Each fall the Miramichi Salmon Association increases the spawning habitat available to adult salmon by removing beaver dams on tributary streams. Beaver dams can impede the upstream progress of adult salmon and can prevent them from reaching headwater spawning areas, especially in years of low flow conditions. MSA staff canoe or hike into areas with known beaver dams and remove old dams or notch active beaver dams just prior to or during the spawning time for Atlantic salmon. Adult salmon which are held up below the dam can move upstream through the notch and the beaver later repairs the dam.
Beavers can block off access to spawning areas by building large dams or building dams in culverts or fish ladders. The effect of beaver dam blockages can be pronounced during a fall season with little rainfall and low flow, which do not afford Atlantic salmon enough water to jump over the dams. Salmon will congregate below the dams and if they cannot access the additional habitat in time, they will dig nests on top of each other which can kill the eggs in the underlying nests, thus reducing the number of juvenile salmon that will hatch the following year. Areas that fish cannot access for spawning become devoid of juveniles, do not contribute to the production of salmon on the river or provide food for wildlife (ie. eagles, otters). Beavers typically build dams on smaller streams which are excellent rearing areas for juvenile salmon due to the habitat quality, fewer numbers of large predators and cooler stream temperatures.
Beaver numbers have likely increased due to the decrease in people trapping beaver, resulting in more beaver dams and more blockages for migrating fish. Most people trap to supplement their income with few people relying on it for their sole income. Over the past three years beaver pelt prices have been at the lowest point since the 1993/1994 season, and beaver harvests have declined over the past 5 years.
Maintaining and increasing the number of adult Atlantic salmon that return to the river each year will ensure a strong and stable outfitting and guiding industry in New Brunswick, and provide the highest quality Atlantic salmon fishing experience in the province. One of the ways that we can do this is to increase juvenile salmon production by allowing adult fish access to spawning habitat above beaver dams.
Cains River Project
In 2011, using donations from many MSA members and friends, we began a project focused on the lower section of the Cains River from Route 123 downstream. This section was chosen because the lower sections of the river are warmer in summer than the upper reaches, there are large tributaries with good habitat that are blocked by beaver, and the Cains has lower juvenile production than should be expected.
In the fall of 2011, the Miramichi Salmon Association staff surveyed brooks on the lower section of the Cains River from Route 123 downstream to the mouth to locate active beaver dams and have the beavers and dams removed. The rivers and brooks that were surveyed included Blue Rock Brook, Ten Mile Brook, McKenzie Brook, Mahoney Brook, Trout Hole Brook, Six Mile Brook, Muzroll Brook, Sabbies River, Little Otter Brook and an unnamed brook.
Active beaver dam locations were given to a “nuisance wildlife trapper”, and he removed the beavers. A nuisance trapper possesses a special permit to remove beavers out of season, since the furbearer season is from October 30 to January 1st, after the majority of salmon have spawned. On the brooks where the beavers were removed by the nuisance trapper, all of the beaver dams were removed. On the brooks where beavers were not removed, all of the active dams (dams with beavers) were notched so that salmon could pass through and abandoned dams were removed from the brook so that salmon could swim upstream in time to spawn. The dams on these brooks were notched at least one time with some being notched twice.
It has been decided that as the Cains River project continues only beaver dams blocking mouths of brooks will be removed – all others will be notched and beavers left to reclaim the dam.
The beaver dam surveys took place in September and continued into October and removing and notching of dams took place in October. The main stem of the Cains from Route 123 to Shinnickburn was canoed in order to survey small brooks that were not accessible by road. Salmon Brook was not surveyed due to issues with accessibility.
Some of the streams were difficult to canoe due to the water depth. In some cases the canoes were dragged downstream over 1 km before there was enough water to paddle downstream. Many of the upper stretches of brooks, such as McKenzie Brook, were full of alders which made walking or “paddling” through them very difficult. Weather conditions were favorable as there was no early snow in October; however the rain was both a blessing and a curse. It provided more water so brooks could be canoed easier however made for unpleasant working conditions while tearing out dams. In total 88 beaver dams on the Cains were removed/notched and 15 beavers were trapped.
Atlantic salmon were observed below beaver dams on the West branch of the Sabbies River this fall. The dams were notched by the MSA crew, and the salmon immediately continued swimming upstream to available spawning habitat.
Table 1. The approximate number of kilometers (km) of brook surveyed, number of active and abandoned beaver dams found on each stretch and the numbers of beavers removed from each stretch.
|Tributary||Km of Brook Surveyed||Active Dams||Abandoned Dams||Total Dams||Beavers Removed|
|Blue Rock Brook||4.3||3||5||8||0|
|Little Otter Brook||0.8||5||5||10||2|
|Six Mile Brook||21.6||10||1||11||5|
|Ten Mile Brook||3.5||9||9||18||3|
|Trout Hole Brook||0.5||0||0||0||0|
Bett’s Mills Brook
Prior to 2006, few salmon fry were found on Bett’s Mills Brook despite the building of a new fish ladder near its mouth. In 2006, the beaver dam blocking the fish ladder, as well as 21 additional beaver dams, were notched or removed on Bett’s Mills Brook resulting in access to more than 50,000m2 of spawning habitat and in fry being found in the brook the following year. Bett’s Mills Brook continued to be targeted by MSA staff each year with electrofishing survey results indicating few fry and parr in 2007 and 2008. However, in 2009 high densities of fry were captured in the brook, indicating that or persistent efforts at removing the dams were successful. Bett’s Mills Brook is one of many brooks we continue to target every year.