On the results of measuring the amount of plastic found in a sample of 31 fish:
The result (was that) from 9 fish the size was at least 5mm of plastic but on average they found 1.1mm.
I'm struggling with several aspects of the grammar in this sentence:
1) Is the first が in bold a subject marker and the second が the conjunctive particle? Is there a だった omitted before this が?
2) Is the counter word 個 somehow used as a substitute for repeating the unit mm?
If not, then I'm lost on how to parse this sentence.