Growth and age structure in captive and wild stocks of the endangered western ruivaco Achondrostoma occidentale (Cyprinidae)

Abstract

Growth and age structure in captive and wild stocks of the endangered western ruivaco Achondrostoma occidentale (Cyprinidae)Declines in freshwater fish populations are occurring at a fast rate, increasing the importance of ex-situ conservation programs supported by sound knowledge of population dynamics and life-history traits of the target species. We analysed the growth and age structure of wild and captive stocks of the western ruivaco Achondrostoma occidentale, a Portuguese endangered cyprinid, targeted for captive breeding and restocking since 2007. Specifically, we compared maximum size, longevity, and length-at-age among captive and wild populations, restocked and non-restocked. We found considerable variation in length-at-age and longevity between captive-bred and wild fish, with the former generally growing faster and living longer. Analysis of length-age distributions among wild populations suggested a positive effect of restocking actions in fish abundance. Results highlight the value of captive breeding for the conservation of endangered cyprinids, and reinforce the need for detailed data on life-history trait variation between captive and wild stocks to assess the efficiency of ex-situ conservation programs.

Size, fecundity and condition factor changes in endangered delta smelt Hypomesus transpacificus over 10 generations in captivity

“…Cultured fish were longer, heavier and were more fecund than the wild fish. Similar results in other species have also shown cultured fish grew faster than the wild ones, such as western ruivaco Achondrostoma occidentale (Mameri et al, 2018), Atka mackerel Pleurogrammus monopterygius (McDermott et al, 2011), steelhead Oncorhynchus mykiss (Kostow, 2004), Atlantic salmon (Blanchet et al, 2008), gilthead sea bream Sparus aurata (Grigorakis et al, 2002) and brown trout (Hedenskog et al, 2002). O'Sullivan et al (2020) showed that the fecundity of cultured Atlantic salmon was approximately 1.4 times higher than wild ones.…”

A conservation genetics perspective on supportive breeding: A case study of the common nase (Chondrostoma nasus)

“…Spawning adult nase are easily accessible as they congregate to spawn. Nase larvae can be reared in ponds with a high rate of success, which makes supportive breeding and restocking a potentially valuable conservation tool for this species (Mameri et al, 2018; Lepič, Blecha & Kozák, 2019). However, supportive breeding can have a detrimental impact on the genetic diversity (i.e.…”

“…As a result of the strong decline of many freshwater fish and mussel populations, ex‐situ conservation programmes, including captive breeding and restocking, are gaining increasing importance in their conservation (Targońska, Żarski & Kucharczyk, 2008; Roques et al, 2018; Lamothe & Drake, 2019; Lepič, Blecha & Kozák, 2019; Strayer et al, 2019; Manubens et al, 2020; Wetjen et al, 2020; Geist et al, 2021). A successful implementation of supportive breeding measures is particularly crucial if populations are declining very quickly or where species are not able to survive in natural habitats despite extensive in‐situ habitat restoration efforts (Mameri et al, 2018; Manubens et al, 2020). One example is the common nase, Chondrostoma nasus L. (subsequently referred to as nase), a key species of European river systems that was once very widespread.…”