KEY POINTS:
Predicted climate change could reduce trout numbers in Rotorua's lakes and change the way foresters and farmers operate.
A new climate change report shows Rotorua's temperature is expected to rise between 0.5C and 3.5C by the end of the century, which will see lake temperatures warming by similar
degrees.
Niwa scientist Jim Salinger said the predicted temperature rises would be gradual, having an effect on life in the lakes, farming and forestry.
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 from and the possibility of increased fire risk with much less rainfall predicted.
Algal bloom in lakes will become a bigger problem. Lake water quality will deteriorate as water temperatures rise and droughts increase.
"This will have a significant effect on lake life and a significant risk of more fires with less rainfall expected," Dr Salinger said.
Fish and Game Eastern Region manager Steve Smith said Rotorua's more shallow lakes, such as Rotorua and Rotoehu, would see a reduction in both the number and size of fish if water temperatures rose.
However, deeper lakes such as Tarawera and Okataina could see an increase as fish would seek refuge in deeper parts of those lakes.
Environment Bay of Plenty resource and policy planner Martin Butler said climate change could have a significant effect on the quality of both the region's lake water and wetlands. It could also see an increase in pests such as carp.
The regional council is working closely with the region's lakes communities to reduce nutrients flowing into the lakes, which will also reduce algal blooms.
Reporoa Vet Centre veterinarian Darren Florence said farmers might be forced to deal with more pests for longer periods and would face challenges to maintain quality feed for stock in hotter temperatures.
Pests such as black beetles and clover fleas, which can damage pastures and affect new pasture growth, might become more of a problem. Warmer temperatures on the ground could lead to an increase in spores, and facial eczema in sheep and cattle. Production could eventually drop 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. 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 might have to look at different tree species to cope with predicted climate changes. "We understand the changes will be slow, and we will slowly adapt and take the appropriate steps needed."
- NZPA
