Predicted climate change could reduce trout numbers in Rotorua lakes and change the way foresters and farmers operate.
A new climate change report shows Rotorua's temperatures are expected to rise between 0.5C and 3.5C by the end of the century, which will see lake temperatures in the region warming by similar degrees.
Niwa scientist Jim Salinger said predicted temperature rises would be gradual, having an effect on life in the lakes, farming and forestry in the region.
It will result in fewer and smaller fish in our lakes, more pests for farmers to deal with, lack of quality pastures for stock to feed and the possibility of increased fire risk with much less rainfall predicted.
Geothermal activity is not expected to be affected by climate change as it forms underground.
However, algal bloom in lakes will become a bigger problem and lake water quality will deteriorate as water temperatures increase and droughts plague the region.
"As the water gets progressively warmer there will be more blooms for longer periods. There will be less rainfall which will result in less water in the lakes and water temperatures will go up. This will have a significant effect on lake life and a significant risk of more fires with less rainfall expected," Mr Salinger said.
Fish and Game Eastern Region manager Steve Smith said Rotorua's more shallow lakes like Rotorua and Rotoehu would see a reduction in both trout and the size of the fish if water temperatures rose.
However, deeper lakes like Tarawera and Okataina could see an increase as fish would seek refuge in deeper parts of those lakes.
"Anything over 22C is not very healthy for trout. When it is hot and calm the lakes are going to be less desirable for trout. They will have to find refuge in colder streams."
Environment Bay of Plenty resource and policy planner Martin Butler said climate change could have a significant effect on both the quality of the region's lake water and wetlands.
It could also see an increase in pests like carp.
The regional council is working closely with the region's lakes communities to reduce the amount of nutrients flowing in, which will also reduce alga bloom break outs.
Reporoa Vet Centre veterinarian Darren Florence said farmers may be forced to deal with more pests for longer periods of time and would face challenges to maintain quality feed for stock in hotter temperatures.
Pests like black beetles and clover fleas, which can damage pastures and affect growth of new pastures, may become more of a problem in the region. With warmer temperatures on the ground, spores could increase, leading to a rise in facial eczema in sheep and cattle. Production could eventually drop off unless farmers adapted.
"Farmers will have to spend more money on zinc treatments as spore counts rise. Shade is important too because heat can have an effect on production. If it gets hot cows can become heat stressed which will result in less production. It's going to become more technical for farmers in the future but the switched-on managers will adapt and make the necessary changes."
Hancock Forest Management oversees about 200,000ha of forestry in the Central North Island. Half of that is in the Rotorua region.
Manager Bill McCallum said foresters may be forced to look at different species of trees to plant in future to cope with predicted climate changes. It would be a matter of everyone adapting to meet future environmental changes.
"We understand the changes will be slow and we will slowly adapt and take the appropriate steps needed."
Too hot to handle?
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