Artisanal fishing net float loss and a proposal for a float design solution

Abstract Plastic floats from fishing nets are commonly found washed up on beaches in southern Brazil. They are usually broken and show signs of having been repaired. Characteristics of floats and interviews with fishermen suggest two main causes of float loss. First, collisions between active gear, bottom trawl nets for shrimp, and passive gear, drift nets for fish, destroy nets and release fragments of them, including floats. Second, the difficulty with which floats are inserted on the float rope of the nets when they are used near the surface. Floats are inserted to replace damaged or lost floats, or they may be removed if it is desired that the nets be used in deeper waters. Floats may thus be poorly fixed to the cables and lost. Here a new float design that offers greater safety in use and for the replacement of floats is described and tested.

【摘要】在巴西南部海滩上，常可发现被冲上岸的渔网塑料浮标。这类浮标通常已破损，且带有修复痕迹。通过对浮标特征的分析及对渔民的访谈，可明确浮标丢失的两大主要成因：其一，作业渔具（active gear，即虾用底拖网（bottom trawl nets for shrimp））与被动渔具（passive gear，即鱼类流刺网（drift nets for fish））发生碰撞时，会损毁网具并释放包括浮标在内的网具碎片；其二，当网具在近海面作业时，浮标难以安装至网具的浮绳上——浮标安装既可用于替换破损或丢失的浮标，若需将网具投入更深水域，则需移除浮标，因此浮标可能未牢固固定于缆绳上而发生丢失。本文描述并测试了一款新型浮标设计，其在使用环节及浮标更换流程中均具备更高的安全性。