Pamehac Brook: a case study of the restoration of a Newfoundland, Canada, river impacted by flow diversion for pulpwood transportation

Abstract

1. In the early 1970s, dams were constructed in the upper reaches of Pamehac Brook, Newfoundland, Canada, and the headwaters of the system were diverted into the main stem of the Exploits River to facilitate waterborne transport of logs to a pulp and paper mill. This de-watered 12 km of high quality brook trout (Salvelinus fontinalis) and Atlantic salmon (Salmo salar) rearing and spawning habitat. In 1989, a project was conceived to address the man-made obstructions to fish migration and restore (re-water) the lower reaches of Pamehac Brook. This project was pursued as a partnership between the Environment Resources Management Association (a local conservation group), Abitibi-Price Inc. (a pulp and paper company), the Environmental Partners Fund (of Environment Canada), and the Canadian Department of Fisheries and Oceans. 2. The restoration of Pamehac Brook in August 1990 included replacement of the control dams with bridges and culverts and removal of the diversion dyke to re-water the stream. Habitat surveys conducted before and after the project indicated a gain in fluvial habitat of 450 units (1 unit=100 m2), a 62% increase, through re-watering of the stream channel. Improved access was provided to 175 habitat units in the headwaters which had previously been obstructed. 3. Population estimates of juvenile fish from electrofishing surveys were used to document the rate of recolonization of the re-watered habitat and to estimate the increase in fish production potential. Results suggested limited response by fish populations in the initial 2 years after restoration. Electrofishing results in 1996 indicated a dramatic increase in biomass of larger juvenile salmon and trout (>0+), attributable to the increased habitat area and altered microhabitat conditions, in part, related to creation of standing water areas from beaver dams. Population estimates in 1996, in consideration of available fluvial habitat, indicated a production potential of juvenile fish of 330 kg, an 18-fold increase from pre-project estimates. © 1998 John Wiley & Sons, Ltd.