Academic literature on the topic 'Shoal/school'

Based on the swarm behaviors in shoal of fish, this paper analyzes motion behavior of fish school when fish are foraging. This paper has simulated the pattern of motion behaviors for the fish school quantificationally. Using iterative and updating algorithm, it has modeled the 1-D procedure when fish school gradually approach food. These individual fish that constitute shoal of fish have finite perception and obey simple behavior rules. This paper further adopts modified intelligent optimization algorithm to model the process that individual fish interact with each other, changing position and velocity to gradually be close to food for the 2-D case. Experiment result shows the modified model successfully simulates the swarm behavior in shoal of fish when fish are looking for food, with small relative and absolute error.

Abstract Synchronized movements (schooling) emit complex and overlapping sound and pressure curves that might confuse the inner ear and lateral line organ (LLO) of a predator. Moreover, prey-fish moving close to each other may blur the electro-sensory perception of predators. The aim of this review is to explore mechanisms associated with synchronous swimming that may have contributed to increased adaptation and as a consequence may have influenced the evolution of schooling. The evolutionary development of the inner ear and the LLO increased the capacity to detect potential prey, possibly leading to an increased potential for cannibalism in the shoal, but also helped small fish to avoid joining larger fish, resulting in size homogeneity and, accordingly, an increased capacity for moving in synchrony. Water-movements and incidental sound produced as by-product of locomotion (ISOL) may provide fish with potentially useful information during swimming, such as neighbour body-size, speed, and location. When many fish move close to one another ISOL will be energetic and complex. Quiet intervals will be few. Fish moving in synchrony will have the capacity to discontinue movements simultaneously, providing relatively quiet intervals to allow the reception of potentially critical environmental signals. Besides, synchronized movements may facilitate auditory grouping of ISOL. Turning preference bias, well-functioning sense organs, good health, and skillful motor performance might be important to achieving an appropriate distance to school neighbors and aid the individual fish in reducing time spent in the comparatively less safe school periphery. Turning preferences in ancestral fish shoals might have helped fish to maintain groups and stay in formation, reinforcing aforementioned predator confusion mechanisms, which possibly played a role in the lateralization of the vertebrate brain.

Prey abundance is only a useful correlate of fish growth rate if it is considered within a match/mismatch hypothesis framework. We developed a model to explore the extent to which the growth rates of juvenile anchovies (Engraulis capensis) are influenced by temporal and spatial match/mismatches with the copepod Calanoides carinatus, a major component of their diet. The distributions of copepods and anchovies are dynamic, so that predation by anchovy may dramatically impact on its prey's spatial distribution. Predation rates by resident fish were commensurate with the average and maximum specific copepod production rates at fish densities of approximately 1 and 3.5 t·km-2, respectively. The spatial arrangement of fish biomass and the temporal overlap between fish and copepod abundances substantially modified both anchovy and copepod growth estimates. Predicted optimal shoal sizes suggest that additional factors such as predator avoidance or the energetics of maintaining school structure may be important. The model emulated observed variability in anchovy growth rates and confirmed the prediction that the availability of high-sustained abundances of food along the West Coast may be a critical "bottleneck" contributing to the strength of recruitment to the South African pelagic purse-seine fishery.

An investigation of the predator-evasion behaviour of minnow ( Phoxinus phoxinus ) shoals confronted with a pike ( Esox lucius ) showed that individual minnows generally chose the behaviour that minimized their chance of being eaten by the predator. As soon as the pike had been detected, minnows switched from dispersed small shoals to a single compact school. They then commenced inspection behaviour, during which individuals or groups approached the predator. This inspection served to confirm recognition of the pike and provide information on its behaviour. Avoidance and skittering behaviour took place when the pike began stalking. It was only when the predator escalated its attack and struck at the shoal that the minnows performed their most costly predator evasion tactics, such as flash expansion and fountain. After such tactics individuals often became separated from the shoal and as such were most vulnerable to capture. As a last resort, individual minnows hid among stones. Minnows from provenances with and without pike exhibited a similar repertoire of antipredator behaviour patterns, but those sympatric with the predator integrated their tactics more effectively and regained pre-exposure behaviour sooner after each encounter. Shoal size had an important effect on the execution of tactics. Minnows in shoals of 10 were more likely than minnows in shoals of 20 or 50 to abandon schooling behaviour and seek cover as individuals.

De har gjorts få studier på akvariesfiskars beteende. För att bemöta intresset för akvariefiskar så behöver vi veta mer om deras beteende i en artificiell miljö. Syftet med den här studien är att jämföra det utforskande beteendet hos vildfångade och odlade diamanttetror som är en vanlig akvariefisk. Hypotesen är att det finns en skillnad i deras beteende där vildfångade är mer djärva än de odlade. Grupper om fem individer av diamanttetra vildfångade och odlade släpptes ner i en ny artificiell miljö. De filmades i 20 minuter från de att de släpptes i. Testet upprepades 10 gånger med nya individer och för varje försök togs tiden det tog för varje individ att lämpa botten av akvariet och sedan mättes storleken på stimmen för varje grupp. Jag hittade en skillnad i hur lång tid fiskarna tog på sig för att lämna botten men det var ingen skillnad i höjd eller längd på stimmen. Detta visar att de vildfångade visade ett djärvare beteende än de odlade genom att lämna botten snabbare. Den här studien gav information om skillnaden i beteende för vildfångade och odlade diamanttetror och informationen kan användas för fortsatta studier kring akvariefisk.
The behaviour of ornamental fish is not well studied. To meet the needs of ornamental fish hobbyists, we need to know more about the behavior of fish in artificial environments. The aim of this study is to compare the explorative behaviour of wild-captured and farmed fish in a common ornamental fish, the diamond tetra. The hypothesis is that there is a difference between the two groups behavior where the wild-captured tetras are bolder. Groups of five individuals of farmed respectively wild-captured diamond tetra were released in a new artificial environment where they were monitored for 20 minutes. The test was repeated 10 times with new individuals, and the time it took for them to leave the bottom of the aquarium was measured as well as the size of the shoal. I found a difference in the time it took for the individuals to leave the bottom, with the wild-captured tetras leaving the bottom earlier than the farmed fish. There were no differences in height or length of the shoal. Thus, the wild diamond tetra were bolder than the farmed tetras. The study gave information about the differences in behavior between wild-captured and farmed diamond tetra and can give information to further studies about ornamental fish.