Unusual depth profile for Gulf of St Lawrence North

[mikeallen-eco]

There is an unusual spike in depth in the diagnostic plot regional-depth.png for Gulf of St Lawrence North around the years 1991-1993 (https://github.com/pinskylab/OceanAdapt/blob/master/plots/regional-depth.png). We should contact the data provider at some point to verify.

The relevant section of code was checked line-by-line on 12/17/21. Nothing unusual was found in the code.

Dan Forrest reran the plot with a non-weighted mean and the spike disappeared, but then reappeared when the usual weighted mean (by biomass) was used.

We plotted biomass (wtcpue) by year and there seemed to be some especially deep points on the "heavy" end of the biomass distribution for those years.

We plotted the depth profiles by species and many individual species appear to have peaks around the same years.

That all led us to conclude that it was likely a real decrease in biomass-catch-depth in the data during those years and not a coding or data error. The data provider should be contacted at some point to verify that the data are accurate.