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Interesting but???? brief, not very specific and lacking a lot of detail. For example. Handling tuna directly by the tail peduncle can cause it, the tail, to fall off in about a week, it happened to a LT tuna in a aquarium tank in Perth years ago. Kind of suprises all round.
With swim bladder species it doesn't say anything about capillary fracture due to internal pressure stopping the heart and the circulation and as the pressure is increased, decreasing depth, the gasses expand, no circulation, and capillaries explode. called the bends. Kills fish in three days. They slowly bleed to death. At least it killed a lot of Dhu fish caught and put into tanks in Fremantle for breeding purposes. Mortality rate from depths over 20 metres is very high on adult fish no matter how you go about releasing them.. I'm a bit iffy about fish tag and release generally, and I have doubts about sticking a non sterile bit of plastic into sick fishes, through that slimy muck, the scales, skin, dermis and epidermis, taking sundry bits and pieces with it into the white muscle tissue. Bit like a very large and very dirty hypo needle. I wouldn't want it done to me. I'm pretty sure it would be a human no no. But then I'm old and fragile and a bit hard to convince these days. Max
I agree its general and non specific, but most fishos dont need to know and dont really care about the underlying pathophysiology. But having said that its probably the most stuff on releasing fish I've read in the one place.
I knew tail wrapping was bad but tails falling off - thats a new one!
In regards to barotrauma, not much can be done, except, dont pull them up to surface at all. Injuries like those suffered by fish with barotrauma are extensive
1. expansion of all gas filled volumes
2. dissolution of nitrogen in solution
3. widespread clotting from embolism of these bubbles and subsequent capillary damage secondary to the inflamatory reactions to clots.
4. direct pressure effects of gasous expansion, leading to decrease in venous blood return, and difficulty in pumping blood forward - i.e. cardiac arrest (this is what kills them almost immediately)
I regards to tagging, depends on a couple of things, but I cant disagree with you. Insertion of a non-sterile (or sterile for that matter) foreign body through the skin and into muscle is normally associated with secondary infection. The reason some dont get infected is due to epithelialisation, like a pierced ear, or nose. But yep, I wouldnt want it done to me!
Hi all
My two bobs worth
I am the tasmanian state ANSA tagging officer and probable the most comprehesive study done in tassie was, 180 small flathead tagged (upto about 320mm) kept in captivity for some months (not sure of exact time, still waiting on info) and during that time only 3 fish died. They were all released in the same area, so hopefully some more data will become available. This research is being done by the launseston Marintine college
cheers
blaze
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