Status of the burbot (Lota lota L.) in the Lower Danube (Bulgaria) – a species threatened by climate change

Abstract

Citation: Pandakov PG, Teofilova TM, Kodzhabashev ND (2020) Status of the burbot (Lota lota L.) in the Lower Danube (Bulgaria) -a species threatened by climate change. ZooKeys 910: 143-161. https://doi.org/10.3897/ zookeys.910.47866 AbstractThe study provides data on the catch composition, length-weight relationship, age structure, gender structure, growth, maturation, fecundity, distribution and conservation status of the burbot Lota lota (Linnaeus, 1758) in Bulgaria. During six consecutive winters (2008-2014) a total of 395 burbot specimens were caught. The total length and the weight of the specimens ranged from 16 to 51 cm and 29.8 to 1057 g, respectively. Seven age classes were represented (3-to 9-years-old), with 3-, 4-, and 5-years-old most abundant. The maximal life expectancy was estimated as 12 years. Male-female ratio was 1:1. Maturity happens at the age of four at the earliest, valid for both sexes. One-quarter of the fish, older than 5 years were determined as non-reproducing in the particular year. The absolute fecundity varied between 47 462 and 810 236 eggs for females ranging from 5 to 7 years old and from 25.7 to 41.5 cm in length. A dramatic decrease of burbot population was observed in the last two decades. Warming water temperatures of the Danube, together with fragmentation in its tributaries are considered as the major threats affecting the species. Therefore, the burbot in Bulgaria is classified as Endangered.

Effects of Temperature Fluctuation on Burbot Embryos: Implications of Hydropower and Climate Change

“…One of the most extreme examples of a winter specialist among freshwater fish is the Burbot Lota lota (family Gadidae), which typically spawns from December to March in spawning aggregations under the ice (McPhail and Paragamian 2000;Shuter et al 2012). The occurrence of Burbot in lowland waters increases its vulnerability to anthropogenic alterations (Walters et al 2018)-particularly changes in water temperature (Pandakov et al 2020). Warming of some freshwater ecosystems has been linked to population declines along the southern extent of the species' distribution (Stapanian et al 2010).…”

“…2018)—particularly changes in water temperature (Pandakov et al. 2020). Warming of some freshwater ecosystems has been linked to population declines along the southern extent of the species’ distribution (Stapanian et al.…”