The establishment of Scotland’s rarest freshwater fish, the vendace (Coregonus albula), in conservation refuge sites

Abstract

In recent decades conservation measures for the rarest freshwater fish in the U.K., the vendace (Coregonus albula), have included attempts to form conservation refuge populations in Scotland. Here we report that at two of these refuge sites where the status of the introduced vendace was previously unknown (Loch Earn and Daer Reservoir) surveys have established that vendace are reproducing successfully in situ, albeit that these populations appear to be relatively numerically small. At a third site, Loch Valley, there was no evidence of vendace in the survey, but it is possible that a small, but as yet undetectable population is in the process of establishing.

Extinction risks and threats facing the freshwater fishes of Britain

“…Two additional populations in Scotland were extirpated in the 1910s (Castle Loch) and 1970s (Mill Loch) owing to eutrophication and the introduction of non‐native fish species (Winfield et al, 2012). Attempts have been made to establish refuge populations at one site in England (Sprinkling Tarn) and five in Scotland (Doune North Pond, Loch Earn, Loch Skeen/Skene, Loch Valley and Daer Reservoir) (Lyle et al, 2019). The Doune North Pond attempt failed and there is not yet any evidence of self‐sustaining populations in Sprinkling Tarn or Loch Valley (B. Hänfling, pers.…”

“…European whitefish is native to four sites in England (Ullswater, Haweswater, Brotherswater and Red Tarn), two in Scotland (Loch Lomond and Loch Eck) and one in Wales (Llyn Tegid) (Winfield et al, 2013). There are also nine confirmed benign introductions (Blea Water and Small Water in England; Loch Sloy, Carron Valley Reservoir, Lochan Shira, Loch Tarsan, Loch Glashan and Allt na Lairige in Scotland; Llyn Arenig Fawr in Wales) (Winfield et al, 2013; Lyle, Stephen & Adams, 2017). The population size is unknown, but the geographical range is small and climate change has been identified as the main threat and is likely to affect most subpopulations simultaneously (Winfield et al, 2013).…”

“…For example, some of the sites are supply reservoirs and exposed to substantial fluctuations in water levels, which has the potential to expose spawning habitats at critical times of the year. However, the suitability of at least some of the sites was assessed using the IUCN guidelines for conservation translocations (Adams et al, 2014), and monitoring indicates that populations have established and, hence, that conditions are currently adequate (Lyle, Stephen & Adams, 2017; Lyle et al, 2019). Furthermore, the native populations of European whitefish in Haweswater and Llyn Tegid are also exposed to considerable fluctuations in water level caused by abstraction.…”

“…There is no possibility of a rescue effect in the event of the British population's extinction. Stephen & Adams, 2017). The population size is unknown, but the geographical range is small and climate change has been identified…”

Allelic losses and gains during translocations of a high conservation value fish, Coregonus lavaretus

“…12,200 to a second reservoir site, Loch Sloy (56° 16.3′ N 004° 46.6′ W); both sites are located within the Loch Lomond catchment (Figure 1). In addition, 85 adult whitefish (sex ratio unknown) were also translocated from Loch Lomond to Loch Sloy (Maitland & Lyle, 1991; Etheridge et al, 2010; Lyle, Stephen & Adams, 2017). Thus a maximum of 44 families, of which 22 family pairs comprised half sibs, was translocated to Carron Valley Reservoir and to Loch Sloy with a maximum of 42 breeding pairs also translocated to Loch Sloy.…”