm current travels in a west to south west direction, it meets the cold Benguela current which moves up past the tip of Africa, past Cape Town and into the Atlantic Ocean.
The convergence of these two currents results is a mixing zone along the southern Cape coastline, and can result in a sudden change of sea temperatures. For marine species, particularly poikilothermic species such as turtles, the sudden decrease i temperature can cause them to go into thermal shock. While it won’t kill them, it does decrease their ability to respond to strong currents or rough seas caused by storms or strong winds. It is under these conditions that some species will wash ashore and need assistance to recover before being released back into the ocean.
The South African coastline has a number of annual marine migrations which occur up the east coast. Marine mammals like Southern Right Whales make an annual migration from the tropics to the Cape waters for the winter months to calve. Another annual migration that occurs is that of the Humpback Whales moving from their feeding ground in the Antarctic to the tropics, usually around late winter. Normally they don’t feed in South African water, but they will not pass up an opportunity to feed as was witnessed in early 2019/2020 summer season where super pods were observed feeding off the west coast of South Africa.
Other marine migrations include some local and regional migrations of some shark species like the Bull, Ragged Tooth and Great White sharks through southern Cape waters. Bull Sharks have been recorded exhibiting possible mating in the Breede River while Ragged Tooth and Scalloped Hammerhead Sharks aggregate on reefs on the Natal Coast for mating and pupping respectively.
Considered the largest migration in the world in terms of biomass, the Sardine Run is an annual migration of shoals of sardines migrating from Cape waters to the warmer waters along the KwaZulu Natal coast to spawn, with accompanying marine predators following and feeding on the sardines.
In South Africa, two species of turtles, the Loggerhead and Leatherback Turtles lay eggs on the warm Kwa Zulu Natal beaches.
When the eggs hatch in mid to late summer, the turtle hatchlings scramble across the beach into the ocean, where they swim out to sea. Some get caught up in the Agulhas Current, a warm continental current flowing southwards down the east coast of South Africa, and get washed down to Cape waters where they can be stranded on the beach as a result of thermal shock in the colder waters or being blown ashore by strong southerly winds.
If you find a stranded turtle hatchling washed up on the beach, the best treatment is to pick it up, place it on a dry cloth in a dry container with ample ventilation and drop it off at one of the Turtle Rescue collection points.
The Two Ocean Aquarium has created a network to facilitate the collection and transport of rescued turtles to their facilities in Cape Town. Once they receive a turtle, the monitor it health and feces and determine if it has ingested any plastic. The turtles are then cared for and fed and when they have recovered, they are liberated in the ocean,
In the Garden Route, collection points are at the SANParks offices at either Rondevlei or Thessen Island.
It is important NOT to place the turtle hatchlings in water on two accounts. Firstly, as they are most likely suffering from thermal shock, being reptiles, they are better able to increase their temperature out of water. Secondly, in a small container, they may have the added risk of drowning as the container moves.
For records, take a photo of the turtle in situ and record a GPS location which can be added to a data base.
Stranded Marine Mammals.
The Garden Route has a healthy population of marine mammals. There are two Cape Fur Seal colonies, one on Robberg Peninsula and one in Mossel Bay. There are three regularly seen species of dolphins, the Bottlenose, Humpback and Common Dolphins. The most frequently seen species of whales seen include the Humpback, Southern Right and Bryde’s Whales.
While seals and dolphins will conduct local and regionl migrations in response to food resources, it is the Humpback and Southern Right Whales which are well known for their annual migrations, particularly along the eastern coastline of South Africa.
Cape Fur Seals are regularly found on beaches in the Garden Route and can do so for a number of reasons, but most common are if they are ill or if they need to rest, usually after a severe storm at sea. Dead seals to wash up, the result of either old age or illness. Some dead seals to wash up that are the result of wildlife conflict with fishing vessels and can have evidence of gunshot wounds.
In the event of finding a washed up seal, if it is alive, don’t disturb it. Cape Fur Seals are used to spending time on land, and if alive it is most like tired or ill. The best thing to do is report it to one of the organisations trained to deal with stranded marine mammals and ensure that no dogs disturb it.
Stranded dolphins, if alive, should be assessed for injury and state of health. Before attempting to move a dolphin or trying to return it to the sea, cover it with a wet towel (to help it remain cool and protect it’s skin) and then contact the local marine mammal stranding organization to report it and get advice. If it looks healthy and and the stranding organization recommends that you return it to the ocean, make sure that you support it well, particularly the abdominal region, with a towel so as not to damage any internal organs.
While most stranded whales are dead, some live whales do wash up and it is natural to wan to make every attempt to return it to the ocean. A few things have to be taken into consideration, in particular the size of the whale. Most of the whales that wash up weigh in excess of 15 tons, and while they are partially buoyant in shallow water, if a wave should roll it onto a rescuer, it could be life threatening for the rescuer.
Secondly, whales are good swimmers and for the above species to wash up alive, there is most likely to be a health or entanglement condition which has caused it. The best action that you can do is to call either STRAND, if the whale is between Mossel Bay and Sedgefield, or the Plett Stranding Group if the whale is between Storms River and Sedgefield. If in doubt, call the SANParks, Cape Nature or the PE Museum to report the location, species and condition.
Who do you call?
- STRAND (082 887 5423 or 076 839 6712),
- Plett Stranding Group (079 463 4837),
- PE Museum ( 072 679 4643)
- Cape Nature (064 608 9270),
- SANParks (084 714 7793),
- Strandloper Project (082 213 5931),
- Natures Valley Trust (084 549 8498).