Collecting data on a great white shark cage diving boat
First thing to collect once we anchor are environmental conditions. To do this we use YSI sonde equipment, that measures water temperature, pressure, and dissolved oxygen levels. These pieces of data are first collected at the surface, then 5m and 10m depths. Other environmental conditions are collected through observation such as under water visibility and cloud cover while an anemometer is used to measure wind speed.
The last thing that we always record is the GPS coordinates of our anchor location. Of course, once this is collected the crew has already started the chumming and process and we wait for sharks. If a shark appears, we record the time, sex, size and any distinguishable markings on the animal.
It is crucial that we collect good quality photos (using those photography skills I talked about last week) to get a good image of the shark’s dorsal fin so we can input the sighting of this individual into our fin data base. Some examples of things to analyse with this data are the effect of presence or activity of sharks in relation to various environmental conditions that we record. We can also combine things such as geographic coordinates with photographs of individuals to map local movement patterns of these animals.
A surprise change to our schedule
An important thing in the field of marine biology is knowing how to be flexible and adaptable with your schedule. While working away in the office on the shark fin catalog, we got a message that a deceased common dolphin calf had just been found on shore. Next thing we knew we were changed into grungy clothes and were measuring the dolphin in preparation for a dissection. Eventually, the rain started coming down to strong, so the dissection itself was moved to the next morning.
The dissection took a total of 4 hours- and this was just a small calf! Processes like this require patients and attention to detail, especially when trying to determine a cause of death. We carefully analysed any external wounds on the animal and inspected multiple samples from the bladder, tongue, eye and lungs for evidence of parasites.
The cause of death is unknown but we were able to collect all the necessary measurements to help us better understand the anatomy of the common dolphin. It would be interesting to compare this data to that taken from a dissection of a mature common dolphin to look at anatomical growth patterns or to compare it to a calf of a different dolphin species-something for a rainy day!