Salmon Parr Investigations
DMR staff estimate juvenile Atlantic salmon abundance by electrofishing at individual sites on rivers through out Maine. These data sites will soon be available though the PEARL website. Staff use these data to evaluate the effectiveness of annual stocking, estimate juvenile survival, evaluate habitat quality, and document temporal and spatial trends in juvenile densities.
On the Narraguagus River, Dennys River, and Sheepscot River and their tributaries, individual site estimates are combined to derive drainage-wide estimate of parr abundance. Rearing habitats are grouped into strata, each consisting of adjacent rearing habitats that share similar ecological characteristics. Staff sample multiple sites within each stratum to estimate site-to-site variability. For example, each year staff estimate juvenile salmon densities at 40-50 sites distributed among x strata, encompassing about 4-5% of the parr nursery habitat in the Narraguagus drainage (6,013 units). The individual stratum estimates and their variances are combined to derive drainage-wide population estimates.