Large Scale Recirculating Wet-Storage and Validation for Treatment of Vibrio parahaemolyticus in BC Oysters

Final Report

Taylor Shellfish Canada ULC
AIMAP-2010-P18

Table of contents

Executive Summary
Introduction
Technological Advancement
Deliverables (Results)
Challenges and Learning Experiences
Data Collection

Executive Summary

Fanny Bay Oysters has completed an innovative state-of-the-art live shellfish storage system. This project scaled-up and improved an existing flow-through wet-storage facility located at the Fanny Bay Oysters plant by adding new, advanced technology.

The fully recirculating and refrigerated wet-storage system can hold a volume of up to 18,000 dozen small oysters, using filtered, UV treated and refrigerated sea water. This facility will ensure inventory is always available to fill orders despite weather, Vibrio parahaemolyticus (Vp) closure, or other impediments to direct harvesting. Fanny Bay Oyster is now equipped to purchase product from independent growers during the hot summer months. They are able to run product through the new wet storage facility to ensure product safety that meets the Vp control requirements set by the Canadian Food Inspection Agency.

This project clearly improved the company’s production processing capacity with the addition of controlled wet storage of shellfish.  This has improved assurance of product quality by avoiding the necessity for post harvesting processing (PHP).  In addition, the project supports many other growers who will benefit from the increased capacity at the Taylor processing plant.   These factors clearly indicate that the project has improved the economic and environmental sustainability of shellfish farming in Canada.  

Introduction

The standard practice in the BC shellfish culture industry involves the collection of product from grow-out sites and transfer to an intertidal wet storage location nearby the processing plant.  This method creates an inventory of marketable product in cargo nets, which then can be picked up either at high tide with a crane on a boat, or during the receding tide by hand and truck.  One of the challenges with this method is that anticipated orders for processing and shipment tomorrow need to be available today and ultimately during favourable tide elevation and weather conditions. 

During the warm summer months, there are strict time and temperature controls to account for development of Vibrio parahaemolyticus (Vp) bacteria that concentrate in oysters during the summer and early fall.  A good solution to this problem (the industry standard) is a land-based flow-through storage facility, designed for short-term storage of product directly at the plant, available for processing and shipment.  However, the challenge with such a system is that there is no control over the water quality parameters (salinity, temperature, food availability, etc); the shellfish are exposed to the same phytoplankton and bacteria as if they were on a beach. 

The best and most innovative solution is the deliverable of this project: a closed circuit, refrigerated, recirculating storage facility that will keep shellfish at the most optimum state immediately prior to market delivery.  In this type of system, plant personnel can control the physiological characteristics of the shellfish through control of water quality, based on the parameters determined by the Canadian Shellfish Sanitation Program (CSSP).

In this 2010 AIMAP funded project, Taylor Shellfish Canada ULC (doing business as Fanny Bay Oysters) sought to advance (1) the design of technological processes for a large-scale closed-circuit wet-storage systems for shellfish, and (2) to apply the knowledge for the validation of a process for treating oysters for Vp during the warm summer months. 

This project commenced in April 2010, and was designed, constructed and commissioned by October 2010.  The project managers and associates at Fanny Bay Oysters have confirmed this project a success and various benefits have already been accrued by the Recipient.  These include:

• Increased product wet-storage and product holding capacity by a factor of 2.4 (from 7,500 dozen to 18,000 dozen oysters);
• Increased dependability on water quality and subsequent product food safety; and
• The anticipated benefits of now being able to treat for Vp, which will allow ongoing harvest from the storage system during summertime Vp closures – the time of year when demand for fresh live oysters is highest.

Technological Advancement

This new wet-storage system is highly innovative (beyond any existing system in Canada) in three unique ways:

• Pressure transducers sense water flow changes and ‘talk’ to speed control to slow flow rates, if necessary.  This is important in that it is able to maintain water at exactly the right level, according to stated objectives; 
• Dial-out alarms allow monitoring from anywhere in the world.  The alarms are programmed to call the plant manager’s mobile phone if variables unintentionally change from programmed and stated parameters; and 
• Frequency drives control the speed of pumps by controlling the frequency of the electrical power supplied to the motor, essentially allowing the volume of water moved to match the system demand. 

These innovations are designed to be as functional and user friendly as possible, while incorporating the latest technology. In addition, the new water pumping systems are much more efficient and consume less energy relative to the former system (the former pumping system operated full time using 50 Hp pumps; the new system incorporates pumps with a maximum of 23 Hp). 

Finally the latest bio-filtration and particulate removal technology provide the plant with the most innovative and state-of-the-art wet storage system in North America. This method of using the latest technology in the design and operation of the wet storage system provides a holding capacity of 18,000 dozen oysters (increased by a factor of 2.4 ) in the hot summer months when temperature control is critical for controlling the growth of VP in oysters.

Deliverables (Results)

• This report confirms the completion and successful operation of the new wet storage project and deliverable as of August 15, 2011;
• The complete system has been built, the equipment installed to full satisfaction, and the system was fully operational during the summer of 2011;
• The system was put to test (holding up to 15,000 dozen oysters) during the hot summer months of 2011. The system continued to run in the fall of 2011 however there was no VP detected therefore no additional data was collected. However, we will continue to collect data in the summer of 2012. Communication with CFIA indicated that more data has to be collected before validation of the new technology can be granted;
• The system’s operations enable our company to continue harvest of our own product and also to purchase product from independent growers during the summer of 2011. Without the system the volume would be reduced substantially. This procedure provides great economic benefit to us and independent growers as there is an opportunity to have continued revenue in the summer months;
• The value of product which went into the market for the months of July, August and September is over half a million dollars. Without this wet storage system, that value will be at least 60 to 70% less; and
• We have increased product wet-storage and product holding capacity by a factor of 2.4 (from 7,500 dozen to 18,000 dozen oysters).

Challenges and Learning Experiences

Overall, this project is considered a major success by the Recipient and industry partners as it has advanced the technological process for a large-scale closed-circuit wet-storage system for shellfish.  In addition, in terms of 2010/11 AIMAP program priorities, this project (1) improved production (processing) systems through advancement of controlled wet-storage of shellfish, and (2) contributed to the assurance of product quality and food safety. 

Data Collection

Data was collected during summer of 2011, aimed at validating a new and certifiable system that will address the amount of time, the ideal temperature, and the water quality and chemistry that will allow oysters to be treated for Vp. 

In addition to the above mentioned (applied) project, this new knowledge will lead to a more comprehensive and scientifically rigorous project, potentially in collaboration with Fisheries and Oceans Canada’s Aquaculture Collaborative Research and Development Program. This new knowledge will provide data which will affect the decisions on regulations imposed by the Canadian Food Inspection Agency in favour of maintaining raw oyster markets for the BC shellfish farming industry year round.

In conclusion, this project provided us a temperature control wet-storage facility that has the capacity, during the hot summer months, for us to continue and increase purchase product from independent growers. This provides great economic benefit to the industry and at the same time able us to supply the market with a more temperature control product which reduces the growth of Vp. With the wet-storage facility in place and the applied science, we are now equipped to collect data which will eventually lead to CFIA indicating validation of the new technology to treat Vp.