Fish & Game officers survey waterways annually to count spawning fish and identify areas where trout and salmon are successfully reproducing, a statement from the organisation said.
Officers walked sections of streams and recorded the number of adult fish observed, along with ‘‘clear gravel depressions’’ — known as redds — where fish had dug into the gravel to create places to lay and fertilise their eggs.
Otago Fish & Game ecologist Jayde Couper said the annual surveys provided important insights into the health of fish populations and helped to guide 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 quadbikes and four-wheel-drives, people should avoid disturbing gravel beds where fish may have spawned.’’
The work would help the organisation understand reports of changing catch rates and spawning locations for landlocked salmon, as well as help to support efforts to improve fish passage.
Fish & Game was also trialling drone surveys by comparing aerial monitoring with traditional foot-based surveys, the statement said.
‘‘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 [help us] make informed decisions about how best to protect and manage these valuable fisheries.’’ — Allied Media
