Small Groups Of Fish Research Articles

Dynamical order and many-body correlations in zebrafish show that three is a crowd

Zebrafish constitute a convenient laboratory–based biological system for studying collective behavior. It is possible to interpret a group of zebrafish as a system of interacting agents and to apply methods developed for the analysis of systems of active and even passive particles. Here, we consider the effect of group size. We focus on two– and many–body spatial correlations and dynamical order parameters to investigate the multistate behavior. For geometric reasons, the smallest group of fish which can exhibit this multistate behavior consisting of schooling, milling and swarming is three. We find that states exhibited by groups of three fish are similar to those of much larger groups, indicating that there is nothing more than a gradual change in weighting between the different states as the system size changes. Remarkably, when we consider small groups of fish sampled from a larger group, we find very little difference in the occupancy of the state with respect to isolated groups, nor is there much change in the spatial correlations between the fish. This indicates that fish interact predominantly with their nearest neighbors, perceiving the rest of the group as a fluctuating background. Therefore, the behavior of a crowd of fish is already apparent in groups of three fish.

Whole-Genome Survey Analyses Provide a New Perspective for the Evolutionary Biology of Shimofuri Goby, Tridentiger bifasciatus.

Simple SummaryGobies form a group of small fish that are extremely adaptable to their environment. However, genomic resources for Gobiidae species are scarce. In this study, high-throughput sequencing technology was used to generate the whole genome data for the shimofuri goby (Tridentiger bifasciatus). In addition to providing basic genomic information, the mitochondrial whole genome, microsatellite markers, and single-copy homologous genes are also explored. The PSMC model is used to provide the historical population dynamics of the shimofuri goby. The results of this study provide a reference for the assembly of a complete genome map and biological research of the shimofuri goby.The shimofuri goby (Tridentiger bifasciatus) is a small and highly adaptable goby, distributed along the coasts of China, the Sea of Japan, and the west coastal and estuarine areas of the Northwest Pacific. Next-generation sequencing was used to generate genome-wide survey data to provide essential characterization of the shimofuri goby genome and for the further mining of genomic information. The genome size of the shimofuri goby was estimated to be approximately 887.60 Mb through K-mer analysis, with a heterozygosity ratio and repeat sequence ratio of 0.47% and 32.60%, respectively. The assembled genome was used to identify microsatellite motifs (Simple Sequence Repeats, SSRs), extract single-copy homologous genes and assemble the mitochondrial genome. A total of 288,730 SSRs were identified. The most frequent SSRs were dinucleotide repeats (with a frequency of 61.15%), followed by trinucleotide (29.87%), tetranucleotide (6.19%), pentanucleotide (1.13%), and hexanucleotide repeats (1.66%). The results of the phylogenetic analysis based on single-copy homologous genes showed that the shimofuri goby and Rhinogobius similis can be clustered into one branch. The shimofuri goby was originally thought to be the same as the chameleon goby (Tridentiger trigonocephalus) due to their close morphological resemblance. However, a complete mitochondrial genome was assembled and the results of the phylogenetic analysis support the inclusion of the shimofuri goby as a separate species. PSMC analysis indicated that the shimofuri goby experienced a bottleneck event during the Pleistocene Glacial Epoch, in which its population size decreased massively, and then it began to recover gradually after the Last Glacial Maximum. This study provides a reference for the further assembly of the complete genome map of the shimofuri goby, and is a valuable genomic resource for the study of its evolutionary biology.

Study of the Behavior of Fish Caught with Sero Through Echofishfinder Observation in the Waters of the Tallo River Makassar

The study of fish behavior with echofishfinder observations was carried out to determine the composition of the catch, economic size of the catch and oceanographic parameters of the behavior of fish caught through echofishfiner observations in the Tallo river. This research was carried out in July-October 2020 at five fishing gear points. sero. The research method used is an experimental method which aims to investigate the possibility of a causal relationship by controlling and controlling. Data collection is obtained from the catch of sero fishing gear from fishermen then the catch is separated based on 3 types of catch, namely main, secondary and waste. Research results show that. The data analysis used in this study is the composition of the economic catch and the Tss test for oceanographic parameters. The results showed that the movement of fish was dominated by small fish groups that came schooling and alone (Solitary). The main types of catch are baronang fish (Siagnus Sp), bycatch, namely tembang fish (sardinella), and puffer fish (Diodotinidae). The measured oceanographic parameters were temperature, current velocity, and chlorophyll-a from several parameters that were closest to the total main catch, namely the chlorophyll a parameter.

Picky predators and odd prey: colour and size matter in predator choice and zebrafish’s vulnerability – a refinement of the oddity effect

Many fish species typically assort into homogeneous groups and thus reduce the risk of predators targeting individuals that are phenotypically odd compared to the majority of the group. The confusion and oddity effect hypotheses predict, that phenotypically odd individuals in a group are preferentially targeted by predators. Therefore, heterogeneous groups of prey should be more vulnerable to predator attention and attacks than homogeneous (all prey is the same colour, size, etc.) groups. Predators might use different cues to select a target, depending on their sensory abilities (sound, smell, vision, etc.). Visual-hunting predators that can see colour, for example, may be more likely to select prey based on colour than size oddity of prey. Previous studies on the oddity effect have found support for the colour-oddity and predator response, and to a lesser extent on size oddity. We thus predicted that, given a choice, a group with an odd-coloured individual would be targeted more often by a predator than a group with an odd-size fish but not odd in colour. Heterogeneous groups of six zebrafish (Danio rerio) containing either one odd-coloured (wildtype or red) or one odd-sized (large or small) individual were used as stimulus prey in dichotomous choice experiments examining prey preference in needlefish (Xenentodon cancila). Needlefish preferred heterogeneous groups regardless of the colour of the odd individual and when the odd individual was smaller than the other group members. However, when the odd individual was larger than the rest of the group, the predators preferred homogeneous groups of small fish. These new findings are inconsistent with the predictions of the oddity effect and warrant investigation of alternative hypotheses for size-assorted grouping in fish.

The Anesthetic Effects of Clove Oil and MS-222 on Far Eastern Catfish, Silurus asotus.

The objective of this study is to evaluate the anesthetic effects of clove oil and tricaine methanesulfonate (MS-222) on the Far Eastern catfish, Silurus asotus, by measuring the times to anesthesia and recovery. Each anesthetic effect of clove oil and MS-222 was tested in two groups of fish with different body sizes: a group of small fish (mean body length: 15.5±1.58 cm, mean body weight: 50.1±5.91 g, n=20) and a group of large fish (mean body length: 31.5±4.19 cm, mean body weight: 302.1±15.22 g, n=20). The anesthetics were used at concentrations of 200, 300, 400, 500, and 600 ppm. The results showed significant relationships between the concentration of the anesthetic and the body size of the fish. Each of these variables showed statistical significance (p<0.05). The time to anesthesia decreased linearly with increasing concentration in the large fish for both clove oil and MS-222 (p<0.05). Based on an optimal anesthetic time of approximately 1 min, the preferred concentrations of the anesthetics were 500 ppm for clove oil and 600 ppm for MS-222. Both the anesthetic time and the recovery time were shorter for the small fish than for the large fish (p<0.05). Our study showed that the smaller-sized Far Eastern catfish was more easily anesthetized and recovered more rapidly from anesthesia than the larger-sized fish.

Brazilian killifishes risk extinction

The annual killifishes are a diversified group of small fish in Africa and South America ([ 1 ][1]). Annual killifish are unique in their ability to survive in ephemeral pools; they have short, seasonal life cycles, laying eggs that lie dormant in the soil once the pools have evaporated and then

Genetic structure of Chilean populations of Seriola lalandi for the diversification of the national aquaculture in the north of Chile

Seriola lalandi has been recognized as a potential aquaculture species in Chile, however, little is known about the genetic structure of local populations. This is important, as the current production system is based on an initial wild catching and ill management of these stocks can cause reduced genetic variability. To assess the genetic structure of local S. lalandi we evaluated 27 published microsatellite markers developed from genomic libraries of other species of the genera. However only 12 markers could be used to properly assess the populations, most of these markers showed deviations from Hardy-Weinberg equilibrium with moderate inbreeding (F = 0.12). This species tends to show schooling behavior, so in all likelihood mating between relatives within small groups of fish is not unexpected. The population structure was assessed using Structure software, showing the presence of admixture with varying levels of individual ancestry. This was seen in both populations, without significant genetic differentiation. This may be explained by the migratory behavior, with mating between different populations likely to happen in small groups. Management of aquaculture resources is essential to secure a sustainable production system; this study is the first to provide estimates of genetic diversity of Chilean populations of S. lalandi.

Small-scale environmental variation influences whether coral-dwelling fish promote or impede coral growth.

Mutualistic symbioses are ubiquitous in nature and facilitate high biodiversity and productivity of ecosystems by enhancing the efficiency of energy and nutrient use within ecological communities. For example, small groups of fish that inhabit coral colonies in reef ecosystems potentially enhance coral growth through defense from coral predators, aeration of coral tissue and nutrient provisioning. This study examines whether the prevalence and consequences of fish-coral interactions vary among sites with different environmental conditions in a coral reef lagoon, using the humbug damselfish Dascyllus aruanus and its preferred coral host Pocillopora damicornis as a study system. Using a field experiment, we tested the site-specific effects of D. aruanus on coral growth, and show that the cost-benefit ratio for corals hosting fish varies with local environmental variation. Results of this study also demonstrate that fish prefer to inhabit coral colonies with particular branch-spacing characteristics, and that the local abundance of D. aruanus influences the proportion of coral colonies within a site that are occupied by fish rather than increasing the number of fish per colony. We also show that corals consistently benefit from hosting D. aruanus via defense from predation by corallivorous butterflyfish, regardless of local environmental conditions. These findings highlight the need to consider the potential for multiple scale- and state-dependent interaction effects when examining the ecology of fish-coral associations. We suggest that fluctuating cost-benefit ratios for species interactions may contribute to the maintenance of different colony phenotypes within coral populations.

Use of RFID Tags to Capture Dynamic Behavior of Individual and Groups of Small Fish

We describe a system by which we can implant RFID tags into small fish (such as carassius auratus) to use with readers to capture group dynamics as they interact with a variety of standard experiments including the signaled avoidance paradigm with an aquatic shuttle box, and operant responding on a variety of schedules. This innovative approach will allow for fish to be housed in groups, as well as used to determine what individuals do within group behavior. Instrumentation provided by Florida Research Instruments, Inc.

MicroRNAs revive old views about jawless vertebrate divergence and evolution

Most living vertebrates are jawed vertebrates or gnathostomes, like sharks or mammals. However, two small fish groups, hagfishes (67 species) and lampreys (about 40 species), are devoid of jaws and are either ignored by the public or regarded as pests. Both are eel-shaped, cartilaginous, and scale-less, and their overall anatomy is roughly similar to that of other fishes, with a brain, spinal cord, and sensory capsule, although more simple than that of gnathostomes (Fig. 1). First regarded as intestinal worms or degenerate jawed vertebrates (1) and then gathered into a group, the cyclostomes (rounded mouth), on the basis of basic anatomical characteristics (horny teeth, pouch-shaped gills, single nostril, and lack of paired fins) (2), these fishes became finally considered in evolutionary times as a monophyletic offshoot of primitive vertebrates, sister group to jawed vertebrates (3), and this became the received view for most of the of the 20th century (4).

Juvenile growth and aggression in diploid and triploid Chinook salmon Oncorhynchus tshawytscha (Walbaum)

Multilocus heterozygosity, aggressive and feeding behaviour, plasma cortisol levels and growth rate were evaluated among three groups of juvenile Chinook salmon Oncorhynchus tshawytscha: diploid, triploid and mixed groups of diploid and triploid fish. There was no difference between diploid and triploid fish in measurements of heterozygosity calculated using seven microsatellite loci, and these measurements did not correlate with performance measurements including feeding rate and growth rate. Aggression trials that examined small groups of fish revealed that after 4 days together in tanks, triploid fish were significantly less aggressive during feeding than diploid fish or fish in mixed groups. At the end of the trials, however, plasma cortisol levels did not differ among the three groups. Thirty‐day growth trials in duplicate tanks of 60 fish revealed no difference in growth rate among diploid, triploid and mixed groups, but plasma cortisol levels were significantly lower in triploid fish than in either diploid fish or the mixed fish. Overall, independent of the above differences in aggressive behaviour and cortisol levels, these results suggest similar performance in diploid and triploid Chinook salmon, and thus provide support for the viability of triploid Chinook salmon culture in commercial aquaculture.

Quantifying non-target seahorse fisheries in central Vietnam

Tropical shrimp trawling results in large amounts of highly diverse, non-target bycatch. We assessed the incidental catch of seahorses from shrimp trawls in central Vietnam to investigate the effects of fishing on an example group of small fishes that are potentially vulnerable and economically important. We used logbooks and catch landings surveys to quantify seahorse catches from 1996 to 2000. The majority of the seahorse catch consisted of two species, Hippocampus spinosissimus and Hippocampus trimaculatus, whose proportions varied by season and year. We found no consistent, directional patterns across years in key biological and fisheries parameters including seahorse size, sex ratio, reproductive state, life-history stage or catch-per-unit-effort but we had no information on distribution of trawl effort. However, there were strong seasonal patterns in reproductive state and catch-per-unit-effort. Overall, we calculated that the total catch was 36,000–55,000 seahorses year −1 from a fleet of 150–170 trawlers (a small part of the total Vietnamese fleet), even though the catch was only 0.9–1.6 seahorses boat −1 night −1. Other aspects of the trawling process, such as displacement or injury of seahorses, community disruption, and/or habitat damage may still pose a threat to the seahorses, particularly as Vietnam's fisheries intensify.

Ontogenetic changes in the bathypelagic distribution of European perch fry Perca fluviatilis monitored by hydroacoustic methods

The behaviour of bathypelagic perch fry (BPF) was monitored during 21 May, 24 June, 8 August and 5 September 1996 along the longitudinal profile of Řimov reservoir (Czech Republic), using acoustic methods (SIMRAD EY 500 echosounder, elliptical split-beam transducer, Sonar5 postprocessing software). In May, the BPF layer comprised a mass of solitary perch larvae at an abundance of over 31,000 ind. ha−1. In contrast, in June, the BPF layer consisted almost exclusively of shoaling individuals. The abundance of BPF increased up to 166,000 ind. ha−1. Similary, in August, fish in shoals prevailed in the BPF layer but the abundance dropped to less than 3,000 ind. ha−1. In September, the BPF layer consisted of both individuals and small groups of fish. At this time the abundance of BPF slightly increased to almost 5,000 ind. ha−1. Individual parameters describing the BPF layer, depth of the main layer, abundance of BPF in the main layer and thickness of the whole layer, differed significantly among months. The negligible abundance of potential predators below the thermocline, both in June and in August (exclusively adult perch), suggests that the BPF shoals were more likely to be created as a result of a social need rather than as a defense against predators. During similar surveys carried out prior to (25 April, 5 May, 7 May, 12 May, 15 May) and after this period (3 October, 7 November, 2 December), the BPF layer was not recorded.

Osteology and phylogeny of Parioglossus (Teleostei, Gobioidei), with a revised key to the species

The seventeen species of Parioglossus (Perciformes, Gobioidei) form a group of small fishes that inhabit the warm temperate to tropical regions of the western Pacific and Indian Oceans. A revised key to the species, based on external characters, is provided. Using external characters and osteology, a parsimony analysis of 24 characters of the 17 described species resulted in five equally most parsimonious trees. The strict consensus tree of these five trees supports the monophyly of Parioglossus. There is a basal polytomy, within which are monophyletic subgroups, one consisting only of P. dotui and P. neocaledonicus. The other subgroup is fully resolved, and consists of (P. galzini (P.aporos (P. nudus, P. philippinus) (P. rainfordi (P. palustris (P. interruptus (P. taeniatus (P. formosus (P. sinensis, P. raoi)))))))). However, only two of the nodes have a support value of greater than one.

Environmental dependence of inbreeding depression in cultured Coho salmon (Oncorhynchus kisutch): aggressiveness, dominance and intraspecific competition

We evaluated the effects of inbreeding on traits related to territorial dominance and tested whether the magnitude of inbreeding depression (ID) was modified by social environment in Coho salmon. Evaluation of behaviour in paired contests between juvenile salmon with different inbreeding (low, LI=9.5%; medium, MI=29.6%), did not show significant differences between their capacities for establishing territorial dominance (mean aggressiveness score, LI=20.0+/-22; MI=16.7+/-23 or for feeding attempts, LI=18.3+/-12; MI=21.1+/-12). However, fish with low inbreeding (LI) showed almost twice the aggressive pursuit of fish with medium inbreeding (MI), and had a higher specific growth rate (SGR) in culture (SGR(MI)=1.83+/-0.58; SGR(LI)=2.20+/-0.67). Additionally, we found evidence that the magnitude of ID was modified by social environment: (1) Masking: In small groups of fish (N=20), large dominant fish of MI, cultivated with small subordinate fish of LI, showed the same SGR as dominant fish of LI cultivated with small subordinate fish of MI. (2) Magnifying: A significant effect of ID on juvenile survival was detected only in high-density competitive environments. Thus, the number of lethal equivalents was 2.70 at high-density, and only 0.24 in a low-density environment. Our results show that differences in size associated with territorial dominance may mask deleterious effects of inbreeding under certain conditions, and support the concept that intraspecific competition usually magnifies the deleterious effects of inbreeding.

Predicting indirect effects of fishing in Mediterranean rocky littoral communities using a dynamic simulation model

Modelling may significantly enhance our understanding of the potential impacts of fisheries at larger spatial scales and on groups that would otherwise be very difficult to study. An aggregated biomass-based simulation model of a Mediterranean infralittoral zone was developed and used to carry out fishing ‘experiments’ where fishing intensity and catch selection were varied. The model was constructed for the Bay of Calvi, Corsica, using the Ecopath with Ecosim software, and was composed of 27 compartments, including seabirds, 11 groups of fish, 12 groups of invertebrates, 2 primary producers, bacteria and detritus. Several instances of indirect fishing effects (‘trophic cascades’ and ‘keystone predation’) have been proposed from anecdotal evidence in the western Mediterranean. Model outcomes provided little support for the widely accepted paradigm that fishing, by removing invertebrate-feeding fish, allows increases in the biomass of sea urchins and as a consequence the formation of overgrazed ‘barrens’ of bare substrate. Simulated harvesting of sea urchins by humans did, however, results in an increase of macroalgal biomass as reported previously. Intensified fishing pressure on ‘macrocarnivorous’ fish resulted in a ‘release’ of small fish species (e.g. blennies), and as a consequence a decline in the biomass of some small invertebrates on which they feed (e.g. amphipods). Increased fishing on large ‘piscivores’ resulted in increases in other small fish groups and consequential effects on other benthic invertebrate groups (e.g. polychaetes). Depletion of piscivorous fish resulted in a dramatic increase in the biomass of seabirds, which apparently compete with piscivores for small demersal and pelagic fish. An intensification of fishing pressure overall resulted in an increase in cephalopod biomass. Responses of target species to increased fishing pressure were most marked within the first 5 years of the new fishing regime. Indirect responses exhibited varying degrees of inertia, and biomasses of many groups did not assume a new equilibrium within the first 20 years of the simulation. The Mediterranean infralittoral rocky-bottom ecosystem was predicted to be relatively resilient to pulses of increased fishing and exhibited a high degree of detritus recycling. However, the speed and magnitude of ecosystem responses was shown to depend greatly on the extent of ‘top-down’ or ‘bottom-up’ control assumed for components within the system.

Effects of commercial diets with different P/ E ratios on sharpsnout seabream ( Diplodus puntazzo) growth and nutrient utilization

In order to improve the rearing conditions and profitability of cultured sharpsnout seabream, it appears essential to learn about this species' feeding demands. As a first step, we have studied sharpsnout seabream nutritional utilization of three commercial diets with different protein/energy ( P/ E) ratios. Experiments were performed with two fish sizes: 47.7±1.0 and 277.6±1.2 g. Three groups of small fish (3 replicates/group, 20 animals/replicate) were fed three diets with P/ E ratios of 24.24 (H), 23.25 (M) or 21.04 (L) g of crude protein/MJ, for a 2-month period. In addition, three groups of large fish (3 replicates/group, 7 animals/replicate) were fed three diets with similar P/ E ratios to those used for small fish, 25.80 (H), 22.57 (M) and 19.67 (L) g of protein/MJ, for 3 months. Higher growth rates were associated with diets with lower P/ E ratios. The level of feed intake was inversely related to the feed's energy content (H>M>L). Protein productive values (PPV) were similar for feeds M and L, the former having a higher carbohydrate, but lower fat percentage, than the latter. It can be concluded that sharpsnout seabream uses both fat and carbohydrates as non-protein energy sources. The growth performance with both feeds was similar, although fish fed with feed M had to eat a larger amount to compensate for its lower energy content.

Dominance hierarchies in Arctic charr,Salvelinus alpinusL.: differential cortisol profiles of dominant and subordinate individuals after handling stress

We examined the effect of social rank on plasma cortisol dynamics after handling stress in juvenile Arctic charr, Salvelinus alpinus L., reared in groups of 200 individuals in 1.5 m(3) circular tanks (rearing density 0.022 kg L(-1)). Fish obtained by dip-netting were categorized as either socially subordinate, dominant or as holding an intermediate position on the basis of size, skin coloration and occurrence of bite marks. In undisturbed fish, the highest cortisol levels were found in fish ranked as intermediate and the lowest in dominant fish. In contrast to what has been found under conditions of artificial rearing in small groups (two to ten individuals), cortisol was not significantly elevated in subordinates compared with dominant individuals. In small groups of fish, aggressive interactions and restricted access to food may be significant factors leading to increased stress in socially subordinate individuals. Following stress by dip-netting and transfer, the quickest and largest cortisol response was seen in dominant individuals. These results suggest that hypothalamus-pituitary-inter-renal/adrenal axis responsiveness as well as baseline cortisol production is influenced by social rank in fish, as has been shown in other vertebrates.

Body composition and sensory assessment of three weight groups of Atlantic halibut ( Hippoglossus hippoglossus) fed three pellet sizes and three dietary fat levels

In the present investigation, we tested the effects of varying initial fish weight (0.8 to 1.8 kg), pellet size (12–27 mm Φ), dietary fat level (10–39% of dry matter) and their cross-terms upon the fat content in a standardized fillet cut of farmed Atlantic halibut (1.3–2.7 kg) after 6 months. A factorial design (FD, 2 3) plus four centre points was applied. The fish were individually tagged and reared at a mean temperature of 8.2°C. Lipid content in the fillet was modelled with the aid of PLS (partial least squares) regression on size and sex subgroups. A sensory panel consisting of 11 trained assessors tested the effects of final fish weight and dietary fat contents on multiple sensory parameters. These data were analysed by ANOVA and principal component analysis (PCA). Wide intra- and interindividual variation in fat content were observed. A standard Atlantic halibut fillet quality cut (A) is suggested for future work on fillet quality, together with measurements of fat along the dorsal and the ventral fin base. The PLS models of lipid deposition in the fillets showed a positive influence from increased initial fish weight and increased dietary fat content. Pellet size showed a minor positive contribution to the fat deposition in the fillet. The sensory test showed that larger halibut (2.1–2.7 kg) fed diets containing 20 or 39% fat were characterized by a fresher and more acidic flavour and a more juicy consistency, compared to smaller fish (1.4 kg), irrespective of the small fish groups' dietary regime. The smaller fish were characterized by rancid flavour and off-flavour. In addition to the sensory data, the evaluation of the feed from a feed production viewpoint showed that it is more economical to utilize herring filleting offal to produce a high fat feed (39%) that ensures the same fillet quality in the Atlantic halibut as the medium fat feed does. We, thus, conclude that the fat content in the feed for Atlantic halibut should be optimized at a level near 40% in due time before the slaughtering period, and that the fish preferably should pass 2.0 kg before being slaughtered.

Effects of variable discharge on the velocity use and shoaling behaviour of Phoxinus phoxinus

The swimming and shoaling behaviour of Phoxinus phoxinus was investigated in four identical channels connected to the River Frome, U.K. Minnows (mean length 29.5 mm) were stocked at an initial density of 100 fish per channel (22.2 fish m−2). The position of all visible fish in the channels was recorded at basal and elevated discharges, and use of velocity habitats inferred. Although a range of velocities (including zero) was present at both discharges, the fish selected higher mean velocities at elevated discharges than at basal discharges. Habitat suitability was significantly different between periods, emphasizing the effect of habitat availability and past experience upon habitat use. This appeared to result from the fish holding position at points with variable flow conditions, rather than moving to points with more suitable conditions. Shoal size tended to be reduced during and after elevated discharge, although variability between replicates was high. Small groups of fish tended to break off during the high flow events.