Papers by Kazutaka Yanase
Journal of fish biology, 2014
Detailed swimming kinematics of the yellowtail kingfish Seriola lalandi were investigated after u... more Detailed swimming kinematics of the yellowtail kingfish Seriola lalandi were investigated after unilateral ablation of superficial neuromasts (SNs). Most kinematic variables, such as tail-beat frequency, stride length, caudal fin-beat amplitude and propulsive wavelength, were unaffected but lateral amplitude at the tip of the snout (A0 ) was significantly increased in SN-disrupted fish compared with sham-operated controls. In addition, the orientation of caudal fin-tip relative to the overall swimming direction of SN-disrupted fish was significantly deflected (two-fold) in comparison with sham-operated control fish. In some fish, SN disruption also led to a phase distortion of the propulsive body-wave. These changes would be expected to increase both hydrodynamic drag and thrust production which is consistent with the finding that SN-disrupted fish had to generate significantly greater thrust power when swimming at ≥1·3 fork lengths (LF ) s(-1) . In particular, hydrodynamic drag wou...
The sand flathead Platycephalus bassensis is most common in shallow coastal waters (< 100 m) o... more The sand flathead Platycephalus bassensis is most common in shallow coastal waters (< 100 m) off southern New South Wales, Victoria and Tasmania, in the latter two of which it is commercially important. The behavioural responses of the P. bassensisi to a trawl towed at 3 knots were observed using 4 video cameras attached to a trawl. This sys tem enabled simultaneous observations of the fish at several locations in the trawl as fish passed th rough the codend. The camera housing was also equipped with 4 laser lights set 25 cm apart. The l as r beam dots intersecting the bottom of the sea o r the fish body were used as a standard length scale. I n this way we were able to assess any length based response to the trawl. P bassensis (37–56 cm) were observed cruising in front of a tr awl mouth for 128 s on average while using intermittent rapid swi mming and coasting manoeuvres before entry into the trawl . Fifteen percent (15%) of these P. bassensis were excluded from underneath the b...
Limnology and Oceanography, 2021
Isokinetics and Exercise Science, 2019
Biology open, Jan 15, 2016
The boundary layers of rainbow trout, Oncorhynchus mykiss [0.231±0.016 m total body length (L) (m... more The boundary layers of rainbow trout, Oncorhynchus mykiss [0.231±0.016 m total body length (L) (mean±s.d.); N=6], swimming at 1.6±0.09 L s(-1) (N=6) in an experimental flow channel (Reynolds number, Re=4×10(5)) with medium turbulence (5.6% intensity) were examined using the particle image velocimetry technique. The tangential flow velocity distributions in the pectoral and pelvic surface regions (arc length from the rostrum, lx=71±8 mm, N=3, and lx=110±13 mm, N=4, respectively) were approximated by a laminar boundary layer model, the Falkner-Skan equation. The flow regime over the pectoral and pelvic surfaces was regarded as a laminar flow, which could create less skin-friction drag than would be the case with turbulent flow. Flow separation was postponed until vortex shedding occurred over the posterior surface (lx=163±22 mm, N=3). The ratio of the body-wave velocity to the swimming speed was in the order of 1.2. This was consistent with the condition of the boundary layer laminari...
Journal of Experimental Biology, 2015
The boundary layers of rainbow trout, Oncorhynchus myskiss, swimming at 1.02±0.09 L s−1 (mean±s.d... more The boundary layers of rainbow trout, Oncorhynchus myskiss, swimming at 1.02±0.09 L s−1 (mean±s.d., N=4), were measured by the Particle Image Velocimetry (PIV) technique at a Reynolds number of 4×105. The boundary-layer profile showed unsteadiness, oscillating above and beneath the classical logarithmic law of the wall with body motion. Across the entire surface regions that were measured, local Reynolds numbers based on momentum thickness, which is the distance that is perpendicular to the fish surface through which the boundary-layer momentum flows at free-stream velocity, were greater than the critical value of 320 for laminar-to-turbulent transition. The skin friction was dampened on the convex surface while the surface was moving towards a free-stream flow and increased on the concave surface while retreating. These observations contradict the result of a previous study using different species swimming by different methods. Boundary layer compression accompanied by an increase ...
Journal of Fish Biology, 2007
ABSTRACT The behavioural response of the jack mackerel Trachurus japonicus when encountering a ne... more ABSTRACT The behavioural response of the jack mackerel Trachurus japonicus when encountering a netting panel was shown to be influenced by swimming speed and the diagonal mesh-size ratio (vertical:horizontal).
Journal of Fish Biology, 2007
ABSTRACT The swimming performance of Platycephalus bassensis at steady speed was assessed with an... more ABSTRACT The swimming performance of Platycephalus bassensis at steady speed was assessed with an emphasis on hydrodynamics. The minimum swimming speed to maintain hydrostatic equilibrium for P. bassensis of 0·271 m total length (LT) was calculated to be 1·06 LT s−1. At this speed, the required lift to support the mass of the fish was equivalent to 6·6% of the fish mass; 82·7% of which was created by the body as a hydrofoil, and the rest of which was created by the pelvic fins as hydrofoils. The minimum swimming speed decreased with the LT of the fish and ranged from 1·15 LT s−1 for a fish of 0·209 m to 0·89 LT s−1 for a fish of 0·407 m. The forward movement per tail-beat cycle (i.e. stride length) was described with an equation including quantities of morphological and hydro-mechanical relevance. This equation explained that stride length was increased by the effect of turbulence characterized by the Reynolds number and demonstrated the morphological and hydro-mechanical functional design of the fish for maximizing thrust and minimizing drag. The larger span of the caudal fin and caudal tail-beat amplitude was associated with larger stride length, whereas greater frictional drag was associated with smaller stride length.
Fisheries Science, 2009
ABSTRACT The effect of temperature on the swimming performance of jack mackerel Trachurus japonic... more ABSTRACT The effect of temperature on the swimming performance of jack mackerel Trachurus japonicus was examined in a flume tank by measuring the swimming endurance time and heart rate. The lower swimming performance was observed at 10°C (the lowest temperature tested), manifesting as the shortest endurance time and the slowest maximum sustained speed. ECG measurements of the heart rate under free-swimming conditions at zero flow velocity revealed a temperature effect, with 25.3beats/min observed at 10°C, 38.9 at 15°C, and 67.2 at 22°C. The heart rate also increased with swimming speed to maximum levels of 60, 125, and 208beats/min, respectively, at these three temperatures. Heart rate recovery times measured after the fish had been swimming at prolonged speed tended to increase with temperature, while a negative correlation resulting in relatively short recovery times was observed after swimming at close to the burst swimming speed at each water temperature.
Fisheries Science, 2013
ABSTRACT Swimming performance of jack mackerel Trachurus japonicus (18.2 ± 0.8 cm fork length (FL... more ABSTRACT Swimming performance of jack mackerel Trachurus japonicus (18.2 ± 0.8 cm fork length (FL), n = 185) was examined in a flume tank by measuring the stride length at low and high tail beat frequencies with electromyogram monitoring and a muscle twitch experiment. Stride length was analyzed by monitoring the tail beat frequency according to the swimming speed at different temperatures of 10, 15 and 22 °C. In the electromyographic observations, the initiation of ordinary muscle activity occurred between 71.4 and 99.6 cm/s, that is 3.7 to 5.3 FL/s, when the tail beat frequency was over 6 Hz. The swimming speeds increased rectilinearly with the tail beat frequency at each water temperature both for the low and high tail beat frequency. Lower stride length was observed at the lowest temperature (10 °C) tested. The forced swimming exercise significantly affected the muscle contraction time to become longer than the control fish, which indicated a reduction of the maximum swimming speed performance.
Journal of Experimental Biology, 2012
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Papers by Kazutaka Yanase