Hey everyone! I’ve been so busy these past two weeks that I didn’t have any time to put up a blog for week seven. Thus I’m doing a combined blog to include both weeks seven and eight instead. Also, I just recently found out that our last day on the island will be this Friday, the 12th, which means I’m leaving a week earlier than expected so I’ll be ending this blog on week nine. Other than that, I wanted to talk about telemetry and fyke nets in this blog.
The fyke nets are what we’ve been using since day one to capture turtles along the shores of the island. They are huge nets with lines that are set in the water that lure turtles, crabs, fish, and even horseshoe crabs into the net compartment. Every Monday we set up the nets with stakes, and every Friday we take them down and clean them off. Throughout the week we always have two people that go out in the boat every morning to collect the turtles that got caught in the nets and to release the by-catch back into the water. Once we’ve taken the captured turtles back to the turtle shed, we process them. This includes taking all sorts of measurements including the plastron length, carapace length, width, height, right plastron length, mass, and head width. We also tag each turtle with a PIT tag (a micro chip we inject into their leg with a needle that has a specific number when scanned) and a monel tag (a piece of metal with a number engraved on it, that fits through a hole we drill in the ninth right marginal scute of the shell). Both tags are useful as a way of identifying whether we have caught the turtle before. Some monel and PIT tags fall out, so it’s important to have a backup in case either happens. Other than that, we take a tail clipping of each turtle or tissue from when the hole is drilled in their shell. This is important DNA that will be used to determine many aspects of the turtle population when looked at in the lab. Afterwards, all the turtles are released back into the water once processing is completed.
It should be of note that we have had a few turtle casualties in our fyke nets due to unpredicted high tides and failure to tie the nets in the right fashion. Usually the fyke nets are kept afloat in the rear by a buoy so that the turtles have access to the air but, through a series of mistakes, the nets were completely submerged underwater and some turtles have drowned. When this happens, we place them upside down on the seat of the boat, because some of them do come back alive if we get there in time. This problem has mainly been resolved though and hasn’t happened for quite some time.
I should also note that we have had many hatchlings die too due to the heat and being trapped in our metal rings. This has also been resolved by checking the nests more frequently when on the island in hopes that we’ll retrieve them before they dehydrate in the sun.
To a more sobering topic, I’ll tell a little about telemetry. Telemetry is the process by which we attach a transmitter to the shell of a turtle, set it free in the water, and try to track it down with our sonar device in the water. We have two devices used to detect the transmitter on the turtle. One is an omnidirectional device that locates the transmitter in all directions and the second is a unidirectional device that locates it only in the direction is it being pointed. First, we use the omnidirectional to decipher which area the turtle is in, and once the signal is strong and true we switch to the unidirectional to pinpoint its exact location. Basically it involves a lot of time sitting in a boat and reading the sonar screen for signs of a signal. There is a lot of interference in the grassy areas of the cells, so it’s complicated to find a true signal. We have recently lost contact of all the three turtles we released, so fingers crossed that we locate them again soon!
I think that’s enough to cover two weeks’ worth of blogging! See ya!
Tessa Barman
Bug Bite count for week seven and eight: 9
