Loss of genetic integrity and biological invasions result from stocking and introductions of Barbus barbus: insights from rivers in England

Abstract

Anthropogenic activities, including the intentional releases of fish for enhancing populations (stocking), are recognized as adversely impacting the adaptive potential of wild populations. Here, the genetic characteristics of European barbel Barbus barbus were investigated using 18 populations in England, where it is indigenous to eastern‐flowing rivers and where stocking has been used to enhance these populations. Invasive populations are also present in western‐flowing rivers following introductions of translocated fish. Two genetic clusters were evident in the indigenous range, centered on catchments in northeast and southeast England. However, stocking activities, including the release of hatchery‐reared fish, have significantly reduced the genetic differentiation across the majority of this range. In addition, in smaller indigenous rivers, populations appeared to mainly comprise fish of hatchery origin. In the nonindigenous range, genetic data largely aligned to historical stocking records, corroborating information that one particular river (Kennet) in southeast England was the original source of most invasive B. barbus in England. It is recommended that these genetic outputs inform management measures to either restore or maintain the original genetic diversity of the indigenous rivers, as this should help ensure populations can maintain their ability to adapt to changing environmental conditions. Where stocking is considered necessary, it is recommended that only broodstock from within the catchment is used.

Quantifying trophic interactions and niche sizes of juvenile fishes in an invaded riverine cyprinid fish community

“…The study system was the River Teme, a River Severn tributary in western England, where B. barbus is nonindigenous and invasive (Antognazza, Andreou, Zaccara, & Britton, 2016;Wheeler & Jordan, 1990). B. barbus began to be captured by anglers in the River Teme in the 1970s, indicating they have been present in the study river for approximately 40 years (Antognazza et al, 2016). B. barbus began to be captured by anglers in the River Teme in the 1970s, indicating they have been present in the study river for approximately 40 years (Antognazza et al, 2016).…”

Spatial variability in the growth of invasive European barbel Barbus barbus in the River Severn basin, revealed using anglers as citizen scientists

“…A strong example is the European barbel Barbus barbus where, in Britain, this cyprinid fish is only indigenous to eastern flowing rivers, but has now been introduced for angling into numerous rivers in their nonindigenous range (Wheeler and Jordan, 1990;Antognazza et al, 2016). In the River Severn, western England, 509 adult fish were introduced in 1956 for fishery enhancement (Wheeler and Jordan, 1990).…”

“…In the River Severn, western England, 509 adult fish were introduced in 1956 for fishery enhancement (Wheeler and Jordan, 1990). These fish established and dispersed throughout the middle and lower river, with reports in the 1970s of their capture by anglers in the River Teme, a major tributary of the Severn (Hunt and Jones, 1975;Wheeler and Jordan, 1990;Antognazza et al, 2016;Fig. 1).…”

Trophic interactions in a lowland river fish community invaded by European barbel Barbus barbus (Actinopterygii, Cyprinidae)

“…and 2? years (Britton et al, 2004;Antognazza et al, 2016). Studies on the trophic interactions of these stocked fish suggest substantial partitioning in their trophic niches with S. cephalus, the species that has the most similar functional traits and body sizes as B. barbus in these rivers (Bašic & Britton, 2016).…”

“…The focus was on determining the extent of trophic niche sharing within and between species, and how this altered across a range of life stages (as inferred from body sizes). The River Teme, western England, was the study river, where non-indigenous B. barbus have been present since the 1970s (Antognazza et al, 2016). The objective was to determine the trophic niche sizes and overlaps between invasive B. barbus and native fishes at three different life stages: age 0?…”