(no subject)

[senoritafish]

In La Jolla again - we came down this evening so we wouldn't have to leave so early for a meeting at 8 am. I am sharing a room with V. instead of K. thank goodness. Be back Tuesday evening. You'd think these guys would remember the day before is a holiday. Whoopee snort - get to look at sardine earbones for two days. It actually should be interesting since we get to meet up with biologists from Oregon, Washington, Canada and hopefully Mexico, and we can all get on the same page reading them. V. is waiting for me to turn off the light, so I'd better git. This room had better cool down though. We came back from something to eat and it was 85 degrees in here. I can't sleep when it's hot.

Comments

Earbones?

[bakayaro-onna.livejournal.com]

So, how DO you read sardine ear bones and why would someone wish to do so?

Re: Earbones?

[senoritafish.livejournal.com]

Whoops, that was a pretty disjointed entry wasn't it.

Ya ready? This may be more than you ever wanted to know. ;)

We collect sardines from the boats landing them, collect their biological info, such as length weight, sex, maturity (from looking at their gonads). Then we take out their earbones and look at them under a microscope - they have annual rings on them like a tree, caused by water temperatures and food availability between winter and summer (I.e. growth vs. no growth seasons). Determining the age is what we call "reading." All of this data gets put into a big mathematical model that gives us an estimate of how many adult fish are out there spawning, how much spawning they are doing, how many youngsters were hatched that year, and how many are recruited (that is available to the fishery), and the total biomass of sardines swimming around out there (Before you say "wow" I'm not really involved in this end of it - I'm mainly on the data collection end). A percentage of the total is allotted to the fishery, and this is further divided between southern California and the Pacific Northwest.

You'd think counting rings would be easy, but unfortunately, they're not quite as simple as a tree. All the fish are assigned an arbitrary birthday in order to estimate what year it was born, but we all are using different dates, which makes the ages wind up different. Also, sometimes what looks like a ring really isn't and visa versa. It's really pretty subjective and the only way to learn it is to do a lot of it. However, some people here want to assign hard and fast rules to it, which my feeling is that it's just not going to work. Sometimes the people with doctorates forget biology is an inexact science. It's why the person who trained me called reading otoliths (fish earbones) an art, not a science.