Terms of Reference

Modeling and monitoring approaches to evaluate the ecological carrying capacity for shellfish aquaculture

Regional Peer Review – Pacific Region

March 8-12, 2021
Virtual meeting

Chairperson: Cher Lacoste

Context

In British Columbia (B.C.), shellfish culture is located primarily on the west coast of Vancouver Island and the Strait of Georgia, with the most prolific production sites associated with Baynes Sound, Cortez Island, and Okeover Inlet. Although the culture of shellfish was developed over 100 years ago in B.C., little research exists pertaining to the ecological capacity of shellfish production in these prolific, sheltered bays. Shellfish production is influenced by a balance of water quality, hydrodynamics (bay flushing), and food supply (plankton). A carrying capacity assessment is required to assess this balance and identify any bay-wide limitations due to a potential competition for resources or shift in ecosystem functioning.

Ecological carrying capacity (defined as the magnitude of aquaculture activity that can be supported without leading to unacceptable changes in ecological processes, species, populations, communities, and habitats in the aquatic environment) can be investigated using mathematical models that integrate complex interactions between aquaculture activities, bivalve physiology, and the environment. The methodological approaches for assessing carrying capacity range from indices of processes, to farm models, spatial models, and food web models. These models utilize core biogeochemical (nutrient-seston-bivalve interactions) and hydrodynamic (water circulation) equations of varying dimensions and complexity. Most carrying capacity models have focused on the dynamics of phytoplankton or organic seston and their interaction with bivalves, with a focus on the extent to which bivalves utilize these food resources (related to ecological carrying capacity).

Both carrying capacity assessments and potential management thresholds of indicators are bay specific, reflecting the relevance of bay-scale hydrodynamics and characteristics on ecosystem functioning. Indices based on the comparison of key oceanographic and biological processes have been used as proxies for the carrying capacity of bivalve aquaculture sites. These indices compare the energy demand of bivalve populations (based on filtration rates) and the ecosystem’s capacity to replenish these resources. Additionally, monitoring methodologies associated with potential carrying capacity indicators can provide a baseline for a future ecosystem monitoring program. Based on the information collected on long-term monitoring programs, regulatory management thresholds for ecological indicators could be established. These indicators may include shellfish condition index, intertidal sediment quality (redox), and the depletion of suspended food particles (seston, plankton).

Modelling approaches to shellfish carrying capacities were reviewed in a 2015 Gulf Region Canadian Science Advisory Secretariat (CSAS) Regional Peer Review , “Carrying capacity for shellfish aquaculture with reference to mussel aquaculture in Malpeque Bay, PEI” (DFO 2015, Filgueira et al. 2015). The result of the 2015 review was the identification of a high-resolution, spatially-explicit model (e.g. FVCOM -Finite Volume Community Ocean Model – Bivalve Culture Ecosystem Model) as the most efficient approach to assess ecological carrying capacity of shellfish aquaculture.

Due to the significant influence of local environmental conditions on ecosystem functioning, carrying capacity studies are ecosystem-specific. In the Pacific Region, FVCOM will be coupled with a Bivalve Culture Ecosystem Model (BiCEM) resorting to the Dynamic Energy Budget (DEB) to simulate bivalve physiology and their interactions with the ecosystem. The coupled model will be first applied to Baynes Sound. Since Fisheries and Oceans Canada (DFO) Aquaculture Management identified Baynes Sound as a priority site in 2009, based on its production status, DFO Science followed up by acquiring relevant research data to support a carrying capacity assessment. Accordingly, this modelling approach focuses on the traditional nutrient-plankton-zooplankton approach with the addition of bivalve sub-models. The inclusion of other commercial, recreational and aboriginal (CRA) fishery components or a benthic assimilatory assessment would require an additional food web and benthic assimilatory approach, which would increase the complexity and uncertainty of the outcomes that are relevant for shellfish.

DFO Aquaculture Management has requested that Science Branch provide advice on monitoring and modeling methodologies required to determine the potential impacts of new or modified existing shellfish aquaculture applications on the ecological carrying capacity of a specific area. The assessment, and advice arising from this CSAS Regional Peer Review (RPR), will be used to develop decision making frameworks to aid management of new and amendment of existing shellfish aquaculture applications.

Objectives

The following working papers will be reviewed and provide the basis for discussion and advice on the specific objectives outlined below.

T. Guyondet, M.V. Krassovski, T.F. Sutherland, M.G.G. Foreman, and R. Filguiera. An  ecological carrying capacity assessment for shellfish aquaculture in Baynes Sound. CSAP Working Paper1 2013AQU06 (Objectives 1-3)

T.F. Sutherland, T. Guyondet, R. Filgueira, M.V. Krassovski, and M.G.G. Foreman. Monitoring methods to support area-based bivalve aquaculture management in the Pacific region. CSAP Working Paper2 2013AQUO6 (Objective 4)

The specific objectives of these reviews are to:

1. Evaluate the hydrodynamic accuracy of the FVCOM model component and discuss the biological applicability of the biogeochemical (BiCEM) component in the coupled Baynes Sound model.
1. Compare modelled and observed water properties.
2. Identify uncertainties and consequences associated with data availability and modelling parameterizations through sensitivity analyses for this Pacific region application of FVCOM-BiCEM.
2. Assess ecological carrying capacity for shellfish aquaculture in Baynes Sound at a bay wide scale using a high-resolution, spatially-explicit hydrodynamic-biogeochemical coupled model (FVCOM-BiCEM).
3. Include an assessment of the potential influence of new site applications on existing farms across varying spatial scales for use in management decision-making with respect to shellfish aquaculture facilities. 

Recommend monitoring methodologies including field and laboratory protocols for use by regulatory, industry, and science personnel. Recommend indicators and identify/describe known associated changes to shellfish.

Expected Publications

• Science Advisory Report
• Proceedings
• Two Research Documents

Expected Participation

• Fisheries and Oceans Canada (DFO) (Ecosystems and Oceans Science, Aquaculture Resource Management, Aquaculture Programs, Aquaculture Environmental Operations)
• Province of BC
• Academia
• Indigenous communities/organizations
• Aquaculture industry

References

• DFO. 2015. Carrying capacity for shellfish aquaculture with reference to mussel aquaculture in Malpeque Bay, Prince Edward Island. DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2015/003.
• Filgueira, R., L.A. Comeau, and T. Guyondet. 2015. Modelling carrying capacity of bivalve aquaculture: a review of definitions and methods. Can. Sci. Advis. Sec. Res. Doc. 2015/002. v + 31 p.