I’m currently working on similar problems, but trying to count all the fish in the sea using sonar and trawl catches (really). I’ve done a little hacking trying to implement the GMRF/SPDE approach in Julia, but haven’t got it working yet…I’d definitely be interested to hear updates as well.
@jbmuir I don’t know if you saw this thread, but I just managed to get a (slightly hacky) sparse Stheno GP to work inside a Turing model, which may be of use to you…if you’ve got thoughts about how this should work in a less-hacky way, there’s an open issue where it would be great to hear your input!