The SEA-System Infrastructure Innovation Project – Modifying Steel Fish Cage Systems to Accommodate Integrated Multi-Trophic Aquaculture

 

Stephen F. Cross, Ph.D.
Kyuquot SEAfoods Ltd.
Courtenay, British Columbia
Canada V9N 9N8

Table of contents

• Introduction
• Project Summary
• Difficulties Encountered
• Post-Project Performance Evaluation Plan

Introduction

The development of Sustainable Ecological Aquaculture (SEA) systems, often referred to as an Integrated Multi-Trophic Aquaculture (IMTA) approach, requires a balanced combination of species that are selected for their complementary capacity to extract (and utilize) the organic and inorganic waste streams associated with the single ‘fed’ component (fish) of the production system. While the SEA-System model for environmentally sustainable aquatic agri-food production also holds incredible socio-economic potential for the Canadian aquaculture industry, modification and/or development of unique (and compatible) SEA/IMTA system components will be required before full commercialization of this process can be realized in Canada.

Finfish aquaculture, largely salmon, is concentrated primarily in coastal British Columbia and in New Brunswick. Despite a focus on the same salmonid species, the use of comparable feed, employment of similar husbandry approaches, and provision of product to similar markets, each regional industry has evolved using distinctly different cage systems for their respective farm operations. In eastern Canada the farms comprise circular net-cages (e.g., Polar-Circle) secured within an anchor grid and accessed exclusively by boats for feeding, net maintenance, grading, and harvesting. In western Canada the industry focuses its finfish production using galvanized steel net-cages (e.g., Viking, Wave-Master), and has developed these facilities with attached accommodation/feed sheds, automated feeding systems, etc. - boats are used only for net changes or for harvest.

The square, steel cage production system typical of the west coast is viewed as an intensive infrastructure model, with all containment structures in very close proximity (actually attached). Integration of extractive species within these types of systems will require careful consideration of how access to fish cages will be maintained, and how grow-out systems for the additional species can be designed and constructed without compromising the structural integrity and functionality of the original steel cage infrastructure.  The challenges offered by adapting these systems to support SEA (IMTA) integration are considerable. 

In British Columbia Kyuquot SEAfoods Ltd. represents the first commercially approved SEAfarm, licensed to produce 11 species:  sablefish (Anoplopoma fimbria), two species of blue mussels (Mytilus edulis, M. galloprovincialus), scallops (Patinopectin yessoensis), oysters (Crassostrea gigas), the cockle (Clinocardium nuttalli), the sea cucumber (Parastichopus californisanus), the green and red sea urchins (Stronglylocentrottus droebachiensis, S. fransiscanus), and two species of macrophytes (Saccharina latissima and Porphyra spp.). 

With an 18-cage, steel Viking cage system as a base for this SEA-System (IMTA) development, a variety of structural innovations have been conceptualized in order to accommodate the suite of species within the intensive SEA-System infrastructure. The current DFO-AIMAP project has allowed us to begin the key structural and system modifications envisioned to adapt this type of finfish production system to that of a commercial-scale SEA (IMTA) system.

Project Summary

The SEAfood System Infrastructure Innovation Project has successfully designed, engineered and manufactured a prototype SEAfood System component that will support the organic extractive (filtration) species of our Sustainable Ecological Aquaculture (SEA) system. Despite our original intent of modifying the support infrastructure of our current finfish culture system (Viking cages), detailed engineering studies and modelling of weight/balance issues of the conceptual SEA-Tram system suggested that this approach would not be feasible, nor cost-effective. Further, the proposed modifications would be unique to this particular model of cage system and hence would not facilitate integration with other systems used by the salmon aquaculture sector. It is for these reasons that we moved to the development a completely new SEAfood System component for the shellfish, one that now provides the following advantages:

• A stand-alone SEAfood System engineered to support intensive shellfish production – considering maximum weight of product, support of two tram systems (each weighing 4.0 MT);

• It is a system of standardized ‘pieces’, so that it can be manufactured to any overall farm length specification – thus adaptable to any salmon farm given that the fish cages are configured in a single array; the system is being patent-protected and we have dedicated a separate company to deal with marketing, sales and coordination of manufacturing/distribution of the system to interested finfish farmers;

• The system has standardized attachments points for anchoring it parallel to any model of steel netcage – limiting the capital investment to the farmer beyond that of the system purchase itself;

• Internal ‘hooks’ are inherent within the system, and placed to support a variety of shellfish species configurations; external ‘hooks’ (outboard of the system) are placed to support attachment of kelp lines to integrate the inorganic extractive component of the IMTA system;

• The SEAfood System is constructed using finfish industry materials (galvanized steel and foam-filled HPVD billets) and thus has an extremely long operational life (opposed to the wooden raft design of the shellfish sector);

• Although capital costs are high, the cost of operation (reduced fuel – no boats) and materials life-span of the system can be justified; our current SEAfarm will have 600’ of the shellfish SEAfood System, the equivalent growing area of 42 wooden rafts.

The first section of our 600’ SEAfood System (320’) is currently being manufactured and galvanized - with delivery to the KSL farm site in Kyuquot Sound on 15 April 2009; installation will be completed by month end with the anticipated entry of 1.0 million scallops scheduled for early May. The following diagram shows the proposed SEAfarm layout at our site, with the completed SEAfood System running parallel and to the left of the sablefish cages (shown on the right).

Difficulties Encountered

Due to the results of the engineering assessment for the SEA-Tram infrastructure modification component of this project, the decision was made to focus on the development of a new, stand-alone SEAfood System. As a result the cost associated with the development escalated significantly. However, due to the reasons mentioned above, this approach has ultimately proven much better and now lends itself to the future development of IMTA at other, existing salmon farm sites – and without site-specific engineering design and system modifications.

Given that we went far beyond our budget in moving this shellfish component forwards, and in fact to a point where we have a completed modular system that can be pieced together as required, we were unable to start any aspect of the proposed SEA-Tray system. This component, conceptualized for the sea cucumber culture beneath the fish cages, requires that we collect further data on weight requirements (how many cukes, size, etc.) so that a proper engineering assessment can be considered in the design. This has now been postponed until the fall when a Uvic Engineering student will be assigned the task.

Post-Project Performance Evaluation Plan

It is anticipated that significant cost savings will result from the intensive production of shellfish using our patent-pending SEAfood System. The fist 320' (approx. 100 metres) of the system will be installed, with the final segment manufactured and integrated into the farm as financing permits (anticipated later this spring). In the interim scallop seed (1.0 million) will be introduced into the system in early May with other species components to follow. A comparative study of the environmental and socio-economic benefits of this innovation package will be completed using a 3-year graduate student project (2009-2011). This assessment will begin in September/2009 and completed as part of the ongoing, national IMTA Research Initiative - Dr. Cross has been Identified as the Theme Leader for IMTA System Design & Engineering within the proposed NSERC Strategic Network (CIMTAN).