Atlantic Fisheries Research Document 1996/120
Status of Atlantic salmon in the Morell, Mill, Dunk, West and Valleyfield rivers, Prince Edward Island, in 1995
By D. Cairns; R. Angus; M. Murray; K. Davidson
Abstract
Salmon, historically abundant in Prince Edward Island, were eliminated from most streams following European colonization. Since the mid-1980s, enhancement and stocking efforts have re-established salmon runs on several P.E.I. rivers, particularly the Morell. Total conservation targets based on 2.4 eggs m-2 of river area are 537 large salmon and 288 small salmon for the five most important salmon streams on P.E.I., including 159 large salmon and 85 small salmon for the Morell.
Salmon stocking on P.E.I. relies chiefly on fish that are reared in semi-natural open impoundments and released as 2+ smolts. About 66,291 juvenile salmon were stocked in P.E.I. streams in 1995, including approximately 15,568 2+ parr and smolts in the Morell. A licence stub survey indicated salmon fishing effort of 7,669 rod-days in 1995, including 5,073 on the Morell, and a retained catch of 484 small salmon, including 449 on the Morell. In addition, a native harvest of 20 fish was reported.
Adult salmon trapped at the Leard's Pond fishway on the Morell River totalled 201, but fish also entered the pond without being enumerated. A trap on the lower Morell captured 127 salmon. The combined composition of trapped fish was 6% small wild, 87% small hatchery, 3% large wild, and 4% large hatchery. Electrofishing densities of juvenile salmon, measured at 15 sites and scaled up to the entire Morell basin, yielded estimates of 35,077 fish in July-August and 35,927 fish in November-December.
The Bayesian mark-recapture estimate of run size for the Morell was 1,550 fish. Run size as indicated by head-of-tide traps was 30 in the Mill River, 50 in the Dunk River, and 62 in the Valleyfield River.
The return rate of small salmon for the Morell, based on the mark-recapture estimate, was 5.2%. Return rates in the Mill and West Rivers, stocked primarily with semi-natural fish, were higher than those of the Valleyfield, where most stocking has been directly from the hatchery. Angler and native exploitation of the Morell totalled 35% of returning small salmon. Potential spawn deposition of the Morell in 1995 was 159% of target, of which hatchery fish supplied 127% and wild fish supplied 33%.
If the wild fish run remains unchanged and hatchery fish return at the rate calculated for 1995, then 1,030 small and large salmon will return to the Morell in 1996.
Hatchery fish remain the mainstay of P.E.I. salmon runs and, without stocking, fishermen's expectations and spawning targets will not be met. Continuing habitat degradation from siltation works in opposition to the enhancement work done on P.E.I. streams. P.E.I. rivers would have a better chance of rebuilding natural salmon runs if this form of pollution could be brought under control.
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