Canadian Aquaculture R&D Review 2011
CIMTAN: Canada's new network for Integrated Multi-trophic Aquaculture
Fulfilling aquaculture's growth potential requires responsible technologies and practices. Sustainable aquaculture should be ecologically efficient, environmentally benign, product-diversified, profitable and beneficial to society. Integrated Multi-Trophic Aquaculture (IMTA) has the potential to achieve these objectives by cultivating species from different trophic levels and complementary ecosystem functions, in proximity. These are cultivated in a manner that allows one species' uneaten feed and wastes, nutrients, and by-products to be captured and converted into fertilizer, feed, and energy for the other crops. This method also takes advantage of synergistic interactions between species while biomitigation takes place (partial removal of nutrients and CO2, and supplying of oxygen). Farmers combine fed aquaculture (e.g., finfish or shrimps fed sustainable commercial diets) with extractive aquaculture, which utilizes the inorganic (e.g., seaweeds or other aquatic vegetation) and organic (e.g., suspension- and deposit-feeders) excess nutrients from fed aquaculture for their growth. In this way, all the cultivation components have an economic value, as well as a key role in the services and recycling processes of the engineered ecosystem. The aim is to ecologically engineer balanced systems for environmental sustainability (biomitigative services for improving ecosystem health), economic stability (improved output, lower costs, product diversification, risk reduction, and job creation for local communities), and societal acceptability (better management practices, improved regulatory governance, and appreciation of differentiated and safe products). In this way, some of the environmental interactions of fed monoculture are internalized, thus increasing the overall sustainability, profitability, and resilience of aquaculture farms. The economic values of the environmental and societal services of extractive species will have to be recognized and accounted for in the evaluation of the true value of these IMTA components. This will create economic incentives to encourage aquaculturists to further develop and implement IMTA. Seaweeds and invertebrates produced in IMTA systems should be considered as candidates for nutrient/carbon trading credits within the broader context of ecosystem goods and services. Long-term planning/zoning promoting biomitigative solutions, such as IMTA, should become an integral part of coastal regulatory and management frameworks.
Research and development (R&D) on IMTA has been conducted on both the East and West Coasts of Canada since 2001. Significant progress has been made over the last nine years, but a concerted and strategic approach was needed for: the need for better coordination; synchronized complementary R&D to fill the knowledge gaps and explore new ideas; information sharing and intellectual and conceptual exchanges; sharing expensive equipment through joint experiments appropriately planned between the two coasts for optimal data acquisition and result analyses; joint interdisciplinary training of highly qualified personnel; and increased involvement of industrial partners. This will allow IMTA to move from an interesting academic and experimental concept into a valued economic and social reality at a commercial scale.
CIMTAN is focused on developing a key network of researchers, with complementary expertise, from across Canada to further develop IMTA approaches to strategically enhance economically sustainable production systems. The ultimate goal of CIMTAN is to develop aquaculture systems, which can be adopted by its industrial partners. These systems will be able to efficiently mitigate organic and inorganic enrichment of fed aquaculture operations by actively recapturing this material and turning it into the production of extractive crops of commercial value. This will transform associated environmental and socio-economic issues around aquaculture operations into benefits and trusted quality seafood and novel seafood-base products, not only for its industrial partners, but also for coastal and rural communities and all Canadians. With a strong pan-Canadian academic, government, and industry partnership, CIMTAN will provide the interdisciplinary R&D and highly qualified persons (HQP) training,on the following linked areas of IMTA:
- ecological design, ecosystem interactions, and biomitigative efficiency,
- system innovation and engineering,
- economic viability and societal acceptance, and
- regulatory science.
CIMTAN will also go beyond addressing natural science and/or engineering questions, and will address socio-economic and regulatory governance components, required for the full development of the sector. Additionally, CIMTAN will create the conditions for increased economic opportunities in coastal and rural regions, including First Nations communities, providing sustainable, quality seafood to Canadians, concomitant with increased societal acceptance of the aquaculture sector and public policy development for improved government decision-making.
CIMTAN is based on a networking approach among 26 scientists from 8 universities, 6 federal laboratories of Fisheries and Oceans Canada, and 1 provincial laboratory, spread over 6 provinces. The complementary expertise, combined infrastructures, and the common goal of the 26 scientists, is in phase with the priorities of the 3 industrial partners (Cooke Aquaculture Inc., Kyuquot SEAfoods Ltd. and Marine Harvest Canada Ltd.) and the environmental, developmental and social issues of concern to First Nations. This has allowed the network to be structured into 3 linked Domains reflecting the 4 areas identified above. CIMTAN is structurally organized into domains: Domain 1 is environmental; Domain 2 is engineering; and both Domains 1 and 2 are linked by the cross-cutting Domain 3 (economic and social), as biological, environmental, and biotechnological/engineering issues are always linked to economic aspects and social acceptability. Each domain is co-led by a scientist at an academic institution and a scientist at a Fisheries and Oceans Canada laboratory, in recognition of the significant role played by Fisheries and Oceans Canada in this network. Domain 1 is co-led by Drs. MacDonald and Robinson; Domain 2 is co-led by Drs. Cross and Pearce; and Domain 3 is co-led by Dr. Knowler and Mr. Noce.
The management structure of CIMTAN has been designed to provide and ensure effective research planning, research delivery, management, financial control and accountability, and interaction among all actively committed members and partners of this complex inter-disciplinary and multi-institutional network. The key decisional structures of CIMTAN, the Steering Committee and the Scientific Committee, have been designed to give a balanced representation of academics, industry, provincial and federal governments, and non-governmental organizations (in particular the Aboriginal Aquaculture Association). This was designed to ensure a cohesive and effective approach of CIMTAN to the development of responsible aquaculture practices, linked to the priorities of its partners.
CIMTAN's total budget amounts to CAD$9,577,000. The Natural Science and Engineering Research Council (NSERC) support to the level of CAD$5,000,000 (52.2%) was able to leverage an impressive level of cash and in-kind contributions: CAD$637,210 (6.7%) in cash contributions (Fisheries and Oceans Canada, University of New Brunswick, Cooke Aquaculture Inc., and Marine Harvest Canada Ltd.) and CAD$3,939,790 (41.1%) in in-kind contributions (Fisheries and Oceans Canada, University of New Brunswick, Cooke Aquaculture Inc., Kyuquot SEAfoods Ltd., and Marine Harvest Canada Ltd.).
Training of highly qualified persons is a very high priority of CIMTAN (CAD$2.156 million or 43.1% of the NSERC budget). All projects are involved in this very important task of training the scientists, policy influencers, decision makers, regulators, and industrialists of tomorrow. It is anticipated that the 26 scientists of the network will support and train 114 HQP over 5 years: 23 MSc, 2 MASc, 4 MRM, 4 MA, 5 PhD students, 2 postdoctoral fellows, and 6 technicians. A large number of undergraduate summer students (68) will also be hired. CIMTAN is promoting student co-supervision, mobility among the domains, reciprocal laboratory visits, and placement terms at the different partner organizations. This will ensure inter-disciplinary training and versatile multisectoral experience with the different prevailing environmental, economic, and societal conditions of the different domains, institutions, organizations, and regions.
The research articles in this section describe in more detail, each of the 14 projects of CIMTAN.
Jan. 2010 – Dec. 2014 • Funding: All CIMTAN projects are funded by: Natural Sciences and Engineering Research Council (NSERC), Fisheries and Oceans Canada (DFO), University of New Brunswick, Cooke Aquaculture Inc., Marine Harvest Canada Ltd., and Kyuquot SEAfoods Ltd.
Project team: T. Chopin (University of New Brunswick Saint John, Department of Biology), B. MacDonald (UNBSJ), S. Robinson (DFO - SABS), S. Cross (UVic), C. Pearce (DFO - PBS), D. Knowler (SFU), A. Noce (DFO - EAS)
Contact: T. Chopin (firstname.lastname@example.org) • http://www.cimtan.ca
Mathematical modeling for open-water IMTA – Developing tools to support system design and measures of sustainability
Matter and energy flux within open-water IMTA systems and between the culture and the environment needs to be qualified and quantified in order to assess farm design and develop sustainability measures. Empirical measures of concentrations in open-water systems as a means to assigning causality to a particular process or culture niche has obvious challenges in such a highly variable and "leaky" environment. Some degree of modeling will therefore be essential to determine efficiencies and track the 'delivery' of nutrients to co-cultured species. Since most commercial-scale aquaculture in Canada occurs in open-water systems, IMTA will also be practiced in this context. IMTA system modeling must therefore be developed beyond the laboratory and small-scale pilot projects if it is to have 'real world' application. Therefore, the primary objectives of this project are to: reconcile existing ecological and animal/seaweed husbandry efficiency measures; continue the development of both a semi-stochastic nutrient-transfer model; determine the overall IMTA system efficiency of nutrient and energy recovery; and create a mechanistic/deterministic model with time steps to increase the understanding of IMTA systems. Together these will ultimately determine methods with which to quantify system functions for open-water IMTA farm management, economics, and coastal zone policy development. These objectives will be facilitated though the compilation of relevant data from the other CIMTAN projects.
Jan. 2010 – Dec. 2014
Project team:G. K. Reid (UNBSJ/DFO –SABS), B. MacDonald (UNBSJ), P. Cranford (DFO –BIO), M. Quinton (UGuelph),S. Robinson (DFO –SABS), T. Chopin (UNBSJ)
Contact: G. K. Reid (Gregor.Reid@dfo-mpo.gc.ca) • http://www.cimtan.ca
A possible benefit of adding filter-feeding shellfish to the typical monoculture model of salmon farming is the potential for reducing viral, bacterial, and/or parasitic diseases in the cultured fish as a result of the filtering of planktonic dispersal particles (e.g., bacteria, viruses, larvae, nauplii) by the shellfish. This project examines a number of filter-feeding shellfish species for their ability to ingest the planktonic nauplii/copepodids of sea lice under laboratory conditions and assessing the effects of commercial-scale quantities of shellfish on sea lice levels at a commercial salmon farm site. The laboratory phase of the project, currently underway, is designed to determine which of four species of suspension–feeding bivalves (i.e., blue mussel, Pacific Oyster, Basket Cockle, Japanese Scallop) consume sea lice larvae and the ingestion rates at various temperatures (5, 10, 15®C). If species are identified that can consume nauplii/copepodids, then a field experiment will be established to compare sea lice levels on cultured fish in: (1) experimental cages surrounded by commercial-scale densities of cultured shellfish, and (2) control cages and control sites without shellfish. If successful, bivalves grown by salmon farms could potentially reduce the abundance of sea lice on caged salmon using a biological control approach, possibly reducing the need for costly chemo-therapeutants.
Jan. 2010 – Dec. 2014
Project team: C. Pearce (DFO – PBS), S. Cross (UVic), S. Jones (DFO – PBS), S. Robinson (DFO – SABS), J. Webb (UVic graduate student)
Contact: C. Pearce (email@example.com) • http://www.cimtan.ca
Assuming that IMTA can be shown to be an environmentally-favourable system of food production for society, IMTA adoption will depend on the profitability of the system and the necessary economic incentives to promote adoption. This project aims to: 1) examine the net economic benefits of IMTA and compare these to conventional aquaculture systems; 2) assess the private financial incentives for IMTA production at the site level; and 3) investigate appropriate financial incentives for the wider promotion of IMTA. This project will use both financial and economic analysis tools, where financial analysis examines the business's revenues and costs and economic analysis examines the net effects of an activity, including its effects to external parties. Studies to be carried out under this project will examine: 1) the impacts of commercial-scale IMTA on the BC shellfish industry; 2) consumer attitudes and willingness-to-pay for IMTA products in the Pacific Northwest; and 3) comparative economic analysis of nutrient dynamics in IMTA and conventional net pen salmon aquaculture. Additionally, other tentative studies are proposed to examine modeling of private incentives for adoption of IMTA among salmon farmers in BC and additional valuation studies.
Delimitation of the spatial and temporal patterns and dynamics of the nutrient and particulate releases from different IMTA system configurations will provide critical information on the nature of the 'leakiness' of these approaches. It will also inform on how the extractive species of these systems should be configured so as to maximize the ability to effectively intercept these waste streams. How these dispersion processes function within the natural fluctuations in nutrients, particulates and the inherent biotic assimilative capacity (e.g., phytoplankton) are also essential to understanding how IMTA systems should be designed and operated. Results from this project will help develop an appropriate balance of species components of the IMTA system, as well as assist with production infrastructure design and engineering for effectively incorporating these species components into a multi–species design. Two MSc students (one on each coast) are exploring direct and indirect methods for delimiting the spatial extent of these waste plumes, comparing existing profiling techniques with indirect productivity measures of seaweed sentinels (kelps). A third MSc student will examine the dispersion, benthic accumulation and the potential for nutrient release and/or particulate re–suspension from the settling particulate waste stream. A PhD student is developing new, optical (direct) techniques/protocols for delimiting the dissolved nutrient and particulate plumes emanating from the culture systems.
Jan. 2010 – Dec. 2014
Project team: S. Cross (UVic), M. Costa (UVic), F. Page (DFO – SABS), P. Cranford (DFO – BIO), J. Grant (Dalhousie University), G. Reid (UNBSJ/DFO – SABS), T. Chopin (UNBSJ), E. Prussin (UVic graduate student), L. Brager (Dalhousie University graduate student), S. Jabber (UVic graduate student)
Contact: S. Cross (firstname.lastname@example.org) http://www.cimtan.ca
As a general hypothesis, it is likely that the transmission of pathogens – and in particular the exchange of pathogens between the farm site and the "near-farm" environment – could be modified through IMTA practices. This may apply best, or alternatively may be most successfully modeled, for those organisms which possess methods of infection/transmission that allow extended periods of extracorporeal (off-host) survival and for which the severity of infection is quantifiable as a continuous outcome and directly (linearly) related to exposure to infectious dose. Given these considerations, the disease known as Microsporidial Gill Disease of Salmon (MGDS), a serious endemic gill disorder in marine netpen reared and wild Chinook (and other Pacific) Salmon, has potential as a model through which to better understand disease transmission in this modified aquaculture setting. Our goal is to develop a suitable laboratory in vivo branchial xenoma expression model for MGDS and use it to explore our specific aims which include determining to what extent blue mussels may remove, deactivate, or retain Loma spores released from infected fish. Additionally, we also seek a further understanding of the temporal kinetics of spore survival in marine environments and sediments, in addition to their survival (as determined through infectivity) within or on structures that may be used in IMTA settings.
Jan. 2010 – Dec. 2014
Project team: D. Speare (UPEI – AVC), J. Lovy (UPEI – AVC), N. Guselle (UPEI – AVC), E. Ball (UPEI – AVC), L. Collins (UPEI – AVC; Pfizer Health)
Contact: D. Speare (email@example.com) • http://www.cimtan.ca
The potential of an organism as an organic extractive species within IMTA sites depends primarily on its efficiency to capture and convert particles. On the East coast, the potential of the Sea Cucumber (Cucumaria frondosa) as an organic extractive IMTA species is being determined by: 1) quantifying the absorption efficiency and its relationship to the quality of material present; 2) quantifying the time necessary to convert food to faeces (gut passage time); and 3) determining whether it is capable of consuming aquaculture waste. This project will use both controlled laboratory experiments and practical field trials in the natural environment and at East coast IMTA sites. Several species are being considered for use as organic-extractive organisms on the West coast. Ingestion rate, absorption efficiency, energy budget, and biophysical properties of excreted faeces will be determined for individuals fed diets of Sablefish aquaculture waste, and will be compared to 'natural' diets across a range of temperatures. Candidate species for the West coast include the Green Sea Urchin (Strongylocentrotus droebachiensis), the Basket Cockle (Clinocardium nuttallii), the Blue Mussel (Mytilus edulis), the Gallo Mussel (M. galloprovincialis), the California Sea Cucumber (Parastichopus californicus), the Pacific Prawn (Pandalus platyceros), and nereid polychaetes.
Jan. 2010 – Dec. 2014
Project team: B. MacDonald (University of New Brunswick Saint John, Department of Biology), S. Cross (UVic), C. Pearce (DFO – PBS), S. Robinson (DFO – SABS), G. Reid (UNBSJ, DFO – SABS), H. Gurney-Smith (VIU – CSR), S. Balfry (UBC-DFO – CAER), E. Nelson (UNBSJ graduate student), L. Orr (UVic graduate student)
Contact: B. MacDonald (firstname.lastname@example.org) • http://www.cimtan.ca
Quantifying energy and nutrient dispersal and scales of influence on wild species from open-water IMTA sites
The abundance and distribution of wild species associated with IMTA cage sites need to be measured in order to learn how these species are associated with nutrient availability in both the near and far field. Current investigations will design an appropriate field methodology based on feasibility and statistical design. We have been able to quantify rates of bio-colonization (bio-fouling) using standardised collectors that are similar to designs used for monitoring invasive tunicates. Each collector consists of a series of PVC plates that serve as a substrate for native organisms such as bryozoans, hydrozoans, tunicates, and algae. These species colonise new substrates quickly and are suitable as measurements of early responses to nutrient availability. Collectors are deployed at both finfish and IMTA sites as well as at reference locations within the same geographic area but far from aquaculture activity. Upon collector retrieval, total accumulated biomass and surface area colonised can be measured and compared among sites relative to other environmental variables. The next phase of investigation will be to deploy a full array of collectors around several IMTA and finfish sites along with simultaneous measurement of environmental correlates such as temperature, salinity, current, chlorophyll, and oxygen.
Jan. 2010 – Dec. 2014
Project team: A. Cooper (DFO – SABS), S. Robinson (DFO –SABS), C. McKindsey (DFO –IML), F. Page (DFO –SABS), L. Burridge (DFO – SABS), T. Chopin (UNBSJ)
Contact: A. Cooper (Andrew.Cooper@dfo-mpo.gc.ca) http://www.cimtan.ca
The goal of Integrated Multi-Trophic Aquaculture (IMTA) systems is to recycle and reuse excess nutrients from salmon aquaculture farms by culturing other commercially valuable species, thereby limiting environmental impacts. Co-culture of the Clam Worm, Nereis virens - a sediment dweller commonly found in the Bay of Fundy - is being considered as a means to 'process' the organic solids that settle out from fish farms. This worm is often sold as bait. The goal of this project is to determine the effects of the anti-sea lice therapeutant SLICE® (active ingredient emamectin benzoate (EB)) to these worms at fish farms where this chemical is used. Ongoing toxicity studies are assessing acute and chronic effects of this therapeutant on the worms. During an acute exposure study, worms were exposed to EB concentrations of 20, 200 and 2000 μg/Kg sediment for 10 days. This resulted in no mortality, although some behavioural changes were observed. A chronic exposure study will be conducted in which worms will be exposed to similar concentrations but over 60 days. Survival, uptake of EB, and growth will be monitored. This work provides data that will be used to assess the feasibility of culturing worms under salmon farms.
Jan. 2010 – Dec. 2014
Project team: L. Burridge (DFO – SABS), K. Kidd (UNBSJ), G. Reid(UNBSJ/DFO – SABS), S. Robinson (DFO – SABS), T. Chopin (UNBSJ), G. McBriarty (UNBSJ graduate student)
Contact: L. Burridge (Les.Burridge@dfo-mpo.gc.ca) • http://www.cimtan.ca
Since 2001, the inorganic extractive component of IMTA systems on the East coast has been composed of the two kelps Saccharina latissima and Alaria esculenta. On the West coast, Saccharina latissima has been cultivated since 2007. These species are cultivated first in the laboratory, from September to November, and then at the sites from November to June/July. They need to be harvested in late spring/early summer before the erosion of the blades and fouling compromises the harvest and quality of the derived products. Consequently, inorganic biomitigation is not taking place during summer, as seaweeds are absent at IMTA sites. This project is investigating two new macro-algal candidate species, on the East coast Palmaria palmata (Dulse) and Ulva sp. (Sea Lettuce) on the West coast. These macrophytes have cycles and characteristics that allow growth of the macroscopic stages during the summer. This will allow the provision of biomitigative biomass during the summer and, consequently, an overall increase of the inorganic biomitigative capacity of the IMTA systems. Research is also underway to explore the use of seaweeds in fish feed formulation as alternate protein sources to partially offset fishmeal and land plant proteins.
Jan. 2010 – Dec. 2014
Project team: T. Chopin (University of New Brunswick Saint John, Department of Biology), S. Cross (UVic); C. Chianale (UNBSJ graduate student), N. Sherrington (UVic graduate student)
Contact: T. Chopin (email@example.com) http://www.cimtan.ca
Aquaculture sites can be located remotely, far from the electrical grid. As the intent is to reduce environmental impact of aquaculture operations, the provision of clean power on aquaculture sites is being investigated to avoid the need for diesel gensets (fossil-fuel powered generators). The work to date has been focused on gathering resource data for the West coast IMTA demonstration site, and performing initial component sizing. The use of on-site bioreactors to process seaweeds to produce biodiesel was explored but found to be unfeasible due to inefficiencies of scale. There was insufficient seaweed input available from target site operations with which to create the required quantity of biodiesel for energy self-sufficiency. An alternative approach involved employing wind and solar energy sources to power aquaculture operations. Wind and insolation data were gathered from existing weather collection buoys and it was found that significant solar power was available to be used as an alternate power source. To ascertain the wind resource characteristics at the height of candidate turbine installations, a higher anemometer tower is currently being installed. An energy system model has been assembled in HOMER that includes the hoist power requirements, the source of the primary power load (i.e., power consumption). HOMER is a simulation code that is used for analysis of remote energy systems. It simulates the power flows in those systems between, for example, batteries, motors, wind turbines, etc. and produces an output of performance, costs, etc. An energy efficiency audit has also been conducted of the on-site aquaculture staff residence. These data will be included in the custom energy usage model that is being developed to optimize the aquaculture power usage system. A custom model was developed as it was found that existing software was unable to adequately accommodate for the intermittent 'peaky' power loads, a function of hoist use. The custom power model could then be used to size renewable energy systems for current and future aquaculture sites.
Jan. 2010 – Dec. 2014
Project team: C. Crawford (UVic, Department of Mechanical Engineering), S. Cross (UVic), T. Chopin (UNBSJ), E. Hoevenaars (UVic graduate student)
Contact: C. Crawford (firstname.lastname@example.org)
Canadian coastal communities are small, widely dispersed, and have a high degree of economic and cultural diversity. In recent years, many of these communities have experienced economic hardships, the result of downturns in the capture fishery and forestry sectors. One of the goals of this project is to investigate the potential that IMTA has for contributing to the development of sustainable coastal livelihoods in remote communities. This objective requires considerations of the capacity and interest of people in participating in aquaculture and of the policies and training needed to facilitate their involvement. Developing a better understanding of the social and institutional aspects of implementing IMTA in coastal communities directly complements the natural science aspects, and is an essential component in the overall process of helping IMTA reach its full potential. Recognizing that the health of social, economic, and ecological systems are inextricably linked, our research program has been developed with an explicit acknowledgement of the need to move across traditional academic disciplines and managerial "silos". Accordingly, this project is divided into three cross-cutting inquiry streams: a) aquaculture governance; b) the potential contribution of IMTA to Canada's coastal economy and social sustainability; and c) First Nations and IMTA.
Jan. 2010 – Dec. 2014
Project team: T. Chopin (UNBSJ), M. Flaherty (University of Victoria, Department of Geography),G. Murray (VIU), M. Liston (UVic graduate student), A. Belanger (UVic graduate student), J. Foley (UVic graduate student)
Contact:M. Flaherty (email@example.com) • http://www.cimtan.ca
Understanding the various paths and processes by which energy flows through an IMTA site is one of the main objectives in the creation of sustainable aquaculture systems using ecosystem-based approaches. As food from one trophic level is recycled through another, the energy associated with organic particles is stripped out and is converted to inorganic waste products, such as ammonia or carbon dioxide or heat. This transfer occurs right down to the lowest trophic levels where the bacteria reside. The objective of this project is to evaluate the role that bacteria play in nutrient recycling at a salmon aquaculture site and to evaluate the relative scale of their ability to convert organic particles into inorganic components. Specifically, we will be enumerating bacteria and their respiration rates on and away from finfish aquaculture sites in both the water column as well as the benthos. This will be done on a seasonal basis at IMTA sites on both the East and West coasts. Additionally, we will also identify the bacterial communities associated with the aquaculture sites and how they evolve over the year. These results will be fitted into a model of energy flow through an IMTA site.
Jan. 2010 – Dec. 2014
Project team: S. Robinson (DFO – SABS), B. Forward (NBRPC), T. Lander (DFO – SABS), T. Chopin (UNBSJ), K. Mitchell (UNBSJ summer student)
Contact: S. Robinson (Shawn.Robinson@dfo-mpo.gc.ca) • http://www.cimtan.ca
In light of the differing regional IMTA developments in Canada, it is clear that the design and engineering challenges manifested in adapting existing finfish aquaculture systems to support IMTA integration are considerable and varied. Hydrographic processes will dictate how dissolved nutrient and particulate plumes flow among these differing major infrastructure components. These characteristics will define how the IMTA production systems should be designed and configured to fully capitalize on the dispersion pathways of these waste streams. However, the interception of these streams by the various extractive species can, in themselves (at commercial production levels), affect the efficiency of the resulting IMTA system. Proximity to the fed (fish) component, density of the grow-out structures (nets, cages, trays), vertical and horizontal orientation with respect to the flows, within-production unit densities, and spatial/temporal integration of multi-species/multi-year classes within each type of IMTA system are all issues that need to be addressed in order to ensure continual and optimal system performance. This work will start in years 4-5 of CIMTAN with two MSc students and will compare the effects of system configuration on extractive performance of 'intensive' IMTA systems on the West coast and 'extensive' IMTA systems on the East coast.
Research and development on IMTA has been conducted in Canada since 2001. During this period IMTA was developed independently on each coast, with integrated aquaculture systems being proposed through modifications of existing infrastructure currently employed for the culture of salmon within these regions – on the East coast using the independent circular cage grid configuration, and on the West coast integrated with the consolidated steel cage systems. Documentation of the dispersion and dilution pathways for these components, specifically the nearfield hydrographic flow properties, is being determined for each of these IMTA production systems in order to provide the most efficient ecological and structural design. This component of the CIMTAN research program supports a comprehensive evaluation of flow impedance by structures, the effects of waste stream deflection (i.e., developed back-eddies, re-direction of flows), the vertical entrainment of particles (for the potential persistence of nutrients), effects of increased biomass on dissolved oxygen dynamics, alteration of phytoplankton supply through the systems, and structural adaptation of IMTA to capitalize on the effect of flow on dissolved nutrient and particle movements. One M.Sc. student is completing a comparative study documenting the near-field hydrographic properties of intensive and extensive IMTA farms, while a second will focus on the influences of infrastructure on near-field flows and its implications for within–system design/engineering of IMTA components.