Specialized Operating Platform for the Husbandry of Mussel Lines and Management of Invasive Species

AIMAP-2009-G09

Table of contents

• Background
• Challenges and Delays
• Site Trials
• Future Plans

Background:

Prince Edward  Island (PEI) mussel growers have been challenged by an increasing degree of marine bio-fouling on mussel lines which have an adverse effect on their product including poor growth rates, diminished quality, and reduced yields. The chief concern has been from invasive species of tunicates which are practically unmanageable due to their rapid rates of growth and reproduction. Existing control techniques are time and labour intensive significantly increasing input costs for growers.

PEI Mussel Farms, Morell, Prince Edward Island is a large scale mussel growing company which has been in business for 30 years. The company has been working on an innovative solution to address the bio-fouling problem that can apply to its operation in a way that is fiscally viable.  On June 13, 2010, the company conducted sea trials on the above referenced project.  This was the culmination of an 18-month intensive effort and investment on the part of the company along with substantial support from the government of Canada through the Department of Fisheries and Oceans Aquaculture Innovation and Market Access Program (AIMAP) and the Atlantic Canada Opportunities Agency.

The goal of the project was to develop and build an apparatus that would be able to clean mussel lines under the surface of the water. The cleaning system was to be attached to a specialized platform.  A single operator would be able to do the work of several boat crews and in much less time.

Challenges and Delays:

Because of the timing of the project, it became apparent that sea trials would need to be delayed until the spring of 2010. While the specialized vessel and main components for the project were completed and on site in by December, final outfitting and assembly took place over the winter of 2010. Because of its prototypical nature, challenges arose throughout the construction and assembly phases that required adaptive and innovative solutions.

A major technical challenge was sharing the power from the two diesel engines between the propulsion, hydraulic, and high- pressure water systems. This required the installation of a hydrostatic propulsion system so that the engines could run at high RPM to power the cleaning equipment while the vessel could maintain a very slow forward speed. Debugging the drive system caused considerable delays between the launch of the vessel and the site trials.

As the completed vessel was too tall to fit through the door of the PEI Mussel maintenance facility, it had to be outfitted inside, disassembled and reassembled prior to launch.

The uniqueness of the vessel and systems required some unexpected innovations; even for transport, a pair of two-wheel dollies had to be fabricated to fit the bi-hull design along with a custom draw bar.  Local utilities were also on site to ensure that the over-height load cleared power and communication lines.  The vessel was launched in Morell on April 21 and sea trials for the vessel and propulsion systems were conducted. The vessel was then sailed to Cardigan, PEI where the cleaning shrouds were installed.  During the mounting process, one of the hydraulic cylinders which raised and lowered the shrouds was damaged. The replacement part was custom made in Montreal, which resulted in an additional 2-week delay.

Generally, the additional time required to prepare for the site trials was probably not atypical for a project of this complexity. Also, contingencies were continually being addressed during the assembly phase as individual systems were tested. This caused delays, but paid dividends during the trial phase.

Site Trials:

Site trials were conducted June 12, 2010 on a PEI Mussel farm lease in the lower Cardigan River (Newport). Unfortunately, there were no heavily fouled mussel lines on which to test the effectiveness of the cleaning equipment. Most of the tunicates (Ciona intestinalis) had disappeared over the winter and spring and commercial product had already been removed during harvest.  The lines tested had socks of smaller mussels from the 2009 year class and were lightly fouled mainly with barnacles and brown algae.

The hydraulic equipment used to raise and lower the cleaning shrouds, rotate brushes, etc., had been tested previously and performed as designed. The high pressure water system was also tested prior to the trials. 

The site trials proved the concept that the shrouds could effectively be guided down a mussel line while the line remained in the water. This was the key innovation differentiating this project from other fouling and tunicate control techniques currently utilized. There were no significant problems in “lining up” the machine with the lines, even on the first attempt. The platform was very controllable, and will be easily manoeuvred as the operator gains experience.

As stated, the effectiveness of the cleaning equipment on heavily fouled mussel socks could not be determined from this trial.  Although we are limited in what we can conclude: the treated socks are definitely cleaner. Barnacles are still present which would be expected; otherwise the socks are evidently washed. When new generations of tunicate, mussel spat, and other marine organisms appear this summer, the results of this project will be more definitive.

The design of the equipment offers a wide range of adjustability such as the distance between the cleaning shrouds (proximity to the socks), speed and rotation of brushes, water pressure, nozzle selection and vessel speed. As experience is gained, it is expected that the right combination of settings will be discovered for dealing with mussel lines and socks with varying degrees and types of fouling.

To summarize the results of the trials: the concept and key innovation of this project was successfully demonstrated.  Without lines heavily fouled with Ciona instestinalis, it is not possible to determine if this equipment will effectively manage the fouling problems; however, the results that were observed are promising.  There is no question that the machine has the throughput potential anticipated in the project work plan.

Future Plans:

The June 13 and subsequent trials have revealed the need for some minor modifications which are presently being made. The “cleaning barge”, will be put to work in mid-July 2012. While the proponent is pleased with the performance of the equipment in the trials, it is yet to be seen if it will meet the expectations set out in the project work plan.