Damage, recovery and survival of 0-group mulloway, Argyrosomus japonicus, after simulated escape through square mesh

Abstract

A laboratory experiment was carried out to quantify and compare the physical damage (measured as scale loss), recovery and survival of two size categories [small: 48-85 mm total length (TL); large: 78-148 mm TL] of 0-group mulloway, Argyrosomus japonicus, after simulated escape through square-shaped mesh (bar length of 21.5 mm). Regardless of their size, fish that were fatigued to exhaustion and forced through square meshes sustained significantly more (i.e. >1.8 times) scale loss than did control fish that were only fatigued. However, the total scale loss incurred was <5% and significantly improved 7 days after treatment. Survival rates over a 2-week observation period were 100 and >97% for treatment and control fish, respectively. The results support the utility of square mesh for reducing the prawn-trawl fishing mortality of unwanted bycatch.