CTD Casts

[These photographs are of the CTD which will be discussed in the following paragraphs. It is used to record conductivity, temperature, and depth. The computer screens and camera are devices used while performing the CTD cast. In the other photo the CTD is about to be sent overboard for a vertical cast. In the final photograph I am communicating with the winch operator who controls the cable wire to perform the vertical cast of the CTD.]

Immediately following the fire and abandon ship drills, we proceeded to have a debriefing regarding appropriate and professional behaviors, as well as, receiving information regarding shift schedules, meals, work expectations, etc. Our Chief Scientist, Victor Nordahl, informed us of the various duties and responsibilities each of us would have during the Sea Scallop Survey. I was paired with another volunteer, Shawn, to help with the measuring of the sea scallops once they were sorted and weighed. I was also assigned the role of performing CTD casts and collecting data from the inclinometer.

CTD casts are performed at every third station. The acronym stands for conductivity, temperature, and depth. It is a hefty contraption that is hooked onto a cable and sent down, a vertical cast, into the water. Basically, while the CTD is sent down vertically, it records the temperature, depth, salinity, and pressure. The saltier the water, the more conductivity is generated. The cast first soaks for about one-two minutes at the surface of the water to record the salinity. It is then sent down, stops about 5-10 meters before reaching the bottom of the ocean floor and then is hauled back. Recording this data is essential for scientists, especially while conducting a Sea Scallop Survey; because the CTD casts helps to associate water temperature and salinity with sea scallop abundance. Scientists record the data to view it later and assess the casts with the other data collected from the work stations.