Today I talked to Ryan, the hatchery manager, a little bit about the possible causes of the mortality I saw over the weekend. In his experience, mortality events are not uncommon when rearing larvae in the summer. He thinks it may have to do with water quality issues (which I can’t really do anything about). He recommended I be more vigilant about culling dead or sick larvae from the tanks.

As I emptied out HC_Tank1 and SS_Tank1 over the weekend to be cleaned for new larvae, I adopted a new labelling scheme on my data sheet. The first attempts in a tank have the letter “a” (i.e. HC_Tank1a, SS_Tank1b) and after totally culling or emptying out a tank of larvae I change the letter in the tank name. I’ll see how this scheme works when it comes to actual data analysis, but for now it’s helping with data entry and keeping track of how many are in a tank at a time.

SS_Tank2a smelled disgusting and had sheets of larvae on the bottom so was also emptied out entirely. For my NF and HC larvae, I made a “sick” tank and a “new” tank. In the sick tanks (NF_Tank1b and HC_Tank2b), I added back larvae that were swimming in the beaker after being filtered out from the tanks. I may have to throw out these too, but until I have too many larvae for the new tanks I figured I would try to save them.

Filtering out larvae tanks:

• HC_Tank2a (160,120) -> swimmers into HC_Tank2sick
• HC_Tank1 (100) -> swimmers into HC_Tank2sick
• NF_Tank2a (160,120,100) -> swimmers into NF_Tank2a
• NF_Tank1 (100) -> swimmers into NF_Tank1sick

Checking for larvae:

• Lots: NF1,HC1,HC2,HC4,HC5,SS4,SS5
• Some: HC3

Set up growth rate experiment #2:

Since I had lots of larvae from every family, I decided to start another growth rate experiment. I combined the larvae from all families in a population, took samples for DNA, and added 1,100 larvae to 3 replicate silos.