Now the industry hopes Otago research will be able to help fishers navigate future spikes in sea temperatures.
CRA8 Rock Lobster Industry Association chief executive Malcolm Lawson said preliminary research by University of Otago scientists indicated the fishery was not at risk.
"If we are going to encounter these [marine heatwaves] in the future, we might have to change fishing patterns — to be fishing when the marine heatwaves aren’t present or shortly after them, because the effects do carry on", Mr Lawson said.
"But the big concern with some people was: ‘Are these heatwaves actually fatal?’
"And that’s not the case.
"There is no long-term negative effect on the viability of the fishery, or the biomass, the abundance of the fishery."
During a La Nina weather pattern last summer, with coastal waters off the southern South Island in the grip of a marine heatwave, apparently heat-stressed rock lobsters pulled up in pots were described by fishers as lethargic.
Their shells were described as thin, soft or weak.
Concerns were raised, but then six months ago, the rock lobsters seemed to recover and prices reached record levels.
Mr Lawson told the Otago Daily Times at the time that after three years of dealing with the effect Covid-19 had on exports and then marine heatwaves, the CRA8 commercial rock lobster industry had bounced back.
The CRA8 quota management area, which covers South Westland, Fiordland, Stewart Island and around to the Catlins, accounted for about 45% of national rock lobster production.
Following the marine heatwaves, University of Otago marine science lecturer Dr Gaya Gnanalingam, along with oceanographer Dr Robert Smith and marine scientist Dr Bridie Allan, collected 53 rock lobsters from Jackson Bay and brought them back to the Portobello marine laboratory for further study.
There, the researchers simulated marine heatwave conditions, raising the temperature of the water the animals were kept in to a maximum of 22°C — the high temperature reached during the recent temperature spikes at Jackson Bay.
The scientists checked the animals’ body conditions, and tracked their vital statistics as the temperatures increased and then came back down. Indicators of stress increased as temperatures increased and then the animals recovered as temperatures came back down, Dr Gnanalingam said.
However, the work was only preliminary and further study and further funding for the project were required, she said.
It was possible different parts of the animals’ life cycle could make them more or less susceptible to the temperature changes in their habitat.
"We don’t necessarily know what the long-term implications are and that’s what we are hoping to be able to do in the next phase of research", she said.
Mr Lawson said the sector was keen for researchers to continue to look at the effect on juveniles in shallow water.
There was also interest in water monitoring in order to get a baseline on things such as dissolved oxygen levels at various depths.
"All of this work is to be better equipped with knowledge of what to expect when the next La Nina weather pattern [and potential marine heatwaves] emerges."
