Performance of a Pool and Weir Fishway for Iberian Cyprinids Migration: A Case Study

Abstract

One of the movement barriers that fish populations must overcome for migration success in the upper basin of Tormes river (Salamanca, Spain) is a 20 m high dam. The design of its pool and weir fishway for potamodromous fishes (mostly Iberian barbel—Luciobarbus bocagei—and Northern straight-mouth nase—Pseudochondrostoma duriense) to overcome the obstacle was improved in 2013. The aim of this study was to assess the efficiency of the fishway using FDX passive integrated transponder (PIT)-Tags inserted into the fish and PIT-Tag detection antennas at the fishway. During several sampling events, 7113 barbel and nase individuals were tagged and released at the point of capture along the basin (2538 and 4575 of which were tagged downstream and upstream, respectively). PIT-Tag Detection Antennas close to the top and bottom of the fishway monitored tagged fish continuously for 10 months (from March to December 2017), to analyze the performance of the fishway. Upstream passage efficiency was greater for barbel (60% and 25% for barbel and nase, respectively). Differences in passage efficiency between species may be due to differences in their size. Mean length for barbels attempting to pass was 336 mm (±47 mm) while for nases was 143 mm (±26 mm). Moreover, both the number of attempts to pass and ascend time for nases were higher than for barbels. Entrance efficiency was low (3.5% and 10.8% for barbel and nase, respectively), although 2017 was a very dry year, thus these results are most likely influenced by flow rates. Therefore, the fishway has proved to be functional but is actually poor for efficiency purposes, especially for small fish.

Pool-Type Fishway Design for a Potamodromous Cyprinid in the Iberian Peninsula: The Iberian Barbel—Synthesis and Future Directions

“…Field studies highlighted the role of key environmental variables, such as flow and water temperature, as triggers of upstream fish migration [92], which typically occurs from spring to early-summer [95,100], which points out the need to conduct fishway studies preferably during this time frame. Another interesting result is that efficiency upon negotiating this type of fishways revealed to be size-related with larger fish displaying a higher efficiency and lower transit time for ascension, relative to smaller ones [42,96].…”

“…Width of the surface notches ranged between 20 and 30 cm, with both studies aiming to compare the performance of a plunging vs. a streaming flow regime through the notches. The other two (50%) NOF studies were conducted in the field (Douro basin) and included a dual-entrance fishway with 23 pools (2.6 m × 1.6 m), slopes ranging 8.8%-9.8%, and a total flow of 395 L·s −1 [92] and a 46-pool high slope (16.3%) fishway, with a flow of 140 L·s −1 [96]. Orifice area in both fishways ranged 0.02 m 2 -0.06 m 2 and their arrangement (as well as those from the lab studies) was set as offset.…”

Effectiveness of New Rock-Ramp Fishway at Miyanaka Intake Dam Compared with Existing Large and Small Stair-Type Fishways

“…Because the sizes of the individuals vary slightly between these species, these differences in preference are likely associated with their swimming abilities. Our results indicate that flow velocity, regardless of fishway type, is more important than water depth and flow rate for many of the target fish species [83].…”

Movement behaviour and fishway performance for endemic and exotic species in a large anthropized river

“…Those results are much higher than the mean international average rates (Noonan et al, 2011) for non-salmonid fish (21,1% average, 19-45% range). More recent studies on rheophic cyprinids in vertical slot or pool and weir fishways showed adjusted passage efficiency from 7.1% to 66.7% for barbel (Ovidio et al, 2017;Grimmardias et al, 2022) and 25% for the Northern Straight Mouth Nase (Pseudochondrostoma duriense) (Pedescoll et al, 2019). Among the eurytopic and the limnophilic species, roach, pike, Esox lucius, perch, Perca fluviatilis, tench, Tinca tinca and carp, Cyprinus carpio did not cross the fishway, but only a few were tagged and/or approached M 1 .…”