Selective pressure of fishways upon morphological and muscle enzymatic traits of migrating glass eels

Abstract

Fishways are built on obstacles to restore the connectivity between aquatic habitats. Our study investigated how species-specific fishways interact with interindividual trait differences among fish. We compared several groups of glass eels (Anguilla anguilla) climbing two types of fishways with those remaining below the water impoundments. We analyzed relative body condition factor, body length, mass, and in vitro activities and gene transcription levels of several enzymes involved in the energy metabolism (LDH, CS, CCO, PK). Differences among groups indicated that glass eel fish ladders can be size-specific, according to the type of substrate covering the surface of apparatus. Moreover, we found that climbing specific glass eel ladders can require higher endurance-related metabolic traits, triggering increased aerobic capacities. Increased aerobic efforts together with potential size selectivity of fishways should be taken into account when designing such devices and choosing appropriate location on eel migratory pathways.