I think that being an activist and a scientist at the same time isn't really working out so well. Best not throw politics in the mix.
Her issues would likely be hand picked...like her seines.
What you are suggesting is that the sampling protocol used by Alexandra is biased in some fashion to select for parasitized juveniles over non-parasitized juveniles. I have personally done sampling and lice counting for Alexandra's data set in the Broughton. The fish are beach seined blindly or by sighting a school, the seine net is then pursed (volume reduced) to a size that is manageable for dip-netting fish. A large dip-net withdraws anywhere from 400-500 fish at a time, and these fish are put into 4-5 large pails of sea-water. A smaller dip net is then slowly swirled around the bottom of the pails to bring all of the fish in the buckets to the top. The fish are all active, moving constantly in circles around the top of the water in the buckets. The smaller dip net is then lifted up from the bottom, taking a random pink or chum juvenile. In the event that more than one fish is dip netted, to avoid bias, all fish are returned to the recovery pail (a pail with only sea-water), and the procedure repeated until a single random sample has been isolated for lice enumeration and morphometrics.
If there is any subjectivity to the selection of a juvenile for lice enumeration, it is extremely miniscule and negligible. The above procedure is a way to make sure the fish remain alive after the lice enumeration, rather than using DFO protocol which kills all juveniles sampled.