Proceedings 2022/044

Proceedings of the National Advisory Meeting to Provide Science advice to the Fish and Fish Habitat Protection Program on estimating impacts and offsets for death of fish; April 12-16, 2021

Chairperson: Keith Clarke

Editors: Cody Dey and Alex Tuen

Summary

A National Advisory Meeting was held to peer review the science advice on estimating impacts and offsets for death of fish. This meeting provided science advice on potential consequences and how to quantify impacts from works, undertakings, or activities (WUAs), other than fishing, that cause the death of fish, and ways that death of fish can be offset. The goals include being able to:

• Conduct reviews of WUAs.
• Develop regulatory tools to avoid, mitigate, and offset the death of fish.
• Provide guidance on the requirements for assessing impacts and offsets for death of fish.

Impacts and offsets were quantified with nine equivalency metrics, with “total biomass lost” suggested as the most appropriate for the client’s goals of protecting standing stock biomass and future productive capacity of fish stocks.

Qualitative Network Models were used to examine community responses from WUA impacts. The models could be useful in many situations. The results can estimate how the whole community will adjust to positive and negative perturbations. The results suggest the outcomes of mortality events are unlikely to simply be the sum of species responses considered in isolation.

Factors were presented that might influence decisions about a death of fish authorization. Discussion included what might influence the responses for fish populations and/or fish communities to fish mortality events, and how such factors may be considered in risk-based decision-making. The top three consequences and considerations were determined to be magnitude of mortality, population size, and population trajectory. It is ideal to have a fully quantitative precautionary approach framework.

Results were presented from a systematic review and meta-analysis assessing different offsetting practices commonly used for aquatic ecosystems and their potential application for offsetting fish mortality. The overall goal is to re-evaluate common offsetting practices and their effectiveness as well as the consideration of less commonly utilized methods and how their usage could be applied to mortality scenarios. The necessary assessment and monitoring requirements were discussed.

Proceedings 2022/044 (PDF, 441 KB)

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