Ranching to the rod: an evaluation of adult returns from hatchery-reared Atlantic salmon smolts released in Scottish rivers : Scottish Marine and Freshwater Science Vol 6 No 5

• Main Author: Stewart, D.C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Marine Scotland Science 2015
• Subjects: Fisheries and aquaculture; Fish behaviour; Atlantic salmon
• Online Access: https://dx.doi.org/10.7489/1610-1; https://data.marine.gov.scot/dataset/ranching-rod-evaluation-adult-returns-hatchery-reared-atlantic-salmon-smolts-released

The introduction of hatchery-reared Atlantic salmon smolts to rivers in support of local salmon fisheries (termed ranching) is a controversial subject with little information available to fishery managers on the value of the method in a Scottish context. Here we present recapture data from monitored smolt releases on four Scottish rivers and compare return rates of hatchery and wild-reared salmon smolts originating from a common stock on two of these rivers. Rod recapture rates from stocked hatchery smolts ranged from 0-0.23%. In comparative tests return rates for wild-reared fish were on average ten times greater than those for stocked fish (range 6 to 13-fold where at least one reared fish returned). Given the relatively poor returns and associated production costs any benefit to fisheries of stocking with hatchery-reared smolts is unlikely to be sustainable in the Scottish context. Furthermore, risks of adverse genetic effects should be considered. : To investigate the effectiveness of smolt ranching as a tool to enhance local salmon fisheries, we examine first, the range of recapture rates from monitored smolt releases in Scottish rivers and second, we compare returns from hatchery and wild-reared smolts originating from the same stocks released concurrently at the same river sites. We then consider a range of practical issues associated with operating a smolt ranching scheme on a Scottish river, both for conservation and fishery enhancement purposes, and then, using best available information, assess the likely financial implications.