Kazutaka Yanase - Academia.edu (original) (raw)
Papers by Kazutaka Yanase
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
Isokinetics and Exercise Science
Fisheries Research, Apr 1, 2007
The maximum swimming speed of Australia's commercially important sand flathead (Platycephalus bas... more The maximum swimming speed of Australia's commercially important sand flathead (Platycephalus bassensis) was assessed by video observation of fish swimming in a tank and measurement of muscle contraction time. Knowledge of the maximum swimming speed is important because it influences the ability or otherwise of fish to escape from various parts of the trawl. In our study fish were collected locally by angling and divided into three groups based on total length. Each group was tested at three water temperatures (10, 15 and 20 • C) to reflect typical changes in seasonal water temperature. Tank-held fish were first induced to swim in a raceway to measure tail beat frequency (in Hz) and distance swum per tail beat (stride length). The highest measured swimming speed was 336.6 cm −1 for a 24.1 cm fish at 20 • C. At this speed the recorded tail beat frequency was 17.9 Hz. The observed swimming speeds of each group of P. bassensis were linearly related with tail beat frequency, and a statistically significant (P < 0.05) increase in stride length was detected with increased swimming speed. For all size groups, tail beat frequency increased with an increase in water temperature. The time taken for the anaerobic swimming muscle blocks dissected from newly euthanased P. bassensis to complete their contraction following an electric stimulus (5 V, 2 ms) was measured at each water temperature. Water temperature significantly (P < 0.01) affected mean contraction times for all fish tested, but fish length did not affect contraction time (P = 0.49). The mean pooled contraction times at each water temperature were 30.2 ms at 10 • C, 22.5 ms at 15 • C and 20.0 ms at 20 • C. For all size groups, the temperature effect on the muscle activity made tail beat frequency greater from 16.6 Hz at 10 • C to 25.0 Hz at 20 • C on average. We then used this data to calculate the maximum tail beat frequency and swimming speed of each group of fish at each water temperature. All estimated maximum swimming speeds were in excess of the typical trawl towing speed of 1.5 m s −1 , and the implications of these results for seasonally varied towing strategies are discussed.
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...
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 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, 2014
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.
Fisheries Research, 2007
The maximum swimming speed of Australia's commercially important sand flathead (Platycephalus bas... more The maximum swimming speed of Australia's commercially important sand flathead (Platycephalus bassensis) was assessed by video observation of fish swimming in a tank and measurement of muscle contraction time. Knowledge of the maximum swimming speed is important because it influences the ability or otherwise of fish to escape from various parts of the trawl. In our study fish were collected locally by angling and divided into three groups based on total length. Each group was tested at three water temperatures (10, 15 and 20 • C) to reflect typical changes in seasonal water temperature. Tank-held fish were first induced to swim in a raceway to measure tail beat frequency (in Hz) and distance swum per tail beat (stride length). The highest measured swimming speed was 336.6 cm −1 for a 24.1 cm fish at 20 • C. At this speed the recorded tail beat frequency was 17.9 Hz. The observed swimming speeds of each group of P. bassensis were linearly related with tail beat frequency, and a statistically significant (P < 0.05) increase in stride length was detected with increased swimming speed. For all size groups, tail beat frequency increased with an increase in water temperature. The time taken for the anaerobic swimming muscle blocks dissected from newly euthanased P. bassensis to complete their contraction following an electric stimulus (5 V, 2 ms) was measured at each water temperature. Water temperature significantly (P < 0.01) affected mean contraction times for all fish tested, but fish length did not affect contraction time (P = 0.49). The mean pooled contraction times at each water temperature were 30.2 ms at 10 • C, 22.5 ms at 15 • C and 20.0 ms at 20 • C. For all size groups, the temperature effect on the muscle activity made tail beat frequency greater from 16.6 Hz at 10 • C to 25.0 Hz at 20 • C on average. We then used this data to calculate the maximum tail beat frequency and swimming speed of each group of fish at each water temperature. All estimated maximum swimming speeds were in excess of the typical trawl towing speed of 1.5 m s −1 , and the implications of these results for seasonally varied towing strategies are discussed.
Fisheries Research, 2009
The species of flatheads, including Platycephalus bassensis (Cuvier, 1829) and Neoplatycephalus r... more The species of flatheads, including Platycephalus bassensis (Cuvier, 1829) and Neoplatycephalus richardsoni (Castelnau, 1872), are common shallow-water (30-160 m depth) teleosts and a valuable component of Australia's largest commercial fishing sector. In this study the behavioural responses of these species to a demersal trawl towed at 1.29 m s −1 (2.5 kt) were observed by the use of a 4-camera video system attached to the trawl. This system enabled simultaneous observations of the fish to be made at several locations between the trawl-mouth and the codend. One of the camera housings was equipped with an optical setup capable of emitting four laser beams 25 cm apart. These beams were shone onto the seabed or fish body to provide a standard length scale. P. bassensis and N. richardsoni were observed cruising in front of the trawl-mouth for an average of 126 s and 67 s, respectively, while using intermittent rapid swimming and coasting manoeuvres before entering the trawl. Eighty-five percent (85%) of the observed flatheads entered the trawl. The remainder escaped through the gap between the footrope and ground gear below the bottom panel of the trawl or allowed the ground gear to run over them. Only a few individuals of P. bassensis that entered the trawl were observed to orient themselves towards the trawl-mouth and swim in the towing direction. These fish reached the codend in 18 s on average. However, the great majority of the flatheads that were observed in the trawl showed little response. Some of these individuals stayed on the bottom net of the trawl ahead of the codend until the trawl was hauled. The others simply drifted towards the codend. On average, this took 7 s for each of the species. This was significantly shorter than the average time for those fish that actively oriented themselves towards the trawl-mouth (P < 0.05). These behavioural characteristics suggested that in order to reduce catches of the undersized flathead species, or of those in excess of the quota, greater efforts are required to stimulate the flatheads to swim actively and attempt to escape as they pass through the trawl. The implications of these results for current Australian fishing practices are discussed.
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 Experimental Biology, 2012
The yellowtail kingfish, Seriola lalandi, shows a distribution of anaerobic and aerobic (red and ... more The yellowtail kingfish, Seriola lalandi, shows a distribution of anaerobic and aerobic (red and pink) muscle fibres along the trunk that is characteristic of active pelagic fishes. The athletic capacity of S. lalandi is also shown by its relative high standard metabolic rate and optimal (i.e. least cost) swimming speed. To test the hypothesis that lateral line afferent information contributes to efficient locomotion in an active pelagic species, the swimming performance of S. lalandi was evaluated after unilateral disruption of trunk superficial neuromasts (SNs). Unilaterally disrupting the SNs of the lateral line impaired both swimming performance and energetic efficiency. The critical swimming speed (U crit ; mean ± s.d., N12) for unilaterally SNdisrupted fish was 2.11±0.96forklengths(FL)s-1 , which was significantly slower than the 3.66±0.19FLs-1 U crit of sham SNdisrupted fish. The oxygen consumption rate (mgO 2 kg-1 min-1) of the unilaterally SN-disrupted fish in a speed range of 1.0-2.2FLs-1 was significantly greater than that of the sham SN-disrupted fish. The least gross cost of transport (GCOT; N6) for SN-disrupted fish was 0.18±0.06JN-1 m-1 , which was significantly greater than the 0.11±0.03JN-1 m-1 GCOT for sham SN-disrupted fish. The factorial metabolic scope (N6) of the unilaterally SN-disrupted fish (2.87±0.78) was significantly less than that of sham controls (4.14±0.37). These data show that an intact lateral line is important to the swimming performance and efficiency of carangiform swimmers, but the functional mechanism of this effect remains to be determined.
Biology Open, 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=4×105) 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 laminarizati...
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
Isokinetics and Exercise Science
Fisheries Research, Apr 1, 2007
The maximum swimming speed of Australia's commercially important sand flathead (Platycephalus bas... more The maximum swimming speed of Australia's commercially important sand flathead (Platycephalus bassensis) was assessed by video observation of fish swimming in a tank and measurement of muscle contraction time. Knowledge of the maximum swimming speed is important because it influences the ability or otherwise of fish to escape from various parts of the trawl. In our study fish were collected locally by angling and divided into three groups based on total length. Each group was tested at three water temperatures (10, 15 and 20 • C) to reflect typical changes in seasonal water temperature. Tank-held fish were first induced to swim in a raceway to measure tail beat frequency (in Hz) and distance swum per tail beat (stride length). The highest measured swimming speed was 336.6 cm −1 for a 24.1 cm fish at 20 • C. At this speed the recorded tail beat frequency was 17.9 Hz. The observed swimming speeds of each group of P. bassensis were linearly related with tail beat frequency, and a statistically significant (P < 0.05) increase in stride length was detected with increased swimming speed. For all size groups, tail beat frequency increased with an increase in water temperature. The time taken for the anaerobic swimming muscle blocks dissected from newly euthanased P. bassensis to complete their contraction following an electric stimulus (5 V, 2 ms) was measured at each water temperature. Water temperature significantly (P < 0.01) affected mean contraction times for all fish tested, but fish length did not affect contraction time (P = 0.49). The mean pooled contraction times at each water temperature were 30.2 ms at 10 • C, 22.5 ms at 15 • C and 20.0 ms at 20 • C. For all size groups, the temperature effect on the muscle activity made tail beat frequency greater from 16.6 Hz at 10 • C to 25.0 Hz at 20 • C on average. We then used this data to calculate the maximum tail beat frequency and swimming speed of each group of fish at each water temperature. All estimated maximum swimming speeds were in excess of the typical trawl towing speed of 1.5 m s −1 , and the implications of these results for seasonally varied towing strategies are discussed.
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...
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 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, 2014
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.
Fisheries Research, 2007
The maximum swimming speed of Australia's commercially important sand flathead (Platycephalus bas... more The maximum swimming speed of Australia's commercially important sand flathead (Platycephalus bassensis) was assessed by video observation of fish swimming in a tank and measurement of muscle contraction time. Knowledge of the maximum swimming speed is important because it influences the ability or otherwise of fish to escape from various parts of the trawl. In our study fish were collected locally by angling and divided into three groups based on total length. Each group was tested at three water temperatures (10, 15 and 20 • C) to reflect typical changes in seasonal water temperature. Tank-held fish were first induced to swim in a raceway to measure tail beat frequency (in Hz) and distance swum per tail beat (stride length). The highest measured swimming speed was 336.6 cm −1 for a 24.1 cm fish at 20 • C. At this speed the recorded tail beat frequency was 17.9 Hz. The observed swimming speeds of each group of P. bassensis were linearly related with tail beat frequency, and a statistically significant (P < 0.05) increase in stride length was detected with increased swimming speed. For all size groups, tail beat frequency increased with an increase in water temperature. The time taken for the anaerobic swimming muscle blocks dissected from newly euthanased P. bassensis to complete their contraction following an electric stimulus (5 V, 2 ms) was measured at each water temperature. Water temperature significantly (P < 0.01) affected mean contraction times for all fish tested, but fish length did not affect contraction time (P = 0.49). The mean pooled contraction times at each water temperature were 30.2 ms at 10 • C, 22.5 ms at 15 • C and 20.0 ms at 20 • C. For all size groups, the temperature effect on the muscle activity made tail beat frequency greater from 16.6 Hz at 10 • C to 25.0 Hz at 20 • C on average. We then used this data to calculate the maximum tail beat frequency and swimming speed of each group of fish at each water temperature. All estimated maximum swimming speeds were in excess of the typical trawl towing speed of 1.5 m s −1 , and the implications of these results for seasonally varied towing strategies are discussed.
Fisheries Research, 2009
The species of flatheads, including Platycephalus bassensis (Cuvier, 1829) and Neoplatycephalus r... more The species of flatheads, including Platycephalus bassensis (Cuvier, 1829) and Neoplatycephalus richardsoni (Castelnau, 1872), are common shallow-water (30-160 m depth) teleosts and a valuable component of Australia's largest commercial fishing sector. In this study the behavioural responses of these species to a demersal trawl towed at 1.29 m s −1 (2.5 kt) were observed by the use of a 4-camera video system attached to the trawl. This system enabled simultaneous observations of the fish to be made at several locations between the trawl-mouth and the codend. One of the camera housings was equipped with an optical setup capable of emitting four laser beams 25 cm apart. These beams were shone onto the seabed or fish body to provide a standard length scale. P. bassensis and N. richardsoni were observed cruising in front of the trawl-mouth for an average of 126 s and 67 s, respectively, while using intermittent rapid swimming and coasting manoeuvres before entering the trawl. Eighty-five percent (85%) of the observed flatheads entered the trawl. The remainder escaped through the gap between the footrope and ground gear below the bottom panel of the trawl or allowed the ground gear to run over them. Only a few individuals of P. bassensis that entered the trawl were observed to orient themselves towards the trawl-mouth and swim in the towing direction. These fish reached the codend in 18 s on average. However, the great majority of the flatheads that were observed in the trawl showed little response. Some of these individuals stayed on the bottom net of the trawl ahead of the codend until the trawl was hauled. The others simply drifted towards the codend. On average, this took 7 s for each of the species. This was significantly shorter than the average time for those fish that actively oriented themselves towards the trawl-mouth (P < 0.05). These behavioural characteristics suggested that in order to reduce catches of the undersized flathead species, or of those in excess of the quota, greater efforts are required to stimulate the flatheads to swim actively and attempt to escape as they pass through the trawl. The implications of these results for current Australian fishing practices are discussed.
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 Experimental Biology, 2012
The yellowtail kingfish, Seriola lalandi, shows a distribution of anaerobic and aerobic (red and ... more The yellowtail kingfish, Seriola lalandi, shows a distribution of anaerobic and aerobic (red and pink) muscle fibres along the trunk that is characteristic of active pelagic fishes. The athletic capacity of S. lalandi is also shown by its relative high standard metabolic rate and optimal (i.e. least cost) swimming speed. To test the hypothesis that lateral line afferent information contributes to efficient locomotion in an active pelagic species, the swimming performance of S. lalandi was evaluated after unilateral disruption of trunk superficial neuromasts (SNs). Unilaterally disrupting the SNs of the lateral line impaired both swimming performance and energetic efficiency. The critical swimming speed (U crit ; mean ± s.d., N12) for unilaterally SNdisrupted fish was 2.11±0.96forklengths(FL)s-1 , which was significantly slower than the 3.66±0.19FLs-1 U crit of sham SNdisrupted fish. The oxygen consumption rate (mgO 2 kg-1 min-1) of the unilaterally SN-disrupted fish in a speed range of 1.0-2.2FLs-1 was significantly greater than that of the sham SN-disrupted fish. The least gross cost of transport (GCOT; N6) for SN-disrupted fish was 0.18±0.06JN-1 m-1 , which was significantly greater than the 0.11±0.03JN-1 m-1 GCOT for sham SN-disrupted fish. The factorial metabolic scope (N6) of the unilaterally SN-disrupted fish (2.87±0.78) was significantly less than that of sham controls (4.14±0.37). These data show that an intact lateral line is important to the swimming performance and efficiency of carangiform swimmers, but the functional mechanism of this effect remains to be determined.
Biology Open, 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=4×105) 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 laminarizati...