ACOUSTIC RECEIVERS (ATAP) DEPLOYMENT
May 27, 2019 Dyer Island Conservation Trust
Over the weekend scientists from the Dyer Island Conservation Trust, in collaboration with the Acoustic Tracking Array Platform (ATAP), replaced several acoustic receivers in the Gansbaai area.
On Saturday afternoon Alison Towner, Ralph Watson and Toby Rogers went out on Lwazi, with skipper Francois Swart, and several Marine Dynamics Academy intern and volunteers, to recover three acoustic receivers near Dyer Island. These receivers hold valuable data on marine animals that have been tagged with acoustic transmitters, including white sharks, and can tell us a lot about how long they reside in an area, and where these animals go afterwards. These receivers are part of a large network around South Africa, under the auspices of ATAP. By collaborating with scientists around South Africa, we’re able to learn a lot about these animals not just within our area, but also around our entire coastline.read more
Dwarf Minke Whale Stranding
May 23, 2019 Dyer Island Conservation Trust
On the evening of the 21st of May 2019, Dyer Island Conservation Trust’s CEO Wilfred Chivell, was contacted by Neil Falck regarding the stranding of a Minke Whale at Struisbaai. A team consisting of Wilfred, and biologists Alison Towner, Kelly Baker and Ralph Watson was dispatched the next morning to investigate.
Based upon colour-patterns and personal investigation, it was determined that the individual was a male Dwarf Minke Whale (Balaenoptera acutorostrata subsp). No external markings were visible that could explain the cause of death. Its eyes were missing, which could possibly be explained by scavenging sea-birds. Its length was suspected to be approximately 2.5 meters. It was clearly a young specimen. “It is rare for this species to wash up and although sad, it is scientifically intriguing,” said Wilfred.
The Dwarf Minke whale was collected by DEA (Oceans and Coast) and taken to Cape Town for the necropsy.
It was great for the team to cross paths with the team from Oceans and Coasts - Deon Kotze and Steven McCue; as well as fellow marine naturalists Peter Chadwick and Jean Trefson.
Marine animal stranding response in the Overberg area is managed by a collaborative group of organisations: CapeNature, Department of Environmental Affairs, Dyer Island Conservation Trust, Hermanus Animal Hospital 24HR Service, Mammal Research Institute Whale Unit, National Sea Rescue Institute, Overberg District Municipality and Overstrand Municipality.
BRONZE WHALER SHARK NECROPSY
May 19, 2019 Dyer Island Conservation Trust
On the morning of Thursday the 16th of May, the Dyer Island Conservation Trust team and Marine Dynamics Academy intern Jade Sookhoo conducted a necropsy at the International Marine Volunteer Lodge on a prenatal bronze whaler shark (Carcharhinus brachyurus). This shark was part of a litter of 12 pups collected from a pregnant female bronze whaler that was found stranded on De Plaat on the 5th of March, 2019. (See link to previous DICT blog on discovery and collection).
The necropsy was performed in the presence of a group of learners from Gansbaai Academia, as part of their Marine Science curriculum, together with teacher Lizelle Carolus and Xavier Zylstra from Two Oceans Aquarium.
The necropsy process is a lengthy one, even for a specimen so small, and starts with an extensive array of external examination including a large collection of measurements of size and form before the first incision is made. This quantitative data is of great importance as it can reveal many things to us and be used to support and complement the classic taxonomic identification or reveal a new species when discrepancies are discovered in these measurements.
This was the first time DICT examined a prenatal specimen. The female pup, which was in the later stages of development, measured a total length of 67.5cm and weighed in at 1.85kgs. Bronze whalers reproduce viviparously: just like humans the embryo is attached to a placenta by an umbilical cord, and is still dependent on nutrients from the mother. As a result of this, the stomach was still empty, and the spiral valve lacked their signature folds.
The gestation period of bronze whalers is still uncertain, but research suggests the female carries the pups for a duration of approximately 12 to 21 months. Based on the development of the pup, we think she was perhaps weeks away from being born.
The Dyer Island Conservation Trust collaborates with various researchers around the country and value the sharing of data to further expand our knowledge base. Apart from collecting fin-clipping samples for genetic analysis, we also isolated both gill-sets for parasite analysis, and the whole head for a project that analyses the neurological network of sharks.
During the necropsy, the learners from Gansbaai Academia asked our scientists loads of questions about sharks, and they learned a lot about why we do these measurements, about shark physiology, and how sharks work internally.
A special thanks to Janine Taylor, Anthony Fouche and Marcelino Henckert for reporting original stranding of the sharks and to the Marine Science programme team at Gansbaai Academia for being part of the necropsy.
RECYCLING DAY 2019
May 17, 2019 Dyer Island Conservation Trust
International Recycling Day was created in 2018 to help recognize, and celebrate, the importance recycling plays in preserving our precious primary resources and securing the future of our planet. The theme of 2019 was ‘Recycling into the Future’ with the aim of driving awareness and pushing the urgency of recycling. Recycling (whether at an industrial level or within schools and home) can save more Carbon Dioxide emissions each year than those generated by the entire aviation industry, while simultaneously protecting the earth’s valuable natural resources.
Recycling Day is used as a catalyst to change the mind-set of governments, businesses, communities and individuals around the world, to see recyclables as a resource and not waste. Without recycling, all our used and discarded tins, plastic bottles, packing boxes, old clothes, glass bottles and paper cups will contribute to the growing waste mountains, which are either burnt or sent to landfill – never to be used again. Without recycling, we have no option but to continue stripping the earth of her resources.
The Dyer Island Conservation Trust’s Environmental Education Programme known as DEEP has taken an initiative to celebrate recycling day by hosting a Trashion Show at Masakhane Primary School to show that we can turn Trash into Treasure. This show was attended by the community members, Marine Dynamics and Dyer Island Cruises staff and the Masakhane learners and teachers.