18 April field and lab work & swimming larvae

Monday morning I awoke to hear a heavy rain. As I walked to work, I imagined an unhappy boat crew soaking wet and cold. Fortunately for the crew the rain stopped falling about an hour into our sampling so crew spirits were high. Here JC and Jean are working to stow the trawl on the front deck after we completed our larval coregonid sampling. We caught a record number of larvae on 18 April, about 3 times more than the last sampling event.

Marine has been very supportive of our project helping with field work and lab work. Here she holds the zooplankton net we are using. It is called a Bongo net. It has one net with a very fine mesh (63 micron) and another with a coarser mesh (200 micron). The nets catch different sizes of zooplankton.

The counting and measuring of zooplankton is a time consuming endeavor.  Since we are doing experimental work to develop a new acoustic method, there is a chance we may not succeed. So instead of processing all the samples thoroughly, we will begin with a more rapid method of measuring zooplankton biovolume. The sample is poured into a graduated cylinder. The preserved zooplankton are allowed to settle, and the volume of zooplankton is read. Thank you Leslie for starting this work.

Here we captured video of a coregonid larvae. All fish start life at more or less a tiny size. The proportion that survive to adulthood is normally astronomically small.