排序方式： 共有5条查询结果，搜索用时 265 毫秒
1
1.
A new device for monitoring the activity of freely swimming flatfish, Japanese flounder Paralichthys olivaceus 总被引：1，自引：0，他引：1
RYO KAWABE KATSUAKI NASHIMOTO TOMONORI HIRAISHI YASUHIKO NAITO KATSUFUMI SATO 《Fisheries Science》2003,69(1):3-10
ABSTRACT: The tail beat and activity behavior of four captive Japanese flounder Paralichthys olivaceus , were monitored with acceleration data-loggers while the fish swam in an aquarium. Depth, swimming speeds and two-axis acceleration data were collected continuously for approximately 20 h per fish. Simultaneously, the swimming behaviors of the fish were filmed at different angles. Using the specific characteristic of the acceleration profiles, in tandem with other types of data (e.g. speed and depth), four behavioral patterns could be distinguished: (i) 'active' swimming; (ii) burying patterns; (iii) 'inactive' gliding; and (iv) lying on the bottom. Tail beat frequency ranged from 1.65 ± 0.47 to 2.04 ± 0.25 Hz (mean ± SD; n = 4). Using the relationship between tail beat frequency and swimming speed, the 'preferred' swimming speed of the fish was estimated to be between 0.6 and 1.2 body lengths (BL)/s. Additionally, fish rarely swam faster than 1.2 BL/s. This study shows that the acceleration data-loggers represent a useful and reliable system for accurately recording the tail beat of free-ranging fish and estimating flatfish behavior. 相似文献
2.
SHINSUKE TORISAWA TOMONORI HIRAISHI KATSUTARO YAMAMOTO KATSUAKI NASHIMOTO 《Fisheries Science》2002,68(5):984-990
Understanding the behavior of Jacopever Sebastes schlegeli to visual stimulation is important and requires determination of visual sensitivity through the use of effective stimulation. In the present study, we measured the visual acuity, visual accommodation and spectral sensitivity of Jacopever. Visual acuity was calculated from the maximum cone density in the retina. In five specimens, the total length ranged from 17.6 to 24.5 cm and the calculated minimum resolving angles and visual acuities were 9.5–10.7 min and 0.09–0.11, respectively. Measurement of lens movement for visual accommodation indicated a mean distance and direction of movement of 0.31 mm and 16.0° in an upward and forward direction, respectively. The direction of accommodation and visual axis measured from the retinal area of maximum cone density were almost identical. The calculated focal distance was 0.74-fold the total length in the nearest point to infinity. We also determined the spectral sensitivity electrophysiologically by recording S-potentials from 45 specimens of total length of 15.4–47.5 cm. The S-potentials were recorded from 300 horizontal cells in the retina. All responses showed a similar spectral pattern, consisting of hyperpolarization in response to various wavelengths of stimulating light; the maximum amplitude of the response was recorded at 522 nm. 相似文献
3.
Vertical movement patterns of five chum salmon (Oncorhynchus keta) during homing migration were examined using archival tags. The standard deviation of the depth and ambient and body cavity temperatures during daytime were larger than those during night‐time. Vertical movements through the thermocline with a periodicity of less than 1 h were observed during daytime in addition to the diel vertical movement patterns in the open ocean. During these periods of frequent short‐term vertical movements, the difference between the body cavity temperature and ambient temperature was large while the variance of the body cavity temperature was less than that of the ambient temperature. From the results of a random simulation, the variation of the body cavity temperature was shown to decrease due to these periodic high frequency movements in comparison with random vertical movements. The whole‐body heat‐transfer coefficient k (s?1), which was estimated by a heat budget model, was 1.48 × 10?3. The k of chum salmon was larger than that of bigeye tuna (Thunnus obesus) by about one order of magnitude for the cooling of the body. The k of chum salmon did not change like tuna, which are physiologically adapted to conserve body cavity temperature. This indicates that the regulation of body cavity temperature by chum salmon is dependent on the vertical movements only. The maintenance of the body cavity temperature is concluded to be advantageous for their maturation and growth from the relationship between energy input and output during their homing migration. 相似文献
4.
5.
AKIRA NISHIMURA TOMONORI HAMATSU OSAMU SHIDA IKUO MIHARA TAKASHI MUTOH 《Fisheries Oceanography》2007,16(3):229-239
Juvenile walleye pollock of the Japanese Pacific population were collected from the Funka Bay [spawning ground; 16–64 mm fork length (FL)] in spring and the Doto area (nursery ground; 70–146 mm FL) in summer. Hatch dates were estimated by subtracting the number of otolith daily increments from sampling dates, and their early growth was back‐calculated using otolith radius–somatic length relationships. Interannual change of the hatching period was observed during 2000–02, and the peaks ranged from mid‐February in 2000 to early‐April in 2002. In 2000, when a strong year class occurred, early life history of the surviving juveniles could be characterized by early hatching and slower growth in the larval stage (<22 mm length). Higher growth rate in 2001 and 2002 did not always lead to good survival and recruitment success. Even though their growth was slow in 2000, the larvae hatched early in the season had larger body size on a given date than faster‐growing larvae hatched in later season in 2001 and 2002. Bigger individuals at a certain moment may have advantage for survival. The delay of hatching period may result in higher size‐selective mortality, and as a necessary consequence, back‐calculated growth in 2001 and 2002 could shift towards higher growth rate, although abundance of such a year class would be at the lower level. Variability in spawning period, early growth and their interaction might have a strong relation to larval survival through cumulative predation pressure or ontogenetic changes in food availability. 相似文献
1