Unique fish behaviour has been captured by NIWA scientists working in Marlborough Sounds.
While analysing the abundance and anatomy of blue cod, researchers used lasers attached to underwater cameras to measure fish size and number.
The project, funded by Fisheries New Zealand,was focused on identifying and understanding the juvenile habitats of blue cod.
But marine ecology technician Charlotte Bodie noticed something unusual when reviewing the footage.
"When trying to count and measure the blue cod, we saw that they were chasing our lasers, just like cats do. I have trudged through a lot of underwater footage in my time but never seen something like this. No other species seemed to be doing it.
"It certainly broke up the monotony of the work. We do a lot of video analysis and see plenty of interesting and unique fish behaviours, but unfortunately don’t have time to investigate everything."
'Quite useful' in the end
Fellow NIWA marine ecology technician Brooke Madden said it was a nuisance at first but the behaviour was quite useful.
"It made it hard for us to count blue cod as they tended to aggregate and follow the lasers. But it also meant we could measure the fish more accurately because they swam closer to the lasers," said Brooke.
Unfortunately, because the research in question wasn’t about fish behaviour, the team were yet to decode why the cod were acting in this way.
New Zealand blue cod was a temperate marine fish that preferred shallow waters and rocky coasts. Adults could grow up to 60cm in length and weigh up to 3kg.
They were also protogynous hermaphrodites, meaning they could change sex from female to male, and were an important recreational and commercially harvested species for New Zealand.
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