Try predicting IPHC index on HBLL grid

[seananderson]

Is the steep HBLL decline a feature of the hard bottom inshore habitat?

[seananderson]

If that does explain most of it, consider combining the two into 1 index.

[quang-huynh]

Perhaps assign this to @LindsayDavidson ?

Also look at substrate map. I can work on this picking up from Quillback Rockfish

[quang-huynh]

The IPHC index does not appear to change much when predicted on the HBLL grid:

[seananderson]

Lindsay did some work subsetting the IPHC set locations to those that overlap the HBLL grid and then fitting and predicting on the HBLL grid. That doesn't appear to make much of a difference either.

[quang-huynh]

Another quick check that the trends in mean CPUE don't really vary by substrate: