Fish School Characteristics Research Articles

Effects of Different Motion Parameters on the Interaction of Fish School Subsystems.

For a long time, fish school swimming has attracted a great deal of attention in biological systems, as fish schools can have complex hydrodynamic effects on individuals. This work adopted a non-iterative, immersed boundary-lattice Boltzmann method (IB-LBM). A numerical simulation of two-dimensional three-degree-of-freedom self-propelled fish, in side-by-side, staggered, and triangle formations, was conducted by adjusting spacing and motion parameters. A comprehensive analysis of individual speed gains and energy efficiencies in these formations was carried out. Furthermore, an analysis of the hydrodynamic characteristics of fish schools was performed, using instantaneous vorticity profiles and pressure fields. Certain studies have shown that passive interactions between individuals cannot always bring hydrodynamic benefits. The swimming efficiency of side-by-side formations in the same phase gradually increases as the distance decreases, but it also brings certain burdens to individuals when the phases are different. This paper also shows that the roles of passive interactions, spacing, and deflections affect fish school subsystems differently. When the low-pressure areas created by a wake vortex act on one side of an individual's body, the tail-end fish are good at gaining hydrodynamic benefits from it. This effect is not universal, and the degree to which individuals benefit from changes in exercise parameters varies. This study provides a theoretical basis for bioinspired robots, as well as providing certain insights into the mechanism of collective biological movement.

Short-Range Movement Pattern of Amphidromous Lagoon Fish Schools: Ecological Applications

High-resolution multibeam sonar allows estimating movements of pelagic fish schools at short range. Taking advantage of this methodology, we calculated a Straightness Index (SI) to quantify the proportion of schools migrating actively from those residents in lagoon channels. This information enhances our knowledge of both fish school displacements and migration processes, which are essential to improve our understanding of ecosystem functioning. Most fish schools (65%) exhibited a SI value demonstrating oriented swimming behavior through the channels displayed by schools reaching the sea during fall migration. This trend appears as an intrinsic property of school movements, allowing monitoring of the school migration process in a channel to provide information for manager vs. fishing regulation measures or lagoon planning. The result strengthens the ‘multi-transit’ hypothesis, as 35% of schools show sinuous trajectories representative of schools staying in the channel or displaying high exploratory behaviors. Lastly, the fish school Exploration Swimming Speed (ESS) was tested as a fishery-independent sampling method to evaluate the proportion of different fish species monitored using hydroacoustics. This approach demonstrates the interest in using swimming behavioral characteristics of fish schools for ecological and management purposes.

Seasonal dynamics in fish distribution and abundance revealed by an acoustic survey in coastal waters of the Suzu Area, Kochi Prefecture, Japan

For Japan's fishery, it is essential to conduct sustainable and efficient fishery owing to the decline in fish catch as well as the fisher population. To obtain information that contributes to sustainable and efficient fishery, we researched appropriate set-net locations with regard to fish distribution, abundance, and environmental characteristics. We conducted surveys from 2017/5 to 2018/2 in the Suzu coastal area, Kochi Prefecture, where the only main industry is set-net fishery. We investigated the seasonal relationships between fish school characteristics, including distribution and size, and marine environmental conditions in the Suzu coastal area, using a quantitative echo sounder (KSE300 SONIC, 38 kHz) and other devices. We observed that every season showed similar trends in the horizontal structure; fish densities were higher on the coast side, and in some seasons, these were higher at approximately 2000 m offshore. In addition, fish densities were higher in seas at depths up to 30 m. Set-net fishery is conducted in Suzu District at 300 m from the shoreand at a depth of approximately 35 m. The point of installation of set-nets is based on fish school distribution. In our study, we determined the most appropriate set-net installation points. This study not only provides a scientific basis for point selection but could also enhance the existing fishery that is limited to an aging fisher population and catch instability.

Predictable changes in fish school characteristics due to a tidal turbine support structure

There is uncertainty on the ecological effects of tidal stream turbines. Concerns include animal collision with turbine blades, disruption of migratory and foraging behaviour, attraction of animals to prey aggregating around turbines, or conversely displacement of animals from preferred habitat.This study used concurrent ecological and physical measurements to show the predictability of fish school characteristics (presence, school area and height above seabed) in a high energy tidal site across spring/neap, ebb/flood and daily cycles, and how this changed around a turbine structure.The rate of schools and school area per hour increased by 1.74 and 1.75 times respectively around a turbine structure compared to observations under similar conditions without a turbine structure. The largest schools occurred at peak flow speeds and the vertical distribution of schools over the diel cycle was altered around the turbine structure.While predictable attraction or aggregation of prey may increase prey availability and predator foraging efficiency, attraction of predators has the potential to increase animal collision risk. Predictable changes from the installation of turbine structures can be used to estimate cumulative effects on predators at a population level. This study can guide a strategic approach to the monitoring and management of turbines and arrays.

The Performance of the New Fishing Gears of the Anchovy Boat Seine Fishery Using a Hydroacoustic Method

The anchovy boat seine fishery is conducted only in South Korea and Japan. This fishery has the largest fishing gear among towing net fisheries in the world. Hence, the expenses of manufacturing and repairing the fishing gear become formidable, and handling the huge fishing gear involves significant labor force and risk. Our research team has developed a small and a large improved fishing gears of the anchovy boat seine fishery. The performance of two improved fishing gears compared to the existent fishing gear was investigated using a hydroacoustic method. In particular, net shapes of the two improved gears and existent one were examined. As a result, it had a tendency that the height of the net mouth increased as the distance between two net vessels broadened. Between the small and large improved fishing gears, the height of the net mouth was not much different. The morphological characteristics of fish schools among two improved fishing gears and the existent one were precisely described. In consideration with the net shape, noise, and the number of escaped anchovy schools, the large improved fishing gear had the best performance. In addition, the water temperature and salinity at 10 ~ 20 m where anchovy schools were mainly distributed was approximately 16 °C and 33.3 psu, respectively. These results can contribute the efficiency and safety of the anchovy boat seine fishing operation.

A Pilot Study on the Application of Acoustic Data Collected from a Korean Purse Seine Fishing Vessel for the Chub Mackerel

This paper describes the first use of acoustic data collected during normal fishing operations from a South Korean commercial fishing vessel. Acoustic data (120 kHz) were collected from a purse seine fishing vessel while targeting chub mackerel (Scomber japonicus) between 13 September and 7 October 2014 in the southern West Sea and near Jeju Island. Acoustic backscatter data from 21 fishing events were used to delineate fish school characteristics and to estimate the chub mackerel biomass which was compared with the catch. With regard to the fish school description, the volume back scattering strength (SV) and thickness of the fish schools presented differently. The average and standard deviation of SV was −47.3 ± 2.1 dB. The fish lengths varied greatly and some schools were inordinately long (average and standard deviation length of 137.0 ± 329.6 m). The fish school area largely altered. The average distributional depth and the distance between fish school and sea bottom were 31.8 m and 42.7 m, respectively, indicating that the fish schools attracted by light were mainly located close to the water surface. On average, the chub mackerel biomass was 1.7 times larger than the catch. The correlation between the chub mackerel biomass and the catch was low positive (r = 0.3, p < 0.05). This paper presented that available echo sounders installed fishing vessels can be used for helping in the chub mackerel resources management in South Korea.

Corrections of fish school area and mean volume backscattering strength by simulation of an omnidirectional multi-beam sonar

Abstract Fish school descriptors extracted from omnidirectional multi-beam data are biased due to beam width-related effects, and echotraces are distorted in a range-dependent manner that is a function of transducer intrinsic properties, as well as fish school characteristics. This work investigates a simulation approach that models the three-dimensional insonification of fish schools by an omnidirectional fishery sonar in order to assess the bias in measuring two key morphometric and energetic descriptors, namely the horizontal cross-sectional area of schools and their mean volume backscattering strength. Simulated fish schools of different sizes and backscattering properties were insonified at various ranges from the multi-beam transducer, outputting volume backscattering strength echograms. The simulated data were used to develop empirical models that correct the examined descriptors using only information extracted from the observed echotraces. Depending on the difference between the observed mean volume backscattering strength of a school and the echogram processing threshold, mean absolute percentage errors in measured area and volume backscatter reduced from 100.7% and 79.5% to 5.2% and 6.4%, respectively. The mean volume backscattering strength of a school is a key parameter for obtaining fish density estimates, and the results highlight the need for descriptor corrections to better interpret the multi-beam data.

Recreational Fish-Finders--An Inexpensive Alternative to Scientific Echo-Sounders for Unravelling the Links between Marine Top Predators and Their Prey.

Studies investigating how mobile marine predators respond to their prey are limited due to the challenging nature of the environment. While marine top predators are increasingly easy to study thanks to developments in bio-logging technology, typically there is scant information on the distribution and abundance of their prey, largely due to the specialised nature of acquiring this information. We explore the potential of using single-beam recreational fish-finders (RFF) to quantify relative forage fish abundance and draw inferences of the prey distribution at a fine spatial scale. We compared fish school characteristics as inferred from the RFF with that of a calibrated scientific split-beam echo-sounder (SES) by simultaneously operating both systems from the same vessel in Algoa Bay, South Africa. Customized open-source software was developed to extract fish school information from the echo returns of the RFF. For schools insonified by both systems, there was close correspondence between estimates of mean school depth (R2 = 0.98) and school area (R2 = 0.70). Estimates of relative school density (mean volume backscattering strength; Sv) measured by the RFF were negatively biased through saturation of this system given its smaller dynamic range. A correction factor applied to the RFF-derived density estimates improved the comparability between the two systems. Relative abundance estimates using all schools from both systems were congruent at scales from 0.5 km to 18 km with a strong positive linear trend in model fit estimates with increasing scale. Although absolute estimates of fish abundance cannot be derived from these systems, they are effective at describing prey school characteristics and have good potential for mapping forage fish distribution and relative abundance. Using such relatively inexpensive systems could greatly enhance our understanding of predator-prey interactions.

음향 자료를 이용한 하계 여수 바다목장 해역에서 어군의 시·공간 분포와 특징

This study assessed dominant fish species, and the characteristics and spatio-temporal distribution of fish schools using acoustic and catch data in the marine ranching area (MRA) of Yeosu in July and August 2013. Acoustic data were collected using a 200-kHz dual beam transducer, and catch data were analyzed through auction data generated by a set net installed in the MRA. More fish schools were detected by acoustic methods in July than in August. The temporal distribution of fish schools differed between July and August, but, many schools demonstrated a high mean volume scattering strength (SV) around artificial reefs. Additionally, the characteristics of fish schools detected by echograms and the species caught by set nets differed between July and August. The dominant fish species were Engraulis japonicus, Pampus argenteus, Scomberomorus niphonius, and Pampus echinogaster in July, and approximately 85% of the catch in August consisted of Scomberomorus niphonius. Therefore, hydro-acoustic tools are useful for estimating fish school characteristics in large areas over a short period. To determine species, it is important to conduct net sampling surveys during the acoustic surveys. However, if a database of fish school characteristics organized by species is constructed through continuous study, it could be possible to identify fish species through acoustic methods alone.

Ontogenetic shift in the schooling behaviour of sardines, Sardina pilchardus

Intraspecific variability in the characteristics of fish schools is often affected by the size of individuals. In this study, juvenile and adult sardine schools detected in five hydroacoustic surveys (2004–2008) in the North Aegean Sea (eastern Mediterranean) were analysed in an effort to identify differences in a suite of school descriptors (i.e. positional, energetic, morphometric) and define the size at which schooling behaviour changed from juvenile to adult. Juveniles exhibited discrete schooling characteristics and microhabitat preferences compared to adult fish. Specifically, schools of juvenile sardines were smaller, more elongated and irregular than those of adults, they backscattered less energy and were located higher in the water column. Based on the length frequency distributions of experimental pelagic trawl catches, the length at which 50% of sardines shifted behaviour from juvenile school structure to the more typical adult school form was estimated at 10.7 cm. This length almost coincides with several ontogenetic changes in biology (i.e. first maturity, allometric change in the length–weight relationship and onset of phytoplankton consumption). Several size-dependent school features observed in this study are partly attributed to the higher feeding demands of juvenile fish and the need to avoid intraspecific competition and predation.

A methodology for acoustic and geospatial analysis of diverse artificial-reef datasets

Abstract Kang, M., Nakamura, T., and Hamano, A. 2011. A methodology for acoustic and geospatial analysis of diverse artificial-reef datasets. – ICES Journal of Marine Science, 68: 2210–2221. A methodology is introduced for understanding fish-school characteristics around artificial reefs and for obtaining the quantitative relationship between geospatial datasets related to artificial-reef environments using a new geographic information system application. To describe the characteristics of fish schools (energetic, positional, morphological characteristics and dB difference range), acoustic data from two artificial reefs located off the coast of Shimonoseki, Yamaguchi prefecture, Japan, were used. To demonstrate the methodology of the geospatial analysis, diverse datasets on artificial reefs, such as fish-school characteristics, marine-environmental information from a conductivity, temperature, and depth sensor, information on artificial reefs, seabed geographic information, and sediment information around the reefs, were utilized. The habitat preference of fish schools was demonstrated quantitatively. The acoustic density of fish schools is described with respect to the closest distance from reefs and the preferred reef depths, the relationship between fish schools and environmental information was visualized in three dimensions, and the current condition of the reefs and their connection to seabed type is represented. This geospatial method of analysis can provide a better way of comprehensively understanding the circumstances around artificial-reef environments.

인공어초 어장에서 수록한 음향학적 다차원 데이터 해석을 위한 GIS의 응용

This study is for the multi-dimensional analysis of diverse data sets for artificial reefs off the coast of Shimonoseki, Yamaguchi prefecture, Japan. Various data sets recorded in artificial reefs ground were integrated in new GIS software: to reveal the relationships between water temperature and fish schools; to visualize the quantitative connection between the reefs and the fish schools; and to compare the seabed types derived from two different data sources. The results obtained suggest that the application of GIS in analyzing multi-dimensional data is a better way to understand the characteristics of fish schools and environmental information around artificial reefs and particularly in the evaluation of the effectiveness of artificial reefs.

Temporal trends in the numbers and characteristics of Lake Huron fish schools between 2000 and 2004

We used hydroacoustics to characterize temporal dynamics of fish schools in Georgian Bay and the North Channel of Lake Huron from 2000 to 2004. Dramatic changes in fish school numbers and characteristics were observed over the 5-year period. In 2000, fish schools had an average trace length of 18.2 m and an average height of 2.7 m. Between 2000 and 2004, there was then an increase in the distance of schools from bottom and a drop in the number of schools per kilometer of transect, in the number and proportion of benthic schools, and in the depth, length, height, area, and volume of schools. Netting data confirm that there was a reduction in alewife ( Alosa pseudoharengus) that could explain the declines in the number of schools and the changes in fish school characteristics. There was also evidence that the alewife schools were replaced, to a degree, by lake herring schools in Georgian Bay and rainbow smelt schools in the North Channel. Our work provides an example of how fisheries acoustics can be used to study the spatial and behavioural dynamics of fish schools in the Great Lakes.

Diel variation in the vertical distribution and schooling behaviour of sardine (Sardina pilchardus) off Portugal

Abstract Zwolinski, J., Morais, A., Marques, V., Stratoudakis, Y., and Fernandes, P. G. 2007. Diel variation in the vertical distribution and schooling behaviour of sardine (Sardina pilchardus) off Portugal. – ICES Journal of Marine Science, 64: 963–972. Diel patterns in the schooling behaviour and vertical distribution of pelagic fish schools were studied by examining their echotraces from repeated acoustic survey transects at three inshore sites off the Portuguese coast. At two sites, sardine was the dominant pelagic species, and echotrace characteristics of fish schools were similar to those reported in the literature. At the third site, where there was a multispecies pelagic assemblage that included sardine, there was more variability in several of the school descriptors. At all sites, fish schools expanded after sunset, enlarging their cross-sectional area along the horizontal plane and reducing their mean internal acoustic density, while maintaining their overall mean abundance. Downward migration was rapid (within 1 h) after sunset and simultaneous with school expansion. School-like aggregations with total backscattering similar to daytime schools were present throughout the night, although the proportion of small schools and scattered fish appeared to increase at that time. At dawn, sardine rose back up the water column and rapidly reformed into the typical daytime schools. This pattern of diel vertical migration is opposite to that described for most clupeoids worldwide. The implications of this behaviour on abundance estimation by acoustic monitoring surveys for small pelagic fish are discussed.

Inferring fish school distributions from long range acoustic images: Main acoustic clutter experiment 2003

Long range scattering from fish schools and bottom reverberation in the New Jersey Continental Shelf environment are modeled using a unified, range-dependent, bistatic scattering, and reverberation model based on the parabolic equation [Ratilal and Makris, J. Acoust. Soc. Am. 114, 2302 (2003)]. The fish swim bladder is approximated as an air-filled bubble, while the bottom reverberation from volume inhomogeneities is modeled using the Rayleigh–Born approximation. The broadband scattered field, in the frequency range from 390 to 440 Hz, is beamformed and spatially charted using two-way travel time. The model output is compared with scattered field levels from fish schools and background reverberation measured during the the Main Acoustic Clutter Experiment 2003 using a long range, bistatic sonar system. The fish school characteristics, such as size, distribution and density, are inputs to the model. These are obtained from measurements made by the fish finding sonar during the experiment. This calibrated model is then used to infer fish school distributions and densities in areas where fish finding sonar measurements are not available.

Individual behavior and emergent properties of fish schools: a comparison of observation and theory

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 273:239-249 (2004) - doi:10.3354/meps273239 Individual behavior and emergent properties of fish schools: a comparison of observation and theory Steven V. Viscido1,2,*, Julia K. Parrish1,2, Daniel Grünbaum3 1Department of Biology, 2School of Aquatic and Fishery Sciences, and 3School of Oceanography, Box 351800 Kincaid Hall, University of Washington, Seattle, Washington 98195, USA *Email: viscido@u.washington.edu ABSTRACT: Polarity, group velocity, and inter-individual spacing are characteristics of fish schools that strongly affect individual school members. However, these characteristics are group-level Œemergent properties¹: collective outcomes of behavioral interactions among members, not under direct control of any single member. The relationships between members¹ behaviors and the emergent group properties they produce are complex and poorly understood. In this study, we quantified 3D trajectories of all individual fish within 4- and 8-fish populations of Danio aequipinnatus, using stereo videography and a computerized tracking algorithm. We compared group polarity, group speed, and mean nearest-neighbor distances of schools within these populations to a simulation model that explored how fish responded to attraction/repulsion, alignment and random forces. Real fish exhibited a high degree of temporal variability in both polarity and group speed. Polarity and speed of simulated schools depended very strongly on the strength of the alignment force. Time-averaged polarity of real fish schools was most similar to simulated schools when alignment force was 1 to 5% of the attraction/repulsion force. For both real and simulated fish, a clear relationship existed between group speed and polarity: polarized groups were faster than non-polarized groups. We propose a multi-dimensional state space where several emergent property statistics are represented along the axes, and suggest certain Œpreferred¹ ranges of state space within which animal groups tend to localize, and in which they can sustain distinct types of regular architecture. KEY WORDS: Social aggregation · Schooling behavior · Emergent properties · Polarity · Group speed · Nearest-neighbor distance · Danio aequipinnatus Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 273. Online publication date: June 08, 2004 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2004 Inter-Research.

Effect of external factors (environment and survey vessel) on fish school characteristics observed by echosounder and multibeam sonar in the Mediterranean Sea

The size of pelagic fish schools depends on several parameters related to internal factors such as species, number of fish, fish swimming speed and physiological status and to external factors, such as hydrological factors and presence of predators. In order to better understand these relations, results coming from echosounder and multibeam sonar databases are analysed. Field data are collected during four acoustic surveys in the Mediterranean Sea in two different areas (Catalan and Adriatic Seas). The analysis shows differences between the two areas regarding size and position in the water column: schools are deeper and their mean size is lower in the Catalan Sea in comparison with Adriatic Sea. The differences in size of schools are mainly related to differences in school length. Moreover, the elongation of schools seen with the sonar is greater than one and half higher in the Adriatic Sea than in the Catalan Sea, whereas one would expect similar values for the two areas. The results are discussed in terms of environmental influence, avoidance reaction and acoustic capabilities of both tools. A hypothesis is proposed: the variation of school length and consecutively the variation of the correlated dimensions is first related to the strength of the avoidance reaction in front of the vessel and this effect can be reinforced depending on the environmental conditions. The model takes into account the effect of the boat, the vertical constraints undergone by the schools, and the internal requirements of the schools, such as the necessity for fish to keep visual contacts and the cohesion of the group.

1997 년 춘계의 동중국해 및 황해에 대한 어군의 분포특성

황해, 동중국 해역에서 서식하는 어업생물 자원의 평가 및 그 관리에 필요한 기초 자료를 수집하기 위한 시도로서, 1997 년도에 부경대학교와 일본 장기대학이 공동으로 실시한 어업자원조사중에서 주로 계량어군탐지기를 이용하여 수집한 자료를 분석, 고찰한 결과를 요약하면 다음과 같다. 1 황해, 동중국해에 설정한 9개의 조사정점에서 저층트롤에 의한 어획량은 7.7~182.48 kg/hour이었고, 그때 어획된 어종수는 7~34 종이었다. 2. 1997년 5월에 동중국해에 있어서의 어군의 분포는 황해 중부의 저층 냉수역과 동중국해 중앙해역의 저층 고온수역, 또 쿠로시오계의 난류와 황해 냉수 및 대륙 연안수의 사이에 형성된 제주도 남부의 전선역에서 그 어군도가 매우 높았다. 3. 황해, 동중국해의 조사대상해역의 전수층부와 저층부에 대한 어군의 평균 체적산란강도는 각각 -74.57 ㏈, -68.24 ㏈로서 저층부가 전수층부에 비해 5.67 ㏈ 더 높았다. 4. 본 연구의 조사대상해역에 대한 어군의 분포밀도를 추정한 결과, 전수층에 대해서는 6.65<TEX>$\times$</TEX><TEX>$10^{-5}$</TEX> kg/㎥이었고, 저층부에 있어서는 2.86<TEX>$\times$</TEX><TEX>$10^{-4}$</TEX> kg/㎥이었다. The combined hydroacoustic and demersal trawl surveys to investigate the distribution characteristics of fish schools in the Yellow Sea and the East China Sea were carried out during the spring of 1997 by the training ship "Nagasaki Maru" of Nagasaki University. Fish samples were collected by bottom trawling from 9 trawl stations randomly selected in the survey area, and the species and length compositions of trawl catches are examined. Hydroacoustic data were collected by using a Furuno FQ-50 scientific echo sounder operating at 50KHz and the data stored in field were later processed in the laboratory. The results obtained can be summarized as follows ：1. In the 9 trawl surveys conducted in the Yellow Sea and the East China Sea, 78 species including 80 species of fishes, 4 species of Cephalopoda and 6 species of Crustacea, were identified. The most abundant species in these stations were swimming crab(Portunus trituberculatus), Japanese horse mackere(Trachurus japonicus), redlip croaker(Larimichthys polyactis) and the catch per one hour in each station ranged 7.7 to 182.5 kg/hour. 2. The mean volume backscattering strength for the entire water column and the bottom layer of the 0-10 m from bottom friction were -74.6 ㏈ and -68.2 ㏈, respectively. That is, the mean volume backscattering strength for the bottom layer was 6.4 ㏈ higher than that for the entire water column 3. In the surveys during the spring of 1997, the geographical distribution characteristics of fish schools suggests a trend of decreasing fish abundance toward the coast area of Korea and the highest demersal concentrations appeared in waters between the Cheju Island and the Tsushima Island 4. The distribution density of fish school in the East China Sea and Yellow Sea during the 1997 acoustic survey were estimated to be 6.65<TEX>$\times$</TEX>10<TEX>$^{-5}$</TEX> kg/㎥ in the entire water column and 2.86<TEX>$\times$</TEX>l0<TEX>$^{-4}$</TEX> kg/㎥ in the bottom layer, respectively.pectively.