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Research Document 2017/047

Methods to determine the efficacy of utilizing artificial scallop and rock reefs as fish habitat compensation in inshore Newfoundland

By Warren, T.N., and Roberge, M.M.


Fish habitat compensation to offset the loss of productive fish habitat (fish and/or shellfish) in the Northwest Atlantic, especially in the offshore marine environment, is challenging. Between 2001 and 2005 works or undertakings associated with two offshore oil projects included activities that, as a condition of regulatory approval, required the creation of scallop shell reefs and a rock reef. Monitoring for the reef compensation projects included metrics used to demonstrate the effectiveness of the compensation including those to determine whether there were any changes in structural integrity and stability and species utilization of the reefs. Methods used to determine structural integrity, substrate stability and fish utilization using SCUBA divers included visual and video surveys to determine shell movement, settling/sinking of materials, changes or impairments to new materials, utilization of reefs by species.  As well, for the rock reef, control sites were established along the shoreline and adjacent seabed as a comparison to the observed conditions on the artificial rock reef.

An evaluation of the metrics used revealed that most were useful in identifying changes over time and have enabled the assessment of the status of the compensation and possible additional data that could be included in future projects.  When assessing compensation, metrics should be collected over a sufficient time period, be used in conjunction with other metrics, and should be detailed enough to provide a clear picture of trends. Baseline data is also critical prior to the placement of reef material as well as having a control site to verify changes in the reef utilization.

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