Address some notes on the salmon ontology

[amoeba]

While doing another scan of the salmon ontology (as checked into git), I'm noticing some things that seemed odd which we might look at.

• Under "Total recruit abundance", we've broken out freshwater/saltwater ages in such a way that the freshwater age is the parent class of the total age.

  

  The parent classes with just freshwater age don't have definitions yet but maybe the label should be updated to say it's for al 0-ocean fish, not "age class 0" which sounds odd.

• Recruits per spawner is a subclass of "Recruit abundance" which I guess isn't wrong but it'd fit more naturally as a subclass of "Salmon productivity". I also notice we don't have any terms about productivity.

[mpsaloha]

This is an area I haven't yet reviewed, and need to do so

[amoeba]

Thanks @mpsaloha, I'll be curious to hear your thoughts!