Northwest Miramichi River Smolt Study

Northwest Miramichi River Smolt Study

In 2011 the Miramichi Salmon Association decided to switch the smolt project from the Southwest Miramichi over to the Northwest Miramichi because of concerns that not enough adult salmon were returning to the Northwest Miramichi River each year to meet the conservation requirement to sustain Atlantic salmon. The Northwest Miramichi likely experiences an increased harvest compared to the Southwest Miramichi of grilse and salmon due to the abundance of public pools, crown reserve stretches and First Nation Fisheries Allocations which could reduce the number of salmon available for spawning each year. Additionally, the Northwest Miramichi has an increasing striped bass population which likely contributes to increased mortality of smolts exiting the Northwest system on their way to the ocean.

MSA Smolt Wheel and Scow

MSA smolt wheel and scow

Electrofishing studies on the Northwest Miramichi have consistently indicated an abundance of juvenile salmon (fry and parr) in the river, the adult returns have been much lower than should logically be expected. It has been assumed that smolt (young salmon ready to migrate to the ocean) production would be consistent with the levels of juveniles, however adult returns to the Northwest Miramichi do not seem to reflect this trend. The individual smolt estimates will also allow us to determine which tributaries contribute the most to smolt production on the Northwest Miramichi since the juvenile densities vary between tributaries, with the Little Southwest being the lowest, Sevogle moderate, and Northwest Miramichi the highest.

An accurate estimation of the total smolt population migrating from the Northwest Miramichi River and its tributaries is an essential component to understanding and managing Atlantic salmon in this watershed.

Tagging a Smolt

Tagging a smolt

On the Sevogle, Northwest, and Little Southwest Rivers smolt wheels are used to capture smolts for tagging in May when they migrate downstream to the ocean. The smolt wheel is strung across the river by an overhead cable and floated on the top of the water by two large pontoons. Any fish that enters the trap are guided into the trap’s holding box which is located at the back of the smolt wheel. Each fish species caught is identified, counted and released, except for salmon smolts, which are measured for fork length and then tagged with streamer research tags. After the smolts are tagged they are moved upstream of the smolt wheel. The percent of tagged smolts that are recaptured at the smolt wheel allows us to estimate the number of smolts moving out of each river.

Cassilis Smolt Trap

Cassilis smolt trap

A large trap net is installed in the estuary of the Northwest Miramichi at Cassilis to capture smolts moving from freshwater into the estuary. Tagged smolts captured at the Cassilis trap net allow us to get an estimate of the smolts moving out of the entire Northwest Miramichi system. The percent of tagged smolts from the Little Southwest, Sevogle, and Northwest Miramichi that are recaptured at the trapnet allow us to estimate the number of smolts moving out of the Northwest Miramichi River system.

2013 ¦  2012 ¦ 2011