Canadian Aquaculture R&D Review 2017

Shellfish: Other

Developing an Ecological Carrying Capacity for Shellfish Aquaculture in Baynes Sound, British Columbia

In British Columbia (BC), 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 BC, 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. A high-resolution, spatially-explicit hydrodynamic-biogeochemical coupled model [e.g., Finite Volume Community Ocean Model (FVCOM)–Bivalve Culture Ecosystem Model] is being developed to assess the ecological carrying capacity of shellfish aquaculture in Baynes Sound. These mathematical models, groundtruthed with local data, will integrate the complex interactions among aquaculture activities, shellfish physiology, and the ecosystem.

Date: OCT. 2011–MAR. 2018

Funded by: DFO–Program for Aquaculture Regulatory Research (DFO–PARR)

Project Lead: Terri Sutherland (DFO)

Project Team: Peter Cranford, Chris Pearce, Hannah Stewart (DFO)

Collaborators: BC Shellfish Growers Association; Mac’s Oysters Ltd.; Hollie Wood Oysters Ltd.



Juvenile oyster seed in culture trays in Baynes Sound, British Columbia. Photo: Terri Sutherland (DFO)

Understanding the Distribution of a Nemertean Predator, Cerebratulus lacteus, in Clam Flats: Implications for Control Measures

The results of this project will provide information to better understand the factors involved in the patchy distribution and abundance of Cerebratulus lacteus. This information will aid in the development of efficient management strategies to minimize the effect of this predator on clam populations.

Clams have been identified as an important alternate species for the future development of aquaculture in Atlantic Canada. One of the major obstacles in the development of clam culture has been controlling predators on culture sites, particularly endobenthic species (those that live in the sediment). In recent years, commercial size Quahaug and Soft-shell Clam densities have reportedly been lower. While the cause for these declines has not yet been documented, harvesters have noted the important presence of predatory worms at clam harvesting sites. The Milky Ribbon Worm, C. lacteus, is an important predator of many endobenthic bivalve species and its presence has been correlated to high field mortality in Soft-shell Clams. Very little, however, is known about the factors regulating the patchy distribution of this predator. The present study will examine the factors regulating the patchy distribution and abundance of C. lacteus to allow for the development of predator management strategies.

Date: APR. 2014–JUN. 2017

Funded by: DFO–Aquaculture Collaborative Research and Development Program (DFO–ACRDP)

Co-Funded by: Innovation Fisheries Products Inc.; Mills Seafood Ltd.

Project Leads: Daniel Bourque, Angeline LeBlanc (DFO)

Project Team: Jeffery Clements (DFO)

Collaborators: Doug Bertram (Innovative Fisheries Products Inc.); Tim Williston (Mills Seafood Ltd.)



Improving Ecological Models for a Sustainable Development of Bivalve Culture in Eutrophic Estuarine Complexes

Carrying capacity of coastal systems for bivalve culture has typically been investigated using mathematical models restricted to a Nutrient-Phytoplankton-Zooplankton-Detritus-Cultured Bivalve representation. The present project aims to generate a more detailed understanding of nutrient dynamics in order to accurately gauge the influence exerted by cultured bivalves. Specifically, macroalgae, a primary producer whose contribution can be significant, especially in eutrophic systems and wild bivalve population modules, will be coupled to an existing ecosystem carrying capacity model. These new ecophysiological modules will be built using the Dynamic Energy Budget theory to account for the use of resources by bivalves and macroalgae and also reproduce the effects of various aquaculture scenarios in terms of wild bivalve productivity. Model development will be supported by field and experimental work to characterize distribution, abundance, and growth for both macroalgae and wild bivalves. Model application will be performed for Malpeque Bay (Prince Edward Island); however, the model will be given a generic structure allowing future applications to other coastal embayments. Adding these new modules will increase model veracity and provide new insights into aquaculture-coastal ecosystem interactions, especially in quantifying the influence on species with commercial, recreational, and aboriginal fishery value.

Results of this project should further our understanding of interactions between bivalve aquaculture and coastal ecosystems.

The model developed will provide relevant information and a generic tool to improve the management of bivalve culture activities.

Date: NOV. 2015–APR. 2018

Funded by: DFO–Program for Aquaculture Regulatory Research (DFO–PARR)

Project Lead: Thomas Guyondet (DFO)

Project Team: Luc Comeau, Romain Lavaud, Marc Ouellette (DFO)

Collaborators: Ramón Filgueira (Dalhousie U); Cindy Crane (PEI Department of Communities, Land and Environment); Jeff Davidson (UPEI–AVC); Réjean Tremblay (UQAR–ISMER)


The Effects of a Hydraulic Dredge and Adding Shells on the Environment and Soft-Shell Clam Population Dynamics

To improve the profitability of Soft-shell Clam farms in Atlantic Canada, growers want to use hydraulic dredging as a means of harvesting clams. The effects of dredging, however, are variable across sites. Concerns regarding mechanical clam harvesting include shell damage, impacts on recruitment and survival of juveniles, impacts on biodiversity, and the release of buried organic matter and reduced metabolites. In the presence of oxygen, this matter oxidizes, thereby lowering the pH, which can reduce growth and survival of bivalves.

Successful methods of increasing post-seeding survival rates, crucial to bivalve farming, have been demonstrated in U.S. east coast Quahog farming and Canadian west coast Manila Clam farming.

Several studies show that:

  1. Hydraulic dredging enhances settlement and/or survival of bivalves–it will be important to understand the effects of mechanical harvesting on clams and the environment.
  2. The presence of adults or shells increases recruitment of juvenile bivalves–thus, the addition of shells to the sediment may increase survival of juveniles.

Adding shells to the sediment acts as a buffer by raising the pH and the saturation states, and has been shown to increase Quahog and Soft-shell Clam recruitment. Results from this project (i.e., the addition of shells) may mitigate the potential negative effects of dredging.

The project seeks to compare the effects of hydraulic dredging and addition of shells to the sediment on the survival of juvenile Soft-shell Clams, and on the depth profile of physical and chemical parameters of the sediment (including grain size, sediment compaction, pH, carbonate/aragonite saturation states, and sulphides). In addition, this project will provide insights related to the potential environmental effects from shelling activity on surrounding areas (habitats) which are currently not well understood.

Date: OCT. 2015–JUN. 2018

Funded by: DFO–Aquaculture Collaborative Research and Development Program (DFO–ACRDP)

Co-Funded by: Mills Seafood Ltd.

Project Lead: Angeline LeBlanc (DFO)

Project Team: Jeffery Clements (DFO)

Collaborators: Marilyn Clark (Mills Seafood Ltd.)



Bay Characterization for Nova Scotia Shellfish Aquaculture

In the Gulf Region waters of Nova Scotia, shellfish aquaculture remains in its early stages of development. A recent report based on an independent aquaculture regulatory review concluded, among other things, that licencing decisions needed to consider compatibility between aquaculture and other uses of coastal waters. Balance between sustainable development of shellfish aquaculture, fisheries, and other resource uses (e.g., harbours, marinas, cottages, etc.) can be achieved through marine spatial planning and the implementation of a bay management plan designed to protect valued species in fisheries and conservations areas, while avoiding conflicts with other users of the marine resource. Although Nova Scotia has not yet developed such a plan, describing and mapping of coastal areas identified for aquaculture would provide critical information for planning and science-based decisions making, and could provide the basis for a bay-scale management plan.

Fisheries and Oceans Canada (DFO) has identified a number of bays in Nova Scotia where future aquaculture development may be likely. Key variables including hydrodynamic characteristics, fisheries, and ecologically sensitive species’ habitat and distribution, as well as aquaculture- specific activities and mitigation options will be described for these bays. The results from this project will support departmental regulatory decisions that are consistent with the ecosystem-based approach to managing the shellfish aquaculture industry.

Date: APR. 2015–MAR. 2018

Funded by: DFO–Program for Aquaculture Regulatory Research (DFO–PARR)

Project Lead: Monique Niles (DFO)

Project Team: Marc Ouellette, Thomas Guyondet, Thomas Landry (DFO); Andrew Bagnall (NSDFA); Tim Webster, Kate Collins (AGRG–NSCC)



The Ecological Effects of Clam Harvesting by Mechanical Means in St. Mary’s Bay, Nova Scotia

The clam aquaculture industry has experienced major challenges recruiting and retaining clam diggers, and the disinterest from the younger employable generation has resulted in an aging employee-base. Traditional hand harvesting is not considered to be socially nor economically sustainable due to being very labour-intensive, involving the manual use of a clam hake with tines that measure 15 cm in length to dig up and turn over the sediment. There is interest in using mechanical clam harvesters to complement hand harvesting of quahogs (Mercenaria mercenaria) in St. Mary’s Bay, Nova Scotia.

This study compared the ecological effects of manual digging versus a mechanical clam harvester. It investigated the effects of both techniques on the ecological health and production of the area by monitoring the clam population, associated fauna and flora, and various physical and chemical parameters. Methods for mitigating the ecological impact of harvesting, such as replanting pre-recruits on size-class plots and reducing repeated harvesting efforts, were also investigated. Specifically, the following results were found: 1) no difference was found in physical or chemical characteristics of the sediment between non-harvested, manually, or mechanically harvested plots; 2) no differences were found before and after harvesting; and 3) both harvesting techniques either have no impact on the sediment and on faunal assemblages, or that recovery is rapid.

Neither harvesting technique was better or worse than the other regarding its effects on sediment characteristics. While manual digging is possible in any sediment type, the prototype harvester used in this project was better suited for firm sandy bottoms and some mud, but did not perform very well in soft mud. It will need to be improved to be commercially useful.

Date: APR. 2012–JUN. 2015

Funded by: DFO–Aquaculture Collaborative Research and Development Program (DFO–ACRDP)

Co-Funded by: Innovative Fisheries Products Inc.

Project Lead: Thomas Landry (DFO)

Project Team: Angeline LeBlanc (DFO)

Collaborators: Doug Bertram (Innovative Fisheries Products Inc.)



Microplastics and Shellfish Aquaculture: Investigating Presence, Extent, and Potential Impacts and Mitigation Measures

Microplastics (i.e., plastics < 5 mm) are an emerging contaminant of increasing concern to industry, scientists, and the general public. Microplastics are ubiquitous in the marine environment and come from a wide range of sources including sewage effluent and general degradation of larger plastics. There are several types of microplastics such as microbeads, fibres, and fragments which are ingested by a wide range of organisms. Ingestion of microplastics can have negative physical and chemical impacts on the organisms that consume them. Because of this, the aquaculture industry has the potential to be negatively affected by microplastic pollution. Conversely, because of the use of plastics in the aquaculture industry there is also the potential to contribute to microplastic pollution. To address these issues, we are conducting a collaborative study with VIU, DFO, BCSGA, Vancouver Aquarium, and UVic. This research will: 1) determine the concentration of microplastics in clams and oysters cultured in coastal British Columbia; 2) determine the concentration of microplastics in the surrounding environment; 3) characterize the type of microplastics found and identify potential sources; 4) evaluate depuration as a potential mechanism to eliminate microplastics; and 5) investigate the impact of microplastics on shellfish health and resilience.

This research will show the level of microplastic pollution within commercial shellfish and their surrounding environment. It will also indicate the efficacy of depuration to remove this contaminant, the implications of microplastic ingestion on shellfish health, and potential microplastic sources.

Date: JUL. 2016–MAR. 2018

Funded by: DFO–Aquaculture Collaborative Research and Development Program (DFO–ACRDP)

Co-Funded by: BC Shellfish Grower’s Association (BCSGA)

Project Leads: Sarah Dudas (VIU); Helen Gurney-Smith, Chris Pearce (DFO)

Project Team: Chris Pearce (DFO); Peter Ross (Vancouver Aquarium); Garth Covernton, Maggie Dietterle, Matt Miller, Kayla Balmer, Monique Raap (VIU)

Collaborators: Darlene Winterburn (BCSGA); Yves Perreault (Little Wing Oysters); Andre Comeau, Chris Roberts (Okeover Organic Oysters); Dave Ritchie, Steve Pocock (Sawmill Bay Shellfish); Brian Yip (Taylor Shellfish); Keith Reid (Stellar Bay Shellfish); Andrew Dryden (Evening Cove Oysters); Pete McLellan (Nanoose Bay Oysters)



Oyster up close. Photo: Kayla Mohns (DFO)

Netting. Photo: Kayla Mohns (DFO)

The Effect of Cultured Shellfish on Eelgrass Productivity in Estuaries of New Brunswick

Canada’s Oceans Act promotes an ecosystem-based approach in managing human activities in coastal and marine environments. As such, enhanced protection should be provided to species, such as eelgrass (Zostera marina), and community properties that are particularly significant to maintaining ecosystem structure and function, while allowing sustainable activities to be pursued. One of the human activities considered is shellfish aquaculture, an increasingly important economic driver in coastal communities. Recent studies have documented some negative effects on eelgrass from oyster aquaculture, in some areas and at a local scale, mostly linked with shading effects from aquaculture gear. However, another important aspect to also consider in the overall risk characterization is the potential off-setting effects from the cultured bivalve biomass, as filter feeders, on eelgrass productivity by influencing turbidity patterns of natural and cumulative anthropogenic sources.

This study is investigating the effects of cultured shellfish on eelgrass productivity at the bay scale. This will be achieved through field studies that describe the seascapes of study bays, with a focus on the distribution of shellfish populations (wild and cultured) and eelgrass beds, using novel remote sensing tools and strategies, and turbidity patterns of the water column. A laboratory study will evaluate the resulting effects of oyster filtration on turbidity (water clarity) and light attenuation. Finally, bay scale hydrodynamic computer models will be developed for two study bays to include a turbidity module and clearing coefficients of cultured oysters, allowing for improved assessments of bay-scale effects from existing (or proposed) shellfish leases on eelgrass productivity.

Date: APR. 2014–MAR. 2018

Funded by: DFO–Program for Aquaculture Regulatory Research (DFO–PARR)

Project Lead: Marc Ouellette (DFO)

Project Team: Monique Niles, Thomas Guyondet, Michael Coffin (DFO)

Collaborators: Tim Webster, Kate Collins (AGRG–NSCC)