Journal articles: 'Small-bodied fish'

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MacRae, Pamela SD, and Donald A. Jackson. "The influence of smallmouth bass (Micropterus dolomieu) predation and habitat complexity on the structure of littoral zone fish assemblages." Canadian Journal of Fisheries and Aquatic Sciences 58, no. 2 (February 1, 2001): 342–51. http://dx.doi.org/10.1139/f00-247.

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Fish assemblages in small lakes ([Formula: see text]50 ha) in central Ontario were characterized to determine the impact of smallmouth bass (Micropterus dolomieu) predation and habitat complexity on the structure of littoral zone fish assemblages. Data were collected employing minnow traps and visual assessment. Although species richness did not differ between lakes with and without smallmouth bass, species composition and relative abundance did differ. We identified two distinct fish assemblage types: one characterized by small-bodied species, mainly cyprinids, and a second by large-bodied centrarchid species, e.g., smallmouth bass. Smallmouth bass appear to reduce abundance, alter habitat use, and extirpate many small-bodied species such as brook stickleback (Culaea inconstans), fathead minnow (Pimephales promelas), pearl dace (Margariscus margarita), and Phoxinus spp.

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Knapp, Morten, John Montgomery, Colin Whittaker, Paul Franklin, Cindy Baker, and Heide Friedrich. "Fish passage hydrodynamics: insights into overcoming migration challenges for small-bodied fish." Journal of Ecohydraulics 4, no. 1 (January 2, 2019): 43–55. http://dx.doi.org/10.1080/24705357.2019.1604091.

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Langlois, T. J., L. M. Bellchambers, R. Fisher, G. R. Shiell, J. Goetze, L. Fullwood, S. N. Evans, N. Konzewitsch, E. S. Harvey, and M. B. Pember. "Investigating ecosystem processes using targeted fisheries closures: can small-bodied invertivore fish be used as indicators for the effects of western rock lobster fishing?" Marine and Freshwater Research 68, no. 7 (2017): 1251. http://dx.doi.org/10.1071/mf16022.

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Ecosystem modelling has predicted that fishing for western rock lobster Panulirus cygnus in deep water (50–80m) habitats will result in increased abundance of their macroinvertebrate prey, which would, in turn, support greater production of small-bodied invertivore fish species. To investigate the potential ecosystem effects of rock lobster fishing, a targeted fisheries closure was proposed in deep water habitats along the coast of Western Australia. Data on small-bodied invertivore fish abundance, from baited video, were used to investigate differences across habitats and simulate the likely power of any study to detect change. In general, small-bodied invertivore fish were more abundant at shallower macroalgae-dominated sites, whereas the most abundant single species, the western king wrasse Coris auricularis, was abundant across all habitats and sites. Power simulation of a mixed-model before–after–control–impact (BACI) design found that a 40–50% decrease in either Coris auricularis or small-bodied invertivore fish in general would be very likely to be detected (power ~0.8). Based on the power simulation, we suggest a general sampling design to investigate change before and after the establishment of the fishery closure and make suggestions for further ecological studies to investigate the predicted ecosystem effects of rock lobster fishing.

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Palace, Vince P., Cecilia Doebel, Chris L. Baron, Robert E. Evans, Kerry G. Wautier, Jack F. Klaverkamp, Jeffrey Werner, and Suzanne Kollar. "Caging Small-Bodied Fish as an Alternative Method for Environmental Effects Monitoring (EEM)." Water Quality Research Journal 40, no. 3 (August 1, 2005): 328–33. http://dx.doi.org/10.2166/wqrj.2005.037.

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Abstract The utility of using fish held in cages for investigating the potential effects of industrial and municipal effluents has been demonstrated. These types of exposures are able to control the influence of some confounding factors and also provide a measure of certainty with regard to exposure. However, Canada's current Environmental Effects Monitoring (EEM) Program for metal mines does not accept caged fish as a viable alternative for use in place of wild fish surveys. Concerns appear to be focused on the confounding influences of confinement stress on typical EEM endpoints. Confinement stress may be reduced in smaller-bodied fish relative to larger fish, increasing the relevance of their use for EEM. A standardized technique for deploying small-bodied fish in cages that may be useful for EEM programs is described.

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Caiola, Nuno, Sílvia Rodríguez-Climent, and Carles Ibáñez. "Salinity as the main factor structuring small-bodied fish assemblages in hydrologically altered Mediterranean coastal lagoons." Scientia Marina 77, no. 1 (February 28, 2013): 37–45. http://dx.doi.org/10.3989/scimar.03698.26b.

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Tilley, Ceinwen, Iain Barber, and William Norton. "Skin swabbing protocol to collect DNA samples from small-bodied fish species." F1000Research 10 (October 19, 2021): 1064. http://dx.doi.org/10.12688/f1000research.73115.1.

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Fish species are commonly used as experimental models in the laboratory. DNA is routinely collected from these animals to permit identification of their genotype. The current standard procedure to sample DNA is fin clipping, which involves anaesthetising individuals and removing a portion of the caudal fin. While fin clipping reliably generates good quality DNA samples for downstream applications, there is evidence that it can alter health and welfare, leading to infection and impacting on the fish’s behaviour. This in turn can result in greater variation in the data collected. In a recent study we adapted a skin swabbing protocol to collect DNA from small-bodied fish, including sticklebacks and zebrafish, without the use of anaesthetics or sharp instruments. A rayon-tipped swab was used to collect mucus from the flank of the fish, which was then used for DNA extraction. We subsequently demonstrated that compared to fin clipping, skin swabbing triggered fewer changes in stress axis activation and behaviour. We also found that data collected from fish that had been swabbed were less variable than data from fish that had been fin clipped, potentially allowing smaller sample sizes in experimental groups after using this technique, and thereby reducing animal use. Here we provide a detailed protocol explaining how to collect DNA samples from small laboratory fish using skin swabs.

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Pennock, Casey A., David Bender, Jordan Hofmeier, Jessica A. Mounts, Ryan Waters, Vaughn D. Weaver, and Keith B. Gido. "Can fishways mitigate fragmentation effects on Great Plains fish communities?" Canadian Journal of Fisheries and Aquatic Sciences 75, no. 1 (January 2018): 121–30. http://dx.doi.org/10.1139/cjfas-2016-0466.

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Fishways are a common tool for mitigating the effects of habitat fragmentation on fish, but their utility in low-gradient, sand-bed rivers of the Great Plains is not well studied. The Lincoln Street Fishway on the Arkansas River became operational in 2015 and was built specifically to pass small-bodied threatened fishes. We compared current and historical surveys up- and downstream of the barrier to test the effect of the fishway on community structure and conducted tagging experiments to test the ability of fishes to move into and through the fishway. Differences in community structure and species richness between communities up- and downstream of the dam were reduced following construction of the fishway. Surveys within the fishway revealed that 74% of species from the sampled community were using the fishway. Fishes marked with visible implant elastomer downstream of the dam were recaptured in the fishway, qualitatively showing that small-bodied fishes could move into and upstream within the fishway. We further quantified upstream movement for three species of small-bodied minnow tagged with passive integrated transponder tags during manipulations of flows through the fishway. Our results illustrate the potential for fishways to mitigate the effects of habitat fragmentation on fishes in sand-bed rivers.

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Marsden, Tim, and Ivor Stuart. "Fish passage developments for small-bodied tropical fish: field case-studies lead to technology improvements." Journal of Ecohydraulics 4, no. 1 (January 2, 2019): 14–26. http://dx.doi.org/10.1080/24705357.2019.1646616.

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Cook, Denham G., Peter Jaksons, and Alistair R. Jerrett. "Tagging investigations with small estuarine-associated fish: tag evaluation, capture methodologies and assessment of capture stress and survival in yellow-eyed mullet Aldrichetta forsteri." Marine and Freshwater Research 69, no. 10 (2018): 1595. http://dx.doi.org/10.1071/mf17175.

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Estuarine ecosystems present a dynamic and often biologically challenging marine environment. Resident and migratory fish occupying these environments must cope with a multitude of variations associated with physiochemical characteristics, interspecies interactions, environmental degradation and variable feed availability. Using the yellow-eyed mullet Aldrichetta forsteri as an exemplar of many other small-bodied, estuarine-inhabiting fish, we sought to assess the suitability of an array of different tag types in tank-based experiments. The survival consequences of wild capture, handling and tagging procedures were then investigated using condition and reflex impairment criteria and simulated release. It was determined that T-bar and passive integrated transponder tags were suitable tag types, but that tagging fish smaller than 50g (~170mm) was detrimental to survival. Using a ‘low-impact’ trap design improved post-capture tagging and survival compared with an alternative capture method. In combination, the possibility of using small-bodied fish for tag–recapture studies is demonstrated and the utilisation of comparable fish for investigations into estuarine population dynamics and ecosystem interactions is advocated.

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Gray, Michelle A., Allen R. Curry, and Kelly R. Munkittrick. "Non-Lethal Sampling Methods for Assessing Environmental Impacts Using a Small-Bodied Sentinel Fish Species." Water Quality Research Journal 37, no. 1 (February 1, 2002): 195–211. http://dx.doi.org/10.2166/wqrj.2002.012.

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Abstract Under the Canadian Fisheries Act, pulp and paper mills and metal mines must conduct a cyclical monitoring program for potential environmental effects that includes a fish survey. Study designs for the fish survey have been evolving over the past few years, and there has been increased emphasis on the use of small-bodied fish species. Increasing concerns about the potential impacts of sampling programs on the fish populations in smaller receiving waters have led us to develop non-lethal sampling methodologies that will satisfy the information requirements for the environmental effects monitoring program. This manuscript outlines the use of a non-lethal sampling program to collect information on age distributions, growth rates, reproductive performance and fish condition in populations of slimy sculpin inhabiting forested and agricultural sections of a small New Brunswick river.

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Utama, Andria Ansri, and Setiya Triharyuni. "ABUNDANCE AND BIOMASS ESTIMATES OF COMMERCIAL FISH SPECIES USING HYDRO-ACOUSTIC METHOD IN JAKARTA BAY, INDONESIA." Indonesian Fisheries Research Journal 21, no. 1 (June 1, 2015): 39. http://dx.doi.org/10.15578/ifrj.21.1.2015.39-44.

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The Jakarta Bay is known as a fishing ground area for several traditional types of fishing gears. The fishery has important role to provide nutrition, sustainable livelihoods, and poverty alleviation around the area. Abundance estimation of commercial fish species in the Jakarta Bay is essential particularly comparable of series data in order to evaluate the potential changes in distribution and abundance. The purpose of this study is analyzing the distribution of commercial fish species in the Jakarta Bay and estimate their abundance and biomass. Fish assemblages were concentrated in the eastern and central part of bay. Apparently salinity and DO associated with rich density of phytoplankton and zooplankton may explain the spatial variability of short-bodied mackerel and pony fish, while assemblages pattern of spiny hairtail and croaker might be driven by the availability of small planktivorous fish as their diet. The most abundant commercial fish in the Jakarta Bay are Short-bodied mackerel (Rastrelliger brachysoma), Ponyfish (Leiognathus sp.), Croaker (Johnius sp.) dan Spiny hairtail (Lepturacanthus savala) respectively. Furthermore, biomass estimates for those species showed short-bodied mackerel has the highest biomass followed by spiny hairtail, croaker, and ponyfish.

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Magaju, Dipendra, John Montgomery, Paul Franklin, Cindy Baker, and Heide Friedrich. "Spoiler baffle patch design for improved upstream passage of small-bodied fish." Ecological Engineering 169 (November 2021): 106316. http://dx.doi.org/10.1016/j.ecoleng.2021.106316.

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Clark, Scott R., Brian R. Kreiser, Jacob F. Schaefer, and Laura K. Stewart. "Scale dependence of sex‐specific movement in a small‐bodied stream fish." Freshwater Biology 64, no. 7 (May 6, 2019): 1342–53. http://dx.doi.org/10.1111/fwb.13309.

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Silveira, RML, and B. Weiss. "Evidence for herbaceous seed dispersal by small-bodied fishes in a Pantanal seasonal wetland." Brazilian Journal of Biology 74, no. 3 (August 2014): 588–96. http://dx.doi.org/10.1590/bjb.2014.0089.

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We analysed the germination of seeds after their passage through the digestive tract of small floodplain fishes. Samples were collected in five open flooded fields of the northern Pantanal in March 2011. All fishes were sacrificed and their intestinal contents were removed. The fecal material was weighed and stored at 4°C in a GF/C filter wrapped in aluminum foil. The material was then transferred to a receptacle containing sterilised soil from the sampling area. The fecal samples were kept in a germination chamber for 68 days and then transferred to a greenhouse for another 67 days. We collected a total of 45 fish species and 1014 individuals which produced a total amount of 32g of fresh fecal mass and 11 seedlings. We were able to identify six seedlings: two Banara arguta, two Steinchisma laxa, one Hymenachne amplexicaulis and one Luziola sp.. The fish species that produced samples with seedlings were Astyanax assuncionensis, Metynnis mola, Plesiolebias glaucopterus, Acestrorhyncus pantaneiro and Anadoras wendelli. With the exception of B. arguta the remaining plant species and all fish species were not known to be associated with the seed dispersal process of these plants. We found a ratio of 0.435 seedlings.g–1 of fresh fecal material, which is 100 times higher than the amount of seedlings encountered in fresh soil mass (92,974 grams) in seed bank studies conducted in the same study area. In particular, Astyanax assuncionensis and Metynnis mola were among the most frequent and most abundant fish taxa in the area. Together with the high seed concentration in the fish fecal material, this evidence allows us to conclude that such fish species may play an important role in seed dispersal in the herbaceous plants of the Pantanal.

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Benoît, Hugues P., and Douglas P. Swain. "Impacts of environmental change and direct and indirect harvesting effects on the dynamics of a marine fish community." Canadian Journal of Fisheries and Aquatic Sciences 65, no. 10 (October 2008): 2088–104. http://dx.doi.org/10.1139/f08-112.

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We describe dramatic shifts in the species composition of the marine fish community of the southern Gulf of St. Lawrence using a 35-year time series of catch rates in an annual bottom-trawl survey. We attempt to understand the causes of these changes using a traits-based approach that relates the similarity among species in their abundance trends to similarities in their ecological traits. We selected traits based on a priori beliefs of how each should reflect susceptibility to changes in a different external factor potentially affecting the community. We found evidence for an effect of ocean climate and top-down effects of fishing and seal predation, but not for bottom-up effects of prey availability on adult fishes. Mean body length in the community decreased dramatically in the 1990s. This reflected the removal of large-bodied fishes by fishing and sharp increases in the abundance of small fishes. The biomass of small fish was inversely correlated with an index of predation on those fish by larger fish, suggesting strong predator control of the abundance of small-bodied fishes. Our results suggest that changes in ocean climate combined with direct and indirect effects of harvesting can dramatically and rapidly alter the composition of marine fish communities.

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Turner, Andrew M., and Gary G. Mittelbach. "Effects of Grazer Community Composition and Fish on Algal Dynamics." Canadian Journal of Fisheries and Aquatic Sciences 49, no. 9 (September 1, 1992): 1908–15. http://dx.doi.org/10.1139/f92-211.

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We examined the effects of grazer community composition and fish on phytoplankton abundance by manipulating zooplankton community structure and the intensity of planktivory in a factorial experiment. Enclosures (1700-L bags) were treated with fish (present/absent) and two grazer communities (one a large-bodied community dominated by Daphnia and the other a small-bodied community dominated by Ceriodaphnia) in a 2 × 2 factorial design. We sampled zooplankton and algae every 4–8 d during the 5-wk experiment. Algal biovolume, chlorophyll a, total particulates, and light extinction were all significantly higher in the presence of fish. Further, the effect of fish on algal standing crop did not depend on which grazer assemblage was initially present. Fish enhanced algal standing crop to the same degree in both Daphnia and Ceriodaphnia treatments. We discuss these results in light of patterns reported in the literature, and the nature of size-structured interactions among fish, zooplankton, and algae.

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Magaju, Dipendra, John Montgomery, Paul Franklin, Cindy Baker, and Heide Friedrich. "Machine learning based assessment of small-bodied fish tracking to evaluate spoiler baffle fish passage design." Journal of Environmental Management 325 (January 2023): 116507. http://dx.doi.org/10.1016/j.jenvman.2022.116507.

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Evans, Marlene S. "Large-Lake Responses to Declines in the Abundance of a Major Fish Planktivore—the Lake Michigan Example." Canadian Journal of Fisheries and Aquatic Sciences 47, no. 9 (September 1, 1990): 1738–54. http://dx.doi.org/10.1139/f90-198.

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Alewife abundances declined dramatically in southeastern Lake Michigan over 1973–77, several years before the lakewide decline occurred. The regional effects of this decline on adult copepod abundances, zooplankton biomass, and water clarity are examined. In the offshore region, the two largest copepods, Limnocalanus macrurus and Diaptomus sicilis, increased in abundance during the mid-1970's, reflecting the decrease in alewife predation. Limnocalanus macrurus abundances declined in later years, reflecting increased prédation pressures from the increasing bloater population. The small-bodied D. minutus and the medium-bodied D. ashlandi exhibited no apparent response to the decline in alewife abundance. Large-bodied D. oregonensis and small-bodied C. bicuspidatus thomasi declined in abundance. Size-selective fish prédation pressures continued to remain high in the inshore region: increased abundances of yellow perch and rainbow smelt apparently compensated for the alewife decline. Zooplankton biomass, zooplankton mean dry weight, and water clarity apparently were not affected by the decline in alewife abundance in either the inshore or offshore region. The results of this study are evaluated in terms of the lakewide decline in alewife abundance, the summer 1983 dominance of Daphnia pulicaria in offshore waters, the 1983 marked improvement in offshore water clarity, and later changes in summer offshore D. pulicaria populations.

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Hohausová, Eva, Richard J. Lavoy, and Micheal S. Allen. "Fish dispersal in a seasonal wetland: influence of anthropogenic structures." Marine and Freshwater Research 61, no. 6 (2010): 682. http://dx.doi.org/10.1071/mf09140.

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Knowledge of fish dispersal routes when exploiting temporary habitat is important for understanding the ecology of species and for designing and conducting conservation and land-management activities. We evaluated fish dispersal in a network of seasonal habitats and a permanent fish source (a lake) in a subtropical wetland, in Florida, sampled biweekly from May 2002 to May 2003. Fish dispersal routes were influenced by (1) local physical conditions, (2) anthropogenic alterations and (3) fish species and size. Fish from the source dispersed into 9 of the 25 seasonal sites evaluated, via temporarily formed dispersal corridors between the source and the sites. Low connection depths along the corridors were a key factor, allowing small-bodied species (e.g. Gambusia holbrooki, Elassoma evergladei) to travel farther than large-bodied fish (e.g. Erimyzon sucetta, Lepomis macrochirus). Fish travelled distances of 0.7–4 km. Anthropogenic structures both enhanced (ditches, sand roads) and blocked (a railroad, soil dumps) fish dispersal routes. We demonstrated extensive opportunistic use by fish of seasonal wetlands. Our results indicated that anthropogenic alterations to the landscape can provide habitat for native fish and also allow dispersal of non-native fish and thus should be implemented with care.

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Flower, Jason, Andy Estep, Keinan James, Robin Ramdeen, Claire A. Runge, Lennon Thomas, and Sarah E. Lester. "An experimental evaluation of the effect of escape gaps on the quantity, diversity, and size of fish caught in traps in Montserrat." PLOS ONE 16, no. 12 (December 10, 2021): e0261119. http://dx.doi.org/10.1371/journal.pone.0261119.

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Coral reef fisheries are vital to the livelihoods of millions of people worldwide but are challenging to manage due to the high diversity of fish species that are harvested and the multiple types of fishing gear that are used. Fish traps are a commonly used gear in reef fisheries in the Caribbean and other regions, but they have poor selectivity and frequently capture juvenile fish, impacting the sustainability of the fishery. One option for managing trap fisheries is the addition of escape gaps, which allow small fish to escape. We compared catches of traps with and without two 2.5 cm (1 inch) escape gaps on the Caribbean island of Montserrat. No significant differences were found in the mean fish length, total fish biomass, number of fish, fish species richness, and Shannon diversity index between hauls of the two trap designs, though traps with escape gaps did catch larger proportions of wider-bodied fish and smaller proportions of narrow-bodied fish. Furthermore, traps with gaps caught a smaller proportion of small-sized fish and fewer immature fish (though differences were not statistically significant). Linear mixed effect models predict that soak time (the length of time between trap hauls) increases the mean catch length, total catch biomass and total number of species in the catch. The relatively modest evidence for the effect of the gaps on catch may be explained by the long soak times used, which could have allowed most smaller-sized fish to escape or be consumed by larger individuals before hauling in both traps with and without escape gaps. Despite the small differences detected in this study, escape gaps may still offer one of the best options for improving sustainability of catches from fish traps, but larger escape gaps should be tested with varying soak times to determine optimum escape gap size.

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Stemberger, Richard S., and James M. Lazorchak. "Zooplankton Assemblage Responses to Disturbance Gradients." Canadian Journal of Fisheries and Aquatic Sciences 51, no. 11 (November 1, 1994): 2435–47. http://dx.doi.org/10.1139/f94-243.

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Zooplankton assemblages of 19 New England lakes were evaluated in relation to lake trophic state, riparian land use, fish assemblage features, and physicochemical factors for potential food web indicators of lake ecosystem condition or health. Principal component analysis (PCA) of species abundance data contrasted productive warmwater lakes dominated by rotifers, small cladocerans, and cyclopoid copepods and nauplii with cold-water salmonid systems dominated by calanoid copepods and large cladocerans, and with few rotifers. The use of 12 aggregate zooplankton assemblage variables based on taxonomic group, body size, life-history stage, and feeding guilds improved the amount of the explained cumulative variance (63.2%) over species data (40.3%) in the first two axes of the ordination. In a second PCA the environmental variables were constrained with respect to the zooplankton variables. This analysis identified total phosphorus, chlorophyll a, cold-water fish assemblages, number of introduced fish species, piscivore numbers, and the percentage of disturbed shoreline as dominant gradients. Small-bodied assemblages represented by small cladocerans, rotifers, ostracods, nauplii, and cyclopoid copepodites were associated with the most disturbed systems. The pattern of distribution among large- and small-bodied taxa from the PCA was used to formulate metrics which were then correlated to the gradients.

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Tilley, Ceinwen, Lynne Sneddon, Eamonn Mallon, Iain Barber, and William Norton. "Validating skin swabbing as a refined technique to collect DNA from small-bodied fish species." F1000Research 12 (January 9, 2023): 28. http://dx.doi.org/10.12688/f1000research.122004.1.

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DNA samples are often used to identify fish before they are utilised in other experiments. Our recent research has shown that skin swabbing can be used to collect DNA for genotyping, and that swabbing causes less harm to fish than fin clipping, another common technique. In this study we investigated potential refinements to the skin swabbing protocol by pre-treating fish with the analgesic lidocaine. We could not detect any differences in cortisol release, behaviour or expression of stress axis marker genes in skin swabbed sticklebacks or zebrafish regardless of lidocaine application. In contrast, fin clipping caused changes in cortisol release, gene expression and behaviour when analgesia was not used. These changes were rescued by pre-treatment with lidocaine confirming that analgesia was effective. The results demonstrates that skin swabbing is a refined technique for DNA collection that does not require analgesia.

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Dzul, Maria C., Michael C. Quist, Stephen J. Dinsmore, D. Bailey Gaines, and Michael R. Bower. "Coarse-scale movement patterns of a small-bodied fish inhabiting a desert stream." Journal of Freshwater Ecology 28, no. 1 (March 2013): 27–38. http://dx.doi.org/10.1080/02705060.2012.718250.

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Bayley, Daniel T. I., Andy Purvis, Angelie C. Nellas, Myrtle Arias, and Heather J. Koldewey. "Measuring the long-term success of small-scale marine protected areas in a Philippine reef fishery." Coral Reefs 39, no. 6 (July 31, 2020): 1591–604. http://dx.doi.org/10.1007/s00338-020-01987-7.

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AbstractTropical coral reefs are subject to multiple pressures from both natural and anthropogenic sources. These pressures have caused widespread declines in reef health, resulting in the increased use of spatial management tools such as marine protected areas (MPAs). MPAs have proven generally effective if well designed and enforced, but there are limited long-term studies investigating how the presence of small-scale MPAs affects fish populations and reef communities. Using a 12-year time series, we found that small-scale (10–50 ha) community-managed MPAs along the Danajon Bank of the Philippines preserved average fish biomass within their boundaries over time relative to surrounding fished reefs. Unprotected areas are, however, showing significant long-term biomass decline. MPAs were also found to preserve more key trophic groups and larger-bodied commercially targeted reef fish families. Fish biomass of piscivore, scavenger and invertivore trophic groups inside individual MPAs is, however, still declining at a similar rate as outside. Surprisingly, long-term benthic cover and growth form composition were not significantly affected overall by MPA presence, despite the sporadic use of highly destructive dynamite fishing in this region. Coral cover has remained historically low (21–28%) throughout the study, following widespread bleaching mortality. While management tempered overall abundance declines, we found that irrespective of MPA presence, there was a generalised decline of both large- and small-bodied fish size groups across the study region, most steeply within the 20–30 cm length fish, and a shift towards proportionally higher abundances of small (5–10 cm) fish. This indicates a combination of over-exploitation, inadequate MPA size and coverage for larger fish, and the lingering effects of the 1998 bleaching event. Generalised shifts in body size and trophic structure reported here could lead to future reductions in fishery productivity and stability and will be further exacerbated unless broader fishery regulations and enforcement is instated.

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Cousins, Stephen, Mark J. Kennard, and Brendan C. Ebner. "Corrigendum to: Depth-related composition and structuring of tropical riverine fish assemblages revealed by baited video." Marine and Freshwater Research 68, no. 10 (2017): 1976. http://dx.doi.org/10.1071/mf16278_co.

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The aim of the present study was to determine whether boat-based deployment of remote underwater video cameras is effective for surveying fish assemblages in the deepest reaches of two large tropical rivers in north-eastern Australia. In addition, we compared fish assemblages recorded on baited versus unbaited cameras, and evaluated the sampling effort (duration of recording) required to estimate fish assemblages using remote underwater videos. We found that fish assemblages differed according to the depth, with statistically significant differences largely attributable to the prevalence of small-bodied species (Ambassis sp., Melanotaenia sp. and Pseudomugil signifer recorded in shallow (0.4–2.0m) and intermediate (2.1–4.9m) depths, and larger-bodied fish species (>10cm TL), such as Lutjanus argentimaculatus, Mesopristes argenteus and Caranx sexfasciatus, in deep water (>5.0m). Estimates of fish assemblage attributes generally stabilised after 60min recording duration, suggesting that interrogation of video footage beyond this duration may not be cost-effective. We conclude that depth is an important consideration when surveying large and deep river fish assemblages and that where water clarity is favourable, underwater video provides one of the means by which an assemblage can be investigated across the entire depth profile.

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Schultz, Luke D., Mariah P. Mayfield, and Steven L. Whitlock. "Sample Sizes Needed to Describe Length-Frequency of Small-Bodied Fishes: An Example Using Larval Pacific Lamprey." Journal of Fish and Wildlife Management 7, no. 2 (July 1, 2016): 315–22. http://dx.doi.org/10.3996/112015-jfwm-112.

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Abstract The ability to describe the length distribution of a fish population requires sampling an adequate number of individuals, but collecting more fish than needed is inefficient. While fisheries managers have assessed sample size requirements for many sport fishes, these requirements are not routinely described for small-bodied fishes (i.e., maximum length ≤200 mm), particularly larval lampreys. To improve the efficiency of data collection for these fishes, we used resampling analyses to asses sample size requirements for accurately describing length distributions of larval (freshwater-dwelling) Pacific lamprey Entosphenus tridentatus, an anadromous fish native to western North America (total length 60–156 mm). We found that the highest increases in accuracy occurred with sample sizes <50, and that we needed sample sizes of 40 to 130 to describe length frequency with 95% confidence, depending on length interval used for performing length-frequency analyses. From these results, we recommend collecting 100 individuals if using 5-mm length intervals to examine length frequency of larval lamprey. These findings can also be used to estimate the relative accuracy of sample sizes in existing assessments and develop and refine monitoring programs for larval lampreys and other small-bodied fishes.

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Cousins, Stephen, Mark J. Kennard, and Brendan C. Ebner. "Depth-related composition and structuring of tropical riverine fish assemblages revealed by baited video." Marine and Freshwater Research 68, no. 10 (2017): 1965. http://dx.doi.org/10.1071/mf16278.

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The aim of the present study was to determine whether boat-based deployment of remote underwater video cameras is effective for surveying fish assemblages in the deepest reaches of two large tropical rivers in north-eastern Australia. In addition, we compared fish assemblages recorded on baited versus unbaited cameras, and evaluated the sampling effort (duration of recording) required to estimate fish assemblages using remote underwater videos. We found that fish assemblages differed according to the depth, with statistically significant differences largely attributable to the prevalence of small-bodied species (<10-cm total length, TL), such as Ambassis sp., Melanotaenia sp. and Pseudomugil signifer recorded in shallow (0.4–2.0m) and intermediate (2.1–4.9m) depths, and larger-bodied fish species (>10cm TL), such as Lutjanus argentimaculatus, Mesopristes argenteus and Caranx sexfasciatus, in deep water (>5.0m). Estimates of fish assemblage attributes generally stabilised after 60min recording duration, suggesting that interrogation of video footage beyond this duration may not be cost-effective. We conclude that depth is an important consideration when surveying large and deep river fish assemblages and that where water clarity is favourable, underwater video provides one of the means by which an assemblage can be investigated across the entire depth profile.

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Rodgers, Essie M., Rebecca L. Cramp, Matthew Gordos, Anna Weier, Sarah Fairfall, Marcus Riches, and Craig E. Franklin. "Facilitating upstream passage of small-bodied fishes: linking the thermal dependence of swimming ability to culvert design." Marine and Freshwater Research 65, no. 8 (2014): 710. http://dx.doi.org/10.1071/mf13170.

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Fish passage through road culverts is poorly understood, particularly for small-bodied fishes, despite this information being integral to the restoration of waterway connectivity. We assessed the prolonged swimming performance of a small-bodied fish, empire gudgeon (Hypseleotris compressa; 3.2–7.7 cm total length, TL), and juvenile Australian bass (Percalates novemaculeata; 3.5–7.8 cm TL). Swimming trials were conducted in a hydraulic flume across a range of fixed and increasing velocities in response to acute and long-term thermal treatments. A new statistical approach (Tobit analysis) was used to relate the thermal dependence of swimming endurance to hydraulic characteristics of culverts, providing estimates of maximum water velocity allowing upstream fish passage. Reductions in water temperature of 10°C, similar to those caused by cold-water releases from dams, significantly impaired critical swimming speeds of both species. Traversable water-velocity models identified H. compressa as a weak swimmer, requiring very low water velocities (≤0.10 m s–1 or 2.86 body lengths (BL) s–1) for unrestricted passage, whereas P. novemaculeata was predicted to traverse water velocities of ≤0.39 m s–1 or 12.12 BL s–1. Culvert designs can be improved by limiting water velocities to accommodate weak-swimming fishes and by accounting for the thermal sensitivity of swimming performance.

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Cabonce, Joseph, Hang Wang, and Hubert Chanson. "Ventilated Corner Baffles to Assist Upstream Passage of Small-Bodied Fish in Box Culverts." Journal of Irrigation and Drainage Engineering 144, no. 8 (August 2018): 04018020. http://dx.doi.org/10.1061/(asce)ir.1943-4774.0001329.

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Miller, Jason L., Jim Sherry, Joanne Parrott, and James S. Quinn. "A subchronicin situexposure method for evaluating effects in small-bodied fish at contaminated sites." Environmental Toxicology 29, no. 1 (September 20, 2011): 54–63. http://dx.doi.org/10.1002/tox.20772.

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Gingras, B. A., and C. A. Paszkowski. "Breeding patterns of Common Loons on lakes with three different fish assemblages in north-central Alberta." Canadian Journal of Zoology 77, no. 4 (September 15, 1999): 600–609. http://dx.doi.org/10.1139/z99-013.

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Studies of the Common Loon, Gavia immer, in eastern Canada and the United States suggest that the species' dependence on fish for food limits its breeding habitat to large deep lakes with stocks of fish sufficient to support adults and chicks. In central Alberta, breeding Common Loons are widespread, occurring on nutrient-rich lakes that vary in morphometry and prey base. From 1993 to 1997, small shallow lakes that were fishless (invertebrates were available as principal prey) or contained small-bodied fishes ("minnow lakes"), as well as larger deeper lakes containing large-bodied fishes ("pike lakes"), were surveyed to determine if the occurrence and breeding patterns of Common Loons were influenced by prey assemblage and habitat type. Territorial pairs occurred on all three lake types, but nesting loons and fledglings were more likely to be present on pike lakes than on fishless or minnow lakes. Fishless lakes offered good nesting sites but chicks rarely fledged. Minnow lakes provided good chick-rearing conditions but loons did not often nest on these lakes.

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Bucater, L. B., J. P. Livore, C. J. Noell, and Q. Ye. "Temporal variation of larval fish assemblages of the Murray Mouth in prolonged drought conditions." Marine and Freshwater Research 64, no. 10 (2013): 932. http://dx.doi.org/10.1071/mf12278.

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Estuaries are transition zones that link freshwater and marine ecosystems and are often used as nursery areas by fish. The Murray–Darling Basin, which is heavily affected by flow regulation and water extraction, is the largest river system in Australia and terminates at the Murray Mouth estuary. Protracted drought conditions resulted in extremely low flows to the Murray Mouth that affected water condition, fish abundance, community structure and fish use of the estuary (e.g. nursery areas). The aims of the present study were to examine temporal changes in larval fish assemblages in this estuary. The assemblages were dominated by two gobiid species, Arenigobius bifrenatus and Tasmanogobius lasti. There was a noticeable absence or low abundance of freshwater, diadramous and large-bodied marine species that use this estuary for reproductive functions. Monthly differences in larval fish assemblages, between August–September and October–November, were attributed to increases in the abundances of A. bifrenatus in October and November and oscillation in T. lasti during the entire sampling period. The outcomes of the present study suggested that larval fish assemblages in drought conditions are limited to small-bodied species tolerant of high salinities and that freshwater flows are needed for the estuary to function as a nursery for other species.

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Aiken, James K., C. Scott Findlay, and François Chapleau. "Long-term assessment of the effect of introduced predatory fish on minnow diversity in a regional protected area." Canadian Journal of Fisheries and Aquatic Sciences 69, no. 11 (November 2012): 1798–805. http://dx.doi.org/10.1139/f2012-105.

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Introduced piscivorous fishes had a dramatic impact on small-bodied fish species diversity of small temperate lakes in Gatineau Park, Quebec, Canada, on the basis of three surveys carried out over a 38-year period from 1970 to 2007. For three overlapping sets of lakes based on different combinations of survey years (lakes surveyed in 1970–1971, 1991–1992, and 2006–2007 (N = 14); lakes surveyed in 1970–1971 and 2006–2007 (N = 21); and lakes surveyed in 1991–1992 and 2006–2007 (N = 16)), those with introduced piscivores showed substantial and consistent temporal declines in average minnow species richness but much weaker, if any, declines in total species richness. By contrast, lakes without introduced piscivores showed no such decline. Whereas lakes without piscivores showed a strong species–elevation relationship early in the record, the strength of this relationship was much lower in lakes with introduced piscivores. Moreover, the strength of the species–elevation relationship declined precipitously over time in lakes with introduced piscivores, but remained stable in lakes where introduced piscivores were absent. The negative impact of piscivore introductions on small-bodied fish biodiversity in small lakes underscores the importance of action to mitigate the risk of future introductions or invasions.

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Carim, Kellie J., Scott Relyea, Craig Barfoot, Lisa A. Eby, John A. Kronenberger, Andrew R. Whiteley, and Beau Larkin. "Ultrasound imaging identifies life history variation in resident Cutthroat Trout." PLOS ONE 16, no. 2 (February 3, 2021): e0246365. http://dx.doi.org/10.1371/journal.pone.0246365.

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Human activities that fragment fish habitat have isolated inland salmonid populations. This isolation is associated with loss of migratory life histories and declines in population density and abundance. Isolated populations exhibiting only resident life histories may be more likely to persist if individuals can increase lifetime reproductive success by maturing at smaller sizes or earlier ages. Therefore, accurate estimates of age and size at maturity across resident salmonid populations would improve estimates of population viability. Commonly used methods for assessing maturity such as dissection, endoscopy and hormone analysis are invasive and may disturb vulnerable populations. Ultrasound imaging is a non-invasive method that has been used to measure reproductive status across fish taxa. However, little research has assessed the accuracy of ultrasound for determining maturation status of small-bodied fish, or reproductive potential early in a species’ reproductive cycle. To address these knowledge gaps, we tested whether ultrasound imaging could be used to identify maturing female Westslope Cutthroat Trout (Oncorhynchus clarkii lewisi). Our methods were accurate at identifying maturing females reared in a hatchery setting up to eight months prior to spawning, with error rates ≤ 4.0%; accuracy was greater for larger fish. We also imaged fish in a field setting to examine variation in the size of maturing females among six wild, resident populations of Westslope Cutthroat Trout in western Montana. The median size of maturing females varied significantly across populations. We observed oocyte development in females as small as 109 mm, which is smaller than previously documented for this species. Methods tested in this study will allow researchers and managers to collect information on reproductive status of small-bodied salmonids without disrupting fish during the breeding season. This information can help elucidate life history traits that promote persistence of isolated salmonid populations.

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Kendall, Neala W., and Thomas P. Quinn. "Effects of population-specific variation in age and length on fishery selection and exploitation rates of sockeye salmon (Oncorhynchus nerka)." Canadian Journal of Fisheries and Aquatic Sciences 66, no. 6 (June 2009): 896–908. http://dx.doi.org/10.1139/f09-047.

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Conspecific salmonid populations often differ in age and body size at maturity, and these differences can cause fishery exploitation rates and patterns of directional selection on size to vary among populations. Based on age and length data on five representative spawning populations of sockeye salmon ( Oncorhynchus nerka ) in the Wood River system, Bristol Bay, Alaska, USA, we estimated exploitation rates and population-specific patterns of selection from a gillnet fishery between 1963 and 2007. Exploitation rates have differed among age groups and have varied greatly over time, likely due to changes in fishery selectivity. Populations with older, larger fish were more heavily exploited than populations with small, young fish. Differential fishery selection was detected among the populations, linked to persistent differences in size and age of fish among the populations. Specifically, we found evidence of stronger size selectivity on populations with smaller-bodied fish and less directional selection on populations dominated by larger-bodied fish. These results reveal the complex variation in the intensity and selectivity of fishing that can result from exploitation of populations that differ in age and size at maturity and shape. Evolutionary responses to this selection may be taking place, but natural processes provide countervailing selection.

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Engelhard, Georg H., Jim R. Ellis, Mark R. Payne, Remment ter Hofstede, and John K. Pinnegar. "Ecotypes as a concept for exploring responses to climate change in fish assemblages." ICES Journal of Marine Science 68, no. 3 (December 22, 2010): 580–91. http://dx.doi.org/10.1093/icesjms/fsq183.

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Abstract Engelhard, G. H., Ellis, J. R., Payne, M. R., ter Hofstede, R., and Pinnegar, J. K. 2011. Ecotypes as a concept for exploring responses to climate change in fish assemblages. – ICES Journal of Marine Science, 68: . How do species-rich fish assemblages respond to climate change or to other anthropogenic or environmental drivers? To explore this, a categorization concept is presented whereby species are assigned with respect to six ecotype classifications, according to biogeography, horizontal and vertical habitat preference, trophic guild, trophic level, or body size. These classification schemes are termed ecotypology, and the system is applied to fish in the North Sea using International Bottom Trawl Survey data. Over the period 1977–2008, there were changes in the North Sea fish community that can be related to fish ecotypes. Broadly speaking, there were steady increases in abundance of species that were either Lusitanian, small-bodied, or low-/mid-trophic-level ecotypes, and generally declining or only marginally increasing trends of most Boreal, large-bodied, or high-trophic-level ecotypes or combinations of them. The post-1989 warm biological regime appears to have favoured pelagic species more than demersal species. These community-level patterns agree with the expected responses of ecotypes to climate change and also with anticipated vulnerability to fishing pressure.

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Kegerries, Ron B., Brandon Albrecht, Mark C. McKinstry, Ron J. Rogers, Richard A. Valdez, Adam L. Barkalow, Eliza I. Gilbert, Harrison E. Mohn, Brian Healy, and Emily Omana Smith. "Small-Bodied Fish Surveys Demonstrate Native Fish Dominance Over 300 Kilometers of the Colorado River Through Grand Canyon, Arizona." Western North American Naturalist 80, no. 2 (June 3, 2020): 146. http://dx.doi.org/10.3398/064.080.0202.

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Gray, Michelle A., R. Allen Curry, Tim J. Arciszewski, Kelly R. Munkittrick, and Sandra M. Brasfield. "The biology and ecology of slimy sculpin: A recipe for effective environmental monitoring." FACETS 3, no. 1 (October 1, 2018): 103–27. http://dx.doi.org/10.1139/facets-2017-0069.

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Recently, the use of small-bodied fish in environmental monitoring has increased, particularly within the Canadian environmental effects monitoring (EEM) and other adaptive programs. Although it is possible to measure changes with many small-bodied species, interpretation is often complicated by the absence of information on the biology and ecology of fish not of commercial, recreational, or traditional interest. Knowing and understanding the basic biology of these fishes aids in the sensitivity of study designs (i.e., ability to detect change) and the interpretation of all biological levels of responses (e.g., cellular to community). The increased use of slimy sculpin ( Cottus cognatus Richardson, 1836) in impact assessment studies in North America provides a considerable amount of information on life history aspects. The slimy sculpin has the most ubiquitous North American distribution among cottids but yet has a very small home range, thus integrating environmental conditions of localized areas. This paper describes aspects of slimy sculpin life cycle that affect collection efficiency and timing, and describes and provides data collected over more than 10 years of studies at more than 20 reference study sites. This overview provides a functional and informative compilation to support adaptive environmental monitoring and provide a baseline for comparative ecological study.

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Brown, Culum, and Jennifer Morgan. "Predator recognition and responses in the endangered Macquarie perch (Macquaria australasica)." Marine and Freshwater Research 66, no. 2 (2015): 127. http://dx.doi.org/10.1071/mf13258.

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Macquarie perch, Macquaria austalasica, is an endangered species endemic to southern Australia whose distribution is highly fragmented and continues to decline. Key threatening processes include habitat destruction, dams and weirs, overfishing and interactions with introduced species. Here, we examined the responses of small and large Macquarie perch to two native predators and to the introduced redfin perch, Perca fluviatilis. Our results showed that Macquarie perch generally avoided large-bodied native predators but was attracted to small-bodied native predators. Responses to large and small redfin perch lay between these two extremes, suggesting that the Macquarie perch does treat these foreign fish as potential threats. Macquarie perch relied on both visual and chemical cues to identify predators, although its response tended to be stronger when exposed to visual cues. The results suggest that Macquarie perch has the capacity to recognise and respond to invasive species in a threat-sensitive manner, which has positive implications for the conservation management of the species.

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Burbank, Jacob, D. Andrew R. Drake, and Michael Power. "Urbanization correlates with altered growth and reduced survival of a small‐bodied, imperilled freshwater fish." Ecology of Freshwater Fish 30, no. 4 (February 24, 2021): 478–89. http://dx.doi.org/10.1111/eff.12598.

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Cornell, Gabriel L., Robin Hale, John R. Morrongiello, and Barbara J. Downes. "Experimental increases in detritus boost abundances of small‐bodied fish in a sand‐affected stream." Freshwater Biology 67, no. 4 (January 16, 2022): 742–55. http://dx.doi.org/10.1111/fwb.13878.

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Kucukali, Serhat, Bülent Verep, Ahmet Alp, Davut Turan, Tanju Mutlu, Cüneyt Kaya, Yasin Yıldırım, Behçet Uğur Töreyin, and Dursun Özelçi. "Flow structure and fish passage performance of a brush-type fish way: a field study in the İyidere River, Turkey." Marine and Freshwater Research 70, no. 11 (2019): 1619. http://dx.doi.org/10.1071/mf18242.

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The fish passage performance and flow structure of a brush fish pass were investigated at the İncirli Small Hydropower Plant on the İyidere River, located in the East Black Sea region of Turkey. The spatial distributions of velocity vectors, power velocity, Froude number and turbulent kinetic energy are presented. The flow is quasi-uniform and subcritical, which provides different migration corridors with favourable hydraulic conditions; importantly for the fish, these corridors continue through the complete fish pass. The flow–bristle interaction creates a reduced velocity and low-turbulence resting zones. In addition, the passage efficiency of the brush fish pass was assessed using passive integrated transponder telemetry. The results clearly showed that upstream passage efficiency differs between fish species: Salmo coruhensis performed better than Alburnoides fasciatus on the same fish passage. The passage efficiency for the target fish species S. coruhensis was calculated to be 82.4%. The data revealed that the brush fish passage provides passage for small-bodied fish (total body length <15cm) in a high-gradient channel with a slope of 10%. The monitoring data revealed that bristles as flexible hydraulic elements are beneficial for migrating fish.

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Lyon, Jarod, Ivor Stuart, David Ramsey, and Justin O'Mahony. "The effect of water level on lateral movements of fish between river and off-channel habitats and implications for management." Marine and Freshwater Research 61, no. 3 (2010): 271. http://dx.doi.org/10.1071/mf08246.

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Off-channel habitats, such as wetlands and backwaters, are important for the productivity of river systems and for many species of native fish. This study aimed to investigate the fish community, timing and cues that stimulated movement to and from off-channel habitats in the highly regulated Lake Hume to Lake Mulwala reach of the Murray River, south-eastern Australia. In 2004–05, 193 712 fish were collected moving bi-directionally between a 50-km section of the Murray River and several off-channel habitats. Lateral fish movements approximated water level fluctuations. Generally as water levels rose, fish left the main river channel and moved into newly flooded off-channel habitats; there was bi-directional movement as water levels peaked; on falling levels fish moved back to the permanent riverine habitats. Fish previously classified as ‘wetland specialists’, such as carp gudgeons (Hypseleotris spp.), have a more flexible movement and life-history strategy including riverine habitation. The high degree of lateral movement indicates the importance of habitat connectivity for the small-bodied fish community. Wetlands adjacent to the Murray River are becoming increasingly regulated by small weirs and ensuring lateral fish movement will be important in maintaining riverine-wetland biodiversity.

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Courtenay, Simon C., Kelly R. Munkittrick, Hélène M. C. Dupuis, Roy Parker, and Janice Boyd. "Quantifying Impacts of Pulp Mill Effluent on Fish in Canadian Marine and Estuarine Environments: Problems and Progress." Water Quality Research Journal 37, no. 1 (February 1, 2002): 79–99. http://dx.doi.org/10.2166/wqrj.2002.006.

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Abstract Amendments to the federal Pulp and Paper Effluent Regulations in effect since 1992, require mills in Canada discharging effluent to an aquatic receiving environment to conduct an Environmental Effects Monitoring (EEM) Program to determine whether existing regulations adequately protect fish, fish habitat and use of fisheries resources. As one component of the EEM, mills measure indices of growth, survival and reproduction in wild-caught fish exposed to effluent and compare them with fish not exposed to effluent. A review of the first round of Fish Surveys (Cycle 1: 1993-1996) indicated that they contributed useful data in the freshwater receiving environments for which they had been designed, but performed poorly in the more complex marine and estuarine environments. The most prevalent and serious problems were that insufficient fish were caught and the degree of exposure to effluent could not be quantified. Recommendations to address these problems in Cycle 2 (1997-2000) included selection of small-bodied, presumably more sedentary, fish and studies on the alternative approaches: caged bivalves and onshore bioassays (mesocosms). Difficulties encountered in Cycle 1 studies which could not be resolved became reasons to exclude the Fish Survey from 12 of 28 marine EEM studies in Cycle 2. Six marine mills completed the standard Fish Survey with finfish. Three of these used small-bodied fish successfully, though further information will be required on their range of movement and technical guidance on appropriate sampling. Six studies examined wild bivalves or snails in place of one or both finfish sentinels. None of the invertebrate studies provided all of the information required by the Fish Survey, with only two studies providing age information required to assess growth, only one study reporting gender, and none of the studies reporting measures of reproduction. Six mills conducted or participated in developing alternative approaches for fish surveys: two caged bivalve studies, three mesocosm studies using fish, and one onshore bioassay using bivalves. While providing no direct measurements of effects on reproduction these tools evaluated potential impacts of effluent on survival and growth and supplied information helpful for subsequent investigations of the causes of effects observed in wild fish.

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Chan, Bunyeth, Peng Bun Ngor, Zeb S. Hogan, Nam So, Sébastien Brosse, and Sovan Lek. "Temporal Dynamics of Fish Assemblages as a Reflection of Policy Shift from Fishing Concession to Co-Management in One of the World’s Largest Tropical Flood Pulse Fisheries." Water 12, no. 11 (October 23, 2020): 2974. http://dx.doi.org/10.3390/w12112974.

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Inland fisheries management in Cambodia has undergone two major policy reforms over the last two decades. These reforms led to the abolishment of a century-old commercial fishing lot system in 2012 and the establishment of new fish sanctuary and community fishing areas. However, the status of fisheries and fish assemblages following the reforms is not well understood. Here, we investigated the temporal changes in fish catch weight and fish assemblage structure for the period 1995–2000 before fishing lot abolishment (BLA) and for the period 2012–2015 after the removal of all fishing lots (after lot abolishment-ALA) using time-series fish catch data recorded from the Tonle Sap Lake (TSL), one of the world largest inland fisheries. We found (i) mean catch trends vary seasonally, with stable catch trends during the BLA and decreasing catch trends during the ALA and (ii) significant shifts in fish assemblage composition, notably a shift from large-bodied, migratory, and/or predatory species during the BLA toward more short-distance migratory and/or floodplain, small-bodied species during the ALA. Fishing lot abolishment coincided with substantial changes to floodplain habitats and increases in fishing pressure, threatening TSL fish stocks. Flow alterations caused by dams and climate change may exacerbate the problem. Therefore, to realize the fisheries reform objectives, it is imperative to strengthen the fisheries’ governance and management system, including effective law enforcement, institutional strengthening, improved planning, cooperation, and coordination as well as clearly defined roles and responsibilities among concerned stakeholders at all levels.

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He, Xi, and Russell A. Wright. "An Experimental Study of Piscivore–Planktivore Interactions: Population and Community Responses to Predation." Canadian Journal of Fisheries and Aquatic Sciences 49, no. 6 (June 1, 1992): 1176–83. http://dx.doi.org/10.1139/f92-132.

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The population dynamics and behavior of an assemblage of fishes in a small bog lake were studied in a succession of whole-lake manipulations of piscivores. Total prey fish biomass declined after the addition of northern pike (Esox lucius). This decline was the result of emigration by cyprinid prey and consumption by northern pike. The emigration response of the cyprinids was dependent on cyprinid density. At high prey fish biomass, a significant portion of the loss in biomass was the result of emigration; this was not the case at low prey fish biomass. The prey fish community shifted from small-bodied soft-rayed species prior to the introduction of northern pike to species with spines or deep bodies after predator stocking. The community response was analyzed at four levels of numerical resolution: absolute, relative, and ranked abundance and presence–absence of prey species. High numerical resolution captured the dynamic short-term population responses to predation and suggests unstable community structure.

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Johnson, Susan P., and Daniel E. Schindler. "Marine trophic diversity in an anadromous fish is linked to its life-history variation in fresh water." Biology Letters 9, no. 1 (February 23, 2013): 20120824. http://dx.doi.org/10.1098/rsbl.2012.0824.

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We used carbon and nitrogen stable isotopes from muscle tissues accrued in the ocean to examine whether marine foraging tactics in anadromous sockeye salmon ( Oncorhynchus nerka ) are linked to their ultimate freshwater life history as adults. Adults from large-bodied populations spawning in deep freshwater habitats had more enriched δ 15 N than individuals from small-bodied populations from shallow streams. Within populations, earlier maturing individuals had higher δ 15 N than older fish. These differences in δ 15 N suggest that the fish with different life histories or spawning habitats in freshwater either fed at different trophic positions or in different habitats in the ocean. We propose that, nested within interspecific diversity in the ecological attributes of salmon, population and life-history diversity in spawning adults is associated with variation in marine foraging tactics. These results further indicate that the trophic diversity of sockeye salmon in the ocean may be linked to trade-offs in ecological and evolutionary constraints they eventually experience as adults in freshwater ecosystems.

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MacRae, Pamela SD, and Donald A. Jackson. "Characterizing north temperate lake littoral fish assemblages: a comparison between distance sampling and minnow traps." Canadian Journal of Fisheries and Aquatic Sciences 63, no. 3 (March 1, 2006): 558–68. http://dx.doi.org/10.1139/f05-240.

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To determine which sampling method may be best employed to monitor changes in fish species composition in littoral areas of small north temperate lakes (≤50 ha), data were collected using distance sampling, based on the line transect method, and a traditional fish sampling method of baited minnow traps. These methods were independently biased in terms of their estimates of species presence and abundance. However, analyses of fish community structure indicated that minnow trap data alone provided a better measure of community structure than did distance sampling data alone. Distance sampling, although a powerful tool in estimating population density, is hindered by a multitude of environmental variables that do not preclude the use of minnow traps. Lakes with clear water containing few species with abundant individuals are best suited for distance sampling. Minnow traps proved to be a fast, efficacious sampling method capable of fairly accurately defining the littoral small-fish community structure in most lakes sampled. These traps are a reliable method for monitoring presence or absence and relative abundance of small-bodied fish species in north temperate lakes. However, the combination of minnow traps and some form of visual sampling will help to ensure that all species are detected in small north temperate lakes.

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Carrozzo, David, Simona Musazzi, Andrea Lami, Francisco E. Córdoba, and María de los Ángeles González Sagrario. "Changes in Planktivory and Herbivory Regimes in a Shallow South American Lake (Lake Blanca Chica, Argentina) Over the Last 250 Years." Water 12, no. 2 (February 22, 2020): 597. http://dx.doi.org/10.3390/w12020597.

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Shallow lakes are vulnerable ecosystems impacted by human activities and climate change. The Cladocera occupy a central role in food webs and are an excellent paleoecological indicator of food web structure and trophic status. We conducted a paleolimnological study in Lake Blanca Chica (Argentina) to detect changes on the planktivory and herbivory regimes over the last 250 years. Generalized additive models were fitted to the time series of fish predation indicators (ephippial abundance and size, mucrone size, fish scales, and the planktivory index) and pheophorbide a concentration. The cladoceran assemblage changed from littoral-benthic to pelagic species dominance and zooplankton switched from large-bodied (Daphnia) to small-bodied grazers (Bosmina) ca. 1900 due to increased predation. The shift in planktivory regime (ca. 1920–1930), indicated by fish scales and the planktivory index, as well as herbivory (ca. 1920–1950), was triggered by eutrophication. Changes in planktivory affected the size structure of Bosmina, reducing its body size. This study describes the baseline for the lake as well as the profound changes in the composition and size structure of the zooplankton community due to increased predation and the shift in the planktivory regime. These findings will provide a reference status for future management strategies of this ecosystem.

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Reinhold, Ann Marie, Robert G. Bramblett, Alexander V. Zale, David W. Roberts, and Geoffrey C. Poole. "Comparative use of side and main channels by small-bodied fish in a large, unimpounded river." Freshwater Biology 61, no. 10 (July 18, 2016): 1611–26. http://dx.doi.org/10.1111/fwb.12796.

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Journal articles on the topic 'Small-bodied fish'

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