We must apply our minds to what happens to discarded Oyster, Perlemoen and other mollusc shells from the seafood that we consume in vast amounts. Here in Algoa Bay we produce many mussel and oyster shells from the farm off of North End Beach north of the Port of Port Elizabeth.
My tongue in cheek reaction to being introduced to the Shellnurse project by Mr Katayama Masaki, (President, Ocean Construction Co., Ltd.), in association with the Japan International Cooperation Agency, at the SAIMI International Workshop on Marine Resource Sustainability in the Western Indian Ocean at the Ocean Sciences Campus of the Nelson Mandela University on 29 and 30 June 2023:
The many perlemoen poachers in Algoa Bay who shuck and then struggle to discard this ‘evidence’ could go a long way towards redeeming their illegal activities by adopting the Shellnurse approach and giving back to the environment.
Seriously, though, the objective of the Japanes initiatiated Shellnurse project is to reduce sea shell waste and recover fishery resources by building ‘artificial’ reefs made from discarded oyster and scallop shells.
Masaki attributes the idea of using shells to create artificial fish reefs (JF Shellnurse) to his father and previous president of the company, Katayama Keiichi. When Keiichi was diving in the sea, he happened to peek under an oyster raft and saw that it was teeming with fish. Keiichi realized that shells attract fish, and came up with the idea of building a fish reef made of shells. This inspiration came to Keiichi in the 1970s, setting him on a long path of development.
These artificial reefs in association with the adoption of Japans J-Blue Credit Scheme in Algoa Bay could go a long way towards being the Magic Pill for Penguins and general fish stocks?
Shell fish reefs offer a number of advantages. One is that they enable the reuse of enormous amounts of shells that otherwise would have been thrown away, thereby contributing to waste reduction. Another is that the profits of fishermen increase because they can catch more high-value fish. A lot of high-end fish species, such as yellowtail, grouper, sea bream, flounder, and scorpionfish, gather around fish reefs made of shells, enabling fishermen to catch fish of greater market value. Furthermore, it has also been confirmed that 300 times more organisms that fish feed on gather on the shells of fish reefs, than on conventional artificial fish reefs, such as reefs made of blocks. In terms of fishing efficiency, results indicate that this technology enabled an approximately 150% increase in efficiency compared to conventional artificial fish reefs.
The Shellnurse reef is made by placing about 330 oyster and scallop shells into a mesh-like tube 15 cm in diameter and 98 cm in length, creating a case filled with shells and, as a commercial product, JF Shell Nurse had to have a certain level of durability and be able to withstand 30 years in the sea. The tubes are attached to a shelf like steel frame which is sunk to create a reef.
Alan Straton
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