Fishing and Gear Technology

Unit 2 - Fishing gear materials

2.2.Rotting

Vegetable fibres are parts of dead plants and consist of cellulose. When exposed to humid condition they are attacked by cellulose digesting microorganisms, especially bacteria. This process of decomposition of dead organic material releases the inorganic nutrients for new plants. Unfortunately, effect of decomposition on fishing net leads to increased labour and financial loss. This was the main reason for the development of synthetic fibres. In rotted fibre there is a direct relation between the corroded film in a fishing gear and breaking strength.

Factors responsible for rotting

• Kind of fibres: Type of fibre smooth or rough
• Water temperature: The activity of cellular digestion bacteria depends on the extent of temperature. During cold season and decay of vegetable fibre is considerably slower than during the warm season. Tropics net become useless faster than in temperate climates.
• Rotting power of water: Running water generally have greater rotting power than stagnant waters. Fertile water contains high percent of organic materials, lime, and phosphorus, natural fibres quickly deteriorate due to presence of microbes.
• Duration of immersion in water: Fishing net continuously immersed in the water for a long time is more liable to rotting than a net used only temporarily or occasionally.
• Depth/place of net operation: When a net kept in the putrid zone or in contact with mud the rate of deterioration is quicker than a net set on the surface.