Evaluation of DEPOMOD and other depositional models in southwest New Brunswick to predict the zones and intensities of impacts around Atlantic salmon farm sites

Description

Fisheries and Oceans Canada's Maritimes Habitat program is developing a Fisheries Act authorization framework for managing the impacts of finfish aquaculture on fish habitat. This framework will require the ability to estimate or predict the area and intensity of potential benthic impacts associated with proposed fish farm configurations and production levels.

The purpose of this project was to evaluate the suitability of the model DEPOMOD (developed in Scotland and is being used in British Columbia) for use in the hydrographic conditions typical of the Maritimes. The project compared the observed patterns of sediment sulphide with predictions using DEPOMOD and an alternative simple model.

Findings

There was relatively good agreement between the findings of the DEPOMOD model output and the simple model predictions for the spatial extent of the impacted areas. However, when comparing the DEPOMOD predictions of intensity of the impact, no strong relationship existed between the predictions and the measured sediment sulphide concentrations. Except where current speeds were low, DEPOMOD's resuspension module appeared to overestimate the amount of particle transport caused by resuspension, and, therefore, underestimated the spatial extent and intensity of seafloor impacts.

The relationships between sediment sulfide concentration at individual sample locations and DEPOMOD predicted carbon deposition rates (with resuspension off) at the same locations showed wide variability at all study sites. However, where DEPOMOD predicted low deposition rates, sulfide concentrations were usually low, but where DEPOMOD predicted high deposition rates, sulfide concentrations ranged from low to high.

Publications

Chang, BD, Page, FH, Losier, RJ, McCurdy, EP. 2012. Predicting organic enrichment under marine finfish farms in southwestern New Brunswick, Bay of Fundy: comparisons of model predictions with results from spatially-intensive sediment sulfide sampling. DFO Can. Sci. Advis. Sec. Res. Doc. 2012/078.

Chang, BD, Page, FH, Losier, RJ, McCurdy, EP. 2014. Organic enrichment at salmon farms in the Bay of Fundy, Canada: DEPOMOD predictions versus observed sediment sulfide concentrations. Aquacult. Environ. Interact. 5: 185-208.

DFO. 2012. Review of DEPOMOD Predictions Versus Observations of Sulfide Concentrations Around Five Salmon Aquaculture Sites in Southwest New Brunswick. DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2012/042.

Program Name

Program for Aquaculture Regulatory Research (PARR)

Year(s)

2010 to 2011

Principal Investigator(s)

Blythe Chang, Biologist, Fisheries and Oceans Canada, St. Andrews Biological Station, Maritimes Region
Email: blythe.chang@dfo-mpo.gc.ca

Fred Page, Research Scientist, Fisheries and Oceans Canada, St. Andrews Biological Station, Maritimes Region
Email: fred.page@dfo-mpo.gc.ca

Team Member(s)

Randy Losier, Technician, Fisheries and Oceans Canada, St. Andrews Biological Station, Maritimes Region

Paul McCurdy, Biologist, Fisheries and Oceans Canada, St. Andrews Biological Station, Maritimes Region