The use of two nature-like fishways by some fish species in the Swedish River Em�n

Abstract

We studied the use of two nature-like fishways by 15 fish species (N ¼ 240) in the River Emån in southern Sweden. Use of the fishways for both passage and as a habitat was studied by electrofishing, trap catches and PIT telemetry. Of the 187 PIT-tagged fish, 52 individuals from 10 different species ascended one of the fishways for a total passage efficiency of 74%. For the five species that most frequently ascended the fishways, the passage efficiency was 100% for tench (Tinca tinca L.) and perch (Perca fluviatilis L.), 86% for chub (Leuciscus cephalus L.), 60% for burbot (Lota lota L.) and 50% for roach (Rutilus rutilus L.). Individuals that failed to pass the fishways were typically small cyprinids or species that were assumed to have taken up residence in the fishways, such as juvenile brown trout (Salmo trutta L.) and burbot. The nature-like fishways have re-established longitudinal connectivity for most of the studied species and also functioned as rearing and winter habitat for a number of species.

Can a low-gradient vertical-slot fishway provide passage for a lowland river fish community?

“…For the relatively lower number of silver perch and Murray cod, ∼40% of the fish discontinued their ascent and similar results for other species have been reported (Lucas et al 1999;Aarestrup et al 2003;Calles and Greenberg 2007). Likely reasons might include that the dataset was collected under drought conditions, some fish entered the fishway for feeding, fish discontinued at the end of a diel period, some aspect of pool hydraulics deterred ascent, or the fish were disturbed by the cages or nearby human activity.…”

“…A major limitation that remains, however, is the lack of records for PIT tagged sub-adult fish (<300 mm long) and this suggests a need for further investigations on tagging methods, rejection rates, effects on swimming ability and the mortality of PIT tagged fish. Other potential tagging methods may need to be used for sub-adult fish, including dyes, visual implants or micro-tags, to examine the behaviour and movement patterns of smaller individuals (Calles and Greenberg 2007;Knaepkens et al 2007aKnaepkens et al , 2007b.…”

Biological effectiveness of an inexpensive nature‐like fishway for passage of warmwater fish in a small Ontario stream

“…Lower attraction efficiencies were attributed to poor attraction flow and an inability of fish to locate the entrance, while high passage efficiencies were attributed to the swimming ability of brown trout. A later study (Calles & Greenberg 2007) re-examined the same fishways for use by multiple species and considerable variation in efficiency among species was documented. For example, attraction and passage efficiency for the common bream (Abramis brama) was 10% and 100%, respectively, while roach (Rutilus rutilus) exhibited attraction and passage efficiencies of 23% and 50%, respectively.…”

Effects of a surface oriented travelling screen and water abstraction practices on downstream migrating salmonidae smolts in a lowland stream

“…Being physostome species (Thomas and Ollevier, 1992), the tagged fish had access to the water surface while residing in the drum to allow the fish to gulp air to approach neutral buoyancy after the PIT tag insertion (Mccleave and Stred, 1975). The smolts were given 400-600 min for post operative recovery (Calles and Greenberg, 2007;Scruton et al, 2007) and subsequently released in the mid-channel of the stream to avoid any confounding influence of introduction side (Bourgeois and O'Connell, 1988). Smolts are typically nocturnal migrants (Olsèn et al, 2004;Svendsen et al, 2007).…”