Herding and escaping responses of juvenile roundfish to square mesh window in a trawl cod end

KIM, Yong-Hae,WARDLE, Clem S,AN, Young-Su Springer Japan KK 2008 Fisheries Science Vol.74 No.1

<P>ABSTRACT: </P><P>The movements of juvenile roundfish, mainly haddock <I>Melanogrammus aeglefinus</I> and whiting <I>Merlangius merlangus</I>, reacting to a square mesh window in the cod end of a bottom trawl were observed during fishing experiments in the North Sea. Two typical behavioral responses of roundfish are described as the herding response and the escaping response, which were analyzed from video recordings by time sequences of the movement parameters. It was found that most of the actively escaping fish approached the square mesh window at right angles by swimming straight ahead with very little change in direction, while most of the herded fish approached the net at obtuse angles and retreated by sharp turning. The herding and escaping responses showed significant difference when characterized by frequency distributions of swimming speed and angular velocity, and both responses showed large and irregular variations in swimming movement parameters like the panic erratic responses. It is concluded that an escaping or herding response to the square mesh window could be decided by an interaction between the predictable parameters that describe the stimuli of net and angular changes of fish response, such as approaching angle, turning angle and angular velocity.</P>

Parentage assignment of stocked black sea bream <i>Acanthopagrus schlegelii</i> in Hiroshima Bay using microsatellite DNA markers

JEONG, Dal-Sang,GONZALEZ, Enrique Blanco,MORISHIMA, Kagayaki,ARAI, Katsutoshi,UMINO, Tetsuya Springer Japan KK 2007 Fisheries Science Vol.73 No.4

<P>ABSTRACT: </P><P>The genetic contribution of 51 broodstock, comprising 29 females and 22 males, reared at Hiroshima City Marine Products Promotion Center for the production of stocked black sea bream was monitored during two consecutive years using seven microsatellite DNA loci. The high discrimination ability of these markers was reflected in the polymorphic identification content (<I>PIC</I> = 0.831), the exclusion probability (<I>Q</I> ∼ 1), and the low probability of identity index (<I>I</I> = 3.635<SUP>−10</SUP>). The total number of breeders contributing to the mating process was estimated at 32 (62.7%) in 2000 and 30 (58.8%) in 2001. On pedigree reconstruction, 69.3% of the offspring were successfully assigned to a single broodstock pair. Loss of alleles accounted for 16.9% during seed production; nevertheless, 90.9% of males and 69.0% of females participated in the mating process. Based on microsatellite genetic tagging, 58.9% of the fish sampled during the two months after release were identified as hatchery stock, presenting no significant differences from wild conspecifics in either fork length or body weight.</P>

Optimum temperature and salinity conditions for growth of green algae <i>Chlorella ellipsoidea</i> and <i>Nannochloris oculata</i>

CHO, Sung Hwoan,JI, Sung-Choon,HUR, Sung Bum,BAE, Jeanhee,PARK, In-Seok,SONG, Young-Chae Springer Japan KK 2007 Fisheries Science Vol.73 No.5

<P>ABSTRACT: </P><P>The effects of temperature and salinity on growth of green algae <I>Chlorella ellipsoidea</I> and <I>Nannochloris oculata</I> were determined to compare the optimum culture conditions. A four-temperature (15, 20, 25, and 30°C) × three-salinity (10, 20, and 30) factorial design with triplicates was applied. Specific growth rate (SGR), maximum density, and duration to reach maximum density of <I>C. ellipsoidea</I> were significantly affected by both temperature and salinity. The highest SGR was observed in <I>C. ellipsoidea</I> at 25°C and salinity 10, but the maximum density was very low. The highest maximum density was achieved in <I>C. ellipsoidea</I> at 15°C and 10. The slope constant of the linear relationship between semilogarithmic growth of <I>C. ellipsoidea</I> and day of culture was highest at 15°C and 10. The SGR and duration to reach maximum density of <I>N. oculata</I> were significantly affected by both temperature and salinity. However, maximum density of <I>N. oculata</I> was significantly affected by temperature, but not salinity. The highest maximum density was achieved in <I>N. oculata</I> at 25°C and 30, but SGR was significantly lower than that of <I>N. oculata</I> at 25°C and 10. The slope constant of the linear relationship between semilogarithmic growth of <I>N. oculata</I> and day of culture was highest at 25°C and 30. Based on these results, the condition of 15°C and salinity 10 seemed to be optimal for maximum density of <I>C. ellipsoidea</I>, and the condition of 25°C and 10 and 30 for SGR and maximum density for <I>N. oculata</I>, respectively.</P>

Influences of feeding frequency of extruded pellet and moist pellet on growth and body composition of juvenile Japanese flounder <i>Paralichthys olivaceus</i> in suboptimal water temperatures

KIM, Kyoung-Duck,KIM, Kyong-Min,KANG, Yong Jin Springer Japan KK 2007 Fisheries Science Vol.73 No.4

<P>ABSTRACT: </P><P>This study was carried out to investigate the influences of feeding frequency of extruded pellet and moist pellet on growth and body composition of juvenile flounder (initial mean weight 6.3 g) in suboptimal water temperatures. A 2 (diets: extruded pellet and moist pellet) × 2 (feeding frequencies: two and three times daily) × 2 (water temperatures: 12 and 17°C) factorial design with three replications was used. After 60 days of feeding, the feeding frequency did not significantly affect growth performance of fish. Weight gain, daily feed intake, feed efficiency and protein efficiency ratio were significantly (<I>P</I> < 0.05) higher for fish reared at the higher water temperature. At the same water temperature, weight gain, feed efficiency, and protein efficiency ratio were significantly (<I>P</I> < 0.05) higher for fish fed the extruded pellet than moist pellet. The results of this study indicate that feeding frequency of two times daily is sufficient for optimal growth of juvenile flounder when reared in suboptimal water temperatures, and an increase in water temperature from 12 to 17°C improved growth and feed efficiency.</P>

Acoustic monitoring using multi-beam imaging sonar through a set net in the Southern Sea, Korea

Lee, Hyungbeen,Lee, Kyounghoon,Kim, Seonghun,Lee, Donggil,Yang, Yongsu Springer Japan KK 2016 Fisheries Science Vol.82 No.5

<P>This study investigated a method for monitoring fish flux though a set net in the coastal South Sea, Korea, using sideward-looking wide angle multi-beam imaging sonar (blueview). This data set was used to examine the impact of changes in diel variation and current speed from a set net. During nighttime, the influx of fish in the set net was significantly 22 times higher than in daytime. The time when high fish flux was observed corresponded to the time of low current speed during nighttime. In contrast, the fish flux was not affecting current speed during daytime. The study provides implications for understanding fish behavior through use of a set net.</P>

Effect of tooth spacing on the contact selection and available selection of a dredge for the equilateral Venus clam <i>Gomphina melanaegis</i>

KIM, In-Ok,MITUHASI, Takahisa,JO, Tae-Hyun,PARK, Chang-Doo,TOKAI, Tadashi Springer Japan KK 2005 Fisheries Science Vol.71 No.4

<P>ABSTRACT: </P><P>The effect of various tooth spacing on the contact selection and the net-mouth available selection of a dredge for the equilateral Venus clam <I>Gomphina melanaegis</I> is evaluated by applying a contact-probability model based on the SELECT method to the data of paired-gear tests with a control dredge of 12-mm tooth spacing and four test dredges of tooth spacing 16, 20, 24 and 35 mm. A master selection curve was estimated to be <I> s</I>(<I>R</I>) = exp(−11.23<I>R</I> + 4.799)/(1 + exp[−11.23<I>R</I> + 4.799]) where, <I>R</I> is <I>l</I>/<I>d</I>, the ratio of the shell length, <I>l</I>, to the tooth spacing, <I>d</I>. The shell width of 50% retention was slightly smaller than the tooth spacing, which means that size selectivity of teeth was a type of contact selection which was dependent on the tooth spacing. Contact probability, δ, of the clams coming into contact with the teeth were 0.625, 0.467, 0.563, 0.670 and 0.976 for tooth spacing 12, 16, 20, 24 and 35 mm, respectively. This indicates that some clams entered the dredge bagnet without contacting the teeth as the sand clogging the tooth spacing carried them into the bagnet. Available selection curve of the dredge net-mouth with teeth was obtained as δ<I>s</I>(<I>R</I>) + 1 − <I>δ</I>, and examined in terms of the legal landing size of the Venus clam.</P>

Polysaccharide extracted from Sargassum fulvellum leads to macrophage activation and Th1 polarization in splenocytes

Sung, N. Y.,Kim, H. M.,Byun, E. B.,Park, J. N.,Park, C.,Byun, M. W.,Byun, E. H. Springer Japan KK 2015 Fisheries Science Vol.81 No.4

Development of a low-energy midwater trawl with different combinations of trawl nets and trawl doors through model experiments

Lee, Jihoon,Lee, Chun-Woo,Park, Songho,Kim, Jieun,Park, Subong,Kim, Taeho Springer Japan KK 2018 Fisheries Science Vol.84 No.2

<P>Greenhouse gas (GHG) emissions from fisheries are of primary concern because of their effects on the environment. GHG emissions from fisheries are mainly related to their fuel consumption. Furthermore, the fuel consumption of fisheries also influences their economics. Therefore, many studies have been conducted to find ways of reducing fuel consumption in fishing operations that use fishing gear. The fuel consumption of fishing gear is generally related to its hydrodynamic resistance and the distance traveled. It mostly depends on the drag created, which is affected by towing speed. Based on model experiments, this study proposes new designs of trawl net and trawl doors to reduce fuel consumption in fisheries. The low-energy midwater trawl developed here can reduce the resistance force on the gear by 37.5%. It can also save 17% of the fuel consumption per voyage. Furthermore, this study investigates the efficiency of a low-energy trawl from an economic point of view. The findings of this study will be useful in reducing GHG emissions in fishing operations and thus contribute to a reduction in fishing costs through fuel savings.</P>

Classification of sound-scattering layers using swimming speed estimated by acoustic Doppler current profiler

Lee, K.,Mukai, T.,Lee, D. J.,Iida, K. Springer Japan KK 2014 Fisheries Science Vol.80 No.1

There are various techniques for identifying fish species, including the multi-frequency method, in situ target strength characteristics, and digital image processing methods. Acoustic Doppler current profilers (ADCPs) are able to determine multiple current fields simultaneously and have been used to observe the swimming speed and behavior patterns of shoals of pelagic fish under natural conditions. In this study, we evaluated a classification method that can be used to determine the swimming velocity of both the sound-scattering layer and pelagic fish shoals using an ADCP (153.6 kHz) and a scientific echosounder (38, 200 kHz). To calculate the actual swimming speed of the fish shoals, the mean swimming velocity vectors of each stratified bin must be compared with the mean surrounding three-dimensional (3D) current velocity vectors. We found the average 3D swimming velocity of the sound-scattering layer to be characterized by a deviation of > 5.3 cm/s from the surrounding current field. The average 3D swimming velocity of Pacific saury Cololabis saira was calculated to be 91.3 cm/s, while that of lanternfish Diaphus theta was 28.1 cm/s. These swimming speeds correspond to 4.19- and 4.26-fold the body length, respectively. Thus, the use of ADCP swimming velocity data can be expected to be a valuable species identification method for various fishes distributed in a given survey area.

Genotype and virulence of Streptococcus iniae isolated from diseased olive flounder Paralichthys olivaceus in Korea

Kim, M. S.,Jin, J. W.,Han, H. J.,Choi, H. S.,Hong, S.,Cho, J. Y. Springer Japan KK 2014 Fisheries Science Vol.80 No.6