Fin Erosion in Aquaculture and Natural Environments

Abstract

Fin erosion occurs when the fins of afflicted fish become degraded from a variety of sources, which can include abrasion with rough surfaces, fin damage from aggressive encounters between fish, nutritional deficiencies, and bacterial infection. Fin erosion has become a concern in fisheries management because of aesthetic and fish survival issues. Preven-tative measures for controlling fin erosion in hatcheries include: (i) feeding fish to satiation, (ii) increasing water velocities such that the energetic costs of fighting outweigh the gains, (iii) duoculture to reduce intraspecific aggression, (iv) use of a sand or cobble substrate on the bottom of rearing raceways and tanks to reduce abrasion, and (v) tank design. Various effective chemical treatments of fin necrosis have been developed which will be discussed. Fish diet supplementation, particularly with amino acids such as lysine, is a promising area of research to reduce fin erosion. Additionally, fish diets devoid of micronutrients such as copper have been found to lead to substantial fraying of dorsal and caudal fins in salmonids. Fin necrosis is related to fin erosion and is reviewed as well, especially bacteriology and stress-related aspects. For instance, stress is a factor that has been found to exacerbate both conditions. This review examines all the potential causes and effects of this serious condition, which occurs in propagated and wild fish populations.