Site fidelity of farmed gilthead seabream Sparus aurata escapees in a coastal environment of the Adriatic Sea

Abstract

A small escape incident of gilthead seabream Sparus aurata tagged with acoustic transmitters (N = 25) from a commercial farm located in a coastal bay of the eastern Adriatic Sea was simulated to enable evaluation of recapture strategies and escapee management. Over a 3 mo monitoring period, tagged individuals showed spatial distribution closely related to fish farms, where 76 and 68% of tagged fish were present at the farm during the second and third weeks post-release respectively. Upon initial release, escaped seabream had a small total home range (0.142 km 2 ) that encompassed the farm site. Short-term residence differed among tagged fish. Few fish (28%) remained in the proximity of the fish farm for longer than 1 mo; most were likely angled or moved outside the acoustic array. Fish that moved elsewhere have the potential to cause substantial ecological and genetic impact, as they likely are able to quickly adapt to natural conditions. Considering the capture impact of the limited recreational fishery on this small-scale escape event, fish recapture by this type of fishery within 2 wk of escape could be feasible and is highly recommended.

Acoustic Telemetry: A Tool to Monitor Fish Swimming Behavior in Sea-Cage Aquaculture

“…No medical treatment after surgical implantation was used. This tagging procedure and technique has been successfully applied in previous studies on gilthead seabream and documented a good recovery of equilibrium and normal swimming behavior following transmitter implantation, as well as long-term survival and no mid-term stress physiological effects (Arechavala-Lopez et al, 2012;Šegvić-Bubić et al, 2018;Palstra et al, 2019;Alfonso et al, 2020b). In our experiment, tagged gilthead seabream showed 100% short-term survival rate.…”

Identification and quantification of farmed red sea bream escapees from a large aquaculture area in Japan using microsatellite DNA markers

“…Escapees may stay around the farming area even after escape due to forage on excess feed leaving the cages (Gausen and Moen, 1991;Fiske et al, 2006;Šegvić-Bubić et al, 2018). Moreover, farmed red sea bream are acclimated to human presence, unlike wild individuals (Sawayama, personal observation), and therefore, may lack wariness and can be easily captured by angling and basket capture as observed in present study.…”

“…Domestication is known to decrease individual fitness such as reproductive capabilities (Araki et al, 2007) and survivability (Tymuchuk et al, 2007). In some case, fish such as gilthead seabream (Sparus aurata) are known to adapt quickly to the natural environment (Šegvić-Bubić et al, 2018), posing a risk of hybridization with individuals from the wild. Therefore, the escape of farmed fish, especially in the case of welldomesticated species, is likely to adversely affect natural populations.…”

Spatial connectivity pattern of expanding gilthead seabream populations and its interactions with aquaculture sites: a combined population genetic and physical modelling approach

“…It has been suggested that the rapid expansion of sea-cage farming facilities contributed to the population increase through the escape of fish from sea-cage aquaculture and/or escape of viable, fertilized eggs spawned by farmed fish inside sea-cages, i.e. escapes through spawning 4,9–13 . Escaped fish have been shown to have detrimental effects on native fish stocks, due to competition for resources, spread of disease, and alteration of genetic diversity due to hybridisation 14 .…”