Tecnological Innovation and Environmental Optimization for Reducing Mortality in Sablefish Broodstock Production

Table of contents

• Executive Summary
• Background
• 1. Turbine Pump Results
• 2. Broodstock Heat Exchanger Energy Recovery Results
• 3. Ultra-sound project Results
• 4. Header Tank/UV/OZONE/FRACTIONATOR/GAS STRIPPING TOWER/PH Control Results
• Summary of results

Executive Summary

Producing a large supply of high quality juveniles has been the primary limiting factor to establishing a Sablefish aquaculture industry. The goal of this AIMAP was to address some of the obstacles that are reducing hatchery production by implementing technology that increases productivity and enhances Sablefish Canada’s environmental sustainability. This AIMAP allowed Sablefish Canada to purchase the necessary equipment to increase the reliability and quality of the water entering the hatchery, to reduce its electrical consumption by employing heat exchangers, and to increase our knowledge of assessing broodstock sexual maturation using ultrasound equipment. The project has been successful in attaining these three goals.

Hatchery production has increased from 10,000 fish in 2009 to 300,000 in 2010 as a result of this AIMAP grant. The return on investment from the $106,000 AIMAP award is eleven times or $1,200,000 calculated as the 2010 increase in production at a market value of $4 per fish. Total production for 2010 is currently estimated at 300,000 juveniles but may be higher as later 2010 hatchery batches are produced. This increase in production is largely due to the improvements funded by the 2009 AIMAP program.

Background

Sablefish Canada’s hatchery intake water supply was prone to frequent supply interruptions caused by mechanical breakdowns of submersible well pumps due to saltwater corrosion. The submersible motors needed to be replaced twice per year and the pumps every 18 months. The installation of above-ground turbine pump motors has eliminated frequent water supply interruptions because the above-ground pump motors are not as prone to failure as submersible pumps. The new turbine pump should operate for two years before needing replacement.

The second problem addressed was that laboratory analysis revealed that the hatchery intake water quality was substandard because it had unacceptable levels of naturally occurring bacteria and dissolved nitrogen gas. A water treatment system was installed to remove the dissolved nitrogen gas and bacteria from the hatchery intake water. At the same time, SFC saw an opportunity to reduce its environmental footprint by installing a heat exchanger to recover the cold from the discharge water thereby lowering electrical consumption. This project is installed and is saving $6,832 in electrical consumption annually.

The final aspect of this project was the leasing of an ultrasound machine to test whether ultrasound technology could be useful for assessing sexual maturity in Sablefish broodstock. This fieldtest has proven that ultrasound technology can be a very effective tool for determining the sex of Sablefish and their degree of sexual maturity.

The 2009 Sablefish Canada AIMAP project consisted of the following sub projects:

1. Turbine Pump Results

The objective of this project was to decrease the frequency of well pump failures caused by seawater corrosion. A new vertical turbine pump replaced the submersible pump in well #2. The submersible pump motor had been failing twice a year and the submersible pump failed every two years. The turbine pump was installed in March 2010 and has been working without any technical problems since. The well yield increased from 120gpm to 160gpm as a direct result of changing pump styles. With the motor out of the water, the pump should not electronically fail, as has been the case with submersible pumps. Hatchery crew installed a ventilated security shroud and poured a concrete foundation for the motor stand. 

2. Broodstock Heat Exchanger Energy Recovery Results

The objective of this project was to increase environmental sustainability by installing a heat exchanger to recover the cold from broodstock discharge water thereby lowering electrical consumption. A titanium heat exchanger, a pump, pipe and fittings were purchased and an electrician installed and commissioned the pump circuit. Temperature measuring thermistors were installed and a data-logging application was programmed. The project is complete and has performed to its designed specification. The equipment is expected to last ten years with a projected energy saving over that time of $68,320, a ten-year return on investment of about 2.5 times. The goal of the project was to recover 2.5 degrees through the heat exchanger and this is exactly what the system has provided.  Hatchery crew did the installation and plumbed the heat exchanger so that flow could be reversed to CIP the heat exchanger with minimal effort.

3. Ultra-sound project Results

The objective of this project was to evaluate whether ultrasound technology could be used to assess Sablefish broodstock sexual maturity and to differentiate males from females. The project is ongoing but preliminary results indicate that ultrasound is a very effective tool for determining the sex of Sablefish and their degree of sexual maturity. Sablefish Canada leased a Micro Max ultrasound machine for five years and is developing protocols for scanning Sablefish broodstock. It is hoped that techniques can also be developed to allow staff to measure individual egg size and to sex broodstock and differentiate developing from immature female broodstock without the need to biopsy them.

The ultrasound was acquired through Dr. Andrew Bronson via Digital Vet Imaging. Dr. Briony Campbell and Dr. Hamid Marvasti of Sablefish Canada have developed standard operating procedures to determine males from females and immature from mature fish. To date we have been unsuccessful in consistently measuring egg size with the ultrasound. The advantages of ultrasound are that it provides us with the ability to select and carry appropriate ratios of male and female broodfish by predetermining their sex before transporting them back to the hatchery. By separating maturing females from immature females early, salinity can be controlled for these maturing fish. We still require a biopsy to determine implant timing for mature female broodfish due to our inability to consistently measure individual egg diameter. One needs to measure to an accuracy of 0.1mm to do this.

The project succeeded in significantly reducing the number of broodstock that would otherwise need to be anaesthetized for biopsy. It is a tremendous tool in broodstock management and should significantly decrease broodstock mortality. Dr. Campbell has recently completed writing the ultrasound manual and will forward a copy to DFO and NSERC. It can be freely distributed to any parties interested in the use of ultrasound.

4. Header Tank/UV/OZONE/FRACTIONATOR/GAS STRIPPING TOWER/PH Control Results

The objective of this installation was to improve substandard hatchery water quality that had unacceptable bacterial and dissolved nitrogen gas levels. A water treatment system was installed to remove the dissolved nitrogen gas and bacteria from the intake water. The project involved purchasing and installing an integrated fiberglass header tank water treatment center for all incoming hatchery water. It was designed to treat up to 250gpm as a multipass unit.
 
Water is supplied to a large degassing tower and fills a large primary fiberglass treatment tank. A large in-line fan supplies air into the degassing tower counter-current to the water flow at a ratio of 10 to 1 (gas to liquid ratio). Water is pumped from the primary fiberglass treatment tank into a large fiberglass fractionator at the rate of 300gpm. The fractionator is supplied with ozone and air. The water leaves the fractionator and goes through a powerful twelve-bulb UV unit into the second large fiberglass supply tank. The UV system is designed to deliver 180,000 microwatts/cm2 at 250gpm. This was based on a water sample that calculated the water transmissivity at 88%. The UV also destroys residual ozone left in the water. The fractionator supplies a very efficient mixing chamber with a high turnover rate. It is the second fiberglass tank that supplies the hatchery with water. The combination of both fiberglass tanks greatly increases volume compared to the original header tank system. This added volume gives the hatchery an added safety margin with respect to after hour emergencies. 

The system is called a “multipass” system because the 300gpm fractionator pump moves more water than the 180gpm demand at the hatchery. The extra 120gpm overflows back through an equalization pipe that links the supply tank back to the primary treatment tank and re-enters the treatment system for another pass. This project involved design, site preparation, a large electrical upgrade and a significant amount of plumbing. Hatchery staff did the installation and Ware Electric did the electrical upgrade.

Following installation, bacterial sampling was conducted pre and post UV. Microtech conducted colony counts on the samples and found pre treated water contained 80 colonies per 100ml and post treatment contained 0 colonies per 100 ml. This project has been a complete success with bacteria colonies eliminated from the hatchery intake water and nitrogen gas removed.

Summary of results

The AIMAP funds supplied to Sablefish Canada successfully addressed some of the obstacles that were limiting hatchery production and the commercial viability of Sablefish aquaculture. The production of a large supply of high quality juveniles has been the primary limiting factor to establishing a Sablefish aquaculture industry. The AIMAP project achieved the goal of increasing hatchery production from 10,000 in 2009 to 300,000 in 2010. Installing the heat exchangers increased our environmental sustainability by reducing our electrical consumption by $6,832 a year. The AIMAP funds also allowed Sablefish Canada to advance scientific knowledge related to Sablefish aquaculture by developing ultrasound technology protocols to enable the industry to reliability sex Sablefish and assess broodstock sexual maturation. The return on investment for the $106,000-2009 AIMAP grant is eleven times based on a 2010 hatchery production of 300,000 fish at $4 per fish.