Former distribution and decline of the burbot (Lota lota) in the UK

Abstract

ABSTRACT1. Species reintroductions are an increasingly fashionable tool among conservation practitioners for restoring locally and nationally extinct populations. For a reintroduction programme to be successful, an understanding of the causes of the decline of a species is required. This, however, proves challenging when baseline data on the distribution and abundance of the species are limited.2. This paper uses evidence from historical literature to map the former distribution of the burbot (Lota lota) within UK rivers before its extinction in the early 1970s. A scoring system was developed to model anecdotal descriptions of burbot abundance from the collected literature.3. The former distribution was divided into four geographical areas based loosely on catchment boundaries. The literature identifies 42 rivers in eastern England in which the burbot was likely to have existed. The status of the species in the Thames catchment is still unclear as information from written sources is contradicted by evidence from the archaeological record.4. The findings indicate that the year of source data was a significant predictor of burbot abundance across the former population as a whole and for three of the four geographical areas (the Trent catchment, the Fenland rivers and the Yorkshire rivers). The timing of the burbot's decline showed differences between the geographical regions, with the Trent catchment exhibiting an earlier decline than the Fenland and Yorkshire areas.

Historic decline and recent increase of Burbot (Lota lota) in the Netherlands

“…In the UK, the point at which the overall Burbot population was present at half of the locations was reached around 1907, almost 50 years earlier (a & 1900;Worthington et al, 2010) than in the Netherlands. The decline of Burbot in the UK appears to have been primarily caused by the structural modification and anthropogenic pollution of rivers (Worthington et al, 2010).…”

“…Moreover, varying sources of information yield data of different quality and nature, and as a consequence, are subject to interpretive bias (Van Neer & Ervynck, 2010). Nonetheless, the quantitative analysis showed that, despite the descriptive nature of the historic data and issues mentioned above, anecdotal evidence can still provide valuable insights as to the reconstruction of historic abundance and decline of a species, emphasising the value and necessity of historical information to be taken into account when addressing conservation issues (cf Pauly, 1995;Shaffer et al, 1998;Worthington et al, 2010Worthington et al, , 2011.…”

“…2; Table 3). For the subsets the turning point from a positive to a negative population Table 2 The score of the different descriptors of Burbot population size (adapted from Worthington et al, 2010) Score 1 0 Description More plentiful, common, not uncommon, occurs plentifully, abundant, abounds, many, great plenty, not exactly a rarity, good quantity Rarity of meeting them, not common, rare, by no means plentiful, wiped out, unusual, scarce, occasionally, seldom, extinct, formerly found, absence, reduction in abundance, dwindling numbers, formerly found, no Burbot, sporadic, few, odd specimen …”

“…The historic decline of Burbot in the Netherlands was examined by binary logistic regression of presenceabsence data, using a scoring system adapted from Worthington et al (2010; see Methods section therein for further details). A score of ''1'' equated to a record that referred to positive Burbot abundance and ''0'' where reduced population size was described ( Table 2).…”

“…Following extinction in the 1970s, Burbot was reintroduced to Belgian rivers in 2005 (Dillen et al, 2008). In the UK, research into the feasibility of reintroducing Burbot commenced in 2009 (Worthington et al, 2010) and twenty potential habitat areas have been identified as most suitable for reintroduction of the species (Worthington et al, 2012).…”