Effect of a vertical half cylinder on swimming of silver carp,Hypophthalmichthys molitrix: Implications for microhabitat restoration and fishway design

Abstract

In recent years, the relationship between hydraulics associated with the substrate and fish swimming behaviour has become increasingly important to the design of microhabitat around substrates for river restoration. To better understand the hydraulics associated with substrate on fish swimming, we studied the effects of a vertical half cylinder (hereafter, cylinder) on the critical swimming speed of juvenile silver carp (Hypophthalmichthys molitrix). Absolute and relative critical swimming speeds of fish in the flow field of the cylinder were significantly increased compared with those swimming in free flow. In addition, the amplitude of fish head and tail oscillations were significantly greater in flows created by the half cylinder. This study highlights the importance of roughness elements in stream microhabitat restoration and, possibly, for fishway design.

Effects of obstacles and flow velocity on locomotory behavior in juvenile, silver carp,Hypophthalmichthys molitrix

“…Migrating fish species with different swimming abilities and energy use display different capacities for passing obstacles within the environment. Fish inhabiting habitats with particular types and sizes of obstacles may take advantage of velocity refuges to increase swimming capacity and reduce energy expenditure (Branco, Boavida, Santos, Pinheiro, & Ferreira, 2013; Ke et al, 2019; Muraoka, Nakanishi, & Kayaba, 2017). Although arguably less informative than other speed definitions in terms of swimming physiology and swimming speeds in the wild, U crit provides a good estimation of swimming capacity, as it includes aerobic and anaerobic swimming (Hammer, 1995; Videler, 1993).…”

“…Tail-beat frequency and tail-beat amplitude increased significantly (p < .05) for fish moving forward behind the half cylinder at 3 BL/s, compared to that of fish swimming at 5 BL/s (Figure 6a,b. However, there was no difference between 3 and 5 BL/s in ground swimming speed, swimming acceleration or ground stride for silver carp moving forward behind the half cylinder (Figure 6c (Branco, Boavida, Santos, Pinheiro, & Ferreira, 2013;Ke et al, 2019;Muraoka, Nakanishi, & Kayaba, 2017). Although arguably less informative than other speed definitions in terms of swimming physiology and swimming speeds in the wild, U crit provides a good estimation of swimming capacity, as it includes aerobic and anaerobic swimming (Hammer, 1995;Videler, 1993).…”

Swimming behaviour of silver carp (Hypophthalmichthys molitrix) in response to turbulent flow induced by aD‐cylinder

“…Furthermore, no fish were subjected to any lasting harms or the use of neuromuscular agents, nor were any sacrificed during the experiment. Silver carp was selected as our model species owing to its typical freshwater potamodromous migration and because it typically encounters fishways during its migration (Ke et al, 2019). Due to the dimensions of the testing apparatus (working section 100 cm long  22 cm wide  22 cm high), the juvenile stage was favoured for the experiment.…”

Role of Transient Characteristics in Fish Trajectory Modeling

“…Fish excrement and uneaten food were removed daily. Test fish were unfed for 24 hrs before the tests (Ke et al, 2019). A total of 30 age-0 silver carps were individually tested to avoid confounding schooling effects.…”