Underwater

underwater ROV

challenge

Meet the Giant Australian Cuttlefish.
The Giant Australian Cuttlefish (Sepia apama) is among the largest cuttlefish in the world, can grow to 50cm and weigh up to 10kg. They can be found all along the Southern Coast of Australia from as far north as Brisbane in Queensland to Shark Bay in Western Australia.

Every winter, Giant Australian Cuttlefish come to northern Spencer Gulf near Whyalla in South Australia to spawn. Each year during this spawning event marine scientists perform surveys to monitor the health of the cuttlefish populations in Spencer Gulf.

Over the years, several methodologies have been used to monitor the cuttlefish including scuba diving, towed underwater camera and remotely operated vehicles (ROVs) with specialized software and stereo video cameras.

Survey Method Background

The data we are analysing was captured by Geo Oceans using a vLBV 300 ROV fitted with a stereo video camera system.

The field team recorded the area covered in the transect in real-time using GO Visions software. The software uses an algorithm which calculate the GPS distance covered and the ROV height off seafloor to quantify the monitoring area coverage. During the monitoring program, the stereo cameras were used to measure the size of each cuttlefish. Density results across all sites were extrapolated across the entire area to estimate abundance of the entire cuttlefish population. Size scale and a size to weight ratio were then used to estimate biomass of the entire population.

For more information on the Giant Australian Cuttlefish and the monitoring program of Whyalla you can find a lot of interesting information on the PIRSA website here: https://www.pir.sa.gov.au/fishing/recreational_fishing/cuttlefish

Cuttlefish ROV Challenge instructions

  1. Watch the cuttlefish video and count the number of cuttlefish you see without stopping the video. This is what marine scientists have to do in reality - it’s harder than it looks!

  2. Task One: Record the number of cuttlefish you counted on your answer sheet.

  3. Take Two: Calculate the density of the cuttlefish by dividing the abundance of cuttlefish by the area covered. Record this on your answer sheet as well. 

You can use this formula: Density = # of cuttlefish / m^2

Challenge complete! To submit your answers, register for the challenge.

Looking to challenge yourself even more? We've added extra questions for everyone wanting to test their newly aquired "cuttlefish counting" skills! Check out the rest of the questions on your answer sheet - these ones are just for fun and don't need to be sent in with your challenge registration.

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