I guess I see it as the lesser of 2 "evils": if we are going to allow OPEN net-pens to operate in the environment - their fish will get lice. Lice for them on their fish is a production loss - lice on farmed fish is for wild fish advocates - is a potential lice loading risk, and a risk to outmigrating wild salmon in the spring.
So - good to treat and to do it before spring.
The reason that the industry is now going with H2O2 external bath treatments instead of Slice - is that Slice is becoming way less effective. Sea lice have developed resistance to emamectin benzoate. This was predicted years ago - and the response (predictably) from the FF industry was that Slice resistance happened in the Atlantic (first) - and we are in the Pacific - that wouldn't happen. Sound familiar?
The bizarre and irresponsible excuse from industry pundits is that: since humans called the name of the ocean something different in the Atlantic - so therefore - that mere difference of a name to humans somehow protects us from all the known and documented impacts from the open net-pens in the Atlantic - in the Pacific. Bizarre logic. This is yet but another example of how illogic and unsupported that irresponsible perspective actually is.
Doing sea lice treatments with well boats instead of tarps - gives the applicator control over discharges of the external sea lice treatment.
Tarps do not. I can only assume that the few well boats are now so booked-up that they figured they had to do it instead with tarps because the lice loading and damage on their FF fish is so severe. There is a lice problem now with the industry in BC that the FFs don't wish anyone to know IMHO.
Some lice die - and most are dislodged using H2O2. So - that means there will be a large release of lice from this treatment into the environment - esp when the tarps are removed - some dead and some alive. Some will be viable and looking for new hosts for some time - dependent upon stage and water temperatures. I am glad to see this done before the spring outmigration of juvenile salmon.
There will be effects downstream (from tidal flows and estuarine circulation - that is not taken into consideration) for at least several hundreds of meters from the cages from the H2O2 release - maybe far further. If there are sensitive habitats nearby - that's where the monitoring should be done as in a before-after effects study - for both H2O2 effects AND sea lice loading.
Monitoring 30m from the cages for only levels of H2O2 will not really tell you much - and in any event - once the H2O2 is released - the fat lady sings - and there's really nothing that can be done.
Hopefully; time and dilution effects will rehab the water quality, but...
http://publications.gc.ca/collections/collection_2014/mpo-dfo/Fs97-6-3080-eng.pdf
Preliminary work in the laboratory with Interox® Paramove™ 50 in raw seawater has shown the half-life of 1200 mg·L-1 H2O2 to be 28 days at 10°C.
I am not sure if I would instantaneously label this as "
minor stuff" w/o the studies to support that hypothesis. And that's the real problem with the new regulations that the FF lawyers drafted-up for DFO over sea lice treatments - they didn't want that kind of scrutiny. Otta site - otta mind - yet but again.