Commercial fishermen are being blamed for dead marlin found floating off the Manukau Harbour.
An Auckland boatie, who did not want to be named, said the marlin had been caught up in the purse seine (trawl net) of a commercial fishing vessel.
The man said his group passed the vessel just as it was lifting its net out of the water.
"We could see two marlin thrashing about.
"On our next pass, the seiner had picked up its net and was moving away. We found four dead and dying marlin - their fins were damaged and their beaks were broken from thrashing about in the net."