Optimization of hatchery-nursery practices for production of sea scallop spat in 10-m3 tanks

Final report
Fermes Marines du Québec Inc.
AIMAP-2011-Q01

Background

As part of Phase 1 of the AIMAP-funded project, Antoine Dumais Roy, an aquaculture technician, was hired by Fermes Marines du Québec Inc. (FMQ) in accordance with the Contribution Agreement signed on May 27, 2011. This agreement included financial support to hire one aquaculture technician for fiscal year 2011-12, being from April 1, 2011, to March 31, 2012, and translate this report into English, for a total amount of $17,750.

As previously mentioned, this report summarizes Phase 1 of the project aimed at optimizing hatchery-nursery practices. The two main activities for this phase were the following:

Activity 1 – Performance optimization of the 10-m³ larval tanks

Activity 2 – Use of a settlement room and optimization of nursery equipment

Phase 1 of the project arising from these two activities thus consisted of launching optimization activities pending Phase 2 of the project, in preparation for the aquacultural production phase, supported by the hiring of a biologist. Construction of the hatchery-nursery was already underway during preparation of the AIMAP application for Phase 1 of the project and is still ongoing, although the work is essentially done. As farming operations are scheduled to start in April, Phase 2 of the project will be able to start as soon as Phase 1 is completed, with no down time.

The technician hired was able to achieve the objectives set for the first phase of the project in spite of the unfinished and ongoing nature of construction work. More specifically, Mr. Dumais Roy achieved the following five specific objectives, which are prerequisites for any commercial farming operation and which fall under the two main activities of Phase 1 of the project:

Objective 1:      Monitoring hatchery system construction to ensure compliance with engineering drawings

Objective 2:      Testing flow rates and other equipment parameters

Objective 3:      Systems tuning (water circulation, heating, aeration, filtration, and sterilization)

Objective 4:      Familiarization with and configuration of the automation software

Objective 5:      Revision of commercial farming protocols

These steps all moved the hatchery-nursery project along and prepared the technician for the tasks awaiting him once the organisms are introduced into the various rooms of the building. This can only help optimize farming performance, as each piece of equipment and system will be set to receive the organisms in accordance with its intended function.

The technician's activities during Phase 1 were therefore focused on optimizing the performance of the larval tanks and their systems and components, as had been done for the settlement room and nursery equipment.

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Objective 1 – Monitoring hatchery system construction to ensure compliance with engineering drawings

Description

Engineering drawings produced by the consulting firm initially hired had to be reviewed by an external firm in order to verify that the specified systems were appropriate and in working order. This provided the technician with an opportunity to become familiar with the various systems planned and to be involved in reviewing the drawings, allowing him to contribute his knowledge and suggestions for even more optimal systems.

Methodology

From the moment he was hired by the company and until such time as the external firm left the project in September 2011, Mr. Dumais Roy undertook to become sufficiently familiar with the engineering drawings to have a thorough understanding of the various systems planned. He therefore went over construction, electrical circuitry and water circulation drawings for each room in the building. He spent several hours a day with the two engineers from the external firm and with Jean-Philippe Hébert, the project proponent. He studied the drawings until he understood them thoroughly, and was then involved in their review, sharing the knowledge he had acquired through his education and in his previous job with Merinov.

Once he was thoroughly familiar with all the building systems, and using his relevant expertise, Mr. Dumais Roy also took part in the decision-making process relating to selection and purchase of equipment components for each room, to ensure that they met optimal performance specifications and the strictest sanitary standards. With the engineers' help and in collaboration with other FMQ technicians, Mr. Dumais Roy identified appropriate selection criteria for each piece of equipment, be it for water circulation and treatment or for the farming systems proper, according to the initial specifications in the engineering drawings. He then contacted various suppliers and manufacturers and ordered the selected equipment for the hatchery, settlement and nursery rooms.

Results

Although engineering drawings are not necessarily easy to understand, Mr. Dumais Roy quickly displayed an outstanding ability to adapt in the way he undertook to learn the jargon used in this type of drawings, particularly the legends, abbreviations, symbols, scaling, line thickness and the various themes addressed in such drawings. As a result, Mr. Dumais Roy developed a thorough understanding of the drawings which, to this day, means that he knows exactly where each piece of equipment is located in the building and can therefore quickly troubleshoot any issue or equipment malfunction.

While Mr. Dumais Roy's involvement in revising the drawings with the two engineers also enhanced his understanding of the systems, most importantly, it resulted in the optimization of some of the systems, including the hatchery room water circulation system, which is more complex than, say, the nursery room system, as Mr. Dumais Roy was able to share his expertise on the operation of such systems. This led to parameter optimization for some of the equipment, such as power requirements for pumps and ultraviolet sterilizers, and filter effectiveness. His involvement in pipe and duct configuration design for water circulation drawings resulted in easier installation of those systems and, more importantly, a configuration that leaves the space occupied by the 15 10-m³ tanks uncluttered, thus making it easier for FMQ staff to perform their tasks and improving room safety.

Also with a view to optimizing the performance of hatchery tanks and nursery equipment, Mr. Dumais Roy's involvement in selecting and purchasing equipment components, be it for water circulation, water processing, or tank operation, meant that fully functional systems with properly dimensioned components compliant with engineering drawings specifications were installed, which only required tuning prior to the start of farming operations.

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Objective 2 - Testing of flow rates and other equipment parameters

Description

Once the hatchery-nursery equipment components had been delivered, Mr. Dumais Roy supervised their installation and checked that they worked properly. Several preliminary water flow rate tests were also performed during fall and winter 2011 in preparation for introducing the organisms in the tanks, scheduled for spring 2012.

Methodology

Delivery of the various pieces of equipment took place gradually over the course of the summer and part of the fall of 2011, according to manufacturer- or supplier-imposed timelines. Each time a piece of equipment was delivered, it was added to the inventory list and engraved, and warranties and instruction, maintenance and service manuals were duly read and filed for easy retrieval as required. This document filing may seem quite simple and slightly out of context, but in practice it is entirely consistent with room optimization, because if equipment breaks down and none of the employees present knows how to perform the proper repairs or the relevant warrantee is nowhere to be found, significant delays and costs associated with restoring full room functionality can ensue, leading to a direct drop in performance.

Every component delivered was inspected upon delivery then tested to ensure that it worked properly. The following describes the checks performed for each component. 

Water pump: Check direction of rotation. Ensure that there are no leaks. Once the automation software is installed, check that each pump starts when control screens indicate it is turned on.

Air pump: Check that pump motor is turning when pump is turned on. Check that the safety valve is functional.

Sterilizer (UV treatment): Check that there are no leaks when saltwater flows through the sterilization system. Ensure that system grounding complies with manufacturer specifications.

Automatic valve: Check which way the valves open. Ensure that they can open and close on demand.

Plate exchanger: Check that exchangers are securely attached to the floor. Ensure that there is no fluid leaking between the plates.

Bag filter: Check that there is no leak in piping connected to filter. Check that all pressure gauges work properly.

Sand filter: Check that there are no leaks in piping connected to filter. Check that all pressure gauges work properly. Order filter medium and install it in each sand filter.

Heat pump: Check that there are no glycol or (hot) freshwater leaks. Coordinate start-up tests with manufacturer.

Propane heating: Build propane inlet trench. Test and adjust units with propane supplier. Plan and supervise installation of air inlet and gas outlet stacks. Check that flow switches work properly.

Mr. Dumais Roy supervised the installation of all these components and their connection to the piping systems to ensure that it was done in a sustainable, safe manner that complied with specifications for each of component. Priming of the system as a whole was done only once all the components were installed, in January 2012.

During summer and fall 2011, Mr. Dumais Roy reviewed the FMQ experimental protocols to assess whether water changes planned for the hatchery, settlement and nursery tanks were optimal for growth and survival of the farmed species. He then checked if data obtained based on these requirements were consistent with the systems being assembled. Thus, it was possible to start preliminary flow rate tests in January to compare theoretical data compiled over the course of the previous summer and fall with operational data recorded after priming the system.

For instance, it had been determined that, for optimal larval rearing, each 10-m³ tank would undergo pre-determined water changes per day per tank. Theoretical data were based on water quality requirements for the species, as well as feed retention capacity in the tanks. If flow rate is too high in a larval tank, feed retention capacity and hence larval growth both decrease. Conversely, too few water changes in the tanks means reduced new water input and increased concentrations of toxins from waste production by the organisms, leading to unwanted bacterial proliferation and lower overall survival rate in the tank. Although these data are theoretically relatively easy to obtain, things are different in practice. While it is relatively easy to set automatic valves to produce any number of water changes in 24 hours, incorporation of other data and flow rates makes things somewhat more complicated, as the hatchery water circulation system was designed for constant flow in the tanks under normal operating conditions. However, other measures are planned to increase larval survival, such as the complete emptying of the tanks on a regular basis to allow them to be cleaned and disinfected. A scientific activity is linked to this technical requirement, namely qualitative and quantitative observation of the larvae, as well as their sorting.

Thus, it was theoretically easy to set up a constant flow rate of x m³ in 24 hours and a weekly increase in flow rate to, say, 3 or 5 m³ per hour, so that a tank can be filled in one shift. The challenge was to then try to apply these high fill rates and assess the overall behavior of the system. Some of the questions needing to be addressed during the tests were as follows: Does water level in the stock tanks fluctuate significantly when valves are opened to a greater extent that usual? Is pump power sufficient for efficient filling without putting too much strain on the equipment? Is the contact period for water passing through the UV sterilizer sufficient to allow for effective sterilization?

To answer these questions, Mr. Dumais Roy tested different water circulation flow rates in January and February 2012 and observed the behavior of these various components and the overall system status as the flow rate of water entering the hatchery gradually increased. He tested flow rates for single tank filling then for simultaneous filling of two tanks and even three tanks, while keeping track of the overall system status, as simultaneous filling of several tanks at relatively high flow rates could lead to significantly enhanced tank performance and productivity.

Results

Equipment checking and classification upon delivery made it possible to set up the various systems in each room using equipment that was working properly and ready for use.

Setting water flow rates based on the results of previous testing meant that the rooms were ready for the automation software to be tuned. Preliminary manual testing of flow rates made programming of water circulation parameters in the automation system relatively easy, as basic flow parameters were already known.

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Objective 3 – Systems Tuning

Description

After all equipment components were installed (see Objective 2), the various systems had to be tuned to comply with larval and post-larval farming protocols. Thus, it was possible to check whether parameters used in experimental trials done in previous years could be applied to large-scale systems such as those for the 10-m³ tanks. The systems tested included the water circulation, heat exchange, aeration, mechanical filtration, sterilization and larval sorting systems.

Methodology

Water circulation: Once the flow rates for water entering the tanks were set, water outflow had to be tested to avoid overflowing, which could spell disaster for the organisms. Indeed, during experimental rearing runs, one of the main causes of mortality was linked to overflowing.

Pelagic scallop larvae are very small (60-250 µm) and can therefore exit a tank along with the outflowing water if no device is used to prevent them from doing so. The device most widely used for this in mollusc farming is called a “banjo”, and usually consists of a relatively large-diameter cylinder fitted with a membrane filter. Once a banjo is fitted to the water outlet, everything in the tank is filtered to allow only the water to go through, and not the larvae. In experimental rearing runs by FMQ, two problems were identified: banjos could lead to overflowing or allow larvae to escape with the outflow water. Overflowing was mainly due to phytoplankton clogging the membrane filters, causing the water level to rise in the tank until it overflowed, thus allowing larvae to escape. The type of membrane filter used was also linked to larvae escape. Mr. Dumais Roy studied the problem and determined that “nytex” type nylon membrane filters became deformed after being washed a few times with chlorine (used to disinfect the equipment). He measured mesh size under the microscope and noticed that, after several immersions in chlorine, stretching of the mesh had occurred. After several cleanings, a membrane that had filtered out 60-µm particles would allow particles larger than 80 µm through. This accounted for the decrease in larval density observed during experimental rearing trials carried out in previous years.

Because clogging by phytoplankton was the main cause of overflowing, Mr. Dumais Roy examined the situation by reviewing feeding frequencies and phytoplankton cell concentrations in the tanks. A review of feeding approaches used in experimental rearing runs allowed him to identify possible ways to reduce the risk of banjo clogging, such as decreasing flow rate during and after feedings to allow larvae to consume the phytoplankton before it gets sucked towards the outlet. He also considered reducing phytoplankton concentrations during a given feeding sequence while increasing the frequency of feedings in a given day as another possible solution.

Various banjo prototypes were also developed with different shapes and cylinder diameters. Mr. Dumais Roy also contacted various membrane filter manufacturers and finally found a polyester-based membrane that does not deform when washed with chlorine. The most promising banjo prototype was then installed in one tank and feeding frequency tests were performed using algae paste-based phytoplankton solutions provided by Nutrocéan. While maintaining the basic daily phytoplankton concentration to be fed to the larvae, Mr. Dumais Roy experimented with different feeding frequencies, including once, twice and three times per day, and compared the results.

In order to minimize the risk of overflow (each overflow event leads to a significant reduction in performance for the 10-m³ tanks due to larvae loss), Mr. Dumais Roy endeavored to make a level float prototype (see Objective 4: Familiarization with and configuration of the automation software), which is used to slow or even stop water supply to a tank when water level rises too quickly as a result of the banjo becoming clogged. The addition of a level float device is an extra water circulation system safety feature that minimizes drops in tank performance by increasing larval survival.

Aeration: Larval tank aeration is required for organism survival for two reasons: it ensures a steady input of dissolved oxygen and sufficient water mixing for the swimming of pelagic larvae. As no aeration-related problems were noted during experimental rearing trials, Mr. Dumais Roy simply reused the same aeration method for the large volume tanks. He did, however, set air inlets at different heights in the tank (rim, middle, and halfway between these two positions) to see what the effect on water mixing would be. Finally, he experimented with various diameters for the flexible pipes (which bring air from the intake pipe to the tank) to see if one was optimal.

Heat exchange:  Heat exchange adjustment is done through a plate exchanger system which uses propane heated water to heat glycol, which in turn preheats the water entering the tanks through plate exchangers. Opening of the valves that control this heating system is controlled by the automation system so as to maintain temperature in the tanks. As larval rearing requires constant water temperature at all times, the automation system was tested to ensure that there would be no significant temperature variations. Mr. Dumais Roy monitored water temperature in the tanks during complete filling of a 10-m³ tank and over the course of an entire week, during which water temperature in a given tank was measured twice a day.

Mechanical filtration: Filtration effectiveness in experimental farming runs done by FMQ was in the order of 5 µm, due to constraints related to water inflow originating from the MAPAQ in Grande-Rivière, who provided the saltwater. To avoid any risk of contamination by unwanted microorganisms, FMQ increased filtration effectiveness for larval rearing in the hatchery, which is the stage at which young scallops are most vulnerable. After pumping at sea, the filtration equipment sequence is the following: drum filter, sand filter, #1 cartridge filter and #2 cartridge filter.

Mr. Dumais Roy checked that filtration effectiveness was perfect at the end of the mechanical filtration sequence. To do so, he collected 100 L of water which he ran through a 1-µm phytoplankton net to collect suspended particles. He then looked at the screened particles under the microscope to measure them and ascertain the effectiveness of the mechanical filtration sequence.

Sterilization: Because the company does not have the necessary microbiological laboratory facilities, assessing the effectiveness of UV filtration is more difficult than assessing the effectiveness of mechanical filtration. However, Mr. Dumais Roy did check that the water flow rate through the UV tubes did not exceed manufacturer specified flow rates, which allow for a sufficient contact period to kill all pathogens or unwanted microorganisms.

Larval sorting: As this operation, which is designed to optimize larval growth and survival, is to be performed on a weekly basis, properly sized and operational sorting equipment is essential. Mr. Dumais Roy built a sieve prototype that will be tested with organisms as soon as the first eggs are laid. As with the banjos, research was done on the optimal type of filter membrane to use.

Results

The various water circulation, heat exchange, aeration, filtration and sterilization systems are ready and operational, which means that the rooms are ready to receive organisms for farming operations. This preparation phase also allowed the technician to become familiar with the operation of the various rooms in commercial production mode, which will facilitate the introduction of organisms by reducing mortality risks related to system malfunctions.

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Objective 4 – Familiarization with and configuration of the automation software

Description

Programmable logic controllers (PLC) were installed in the hatchery to increase the safety of the stocks and to optimize energy efficiency. As these types of controllers are quite complex and sophisticated, Mr. Dumais Roy first had to learn how to use them by assisting the programmers hired to program the units according to the target rearing parameters for the hatchery-nursery.

Methodology

Because the automation software controls the hatchery building as a whole, Mr. Dumais Roy was involved in building and installing the control panels and in setting the various parameters to be controlled for each room in the hatchery.

Quarantine room: The quarantine room includes two water supply systems, which goes through the UV sterilizer prior to being supplied to the tanks. A valve system was installed at the outlet to the quarantine room to either send the water directly back to the sea (when the room is only used as a vivarium for stocks that are not quarantined and whose water has not been heated) or through a 1-µm filtration system, after which it is sterilized with the UV sterilizer when the organisms are put in containment. The technician's primary task was to ensure that piping was put in properly before the concrete was poured and to calibrate the automatic gutter pumping system for filtration of water to be sent back to sea. He was also involved in testing and calibrating the flow rate and heating automation system for water entering the quarantine room.

Spawner room: The spawner conditioning room only includes tanks. Mr. Dumais Roy checked that each tank could contain the preset amount of water. When the room was built, he checked that the installation of emptying and overflow piping complied with drawings prior to pouring of the concrete slab comprising the gutter, and tank bottoms and walls. He then ascertained that the right amount of filtered water was supplied through the three water inlets. Mr. Dumais Roy was then involved in testing and calibrating the flow rate and heating automation system for inlet water in the three lines supplying the spawner room.

Egg-laying room: The egg-laying room contains circular 10-m³ tanks with cone-shaped bottom. Mr. Dumais Roy supervised the hook-up of water and air inlets to these tanks to ensure that they were in accordance with the continuous water distribution system used in Norway. He also took part in the design, material take off, costing and building of a work platform for two to three employees, to be used for all tanks during egg-laying operations. He then checked the amount of filtered water supplied through the water inlet. He was also involved in testing and calibrating the flow rate and heating automation system for water entering the egg-laying room.

Hatching room: The hatching room contains  circular 10-m³ tanks with cone-shaped bottom. Mr. Dumais Roy supervised the hook-up of the three water and air inlets to these tanks to ensure that they were in accordance with the continuous water distribution system used in Norway. He then took part in the design, material take off, costing and building of a work platform for one employee, to be used for all tanks during cleaning, as well as larvae recovery and sampling operations. He also checked the amount of 1 filtered water supplied through the three inlets, and he was involved in testing and calibrating the flow rate and heating automation system for the three water lines supplying the hatching room.

Once the systems were primed, Mr. Dumais Roy was involved in setting up the automated high- and very high-water level alarm system (Figures 15 and 16). To prevent overflow from clogging of the banjo filters, a light beam device was rigged on all three water lines into each tank fed by distinct supply pipes. When the high-level float in a tank blocks the light beam, the automated system controller reduces the rate of supply water flow until the light beam is no longer blocked by the float. If water level still continues to rise and the high level float blocks the very-high level light beam, the system controller shuts down water supply from the line and sounds an alarm. Installing this system proved to be a rather complex process, because of problems with crossing light beams, which meant that the float systems were not as effective and reliable as intended. After trying several different float and beam alignment system prototypes, the company now has a safe, reliable overflow protection system.

As with the other rooms, Mr. Dumais Roy took part in the design, as well as material take off and purchasing for the hatching room. He was also involved in building a larvae recovery system for ascertaining the effectiveness of the banjos. This system consists of piping to collect water coming out of the tanks. This water is run through mechanical filters. Samples can be collected from the filters and examined under a microscope to see if larvae are escaping from the tanks in the event that one or more banjo filters are torn or have otherwise become ineffective.

Settlement room: The settlement room contains raceway-type 10-m³ tanks. Mr. Dumais Roy supervised the hook-up of water and air inlets in these tanks to ensure that they are in accordance with the continuous water distribution system used in the Norway nursery. The water inlet is divided into three supply lines, for which the main flow rate is controlled through an automated modulator valve similar to valves used in other systems. He then checked the amount of filtered water flowing in through the three inlets. He was also involved in testing and calibrating the flow rate and heating automation system for the main water line supplying the settlement room. Once the tanks were filled, the high-level and very-high-level float system was installed. Tuning this system turned out to be easier than in the hatching room because the light beams and their sensors are much closer to one another. The experience gained in setting up the hatching room system also contributed to the successful installation of this system. A single light beam system controls five raceway tanks. When differences in water level are detected, the controller activates the modulator valve for the relevant segment of the main water supply to the settlement room.

Automation control panel: Four touch-screen panels were placed in strategic locations in the building for easy control of key parameters. The screens display critical information about the overall status of the system. To ensure that they work properly, Mr. Dumais Roy spent several days planning the design of the screens with the programmers in charge of construction to ensure that all relevant processes would be clearly identified and functional. The technician also ensured that all critical information would be displayed on the screens so that relevant parameters could be adjusted.

Once the interface was developed, it was necessary to check that each device sent the proper information. Pump and flow rate controls, as well as touch-screen routines, such as the automated back wash cycle and the internal-pressure controlled sand filter rinse routine, had to be checked to ensure that they worked properly. A first test with the touch-screens led to the identification of some key missing control parameters, such as on-screen setting of initial pressure during sand filter cleaning cycles and of the duration of back wash and rinse cycles. Mr. Dumais Roy also had to calculate water requirements for the filtered water system to ensure that in-line pumps could automatically respond to these requirements and that the sea pump flow rate would reflect the overall water supply requirements for the building, in order to minimize pumping costs.

Automated control system start-up: In collaboration with the plumbers, electricians and other technicians, Mr. Dumais Roy checked that all control systems selected by the engineers complied with requirements pertaining to the use of electrical devices in saltwater and with initial design specifications as to performance and precision. Many issues were raised, which led to changes being made to the selected devices. Mr. Dumais Roy then saw to it that connection and installation of these devices complied with engineering drawings. After system priming, all piping and devices (filters, water heaters, heat pumps, heat exchangers, manual valves, automatic valves, air hook-ups, pumps, etc.) were checked. After the water circulation system was filled by gravity to repair any leaks, water pressure in the system was gradually increased manually. Any instrument, device, or piping that was found to be leaking was fixed or replaced as problems were detected. Once proper functioning of the overall water circulation system was ascertained following this manual start-up step, the automation system was activated. Configuration, calibration, and testing of this system took several weeks.

Results

The automated control system is now operational and ready for commercial farming operations. Automated remote control of water circulation parameters and equipment will allow for enhanced room control and will increase employee productivity, as employees will have more time to tend to the organisms instead of dealing with equipment issues. This, in turn, will translate into more productive commercial farming operations.

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Objective 5 – Revision of commercial farming protocols

Description

Based on knowledge garnered during system development, assembly and tuning, changes were made to the protocols so that they would reflect actual project conditions.

Methodology

As the commercial farming protocols were prepared prior to construction of the building, Mr. Dumais Roy set out to review them and made some technical changes to reflect the results of new tests done in 2011. All sections of the protocols dealing with water circulation systems and their components were thus modified and adapted to the new project conditions. The scientific and biological aspects of the protocols will need to be revised once farming operations get underway, as part of Phase 2 of the project.

Results

The company now has technically up-to-date commercial farming protocols and is ready to launch its sea scallop farming operations for all life stages of the species.

Conclusion

The five objectives described above moved the hatchery-nursery project along and allowed Mr. Dumais Roy to become thoroughly familiar with all the tasks awaiting him when the organisms are introduced into the tanks. This can only help optimize performance of the rearing operations, since every component and system will be ready for its intended use. Thus, Phase 1 of the project has been successfully carried out, with all its objectives achieved.

However, as the amount of work required turned out to be significantly greater than expected, Fermes Marines du Québec had to hire two new aquaculture technicians, éric Hamelin (on July 18, 2011) and Mr. Guy-Pascal Weiner (on August 23, 2011), both graduates of the école des Pêches et de l'Aquaculture du Québec, to assist Mr. Dumais Roy in carrying out the work described in this report. They were of particular assistance to Mr. Dumais Roy in tuning the various hatchery-nursery systems and revising the commercial farming protocols. FMQ covered both Mr. Hamelin and Mr. Weiner's salaries, as under the current AIMAP agreement, this work was to be performed by a single technician.