Reel Life January 2025 - Auckland Waikato

The fallacy of catch and release

Mortality after release was traditionally thought to be caused by hooking injuries and believed to be very low, but recent research has shown that heat related stress is a far greater threat to released fish with mortality rates of 20-30%. A study of trout caught and released in Lake Otamangakau when water temperatures were in excess of 19°C, documented a mortality rate of around 30%. To put this in perspective, competition anglers on the Whanganui averaged 39 fish each during 2020 national championships with top competitors landing 25 fish an hour. The Whanganui regularly reaches 19°C during the summer and at 20% mortality after release a skilled fly angler could kill the equivalent of a 5 fish limit in an hour without taking any fish home. Sport Fly Fishing NZ has maximum water temperate limits for competitions to protect trout populations for this reason. 

Due to relatively warm water conditions in the A/W region, trout are highly susceptible to post release mortality. Aside from the spring fed streams like the upper Waihou and Waimakariri, the only Auckland/Waikato streams that consistently stay below 19°C are high mountain waterways like the Whakapapa. About half of the overall fishing effort in the A/W region occurs between December and March when temperatures at their peak. The Ohinemuri has already hit 24°C this season.

The Department of Conservation has chosen to close Lake Otamangakau during peak temperatures in February. The Auckland Waikato Fish & Game Council has decided to manage post release heat related mortality with education and are urging anglers to consider water temperature when fishing this summer.

Current water temperature in Waikato streams.

Regulation changes

Staff are completing the fishing regulation report based on angler feedback and the best available monitoring data. We need to find the appropriate balance between maximising angler opportunity with ensuring sustainable trout populations. Some of the results of the proposed regulations changes angler survey were clear, like reducing the limit on streams but others were split. The staff report and recommendations will be available on our website at the end of January. https://www.fishandgame.org.nz/about-us/f-and-g-regional-councils/aucklandwaikato/council-downloads/staff-reports/  If you have made a submission and would like to speak on behalf of it at the February 15^th council meeting (11am Hamilton Deerstalkers Hall) please send an email to adaniel@fishandgame.org.nz so we can allocate a slot for you on the meeting  agenda.

Preferred responses for river/stream bag limits.