Survival and Growth of Unfed and Fed Atlantic Salmon Fry Stocked in a Vermont Tributary of the Connecticut River

Abstract

We studied Atlantic salmon Salmo salar to determine the effect of fry feeding stage on survival and growth to late summer age-0 parr in a Vermont tributary of the Connecticut River. In 1989, the mean mortality rates of unfed fry stocked on 19 May and 31 May were similar to the rate for fed fry stocked on 1 June (range: 0.018–0.031). By contrast, in 1990, mortality of fed fry stocked on 13 June (0.015) was significantly lower than that of unfed fry stocked on 11 May (0.022). The greatest late summer mean density of age-0 parr over the two study years (10 fish/100 m²) was produced by stocking large fed fry in mid-June. By late summer, all fry achieved a total length of 65–80 mm. Stocking large fed fry late in the season may be a means of increasing Atlantic salmon production in streams where unfed fry survival has been poor. However, given the variability of fry mortality rates among treatments, further evaluation is warranted before introductions of fed fry are widely considered, particularly to determine whether increases in age-0 parr densities result in increased smolt production.