My mate has just sent me a text to say that he has just returned a grilse caught on the Garry (Invernesshire) The thing is it was caught half way up the river and covered in sealice!

Ness estuary to Loch Ness 7 miles ?
Loch Ness to mouth of R. Oich 26 miles
River Oich 6-7 miles
Loch oich 4-5 miles
River Garry 3-4 miles

50 miles give or take.

How long do sea lice stay attatched?
Seems some distance to cover and still have lice on.
I always assumed 24 hrs
Some swim in that time.

your thoughts please.
Cheers, Graham

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I believe they can stay attached for up to 48hrs but I am not absolutely sure on that. Perhaps someone else can chip in.
Tight lInes

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Depending upon water conditions (cold vs. warm end of the range) a bit over 48 hours as mentioned above. That said, for there to still be lice, that fish was MOVING!!

"Typical" Steelhead/Pacific Salmon will move 7-10 miles up river per day, but even if these rivers had a very mild incline (not the right word) that's still a heck of a long way over the course of a couple of days.

It's not uncommon to catch sealiced fish this far,or further up river than stated..In fact,it is quite common on many rivers.

Sealice can still be attached to the fish for up to a week in fresh water,in some studys carried out they have found they can survive for up to 3 weeks.The tails of the lice usally drop of first,with in a day or two.
If you do catch one with long tailed lice on,you can be sure that fish as only recently enter the river.

DAZ.

The female sea louse is much larger than the male and carries paired egg sacks, commonly referred to as "tails". These egg sacks fall off quickly, within a day or so, on entry to fresh water. It is thought that sea lice can survive in fresh water for more than a week when the water is cold, less in warmer water.

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Also bear in mind that a fish can move upstream at a steady 3-4 mph...if there's enough water then there'll hardly be a need to stop so the quickest it could do it would be roughly 50/3.5 = 14 hours

Add in rest stops, obstacles etc and it still had time to change it's mind and go for an ice cream before running without losing the sea lice.

J

Sea liced salmon are not uncommon on the Wye as far up as Hay and even beyond. Hay is about 60 miles from the sea.

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There are no sea lice in the south Atlantic.
It shows.
The Rio Santa Cruz steelhead, and the more famous sea trout of southern Patagonia, tend to be in superb condition - much better than their Northern counterparts.

I thought it was better feeding on the krill etc.
I hadn't thought of the debilitating effect that sea lice must have; as well as the high mortality rate on smolts passing through high concentrations. eg by salmon farm cages .


C


C

The fish in both of the examples above (rivers Garry and Wye) have had relatively easy journeys. Over half of the distance run by the Garry fish was in lochs with almost no flow to swim against, in fact it has hardly had to go uphill at all! So I wonder what is the greatest altitude that a sea liced fish has been found at?

Andy