Ecology Of Fishes Research Articles

Index to Titles and Authors/Editors of Books Reviewed

Index to Titles and Authors/Editors of Books Reviewed

DNA Barcoding for Selected Mangrove-Based Estuary Fishes from Way Kambas National Park, Lampung Province, Indonesia

Over the past decade, DNA barcoding has provided new insight into fish ecology and biosystematics and led to new species' discovery. DNA barcoding is a method for the recognition and identification of species using short, standardised DNA fragments. The correct taxonomic identification of species is critical for the assessment and monitoring of biodiversity. This study applied DNA barcoding techniques to identify selected fish species from a mangrove-based estuary in Way Kambas National Park, Lampung Province, Indonesia. The gene encoding cytochrome c oxidase subunit I (COI) was amplified and bi-directionally sequenced from 22 specimens. The resulting 680 base pairs (bp) sequence was used to identify species, obtain phylogenetic information, and analyse genetic distances. A neighbour-joining tree was constructed based on the mitochondrial COI gene using the Kimura two-parameter model. This study also exhibits conservation status for those identified species. Our findings will facilitate future studies of fish species diversity in mangrove estuary-based ecosystems and provide preliminary data in policymaking in conservation areas such as National Park.

Do fish isotopic niches change in an Amazon floodplain lake over the hydrological regime?

AbstractFloodplain lakes are ecosystems characterised by annual flood and dry cycles. Fish ecology is influenced by the flood pulse due to the large influx of allochthonous food resources and diversification of habitats during the flood cycle, while during the dry cycle, fishes tend to be confined in reduced habitat. The aim of this study was to evaluate the seasonal variation in trophic niche width and overlap of four species—Mylossoma duriventre, Prochilodus nigricans, Cichla.pleiozona and Serrasalmus rhombeus—in an Amazonian floodplain lake. Stable isotope analyses were used to estimate trophic niche width and overlap during the flood and dry seasons. We hypothesised broader niche width for all species during the flood cycle and a higher degree of overlap between the two piscivorous fishes during the dry cycle. Isotopic niche width was 72% broader for P. nigricans, 61% for S. rhombeus and 54% for C. pleiozona during the dry cycle, which did not support our hypothesis. Core niche width overlaps were not observed between piscivorous species in either flood or dry cycle. The results indicate that seasonal variation in isotopic niche width is specific to feeding habit. Understanding how fish trophic ecology responds to changes in the hydrological regime during the seasons is crucial for sustainable fishery management in a region where many people rely heavily on fish for nutritional and economic purposes.

Species interactions alter the selection of thermal environment in a coral reef fish.

Increasing ocean temperatures and the resulting poleward range shifts of species has highlighted the importance of a species preferred temperature and thermal range in shaping ecological communities. Understanding the temperatures preferred and avoided by individual species, and how these are influenced by species interactions is critical in predicting the future trajectories of populations, assemblages, and ecosystems. Using an automated shuttlebox system, we established the preferred temperature and upper and lower threshold temperatures (i.e., avoided temperatures) of a common coral reef fish, the black-axil chromis, Chromis atripectoralis. We then investigated how the presence of conspecifics, heterospecifics (Neopomacentrus bankieri), or a predator (Cephalopholis spiloparaea) influenced the selection of these temperatures. Control C. atripectoralis preferred 27.5 ± 1.0°C, with individuals avoiding temperatures below 23.5 ± 0.9°C and above 29.7 ± 0.7°C. When associating with either conspecifics or heterospecifics, C. atripectoralis selected significantly lower temperatures (conspecifics: preferred = 21.2 ± 1.4°C, lower threshold = 18.1 ± 0.8°C; heterospecifics: preferred = 21.1 ± 1.1°C, lower threshold = 19.2 ± 0.9°C), but not higher temperatures (conspecifics: preferred = 28.9 ± 1.2°C, upper threshold = 30.8 ± 0.9°C; heterospecifics: preferred = 29.7 ± 1.1°C, upper threshold = 31.4 ± 0.8°C). The presence of the predator, however, had a significant effect on both lower and upper thresholds. Individual C. atripectoralis exposed themselves to temperatures ~ 5.5°C cooler or warmer (lower threshold: 18.6 ± 0.5°C, upper threshold: 35.2 ± 0.5°C) than control fish before moving into the chamber containing the predator. These findings demonstrate how behavioural responses due to species interactions influence the thermal ecology of a tropical reef fish; however, there appears to be limited scope for individuals to tolerate higher temperatures unless faced with the risk of predation.

Species-level ichthyoplankton dynamics for 97 fishes in two major river basins of the Amazon using quantitative metabarcoding.

The Amazon basin holds the world's largest freshwater fish diversity. Information on the intensity and timing of reproductive ecology of Amazonian fish is scant. We use a metabarcoding method by capture using a single probe to quantify species-level ichthyoplankton dynamics. We sampled the Marañón and the Ucayali rivers in Peru monthly for 2years. We identified 97 species that spawned mainly during the flood start, the flood end or the receding periods, although some species had spawning activity in more than one period. This information was new for 40 of the species in the Amazon basin and 80 species in Peru. Most species ceased spawning for a month during a strong hydrological anomaly in January 2016, demonstrating the rapidity with which they react to environmental modifications during the breeding season. We also document another unreported event in the Amazon basin, the inverse phenology of species belonging to one genus (Triportheus). Overall larval flow in the Marañón was more than twice that of the Ucayali, including for most commercial species (between two and 20 times higher), whereas the Ucayali accounts for ~80% of the fisheries landings in the region. Our results are discussed in the light of the main anthropogenic threats to fishes, hydropower dam construction and the Hidrovía Amazónica, and should serve as a pre-impact baseline.

Rarely Reported Cryptobenthic Fish in Marine Caves of the Eastern Mediterranean Sea

Data on the distribution and ecology of cryptobenthic fish of marine caves in the Mediterranean Sea are extremely scarce but necessary for scientists and marine managers alike in order to understand these fish’s ecological role and assess their conservation status. Broadscale surveys by implementing underwater visual census and photographic sampling in marine caves of the northeastern Mediterranean Sea, within different expeditions during the last 5 years, brought to light new records of eight rarely reported cryptobenthic fish species. To a smaller extent, complementary citizen science data from diving professionals of Crete were used to fill distribution gaps. A total of 36 new records (66 individuals) from 18 marine caves and caverns of the Aegean and northeastern Levantine Seas were assembled, belonging to the gobies Corcyrogobius liechtensteini, Didogobius splechtnai, Gammogobius steinitzi, and Thorogobius ephippiatus, the blenny Microlipophrys nigriceps, the tripterygiid Tripterygion melanurum, the speleophilic bythitid Grammonus ater, and the gobiesocid Lepadogaster cf. lepadogaster. The above species have been rarely reported from the Eastern Mediterranean Sea, with D. splechtnai and G. steinitzi being recorded for the first and second time from Greek waters, respectively, while L. cf. lepadogaster constitutes the second record of a clingfish species in a marine cave of the Aegean Sea. Interesting behavioral and ecological habits were also noted for some species, based on in situ observations and photographic evidence. Our study contributes to filling gaps in the knowledge of cave fish diversity and demonstrates that cryptobenthic mobile species in understudied cryptic habitats are more common than previously thought in the Mediterranean Sea.

A Hemimysis-driven novel ecosystem at a modified rubble-mound breakwater: An Engineering With Nature® Demonstration Project.

The US Army Corps of Engineers (USACE) repairs aging breakwater structures as part of routine maintenance to maintain safe navigation in Great Lakes commercial ports. A USACE repair to an existing breakwater structure in Milwaukee Harbor (WI) implementing Engineering With Nature (EWN) principles created complex rocky habitat by strategically placing cobble-sized stone over conventional 5.4 to 9.1 metric ton boulders, thus creating "control" (boulder) and "treatment" (cobble) habitats. We evaluated the resultant nature-based breakwater (NBBW) developing food web versus an adjacent referencesite on the same breakwater and determined that, unexpectedly, locally abundant Hemimysis anomala were impacting the food-web dynamics and feeding ecology of fishes occupying the structure. Fish and forage communities were sampled using gillnets, night scuba diving surveys, rock collections, and a novel trap to capture invertebrates. The resultant NBBW became home to a prolific population of nonindigenous Hemimysis, with indications that they were more abundant on cobble versus boulders,based on rainbow smelt feeding. This lithophilic/cave swelling mysid provided an important new food resource in Milwaukee Harbor for two introduced pelagic prey fishes: alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax). Gillnetting and night scuba diving surveys confirmed that rainbow smelt preferred to forage on the cobble section (p < 0.05). Hemimysis were also the primary food item consumed by nearshore game fishes such as young-of-the-year (YOY) yellow perch (Perca flavescens), YOY largemouth bass (Micropterus salmoides), and juvenile rock bass (Ambloplites rupestris). We propose that those breakwaters that harbor abundant Hemimysis constitute novel ecosystems (ecosystems that include both native and non-native biota) that might benefit harbor fisheries if well-managed. This project demonstrated how a low-cost design modification could be applied during the repair of rubble-mound, breakwater structures to achieve benefits beyond safe navigation. Integr Environ Assess Manag 2022;18:49-62. Published 2021. This article is a US Government work and is in the public domain in the USA.

Influences of Ocean Currents on the Diets of Demersal Fish Communities in the Western North Pacific Revealed by Their Muscle Carbon and Nitrogen Isotopic Compositions

To study the influence of different ocean currents on the trophic spectra found in a sympatric fish community, we analyzed the radiocarbon contents (Δ14C) and stable carbon (δ13C) and nitrogen (δ15N) isotopic compositions in their bulk muscle tissues and the δ15N of individual amino acids in 26 species of demersal fish collected from off Tohoku (Pacific coast), northeastern Japan. The Δ14C values of the fish varied from –42 to +41‰, consistent with the Δ14C of the dissolved inorganic carbon in the cold Oyashio Current (typically about –50‰) and the warm Kuroshio Current (typically about +50‰). The trophic positions (TPs) of the fish estimated from the δ15N values of amino acids increased from 3.1 to 4.5 with increasing snout length. A negative correlation was observed between Δ14C and TP in gadiform fish and flatfish, suggesting that the Oyashio Current delivers a high TP diet to these fish groups. These results suggest that the trophic ecology of marine fish in the coastal western North Pacific is primarily controlled by the two major surface water currents, but is also significantly influenced by a combination of species-specific feeding and migration strategies.

Measurement and analysis of underwater noise of offshore mussel suspended farming waters

Anthropogenic noise pollutions are gradually increasing in the world, especially in coastal waters due to shipping and seismic exploration. However, the need for high-quality aquatic products has led to more and more marine suspended farming, which may add to the new sources of low-frequency anthropogenic noises in the ocean. Waters around the Gouqi Island, one of the major reef islands in the northern Zhoushan Archipelago, are considered as important suspended farming waters of mussel. The units of suspended farming facilities composed of aquaculture lines with attached mussels, or the sleeves, are suspended in the surface layer by buoys. The length of the sleeves is 2.3-2.8 m and the water layer occupied by the aquaculture system is about 3.5 m. These suspended farming facilities can reduce the current speed significantly. In this paper, the underwater noises of mussel suspended farming waters of Gouqi Island were measured by a passive monitor system at two sites (inside and outside mussel farming waters) with depths of 5 m and 10 m, and boat noises were also recorded to determine the noise source. All sounds were monitored prior to record to ensure the minimum self-noise, and at least 10 recordings were made and separated by at least 5 min. Power spectra of sound recordings were presented as 1/3-octave sound pressure level (SPL) in dB. Results showed that the main frequency of boat motor noise was 250 Hz, and its SPL at 5 m (114.7± 1.7) dB was greater than that at 10 m (97.4±0.9) dB when the boat was anchored. There were three peak frequencies (63 Hz, 250 Hz, 500 Hz) of underwater noises generated outside the mussel farming waters, where the SPL of 250 Hz at 5m was greater than that at 10m, indicating that the environmental noise outside mussel farming waters was greatly affected by fishing boat. The average environmental noise SPL was (87.7±13.7) dB inside the mussel farming waters, there were also three peak frequencies (63 Hz, 250 Hz, 500 Hz), where SPL of 500 Hz at 10 m (85.13±0.5) dB was greater than taht at 5 m (179.4±0.9) dB, indicating that the suspended mussel farming facilities were the main source of 500 Hz inside the mussel farming waters. This vertical distribution of marine environmental noise may be due to the blocking effect of mussel suspended farming facilities on tidal currents. Owing to that tidal current velocity was reduced in the surface layer, underwater noise level at bottom was greater than that in the surface layer. The underwater noise from suspended farming facilities can contribute significantly to the local ocean noise, and it is clear that the frequency of the suspended farming noise overlaps with the frequency used for acoustic communication in fish. It is necessary to increase our understanding of marine soundscapes, especially when ocean soundscapes continue to be suffered from human activity. In the future, more studies on the effects of noise from aquaculture facilities on the biology and ecology of fish are needed to fill the missing link in acoustic ecology.

Microplastics Ingestion by Skipjack tuna (Katsuwonus pelamis) in Ternate, North Maluku - Indonesia

Microplastic (MPs) is a contaminant of concern worldwide. Rivers are implicated as significant pathways of micro-plastic transport to marine and lake ecosystems, and microplastic ingestion by freshwater biota is a risk associated with microplastic contamination, but there is little research on microplastic ecology within freshwater ecosystems. Microplastic uptake by fish is likely affected by environmental microplastic abundance and aspects of fish ecology, but these relationships have rarely been addressed. We measure the distribution and abundance of micro-plastic in skipjack tuna from 3 markets in Ternate. In total 948 MPs pieces were obtained in 16 fish samples. The identified MPs characteristics show that the micro-plastic character is categorized from the type of fiber, film, and fragment, while the colour of microplastic is black, red, blue, green, brown, grey, and white.

Stakeholder Perceptions on the Governance of Fisheries Systems Transformed by Hydroelectric Dam Development in the Madeira River, Brazil

Hydroelectric dams often have significant impacts on freshwater fisheries. Major impacts are known to be driven by changes in river hydrology and fish ecology, but the role of governance arrangements in mitigating or exacerbating fisheries impacts from hydropower development is less understood. This study presents an analysis of stakeholder perceptions about the effects of hydroelectric dam implementation on fisheries governance arrangements in the Madeira River basin, Brazil. Semi-structured interviews were conducted with 50 stakeholders representing the fishers and fish traders, government, non-governmental organizations, and the private sector. Fishers, non-governmental, and private sector agents perceived hydropower development to be the strongest factor driving fisheries decline or change over the past 10 years, while government staff perceived overfishing to be an equally or even more important factor. Most stakeholders affirmed that fisheries governance arrangements have weakened in the face of hydropower development, and that these arrangements have been insufficient to effectively mitigate or compensate for negative impacts on fisheries. Fishers, non-governmental and private sector agents saw lack of opportunities to participate in fisheries governance as a major contributing factor, while government staff emphasized lack of qualified personnel, lack of trust between agencies, and control over the decision-making process held by hydropower companies. Perspectives on other implications of governance arrangements were shared across stakeholder groups. These included increased conflicts; lack of interaction and coordination between agencies; the fragility of fishers’ social organization; lack of trust and reciprocity between organizations; and power imbalances between stakeholders. The results show that hydropower development impairs and changes relationships between diverse players involved in fisheries governance, which can exacerbate existing weaknesses and negatively affect fishery sustainability. Drawing from the perspectives and comments of the various stakeholders who participated in the study, we provide recommendations to improve freshwater fisheries governance in the Madeira River basin and in the Brazilian Amazon.

A needle in the haystack? Applying species co-occurrence frameworks with fish assemblage data to identify species associations and sharpen ecological hypotheses.

Different species can associate or interact in many ways, and methods exist for inferring associations and underlying mechanisms from incidence data (e.g., co-occurrence frameworks). These methods have received criticism despite their recent resurgence in the literature. However, co-occurrence frameworks for identifying nonrandomly associated species pairs (e.g., aggregated or segregated pairs) have value as heuristic tools for sharpening hypotheses concerning fish ecology. This paper provides a case study examining species co-occurrence across 33 stream fish assemblages in southeastern Oklahoma, USA, which were sampled twice (1974 and 2014). This study sought to determine (a) which species were nonrandomly associated, (b) what processes might have driven these associations and (c) how consistent patterns were across time. Associations among most pairs of species (24 species, 276 unique pairs) were not significantly different from random (>80%). Among all significant, nonrandomly associated species pairs (54 unique pairs), 78% (42 pairs) were aggregated and 22% (12 pairs) segregated. Most of these (28 pairs, 52%) were hypothesized to be driven by nonbiotic mechanisms: habitat filtering (20 pairs, 37%), dispersal limitation (two pairs, 0.4%) or both (six pairs, 11%). The remaining 26 nonrandomly associated pairs (48%) had no detectable signal of spatial or environmental factors involved with the association, therefore the potential for biotic interaction was not refuted. Only five species pairs were consistently associated across both sampling periods: stonerollers Campostoma spp. and orangebelly darter Etheostoma radiosum; red shiner Cyprinella lutrensis and bullhead minnow Pimephales vigilax; bluegill sunfish Lepomis macrochirus and redear sunfish Lepomis microlophus; redfin shiner Lythrurus umbratilis and bluntnose minnow Pimephales notatus; and bigeye shiner Notropis boops and golden shiner Notemigonus crysoleucas. Frameworks for identifying nonrandomly associated species pairs can provide insight into broader mechanisms of species assembly and point to potentially interesting species interactions (out of many possible pairs). However, this approach is best applied as a tool for sharpening hypotheses to be investigated further. Rather than a weakness, the heuristic nature is the strength of such methods, and can help guide biologists toward better questions by employing relatively cheap diversity survey data, which are often already in hand, to reduce complex interaction networks down to their nonstochastic parts which warrant further investigation.

Trophic ecology of the juveniles of two jack species (Caranx latus and C. hippos) in contrasted tropical estuaries

Jacks are highly prized tropical marine fish. Most of them complete their whole life cycle at sea but some use estuaries at the juvenile stage before moving back to coastal waters and joining the adult exploited stocks. Little is known about jacks’ trophic ecology in estuaries, although their juveniles' ability to successfully exploit available resources in these productive environments may strongly affect stock recruitment success in the species concerned. In this study, stomach content and stable isotope analyses were combined to investigate diet and food niche overlap of juveniles from two sympatric species of jacks (Caranx latus and C. hippos) in three contrasted estuaries (Suape, Sirinhaém and Santa Cruz) spread along the northeastern Brazilian coast. Overall, although the juveniles of C. latus exhibited a more piscivorous diet than those of C. hippos, the two species had very similar isotopic niches, with mean δ13C and δ15N values of −19.35 ± 2.10‰ and 11.03 ± 1.11‰ and of −19.10 ± 1.82‰ and 10.21 ± 1.21‰, for C. hippos and C. latus respectively. In all the estuaries sampled, both species mostly ate fish (Ni = 20.1–46.2%, Wi = 60.1–75.1%, essentially Gobiidae and Clupeidae) and crustaceans (Ni = 26.0–65.9%, Wi = 23.3–38.2%, mainly Penaeidae shrimps). As a result, the overlap between their global estuarine isotopic niches was >68%. However, diet composition for the two species varied among estuaries, indicating that their juveniles partly adapt their food preferences to local prey availability. Notably, prey preferences differed significantly between the two species only in the Santa Cruz estuary, where δ15N values were the highest for both species. Conversely, interspecific differences in δ13C ratios were greater in the Suape and the Sirinhaém estuaries, likely reflecting a wider diversity in the carbon sources sustaining local food webs. Thus, combined differences in juvenile diet and food web structure at each location resulted in much-reduced local isotopic niche overlaps between the two species (from 27% in Suape to 57% in Santa Cruz). These results have important implications for resource and ecosystem management in northeastern Brazil and call for systematic cross-site comparisons when evaluating fish ecology and resource partitioning within estuarine systems.

Fish Ecology of the Alto Madre de Dios River Basin (Peru): Notes on Electrofishing Surveys, Elevation, Palm Swamp and Headwater Fishes

Our study analyzes the distribution of fish communities related to the environmental variables of the Alto Madre de Dios River, an Andean-Amazon watershed of southern Peru, between 300 and 2811 m a.s.l. within the Manu Biosphere Reserve. We provide new ecological and diversity data on fishes for these poorly studied rivers and new data for palm swamp habitats. With electric fishing techniques, we collected a total of 1934 fish specimens belonging to 78 species, 42 genera and 15 families. To assess main patterns of diversity we combined SIMPER and ANOSIM with canonical correspondence analysis to obtain an overview of the community structure of fish and their distribution related to aquatic habitats. Our results show an important shift on fish diversity at 700 m a.s.l. separating headwater and middle-lowland communities. Electrofishing was a hindrance due to the depth, flow and low conductivity of the rivers, but also allowed us to capture fish not observed with other techniques. We also compared the use of elevation with slope as an alternative variable for statistical analysis. Our results show that slope offers a solid and equivalent explanation for fish distribution variability, avoids redundance, and instead of giving geographical data offers ecologically solid information.

The comparative lake ecology of two allopatric Arctic Charr, Salvelinus alpinus, populations with differing life histories in Cumberland Sound, Nunavut

The lake ecology of high-latitude fishes is strongly influenced by seasonal feeding opportunities and environmental stochasticity in Arctic environments. Arctic Charr (Salvelinus alpinus (Linnaeus, 1758)) populations are prevalent throughout the Arctic and show multiple life history strategies across their range. Unlike Old World populations, the lake ecology of Arctic Charr populations on south Baffin Island remains poorly defined. We examined the comparative seasonal lake ecology of two differing Arctic Charr populations (anadromous and landlocked) in Cumberland Sound, Nunavut. Anadromous Charr showed no evidence of feeding occurring within freshwater once they began seaward migrations. Anadromous Charr achieve sexual maturation at a larger size and younger age than landlocked Charr. Landlocked Charr used more lake habitats than anadromous Charr with feeding opportunities as an apparent influence on habitat selection. Landlocked Charr fed year round. They adopted a cannibalistic feeding strategy in the winter but consumed a variety of prey items in the fall. Littoral habitat was found to be important to all sizes of Charr in both seasons. Smaller anadromous Charr (&lt;350 mm) did not use the benthic habitat. The variable ecology and form demonstrated further emphasizes the phenotypic adaptability of Arctic Charr that allows its widespread distribution in the Arctic.

Disease ecology of wild fish: opportunities and challenges for linking infection metrics with behaviour, condition, and survival

Surmounting evidence supports that infectious agents play a critical role in shaping fish physiology, behaviour, and survival. The exclusion of disease-causing agents from fisheries research has resulted in major knowledge gaps that may limit the predictive capacity of ecological models. A major barrier in wild fisheries epidemiology is the logistical constraints associated with observing disease and obtaining samples from free-ranging fish, restricting the vast majority of research to laboratory studies or aquaculture facilities. For fisheries ecologists, including infectious agents can provide greater insight into observed phenomena, particularly with respect to fish physiology (e.g., metabolism), movement (e.g., migration rates), behaviour (e.g., habitat selection), personality (e.g., bold versus shy), and survival. Here we provide a brief introduction to the current understanding of disease ecology in wild fish and describe technological advances in both epidemiology and fisheries and aquatic sciences that can be used in tandem to create comprehensive studies of disease ecology in wild fishes. Combining nonlethal sampling and molecular genetic-based identification methods with field studies creates vast opportunities for innovative study designs that have the potential to address the true complexity of aquatic ecosystems.

Demonstration of a Multiple Drift Net for Aquatic Organisms

Abstract The distribution of drifting semi-buoyant fish eggs within a river is useful for understanding the ecology of pelagic-broadcast spawning fish. The vertical position of semi-buoyant eggs in the water column is an important parameter describing transport processes for these species. We designed a multiple drift net (five rectangular nets attached to a frame) to vertically divide the water column into stacked horizontal layers to sample drifting semi-buoyant particles. We deployed the multiple drift net gear beside Moore egg collectors in a wadeable channel to sample the vertical distribution of semi-buoyant polyacrylamide gel beads as surrogates for fish eggs in the water column. The vertical distribution of beads was predominantly found in the deeper nets of the multiple drift net gear while the surface nets and Moore egg collectors had fewer beads which is similar to the results in other studies of pelagic-broadcast spawning fish. The multiple drift net gear is a tool that demonstrates the capability to sample the water column under variable flow conditions (depth, velocity and turbulence) for field data on the vertical distribution of drifting eggs (or surrogates). These empirical data can quantify drift patterns of eggs for modeling transport and retention in pelagic-broadcast spawning species.

Understanding fish cognition: a review and appraisal of current practices.

With over 30,000 recognized species, fishes exhibit an extraordinary variety of morphological, behavioural, and life-history traits. The field of fish cognition has grown markedly with numerous studies on fish spatial navigation, numeracy, learning, decision-making, and even theory of mind. However, most cognitive research on fishes takes place in a highly controlled laboratory environment and it can therefore be difficult to determine whether findings generalize to the ecology of wild fishes. Here, we summarize four prominent research areas in fish cognition, highlighting some of the recent advances and key findings. Next, we survey the literature, targeting these four areas, and quantify the nearly ubiquitous use of captive-bred individuals and a heavy reliance on lab-based research. We then discuss common practices that occur prior to experimentation and within experiments that could hinder our ability to make more general conclusions about fish cognition, and suggest possible solutions. By complementing ecologically relevant laboratory-based studies with in situ cognitive tests, we will gain further inroads toward unraveling how fishes learn and make decisions about food, mates, and territories.

Analysing detection gaps in acoustic telemetry data to infer differential movement patterns in fish.

A wide array of technologies are available for gaining insight into the movement of wild aquatic animals. Although acoustic telemetry can lack the fine‐scale spatial resolution of some satellite tracking technologies, the substantially longer battery life can yield important long‐term data on individual behavior and movement for low per‐unit cost. Typically, however, receiver arrays are designed to maximize spatial coverage at the cost of positional accuracy leading to potentially longer detection gaps as individuals move out of range between monitored locations. This is particularly true when these technologies are deployed to monitor species in hard‐to‐access locations.Here, we develop a novel approach to analyzing acoustic telemetry data, using the timing and duration of gaps between animal detections to infer different behaviors. Using the durations between detections at the same and different receiver locations (i.e., detection gaps), we classify behaviors into “restricted” or potential wider “out‐of‐range” movements synonymous with longer distance dispersal. We apply this method to investigate spatial and temporal segregation of inferred movement patterns in two sympatric species of reef shark within a large, remote, marine protected area (MPA). Response variables were generated using network analysis, and drivers of these movements were identified using generalized linear mixed models and multimodel inference.Species, diel period, and season were significant predictors of “out‐of‐range” movements. Silvertip sharks were overall more likely to undertake “out‐of‐range” movements, compared with gray reef sharks, indicating spatial segregation, and corroborating previous stable isotope work between these two species. High individual variability in “out‐of‐range” movements in both species was also identified.We present a novel gap analysis of telemetry data to help infer differential movement and space use patterns where acoustic coverage is imperfect and other tracking methods are impractical at scale. In remote locations, inference may be the best available tool and this approach shows that acoustic telemetry gap analysis can be used for comparative studies in fish ecology, or combined with other research techniques to better understand functional mechanisms driving behavior.

Content-based Fish Classification Using Combination of Machine Learning Methods

Fish species recognition is an increasing demand to the field of fish ecology, fishing industry sector, fisheries survey applications, and other related concerns. Traditionally, concept-based fish specifies identification procedure is used. But it has some limitations. Content-based classification overcomes these problems. In this paper, a contentbased fish recognition system based on the fusion of local features and global feature is proposed. For local features extraction from fish image, Local Binary Pattern (LBP), Speeded-Up Robust Feature (SURF), and Scale Invariant Feature Transform (SIFT) are used. To extract global feature from fish image, Color Coherence Vector (CCV) is used. Five popular machine learning models such as: Decision Tree, k-Nearest Neighbor (k-NN), Support Vector Machines (SVM), Naïve Bayes, and Artificial Neural Network (ANN) are used for fish species prediction. Finally, prediction decisions of the above machine learning models are combined to select the final fish class based on majority vote. The experiment is performed on a subset of ‘QUT_fish_data’ dataset containing 256 fish images of 21 classes and the result (accuracy 98.46%) shows that though the proposed method does not outperform all existing fish classification methods but it outperforms many existing methods and so, the method is a competitive alternative in this field.