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

Abstract

In the Netherlands, Burbot Lota lota have severely declined due to aquatic system modifications and agricultural intensification. The aim of this study was to evaluate the species' distribution and population trends and to interpret its decline for conservation and management-planning. Historic and present distributions were examined by GIS analysis, while the decline was quantified using binary logistic regression of presence-absence data. Records suggest that at the beginning of the twentieth century the overall Burbot population was relatively stable but reached a turning point from a positive to a negative population phase around 1950. Today, only two areas with spawning populations remain. Recently, increasing numbers of Burbot have been recorded in one of these areas, viz. the lakes in the confluence area of the rivers Vechte and IJssel. This increase could be attributed to annual stockings in German reaches of the River Vechte since 2001, with stock material originating from the rivers Elbe and Weser. Because of the low numbers in which Burbot populations were present and the risks of introduction of non-local stock, Burbot requires imperative tools and action plans for recovery and conservation in the Netherlands.

Assessment of burbot Lota lota (L. 1758) population sustainability in central European reservoirs

“…More years are needed to calculate survival rates in order to get reliable estimates, since short‐term assessment is a limitation of this study. Successful restoration of a L. lota population was described for Kootenai River, Idaho, U.S.A. (Hardy & Paragamian, ) and the Netherlands (Bosveld et al, ) where hundreds of thousands of larger juvenile L. lota were stocked. Lota lota in our reservoirs were stocked in late spring at sizes up to 50 mm L T .…”

Genetic diversity and population structure of burbot Lota lota in Germany: Implications for conservation and management

“…As burbot populations have declined during recent decades, it is important to maintain spawning grounds (Worthington et al, 2011) and to ascertain winter migration opportunities to allow for natural gene flow between populations and to preserve their adaptive potential. In recent decades, burbot have also been increasingly stocked into some German rivers, that is the Main, Ems, Vechte (Bosveld et al, 2015), the River Odra in Poland (Witkowski et al, 2012), the River Morava, Czech Republic (Adámek et al, 2013) and the rivers Grote Nete and Bosbeek in Belgium (Dillen et al, 2008). However, overall genetic structure of German burbot seems to be less affected by stocking than other commercial freshwater fishes such as brown trout Salmo trutta L. (Berrebi, Poteaux, Fissier, & Cattaneo-Berrebi, 2000;Vera, Martinez, & Bouza, 2017).…”

“…Burbot, Lota lota L., Teleostei: Lotidae, is a guiding species for oligotrophic lakes in Europe (Volta, Oggioni, Bettinetti, & Jeppesen, ). It serves as an indicator species for habitat heterogeneity, eutrophication and the impact of climate change on coldwater fish species (Bosveld, Kranenbarg, Lenders, & Hendriks, ; Olin et al, ; Stapanian et al, ). These features make burbot a significant and strategic species in the assessment of "Good" ecological status of water bodies in the context of the EU Water Framework Directive (Olin et al, ).…”

“…Burbot is distributed over the entire Holarctic region (Recknagel, Amos, & Elmer, ; Van Houdt, Hellemans, & Volckaert, ) and is not endangered globally according to the IUCN Red List (IUCN, ). However, the species is threatened in wide parts of its distribution are (Stapanian et al, ) and many populations are declining (Bosveld et al, ) or have gone locally extinct, for example United Kingdom (Worthington, Kemp, & Osborne, ). In several European regions, including parts of Germany, localised burbot extinction was presumably due to migration barriers and habitat pressures caused by, for example, invasive species and pollution (Dillen et al, ; Stapanian et al, ).…”

Wetenschappelijke onderbouwing en ondersteuning van het visserijbeleid en het visstandbeheer: Onderzoeksprogramma visserij 2018

“…Allerhande normalisatie-en regulatiewerken en de verlaging van het grondwaterniveau hebben de achteruitgang van de kwabaal in de hand gewerkt maar de allerbelangrijkste oorzaak van achteruitgang is toch wel het verlies van de eenheid tussen de waterloop en haar uiterwaarde mét een natuurlijke overstromingsdynamiek. Hierdoor verdwenen de ideale 'kinderkamers' voor de kwabaal, namelijk de in het voorjaar langdurig geïnundeerde overstromingsvlakten (Bunzel-Drüke et al 2004b, Bosveld 2015, Bosveld et al 2014. Verlaging van het grondwaterniveau zorgde er naast een verdroging van de oorspronkelijke waterrijke uiterwaarden ook voor dat er minder grondwaterinstroom is in de waterloop waardoor de kwabalen in de zomer een bescherming tegen hoge watertemperaturen verliezen.…”