The badly wounded sea-run fish was found by rangers in the lower Leith, near Forsyth Barr Stadium this week.
Fortunately, this fishy tale has a happy ending.
Otago Fish & Game spokesman Bruce Quirey said officers managed to catch the fish and remove the spearhead, before releasing it back to the inner-city river so it could continue its journey upstream for spawning.
It is illegal to spear crayfish, salmon or trout in New Zealand.
Mr Quirey said the penalty for anyone caught with a spear, gaff or net, who disturbs sport fish congregating to spawn, could receive up to two years’ imprisonment or a fine of up to $100,000.
"Poached trout will get you into hot water."
He encouraged people who knew more about this incident, or who had seen suspicious activity in the area, to contact Fish & Game.
Anyone wanting to fish for trout, needed to buy a licence, use a fishing rod, and check the local regulations.
He said sea-run trout were typically brown trout that migrated to the sea and returned to freshwater to spawn.
They congregated in the lower reaches of the Leith at this time of year, before moving to more shallow, gravelly areas upstream to lay eggs.
Adult female sea-run trout typically carry between 1500 and 3000 eggs per kilogram of body weight, which are then fertilised by the males and then covered in gravel by the female.
"Sea-run trout are crucial for driving and maintaining the fishery," Mr Quirey said.
"These trout are renowned for their size, fighting spirit and eating qualities, which makes them prized by legal anglers.
"Allowing them to spawn preserves their important genetics."
He said Fish & Game rangers would continue to patrol the Leith to discourage poaching behaviour.
Keen fishers can now buy winter sport fishing licences.
