bones, as it has been posted before on this thread - and others - and as FI pointed-out - sea lice kill juvie salmon.
Yes - there is a debate on exactly how much to use as a metric (an estimate) for estimating mortality. It depends on the number of lice - the stages of lice - the size/weight - and maybe the species of fish. Lots of things to consider.
I find the assumption that one can use Jones work w/o looking at these details - and pull a magic "7.5 lice" out of the air - very disingenuous.
Let me explain: If I was using an analogy of "how many tigers does it take to kill a human" - yes - one could lead a camera team to a petting zoo - and record kids getting licked to death by tiger kitties/cubs. maybe one or 2 might get a skinned knee - or maybe a rash on their face from getting licked - but you really aren't estimating mortality using the right metrics. It'd take a sh*tload of tiger babies to cause any real trouble - but it could be done I am guessing.
The Romans used to throw real human slaves into the ring and bet on how long it would take a slave to die. The tigers were actually capable of killing a human.
That's the kind of difference between reporting on mortality caused by the attached chalimus stages verses motile lice. Lots of info available on this point.
So - the question still remains, bones: "Why do you think Simon Jones stopped his study before most of the lice on his fish got big enough to harm the salmon?"
We are not dealing with unintelligent nor uninformed people here. I am assuming Jones knew the assumptions underlying his research.
I am also assuming you do too - which is why you want me to generate an answer about the C1, C2,C3, C4 stages. That's why I consider the assumption about the 7.5 lice mortality trigger disingenuous.
Yes - maybe a smolt can take up to 7.5 (average) chalimus stages (i.e. NON-MOTILE) stages before the cubs lick it do death.
That's not what was shown in the picture that Terrin provided. very clearly there were at least 3 MOTILE lice - and maybe more. At least 3 tigers - not cubs.
I repeat - you need to know the weight of the host fish to estimate potential mortality by the tigers.