Study – The New Indian Express
THIRUVANANTHAPURAM: As part of a major initiative that can help preserve marine wealth and ensure its sustainability, the Central Institute of Fisheries Technology (CIFT) and the World Wide Fund for Nature (WWF) have conducted studies who have proven that the use of square mesh cod ends in bottom trawls is beneficial not only for the fishermen but also for the ecology. A recent study conducted by the team at Sakthikulangara fishing port, Kollam, proved that replacing traditional chain-mesh cod with a square-mesh codend reduced juvenile fish and bycatch, that is, ie fish or other marine species that are sustainable fishing method.
Field trials conducted by the organizations involved a comparison of tows caught by identical bottom trawls equipped with a square-mesh codend and chain-link codend. The study was carried out using a 25mm square mesh cod which is used for fishing shrimp varieties. Currently, two types of square mesh cod are allowed – 35mm for fish and 25mm for shrimp. “Only the bottom part of the trawl has been changed and it’s a one-time investment. Bycatch and catch of juvenile fish from trawls is less when we use square mesh trawlers.
Catching uniformly sized shrimp will also increase the price of shrimp compared to shrimp caught using diamond mesh cod, ”said Madhu VR, Principal Secretary of CIFT, who designed the study. The study involved two trawlers, with the same dimensions and the same engine power, with only one change in the codend part. “The catches from the trawler equipped with square cod gave a uniform and good draft. It avoids juvenile fish and other debris. In addition, there has been a better catch and the fishermen are saving a lot of time that is otherwise spent removing debris and juvenile fish.
By using square mesh cod, juvenile fish can escape and a thirty percent survival rate has been observed for juvenile fish, ”he said. All Kerala fishing vessel owners associations, the Maritime Management Board and the Fisheries Department were also involved in the study. “It was essential that we were able to teach fishermen how beneficial square mesh cod is to them. Reducing bycatch is a major element. It is a sustainable fishing method that protects biodiversity, ”said Vinod Malayilethu, team leader, Marine Conservation Program, WWF India.
As the mesh of the cod tip changes from diamond to square, juveniles may escape. “The principle here is that in a diamond mesh, as the net passes through, the diameter of the mesh stretches and becomes smaller. Even if you stretch a square mesh, the diameter remains the same. Thus, juvenile fish that are accidentally caught can easily fall out of the square grid, ”explains marine biologist Vinod.