Perception Of Fish Research Articles

Effects of hydraulic cues in barrier environments on fish navigation downstream of dams

Understanding how hydraulic cues in the barrier environment affect fish navigation is critical to fish migration in dammed rivers. However, most of the current research on the effects of hydraulic cues on fish navigation focuses on the effects of a single hydraulic parameter on fish migration and usually ignores fish sensory perception and swimming ability. This study presents an effective approach that combines a computational fluid dynamics model of a river with a model of fish behaviour to elucidate the effects of hydraulic cues in the barrier environment on fish migration paths and strategies by simulating the fish's perception of flow direction and their regulation of multiple hydraulic parameters. Four release scenarios for the dam were reviewed and it was determined that the modelled fish movements realistically reflected actual observations. In various scenarios, the target fish (Schizothorax chongi) managed to move upstream to the tailrace downstream of the dam, despite the hydraulic barrier created by the mainstem area of the river; they overcame this obstacle by exploiting low-velocity zones on both sides of the mainstem and in the river's boundary layer. During upstream movement, the target fish preferred areas with flow velocities between 0.7 and 1.0 m/s and a turbulent kinetic energy of less than 0.3 m2/s2 to maintain aerobic activity. Additionally, the effects of alternative turbine release strategies on the fine-motor movement of target fish were reviewed and an optimised strategy was provided that could increase the proportion of target fish entering the fish passage facility from 0% to 53.8% in the original scenario to 82.6%. This study provides a feasible method for the simulation of fish fine motion in complex flow environments as well as a scientific basis for the management of fish resources in dammed rivers.

Collective motions of fish originate from balanced local perceptual interactions and individual stochastics.

The movement of a group of biological individuals, such as fish schools, can evolve from disordered motions to synergistic movements or even ordered patterns. However, the physical origins behind such emergent phenomena of complex systems remain elusive. Here, we established a high-precision protocol for studying the collective behavior of biological groups in quasi-two-dimensional systems. Based on our video recording of ∼600h of fish movements, we extracted a force map of the interactions between fish from their trajectories using the convolution neural network. Presumably, this force implies the fish's perception of the surrounding individuals, the environment, and their response to social information. Interestingly, the fish in our experiments were predominantly in a seemingly disordered swarm state, but their local interactions were clearly specific. Combining such local interactions with the inherent stochasticity of the fish movements, we reproduced the collective motions of the fish through simulations. We demonstrated that a delicate balance between the specific local force and the intrinsic stochasticity is essential for ordered movements. This study presents implications for self-organized systems that use basic physical characterization to produce higher-level sophistication.

Something fishy is cooking – A survey of 11- to 13-year-old Danish children’s self-evaluated food neophilia, food behaviour, knowledge, and skills in relation to fish

Danish children aged 10 to 17 consume only one-third of the officially recommended amount of fish. Little is known about Danish children’s perception of fish, their knowledge and skills in relation to preparing and cooking fish nor their status of food neophilia, or the relationship between these areas. This study seeks to address this lack of knowledge.The objective of this survey is to investigate 11- to 13-year-old Danes’ self-evaluated liking of cooking, fish intake, liking of fish, knowledge and skills in relation to fish and cooking, and food neophilia. Furthermore, the aim is to explore possible effects of gender and geographical area.This cross-sectional survey targets 11- to 13-year-old children in Denmark. 669 children from the eastern part of Denmark were recruited through the school subject Food Knowledge.Liking of cooking was high, a general liking for fish was identified, but consumption was low, with 42% of respondents not having eaten fish in the past week. Self-evaluated knowledge of fish and skills related to fish and cooking were generally low. Effects of gender and area were observed: boys had a tendency to rate themselves higher in knowledge and skills than girls, and children from the Greater Copenhagen area liked to cook more and had a more positive fish behaviour than children from provincial Zealand. Furthermore, knowledge and skills related to fish and cooking were strongly correlated, and liking to cook was not associated with skills in food and cooking but rather with food neophilia.

Applying free word association to understand the perception of fish as a meal by Brazilians with different consumption frequencies

AbstractThe aim of the present study was to investigate through free word association the Brazilian consumers' perception of fish as a meal and to explore whether different fish consumption frequencies play a role. The participants were split into high, occasional, and low consumption groups according to their self‐reported fish consumption frequency. Brazilian consumers' general associations with fish were strongly related to health benefits, which was considered a motivating factor for the high consumption group. However, for the low consumption group, the unfamiliarity, the low convenience and the high price represent barriers to fish consumption. Although they did not present negative feelings regarding fish, it was not possible to determine the factors that influence fish consumption for the group of occasional consumers. The elaboration of semi ready‐to‐eat products from fish residues and further studies focusing on occasional consumers can be strategies to increase the Brazilian per capita consumption of fish.Practical ApplicationsFish is an important source of high quality nutrients and its intake contributes to maintaining a healthy diet. However, the per capita consumption of this matrix is still low in Brazil. The present study observed that the perception of Brazilian consumers regarding fish as a meal was significantly affected by their fish consumption frequency. Therefore, the different consumer profiles must be taken into account for the development of more appropriate marketing and communication strategies aimed at increasing the consumption of this important product in the country.

Vulnerability of Baitfishes of Handline and Lift Net Fishing Gear that Landed in Kendari, Bitung, Wakatobi and Larantuka Fishing Port

The high intensity of catching has an impact on decreasing stock, vulnerability, which has the potential affect to stock sustainability; such vulnerabilities include the baitfishs group in tuna fisheries. Vulnerability studies of baitfishs in Bitung, Wakatobi, Kendari and Larantuka in July 2013 were carried out to find out the pressure caused. The data collected is the parameter of productivity and perception of fish. The catches besides tuna are skipjack tuna (Katsuwonus pelamis), Indian Scad (Decapterus russelli), little tuna (Euthynuss affinis), Squid (Loligo loligo.), Anchovies (Stelophorus commersonii) and Sardinella (Sardinella fimbriata). Based on MSC (Marine Steward Council) Vulnerability Criteria, vulnerability index in Bitung (skipjack = 85.6; scad = 98.9; little tuna = 96.2), Wakatobi (scad = 97.9; squid = 98.5) and Kendari (skipjack= 85.6; anchovies = 98.5) and Sardinella fimbriata is about 96 in Larantuka. The conclusion of this research are the baitfishes state as low vulnerability and low risk and potential for sustainability

Fish intelligence, sentience and ethics.

Fish are one of the most highly utilised vertebrate taxa by humans; they are harvested from wild stocks as part of global fishing industries, grown under intensive aquaculture conditions, are the most common pet and are widely used for scientific research. But fish are seldom afforded the same level of compassion or welfare as warm-blooded vertebrates. Part of the problem is the large gap between people's perception of fish intelligence and the scientific reality. This is an important issue because public perception guides government policy. The perception of an animal's intelligence often drives our decision whether or not to include them in our moral circle. From a welfare perspective, most researchers would suggest that if an animal is sentient, then it can most likely suffer and should therefore be offered some form of formal protection. There has been a debate about fish welfare for decades which centres on the question of whether they are sentient or conscious. The implications for affording the same level of protection to fish as other vertebrates are great, not least because of fishing-related industries. Here, I review the current state of knowledge of fish cognition starting with their sensory perception and moving on to cognition. The review reveals that fish perception and cognitive abilities often match or exceed other vertebrates. A review of the evidence for pain perception strongly suggests that fish experience pain in a manner similar to the rest of the vertebrates. Although scientists cannot provide a definitive answer on the level of consciousness for any non-human vertebrate, the extensive evidence of fish behavioural and cognitive sophistication and pain perception suggests that best practice would be to lend fish the same level of protection as any other vertebrate.

Proposal of a sluice-type fish pass

One-dimensional design of fish passes often leads to an unsatisfying solution. The problems are due to insufficient, if not completely missing, collaboration between biologists and civil engineers. In the present paper, a new type of fish pass is presented. A labyrinth flux develops in a system of sequential sluices and baffles in between, which uncouple the supercritical flow of the single sluices. A series of biological, hydraulic and numerical experiments was carried out in order to investigate the optimum configuration in terms of geometric issues, regarding the biological needs and performances of organisms to be transported. Following this optimization, fish can control the prevailing flow conditions quite well. Because the air entrainment into the water is avoided, fish perception is not affected. A geometric extension regarding the needs of small fish, bottom fish, and macrozoobenthos decreases the selectivity and predation pressure on them.

Effects of predator presence on territorial establishment

A variety of factors can affect defensive costs of territorial residents, including familiarity with neighbors, frequency of intrusions, and the topography of the territory. Here we investigate the effects of a predator's presence on fighting during territorial settlement. In a laboratory study of a cichlid fish, the blockhead ( Steatocranus casuarius ), we manipulated the focal fish's perception of predation risk by showing the fish a predator in an adjacent aquarium in half the trials, and we found that fish attempting to establish territories were affected in several ways by the increased risk. First, they reduced the amount of time spent fighting, with fish able to see a predator fighting less than one-tenth as much as fish that never saw a predator. In addition, the blockheads spent more time in refuges when the predator was present, and they reduced the intensity level of the fights that they did have, avoiding for example high-intensity acts that involved physical contact in favor of low-level displays. Finally, fish that saw a predator accepted territories that were smaller than those of fish that did not see a predator suggesting that predation risk could influence territory size in the field, particularly during the period of territorial settlement.