Improving Productivity through Mechanization and Automation of Mariculture Operations

As part of improving productivity through mechanization, several projects have been completed. First project: Optimizing equipment for harvesting mussels at sea

Loss of mussels by dropping out can represent a significant financial loss for a marine farmer. Research into available technologies identified a new type of harvester in the Netherlands that is based on the venturi principle. This harvesting system draws in water at the same time as the mussel sock, detaches the mussels from the sock, and drives them onto the deck with the water. The main objective of the project was to test the effects of the harvesting method on loss from dropping out. The high heterogeneity observed on the socks made analysis difficult, but underwater observations confirmed that the venturi harvesting method results in lower loss than the conveyor harvesting method. The second objective was to compare the effectiveness of mussel sorting by the conventional drum declumper and by the conveyor sorter of the venturi system. The harvesting method associated with the drum declumper provides better sorting efficiency than the conveyor sorter of the venturi system. The percentage of commercial-size mussels collected at the end of the sorter was 83% for the drum declumper and 75% for the conveyor sorter of the venturi system. The third objective was to compare the harvesting methods in terms of labour time. Extrapolating measurements taken during the tests, collection of a complete longline would represent 4 hours of work with the venturi system and its sorter, while it would require 9½ hours for the same work with the conveyor coupled to the drum declumper. Consequently, the venturi system is 3.4 times more efficient.

Second project: Optimization of harvest and separation of softshell clams using mechanical equipment

The objective of this study is to increase yield from harvesting and sorting operations through the design of a new harvester-sorter using the hydraulic rake principle. There are many requirements for harvesting clams. P.G.S. Noël uses a 30-foot catamaran to reach the operating site and to transport equipment required for the harvest. The prototype must therefore be light and portable. It was determined that removing the clams from a submerged environment was the best way to harvest them without breaking their shells. The machine must be able to sort clams of commercial size or smaller, or to collect spat. After many discussions, we have come up with a venturi-type device. The viability and effectiveness of this type of system were demonstrated after tests with this device. The advantage of using a venturi is that it does not require any additional mechanics because jets are used to remove silt from the clams. The clam harvester began to take shape in the summer of 2008. The basic design involves jets and the venturi mounted on a frame equipped with wheels to transport it. The machine was constructed and trials were conducted based on this design. With the design concept proven, further work began the summer of 2009. The components or tools necessary to render the harvester operational were closely studied to ensure mechanical simplicity while allowing for ease of use.

Third project: Developing a decoiler to improve performance of the mechanized socking operation

A prototype decoiler intended to facilitate deployment of rope coils was developed. This prototype was designed to facilitate socking of mussel spat in the oyster industry. During this operation, work must often be interrupted because the rope gets tangled. The decoiler prototype consists of two sub-assemblies, each with a specific function. First, there is the tank itself. The decoiler operates so that the rope is always kept suspended in the water, to keep tension as uniform as possible and to get a better sock. The second sub-assembly of the system is the gooseneck. This device also acts to help maintain a uniform tension on the rope. Even though the tank system greatly helps the rope unroll smoothly, the occasional tangle may occur. The gooseneck offsets this effect. The device weighs roughly 140 pounds and costs about $2,700 to build.

Fourth project: Developing a mechanized washer for floating buoys used in mariculture longlines

As with the sock and other parts of a submerged floating longline, the buoys that support them capture spat of mussel and other epibiont species. To avoid compromising buoyancy and risking the droppers touching the bottom, buoys are cleaned several times during the mussel growth cycle. Various principles were envisioned when designing the buoy washer. The three concepts explored for the buoy washer are: cleaning using scrapers (including blades, combs, rings, etc.), pressure cleaning and cleaning using brushes (fixed brushes or power-driven brushes). After certain failures with the original ideas, the idea emerged for a tunnel into which the buoy is inserted and cleaned by steel cables under pressure. This cleans buoys 12 to 16 inches in diameter without the need for any complex machinery. Results overall were satisfactory. Approximately 75 to 80% of the dirt, regardless of type, was removed after passing through the washer. For best results, the buoy can be passed through the washer a second time and directed; this removes 90 to 95% of the dirt. We observed that using the cleaning machine does not slow down operations on deck. After recording several times, the average cleaning time while harvesting was 7.5 seconds–however, this can vary from 3 to 17 seconds, depending on the line speed. It is not necessary to have one person solely responsible for cleaning, as the same person can be doing something else, which facilitates each person's tasks. It is much less tiring to clean using the washer. The buoy washer's cleaning quality is satisfactory; it spares employees considerable repetitive movement, costs them no time and at an acceptable cost.

Projects validating the growth and survival hypotheses in commercial scallop culture using the ear hanging system in the Magdalen Islands, and evaluating the impacts of mechanizing operations involving ear hanging culture on scallop growth and survival are part of Q1, but were financed by other institutions.

The final Q1 project involves stabilizing anchors for clam culture lines and will be tested this summer (2010). Note that the equipment for this project was designed and built in the fall of 2009. However, given the unavailability of the marine farmer involved in the project, trials could not be conducted as originally scheduled.