Does fin damage allow discrimination among wild, escaped and farmed Sparus aurata (L.) and Dicentrarchus labrax (L.)?

Abstract

Summary The present study compares fin damages in gilthead seabream (Sparus aurata) and European seabass (Dicentrarchus labrax) according to their wild, escaped or farmed origins. In addition, the potential applicability of fin condition indices (Fin Erosion Index ‘FEI’ and Fin Splitting Index ‘FSI’) as identification tools is discussed. Farmed seabream fins evidenced more erosion and splitting (FEI ± SD: 2.1 ± 0.3; FSI ± SD: 1.9 ± 0.6) than wild seabream fins (FEI: 0.8 ± 0.6; FSI: 1.2 ± 0.9), a result of farming conditions in open‐sea cages. Escaped seabream fin erosion was between that of farmed and wild seabream (FEI: 1.6 ± 0.4), which could indicate that fins in farmed fish recover over time from farming abrasions once they are in the wild. However, the fins of escaped seabream seem to be weaker than those of the wild fish, and therefore might be more susceptible to suffer other types of erosion such as splitting or nipping (FSI: 2.3 ± 0.7). No significant differences were found in seabass FEI according to their origins, although wild seabass presented significantly more split caudal fins (FSI: 3.3 ± 2.8) than the farmed seabass (FSI: 1.2 ± 1.1) and escapees (FSI: 2.5 ± 1.6). Therefore, FEI for seabream could be used as tools not only to distinguish between wild and farmed fish, but also to identify recent escapees, improving further assessments on the contribution of seabream escapees in fishery landings. However, the healing potential of damaged fins must be considered for the proper identification of escapees. Use of fin condition indices from both species could be helpful for aquaculture management, to assess fish welfare in fish farms stocks, and improve the knowledge of handling, stock densities and open‐sea cage environment conditions.

Differentiating the wild or farmed origin ofMediterranean fish: a review of tools for sea bream and sea bass

“…) and a higher degree of erosion in the caudal and pectoral fins (Arechavala‐Lopez et al . ). Scale characteristics and fin condition are both strongly related to the stocking density and freedom of movement of farmed sea bream.…”

“…However, fin erosion values of sea bream escapees were intermediate between those of wild and farmed fish, indicating that fin recovery must be considered when determining fish origin (Arechavala‐Lopez et al . ).…”

“…Fin condition is also difficult to use as an indicator of fish origin in sea bass (Arechavala‐Lopez et al . ). However, genetic deformities in a number of fin rays and vertebrae on farmed sea bass have been shown (Sola et al .…”

Influence of a massive aquaculture escape event on artisanal fisheries

“…However, these examples rely on the ability to distinguish between wild and farmed fish (apart from tagging experiments), as escapees share habitats with their wild counterparts. This introduces some degree of uncertainty, as phenotypic plasticity could drive escapee fish to resemble their wild conspecifics (Arechavala-Lopez et al 2012a). The situation is different (and escapees are clearly identified) when the cultured species are known to be introduced or locally absent, and there are no self-sustaining populations in the wild.…”

The Physical Condition and Welfare of Five Species of Wild‐caught Wrasse Stocked under Aquaculture Conditions and when Stocked in Atlantic Salmon, Salmo salar, Production Cages

“…The 5‐point classification scale for erosion and splitting of fins devised by Bosakowski and Wagner (), and developed by Hoyle et al () and Noble et al (), was modified to a 5‐point scale of fin damage for wrasse for the dorsal fin, tail, anal fin, and pectoral fins separately. The fin erosion index (FEI) (terminology proposed by Arechavala‐Lopez et al ) is: 0 = none; 1 = superficial, 1–25% of fin area; 2 = moderate erosion, 26–50%; 3 = high erosion, 51–75%; and 4 = severely eroded, 76–100%. The fin splitting index (FSI) is: 0 = none; 1 = one split in the fin; 2 = 2 splits, 3 = 3 splits; 4 = severe general splitting.…”