Spotlight on stream protection in trout spawning season

Wellington Fish & Game is urging landowners and councils to play their part in protecting streams with trout spawning now in full swing.

Every winter, trout swim up into headwater and small tributary streams to reproduce. The smaller waterbodies are generally more stable than the larger rivers the adult fish inhabit, offering greater protection for eggs and small trout when they hatch.

However, Wellington Fish & Game manager Phil Teal points out that the small size of these waterbodies also makes them fragile and more vulnerable to poor land management practices.

“Allowing stock access, or intensive grazing too close to the margins, can have a significant detrimental impact not just on trout eggs and juveniles, but the entire aquatic ecosystem.”

The main issues are increased sedimentation from stock getting into the streambed or eroding the banks – which also boosts phosphorous loads – and excessive nitrogen from their urine running off paddocks into the water.

“We’ve had a really wet winter in the lower North Island. All that rain when combined with poor farming practice can lead to a toxic soup flowing into the streams, which is catastrophic for the health of the waterbody and the trout population.

“It’s really about landowners having an awareness of what they’re doing on their property and how this can affect the life in the stream. Taking simple measures to avoid putting nutrients and sediment in the stream can make a huge difference.”

Mr Teal says Wellington Fish & Game has also been alerted to dubious logging practice being conducted in the region.

“Regional councils are obliged under the Resource Management Act to protect trout spawning habitat.

“Issuing consents to log vast tracts of steep land, in the middle of winter, in known spawning catchments, runs totally counter to that because you have the potential for a massive sediment load entering the streams along with significant debris.

“This can have a major impact right through the river system and into the harbour too. If you see lots of sediment entering the river from forestry blocks give the regional council compliance team a ring straight away. It is their job to follow up and take action if required.”

Mr Teal says Wellington Fish & Game staff are following up with the regional council in question.  

“Trout are great indicator species for the health of our waterways – if they aren’t around then something is seriously wrong. The species also contributes significantly to the economy through recreation and tourism, so it’s in everyone’s interest to ensure our trout fishery is healthy and sustainable,” says Mr Teal. 

• For more information contact Wellington Fish & Game manager Phil Teal – 021 859120

Tips for Protecting Trout Habitat

Key habitat characteristics that make streams valuable for trout spawning are: Cool water temperature, relatively stable flows, small cobble size, and ensuring fish can access that spawning habitat.

To protect the habitat all land managers should:

-        Prevent stock from being in the water, trampling the eggs.

-        Ensure there are no blockages in the stream hindering or preventing fish passage.

-        Not take too much small cobble from the stream for farm use.

-        Plant the northern side of the stream to shade it and keep the water cooler.

-        Manage nutrient levels at a low level – especially avoiding pulses of nutrients from wastewater treatment plants that can affect egg develop.

• Riparian Management

The riparian zone is the strip of land along riverbanks.

Effective planting of the riparian zone protects the waterway by filtering run-off from the land, helping remove sediment and nutrients so they don’t enter the water. It also contributes to the overall quality of the waterway by reducing erosion and providing habitat and shade for animals and birds.

Excessive riverbank erosion leads to loss of riverbanks, farmland, water quality and habitat. As a result there is a rapid decline in the ecological, recreational and scenic values of the waterway.

Effective riparian zones consist of healthy vegetation cover including ground covering plants and larger trees. When this is combined with good land management, flooding and erosion decreases.

• How To Improve The Riverbank

There are several ways riverbanks can be improved in order to protect and maintain our waterways:

-        Manage the existing vegetation at a level that provides protection for fish and bird life but also allows natural flooding to occur without causing great damage.

-        Improve stock management to reduce overstocking along waterways

-        Stock water can be provided away from the waterway so stock do not wander through the river.

-        Quality fencing will keep stock away from vulnerable areas and will allow vegetation to regenerate.

-        Riverbank planting

Wellington Fish & Game staff are happy to assist landowners with free advice on how to protect spawning streams on their properties. Call our office on (06)3590409.