River users urged to tread carefully as Fish & Game monitors trout and salmon spawning

River users are being urged to watch where they walk this winter, as Otago Fish & Game carries out annual monitoring of spawning trout and salmon across the region.

Each year, Fish & Game officers survey waterways to count spawning fish and identify areas where trout and salmon are successfully reproducing. The work involves walking sections of streams, and recording adult fish, along with the clear gravel depressions where fish have dug their eggs — known as redds.

Pictured: Otago Fish & Game ecologist Jayde Couper walks a Maniototo stream to count spawning brown trout and redds in June 2026. Photo: Bruce Quirey, Otago Fish & Game

Otago Fish & Game ecologist Jayde Couper said the surveys provide valuable information about the health of fish populations and help guide future management decisions.

“Winter is an important time for monitoring because it captures the tail end of salmon spawning and the peak of brown trout spawning. Most rainbow trout will spawn later in the year,” Mr Couper said.

“Trout and salmon generally move upstream from larger rivers and lakes into smaller, clear, stable streams where they lay their eggs in shallow gravel.

“These spawning areas are vulnerable, so we’re asking all river users to take care around waterways this winter. Whether walking, fishing, riding horses, or using vehicles such as quad bikes and four-wheel-drives, people should avoid disturbing gravel beds where fish may have spawned.”

Left: A spawning adult brown trout pushes up a shallow riffle on a Maniototo stream. Photo: Bruce Quirey, Otago Fish & Game

This year, surveys are focusing on several key areas, including the upper Taieri catchment, Southern Lakes tributaries, Poolburn Dam creeks, and Back Stream near Tapanui. The work will help investigate reports of changing catch rates, understand spawning locations for landlocked salmon, and support efforts to improve fish passage.

Fish & Game is also trialling drone surveys by comparing aerial monitoring with traditional foot-based surveys.

“Our role is to actively manage and monitor wetlands and waterways, including native and introduced species, to ensure their health and sustainability,” Mr Couper said.

“The information we collect helps us understand what is happening in our rivers and make informed decisions about how best to protect and manage these valuable fisheries.”