When engineers and ecologists face a fishway design, many issues need to be considered, the type of fishway
being the first and foremost. It is an especially complex issue in areas with species whose migratory and
swimming behavior are as yet poorly known as Mediterranean barbels. The present study focuses on the fish
passage of two of the most common types of technical fishways: Vertical Slot (VS), and Submerged Notch with
Bottom Orifice (SNBO). Both types were studied and compared in terms of ascent ability (as the success rate and
transit time) and motivation (as the proportion of attempts and attempt rate), with Iberian barbel (Luciobarbus
bocagei) as the target species.
Ascent ability in VS and SNBO were similar. More than 90% of fish ascended the fishways successfully and the
median transit time to ascend a total water height of 2.25m was less than 23 min. Fish length had an effect on
ascent time, with the biggest ones being faster. Motivation was greater for VS, although not seeming to have a
relevant influence in the passage.
These results support the use of VS and SNBO in areas with Iberian barbel and provide new data of fishways
performance helping ecologists and engineers with their decision making, mainly in Mediterranean areas with
similar habitats and species.