What evidence exists for evaluating the effectiveness of conservation-oriented captive breeding and release programs for imperilled freshwater fishes and mussels?

Captive breeding programs are widely applied by conservation practitioners as a means of conserving, reintroducing, and supplementing populations of imperilled freshwater fishes and mussels. We conducted a systematic map to provide an overview of the existing literature on the effectiveness of captive breeding and release programs. A key finding is that there is limited evaluation of the effectiveness of such programs at all three stages (i.e., broodstock collection, rearing/ release methods, and post-release monitoring). We identified clusters of evidence for evaluating supplementation associated with rearing/release methods for fish growth and survival metrics, and the monitoring stage for fish genetic diversity, growth, and survival metrics, primarily focused on salmonids. However, many studies had inadequate experimental designs (i.e., lacked a comparator). Overall, there was a paucity of studies on the effectiveness of captive breeding programs for imperilled freshwater mussels, highlighting the need to make such information broadly available when studies are undertaken. Outputs from this systematic map (i.e., the map database and heatmaps) suggest that the effectiveness of captive breeding and release programs requires further systematic evaluation. Des programmes de reproduction en captivite sont largement utilises par les specialistes de la conservation comme moyen de conservation, de reintroduction et de supplementation de populations menacees de poissons d'eau douce et de mulettes. Nous avons realise une cartographie systematique pour dresser un portrait du corpus documentaire existant sur l'efficacite des programmes de reproduction en captivite et de lacher. Une des constatations cles est le fait que revaluation de l'efficacite des trois etapes de tels programmes (c.-a-d., prelevement de geniteurs, methodes d'elevage/de lacher et surveillance apres le lacher) est limitee. Nous avons cerne des groupements de donnees probantes pour les evaluations de la supplementation associees aux methodes d'elevage/de lacher pour des parametres relies a la croissance et la survie des poissons, et l'etape de surveillance pour des parametres relies a la diversite genetique, la croissance et la survie des poissons, axes principalement sur les salmonides. Le schema experimental de nombreuses etudes est toutefois inadequat (c.-a-d., absence de comparateur). Globalement, les etudes sur l'efficacite des programmes de reproduction en captivite pour les mulettes menacees sont rares, soulignant la necessite d'assurer une large disponibilite de ce type d'information quand de telles etudes sont realisees. Les extrants de cette cartographie systematique (c.-a-d., la base de donnees en decoulant et les cartes de densite) font ressortir la necessite d'une evaluation systematique plus poussee de l'efficacite de programmes de reproduction en captivite et de lacher. [Traduit par la Redaction]
Introduction Global freshwater biodiversity has declined by over 80% since the 1970s, to the point where it is clearly in crisis (Harrison et al. 2018). Freshwater fishes have some of [...]