Title:

Design of an Offshore Whale Safe Mussel Farm

The North Atlantic Right Whale (NARW) is a critically endangered whale species with less than 350 individuals left in the wild. Due to their nature of swimming close to the surface, these whales were once hunted by whalers for oil and baleen and came close to extinction. While hunting them is no longer legal, their numbers continue to decline. One of the main contributors to the recent North Atlantic Right Whale decline is entanglement from the aquaculture industry in the form of long-line kelp and mussel farms. Therefore, this project aimed to design a ropeless offshore mussel farm that could withstand environmental conditions while preventing whale entanglement. The team designed a mussel farm with a cage element surrounding the mussel dropper area to avoid entanglement. The cage design measures 12 meters in length, 10 meters in width, and 10 meters in depth. This is because the NARW usually feeds in the top 10 meters of the water column. The mussel lines will be covered in a biodegradable mesh to keep out predators such as the common Eider Duck, which can consume up to 180 mussels in one sitting. The use of biodegradable mesh was found to prevent Eider Duck predation by around 50% and promote more juvenile mussel growth and less biofouling compared to a mussel line that did not have the mesh. To prevent NARW entanglement, the mooring design of the system will use Owens Corning PINKBAR® fiberglass rebar. This is a much more rigid material than rope and will not allow the whale to wrap itself in it. Instead, the whale will either avoid the fiberglass due to its bright pink color or bounce off the fiberglass as it can withstand the force of a NARW traveling at full speed. Bending strength tests were performed on the PINKBAR® to confirm this, and it was found that the rebar has a bending strength of 139.6 MPa and the 0.5” diameter rebar can withstand the full force of a NARW without breaking. In conclusion, the raft-cage design proves much more effective in preventing whale entanglement than the commonly used long-line system and is able to maintain effective mussel growth throughout the mussel’s lifespan.

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