River lamprey, Lampetra fluviatilis L., fishery in Latvia – insight into the origin of catch statistics data

Abstract

Most research to date on the status of the river lamprey, Lampetra fluviatilis L. in Latvia has been done based on catch statistics data. The aim of this study was to explore the present status of the river lamprey fishery in Latvia to improve the understanding of catch statistics data. Currently, river lamprey fishing in Latvia is carried out at 24 fishing grounds located on 17 rivers. The most popular fishing gear is the lamprey fyke net, but lamprey weirs and lamprey trammel nets are also used. The type and design of the fishing gear depends on the parameters of the fishing ground. The catch size is highly variable and is greatly affected by the number of non-resources related circumstances, such as fishing regulations and meteorological factors determining the intensity of lamprey migration during the fishing season and opportunities for fishing during periods of the most intense migration. The fishing effort and the type of fishing gear have also largely changed since the 1960s and 1970s. Therefore, the fluctuation in both the long-and short-term catch data may not correspond to changes in the actual status of the lamprey population.

A Figurally Sculpted Bone Knife from the River Užava (Western Latvia) and the Invisible Lampreys of Prehistory/

“…3: a). However, major commercial fishing for lamprey nowadays occurs only in the region surrounding the northern and eastern parts of the Baltic Sea, namely in Finland, part of north-western Russia, Estonia, and Latvia, 23 these being the countries where the fish has retained a significant place in the culinary tradition. Here, the lamprey's annual mass migration from the sea into the rivers to reach the spawning sites -in the period from late summer up to early spring -provides the main opportunity for catches.…”

Length‐based assessment of larval lamprey population structure at differing spatial scales

“…Accurate methods of assessing the state of lamprey are needed to manage commercial fisheries (Abersons & Birzaks, ; Araújo et al, ), to conserve threatened stocks in the context of habitat loss (King, Wightman, Hanna, & Gilligan, ) and river fragmentation (Nunn et al, ; Pereira et al, ), and to assess the efficacy of control measures (Maitland, Renaud, Quintella, Close, & Docker, ; Moser, Butzerin, & Dey, ). Species with prolonged juvenile stages, such as lamprey (Moser et al, ) and salmonids (Egglishaw & Shackley, ), can be sampled relatively easily by targeting appropriate habitat for this life stage (Bagenal & Nellen, ).…”

“…There is a marked contrast between the management of lamprey in the North American Great Lakes, where they are considered an invasive species with significant adverse impacts on native fish, and the conservation management perspective in the US Pacific Northwest and in Europe (Hansen et al, 2016). The European Union (EU) Habitats Directive (HD) on the conservation of natural habitats and of wild fauna and flora aims to promote the maintenance of biodiversity, taking account of economic, social, cultural, and regional requirements (Council of the European Communities, 1992 Accurate methods of assessing the state of lamprey are needed to manage commercial fisheries (Abersons & Birzaks, 2014;Araújo et al, 2016), to conserve threatened stocks in the context of habitat loss (King, Wightman, Hanna, & Gilligan, 2015) and river fragmentation (Nunn et al, 2017;Pereira et al, 2017), and to assess the efficacy of control measures (Maitland, Renaud, Quintella, Close, & Docker, 2015;Moser, Butzerin, & Dey, 2007). Species with prolonged juvenile stages, such as lamprey (Moser et al, 2007) and salmonids (Egglishaw & Shackley, 1977), can be sampled relatively easily by targeting appropriate habitat for this life stage (Bagenal & Nellen, 1980).…”