“I’ll have a lb of salmon and hold-the-lice-please!”
SPAWN asked the question –
“How many sea-lice can kill a salmon smolt?”….The answers are scary!!!!
A study in Norway (in a lab) found 7 to be fatal almost immediately. No studies have been done that I know of in the wild but obviously it would be far far less even if it took some more time. The immediate cause of death is due to bodily fluid disruption (leakage/osmotic balance).
But, the lice cause 2 or 3 other main issues. 1) Camouflage disruption (lice ruin the fish’s camo), 2) allow points of infection by breaching the mucus and skin layers, 3) they are proven disease vectors for a range of pathogens like ISAv, PRv, SAv, furunculosis, BKD, etc etc (i.e. nature’s dirty needles). Numbers 2, and 3 are proven in the scientific literature but the camo issue is my theory based on underwater video of salmon with sea lice (the lice practically glow) and basic common sense.
Lice have been shown to be able to destroy more than 98% of an entire annual run of smolts from a large healthy salmon river with a substantial run of fish (millions of smolts). One of the largest studies done in Norway showed dramatic negative impacts if a salmon farm was in the bay a salmon river was in.
Lice can have a 2 week life cycle and produce 1000 eggs EACH female each cycle. i.e. Trillions per farm site. The eggs in winter remain viable and free floating for MONTHS waiting for the returning spring runs of salmon. The lice can travel and accumulate in gyrs in the ocean to unnatural levels. Ex. the gyr of Bay d’Espoir along our south coast that many Gulf of St Lawrence salmon swim through from over 100 rivers! Remember, the lice are known ISA carriers.