The Butterfish Smackdown: Great People and Good Probes

Another blog post John sent from the ship:

Josh boarding up the wall of the fishbox.  The wire lifting the net is the whip.

We have maxed out our sensors to better measure the fluid in which the animals live...or don’t live.  What we have right now is pretty simple, consisting of recording and real time temperature/depth sensors. Mike Ball, my main man from NOAA cooperative research, has brought several recording temperature/depth sensors.  As an aside, Mike has been tirelessly working up the catch with the “Karen Elizabeth,” supercrew, confirming species identifications, measuring animals and recording data. I would be helpless out here without him. He has made me look very good.

Mike and Denny at the fish conveyor belt.

I have asked him to reset the sampling rates on the temperature/depth sensors so they make a measurement every second.  We now have one sensor on a net door and download the data after completing each station.  Chris has asked that the other probe be put on the “headrope” at the top of his net.  The headrope is equipped with floats that help keep the net open.  That sensor combined with the bottom depth will tell Chris how high the net is and thus the thickness of the bottom layer it is fishing.  This sensor will also give us the temperature at a slightly higher level in the water column.  Chris has also put a sensor on one of the net doors that reports bottom temperatures in real time to us in the wheel house of the “Karen.”   With the data from these sensors we can begin to analyze the temperature and depth preferences of the animals we are collecting pretty precisely.  I am now sleepless, thinking about the battery of other sensors I’d like to fix to Chris’s net doors in order to measure the properties of the fluid on the next trip out if there is one.

Temperature-Depth measurements taken from the doors of the net for tows a few days ago.  The first is for a tow where the model predicted bad butterfish habitat, the second is for a tow location chosen by Chris, and the third is for a tow where the model predicted good butterfish habitat.

Our sensor data is useful for another reason.  There are many things we need to do to refine our iterative approach for developing habitat models for continental shelf species. One improvement is to couple our habitat models to physical oceanographic models.  Yes this will allow us to evaluate and explore dynamic habitat models in real time when there are clouds between the ocean and the satellites.  But more importantly, moving toward oceanographic models will allow us to consider the properties and processes of the fluid below the surface of the ocean where the fish actually live.  This kind of approach has been used in the Pacific Ocean to model the habitat of tropical tunas.  But we need to evaluate the accuracy and precision of oceanographic models, just as we do our habitat models.  We have begun to send our temperature records over the satellite telephone in our robot glider's tail back to Dr. Avijit Gangopadhyay, an ocean modeler at UMASS Dartmouth.  Using our data he can begin to compare our real time measurements below the ocean's surface to the subsurface temperatures in his simulated ocean.  And he can begin to help us think about the ways we can use his models to inform ours.