Distribution Of Fish Populations Research Articles

Exploring mechanisms of spatial segregation between body size groups within fish populations under environmental change

Ample evidence has indicated shifts in distribution of fish populations in response to environmental stress. However, most studies focused at the whole population scale. This neglects the spatial dynamics between groups of different body size (body size groups), that fundamentally shapes the spatial structure of a population. Here, we explored the mechanisms that modulate spatial dynamics of body size groups, and applied our analyses to three North Sea fish populations which experienced severe declines in biomass from 1977 to 2019: Atlantic cod Gadus morhua, haddock Melanogrammus aeglefinus and whiting Merlangius merlangius. All three populations exhibited strong declines in the overlapped area between body size groups in winter over 43 years, yet their mechanisms differed. These declines were either due to 1) different magnitudes of contraction of the distribution area of body size groups; and/or 2) different speeds and directions of spatial shift among various body size groups, both increasing spatial segregation within populations. These patterns were either associated with ocean warming, and/or declining population biomass, and such associations often varied according to distinct body size groups. Increasing spatial segregation between size groups of a population likely hampers life‐cycle connectivity and stability to local perturbations. Our analytical approach provides a powerful tool for identifying vulnerable populations under environmental stress and can be generalized to study a variety of size/age structured populations at various ecosystem types.

Recent Advancements in Fisheries Systems and Applications for Animal Growth in Water-Borne Animals Fisheries Systems

Advances in fisheries system have been made in the few past years due to different technological progress in the food chain system by improving the mutual communication among different types of organisms. Overfishing, anthropogenic climate change, and pollution are already having measurable impacts on the marine environment throughout the majority of the globe, and their potential long-term repercussions are very concerning. Fishing activity contributes to marine debris; the proportional contribution of recreational fishing has not been quantified. New approaches that are being used in various ways include the precautionary approach, the ecological approach, adaptive management, and harvest control rules. Growth in coastal population has made water and land pollution worse and placed additional pressure on coastal development. Satellite remote sensing has been an essential tool in fishery research, management, and harvesting because it offers synoptic ocean measurements for evaluating environmental influences on the abundance and distribution of fish populations and allows ecological analyses at community and ecosystem scales. Synthetic super-active analogues with higher inducing potency at lower doses were developed using biotechnological techniques including protein engineering and recombinant DNA technology. There are many methods of preservation, including as drying, smoking, freezing, chilling, and brining. Fish that has been smoked or dried has more nutrients and is easier to digest. Fish is often prepared by smoking or drying; both processes eliminate moisture by heating, which reduces the development of germs and increases shelf life. Advances in genetic engineering also helpful for improving the new varieties in the fisheries system.

Influences of Small Hydroelectric Plants on the genetic differentiation of Neotropical freshwater fish populations: a case study

ABSTRACT In view of the growing global demand for electricity, many countries have been looking for ways to diversify production. However, in countries such as Brazil, hydroelectric power plants still constitute the predominant generating source, occupying important drainage systems, such as the Upper Paraná River. At the same time, hydroelectric dams are among the main sources of impacts on freshwater fish, interfering, for example, in the genetic distribution of populations. Although the same could be expected from Small Hydroelectric Plants, very little genetic information has been obtained along Neotropical drainages. Based on this, the present study analyzed the DNA (microsatellite loci) of non-migratory fish species (seven) upstream and downstream of three Small Hydroelectric Plants in the Upper Paraná River basin, obtaining information about the genetic distribution of fish populations in this scenario. In general, the data suggest that populations have been genetically subdivided by Small Hydroelectric Plants and that other factors, such as the number of Small Hydroelectric Plants along a drainage and connectivity with long free stretches, could also influence genetic differentiation levels, which provides information of great relevance to global discussions about the impacts of hydroelectric power plants, as well as for the implementation and management of projects.

Lateral and longitudinal fish environmental DNA distribution in dynamic riverine habitats

AbstractAssessing the status and distribution of fish populations in rivers is essential for management and conservation efforts in these dynamic habitats. Currently, methods detecting environmental DNA (eDNA) are being established as an alternative and/or complementary approach to the traditional monitoring of fish species. In lotic systems, a sound understanding of hydrological conditions and their influence on the local target detection probability and DNA quantity is key for the interpretation of eDNA‐based results. However, the effect of seasonal and diurnal changes in discharge and the comparability of semi‐quantitative results between species remain hardly addressed. We conducted a cage experiment with four fish species (three salmonid and one cyprinid species) in a glacier‐fed, fish‐free river in Tyrol (Austria) during summer, fall, and winter discharge situations (i.e., 25‐fold increase from winter to summer). Each season, water samples were obtained on three consecutive days at 13 locations downstream of the cages including lateral sampling every 1–2 m across the wetted width. Fish eDNA was quantified by species‐specific endpoint PCR followed by capillary electrophoresis. Close to the cages, lateral eDNA distribution was heterogenous and mirrored cage placement within the stream. In addition to the diluting effect of increased discharge, longitudinal signal changes within the first 20 m were weakest at high discharge. For downstream locations with laterally homogenous eDNA distribution, the signals decreased significantly with increasing distance and discharge. Generally, the eDNA of the larger‐bodied salmonid species was less frequently detected, and signal strengths were lower compared to the cyprinid species. This study exemplifies the importance of hydrological conditions for the interpretation of eDNA‐based data across seasons. To control for heterogenous eDNA distribution and enable comparisons over time, sampling schemes in lotic habitats need to incorporate hydrological conditions and species traits.

Evaluation of alternative stratifications for a stratified random fishery-independent survey

Stratified random sampling (StRS) can lead to improved precision and accuracy in estimating key fisheries population parameters, particularly when the spatial distributions of target fish populations have high heterogeneity among different strata and homogeneities within a stratum in the survey area. As the spatial distributions of many fish populations might shift in response to environmental changes and fishing activities, survey designs developed based on previous fish distribution patterns may need to be re-examined. A simulation study was conducted to evaluate the performances and consistency of 12 stratification designs for achieving multiple survey objectives, including the abundance indices of fish species and species diversity indices, for a fishery-independent survey in the coastal waters. Relative estimation error (REE), relative bias (RB) and coefficient of variation (CV) were used to measure the precision and accuracy of mean estimates values for the 12 stratification schemes. The performances of different stratification designs were likely to differ for various survey objectives. As for a multispecies survey, though the current stratification design (design 10) did not always have the lowest REE and absolute RB values, it had the most stable performances for all indices over 3 years. It indicated that the current survey design was still the optimal design according to these measurements. Thus, even though the distribution of fish populations and community composition changed over seasons and years, the current stratification design was robust and could still capture key characteristics of target fish populations and community composition.

Inferred ocean distributions of genetically similar Chinook salmon stocks compared across run timing and river/hatchery of origin

Abstract Klamath River Fall Chinook (KRFC) salmon from the Klamath-Trinity Basin are central to management of the ocean salmon fishery off the coasts of northern California and southern Oregon, with tagged KRFC serving as proxies for other stocks including spring run (KRSC). There has been no formal comparison of fall versus spring run ocean distributions, and published studies using genetic stock identification do not distinguish the runs. We modeled the spatial distribution of hatchery-origin fall versus spring run, inferred from coded-wire tag recoveries in the ocean commercial (troll) fishery while explicitly accounting for fishing effort, sampling rate, and release of sublegal-sized fish before sampling. Distributions for all stocks were confined to a similar core range, but varied seasonally, and with higher relative density of KRSC in the north. Only equivocal evidence was found for differences by age or within-basin source hatchery. The potential for such differences should be considered for analyses of coarser groupings in these and other stocks. Sensitivity analyses revealed differences in distributions inferred from recreational versus commercial fishery data, emphasizing the importance of recognizing the limitations of fishery-dependent data in representing the underlying spatial distribution of fish populations rather than spatial patterns in their interactions with specific fisheries.

Broadband acoustics: A viable tool for quantification of cod egg density and distribution?

Fish eggs are ichthyoplankton with a similar behavior in the water column as small zooplankton. Their specific density relative to sea water determines their vertical distribution and spread; horizontal transport of the layers will then determine their fate and geographical position during the hatching of the larvae. Acoustic techniques are routinely used to assess the quantities and distribution of fish populations. In comparison to fish, zooplankton and ichthyoplankton are very weak acoustic reflectors and this makes the application of acoustic techniques challenging. We assessed the potential feasibility of using broadband acoustics to detect cod eggs in a two stage process: first, we carried out small-scale tank experiments to measure the acoustic reflectivity of individual and grouped cod eggs over the 170 to 360 kHz frequency range. These experiments showed that natural densities of cod eggs could be detected above the background acoustic noise level. This lead to the second stage whereby we conducted a field test in an area with known concentrations of cod eggs, using a combined acoustic-optical towed and moored system. We postulate that the high spatial resolution, yet rapid wide area coverage possible with acoustics will lead to a better description of egg distributions and subsequent larval distributions and help to understand the extremely variable recruitment success in sub-arctic and arctic ecosystems.

Analysis of Prey of Mandarin Fish and Large Mouth Bass and Distribution of Fish Population in Lake Paro, Korea

We quantified temporal and spatial changes in the habitat for fish populations, the distribution of mandarin fish(Siniperca scherzeri) and an introduced species, largemouth bass(Micropterus salmoides) in Lake Paro and inflowing streams. The number of fish species identified in Lake Paro and the tributary streams included 10 families, 24 species and 10 families 30 species, respectively. The dominant fish species in Lake Paro were Zacco platypus, Hemibarbus labeo, Squalidus gracilis majimae, S. scherzeri and Tridentiger brevispinis, Z. platypus, Z. koreanus, and S. gracilis majimae in the inflowing streams. Although the habitat segregation for S. scherzeri and M. salmoides occurs, these two species showed the use of the fishes of the family Gobiidae as an important prey item based on IRI analysis. S. scherzeri and M. salmoides preyed mainly on T. brevispinis(67.4 %) and R. brunneus(84.0 %), respectively. The species preyed on by S. scherzeri and M. salmoides were benthic fishes that inhabit shallow water depths around the lake and have little swimming ability.

Spatial modeling of Bering Sea walleye pollock with integrated age-structured assessment models in a changing environment

Climate change may affect the spatial distribution of fish populations in ways that would affect the accuracy of spatially aggregated age-structured assessment models. To evaluate such scenarios, spatially aggregated models were compared with spatially explicit models using simulations. These scenarios were based on hypothetical climate-driven distribution shifts and reductions in mean recruitment of walleye pollock (Gadus chalcogrammus) in the eastern Bering Sea. Results indicate that biomass estimates were reasonably accurate for both types of estimation models and precision improved with the inclusion of tagging data. Bias in some aggregated model scenarios could be attributed to unaccounted-for process errors in annual fishing mortality rates and was reduced when estimating effective sample size or time-varying selectivity. Spatially explicit models that allow estimation of variability in movement and ontogenetic parameters (specified as a random walk process) were shown to be feasible, whereas models that misspecified ontogenetic movement and climate change effects resulted in biased biomass and movement parameter estimates. These results illustrate that more complex models may characterize processes better but may be less robust for management advice.

Distribution of fish populations in the western part of the French Central Massif. The geographical contribution of electrofishing in headwater catchments

Le departement de la Creuse a une situation hydrologique de tete de bassin, que le bon etat ecologique des cours d’eau permet de considerer comme un espace de reference. Les peches electriques sont utilisees de maniere geographique pour cartographier la repartition des poissons representatifs d’une certaine qualite des eaux et leur suivi pendant sept ans sur un vaste espace de 5 600km². D’annee en annee, les especes peu exigeantes (chevesne et vandoise) progressent de l’aval vers l’amont, tandis que les especes les plus exigeantes (vairon) regressent pour ne plus subsister qu’en tete de bassin. Ces especes sont les traceurs d’une degradation des conditions physico-chimiques ou sedimentaires remontant d’aval en amont.

Distribution of fish and the biotopic structure of the basin of the small salmon river (the Nachilova River, Western Kamchatka)

For one of the small Western Kamchatka rivers, according to the combination of several characteristics (watershed, channel slope, water abundance of the flow, pattern of bottom sediments), the classification of channel processes was performed, and on its basis, six biotopes successively replacing each other from the effluents to the mouth were separated. It was shown that against the background of relatively stable conditions of the summer-autumn period, an independent population of Salmonoidei, an assembly, is formed within each biotope. This is manifested in specific features of species composition, size and age structure, and the density of populating biotopes. The stability of the distribution of fish population is supported by constant species composition in particular biotopes over three years and by a comparatively high level of residence of the dominant salmon species.

Fish distribution in a small domestic water supply reservoir: a case study of Kangimi Reservoir, Kaduna, Nigeria

A study of the composition and distribution of fish populations in the inshore, surface and bottom water habitats of Kangimi Reservoir showed that the most abundant family was the Cichlidae followed in order of abundance by the families Cyprinidae, Schilbeidae, Mormyridae, Mochokidae, Characidae, Centropomidae and Bagridae . Though the overall composition of families caught in the three habitats did not vary significantly (P>0.05) only family Cichlidae showed habitat preference: there was a preponderance of Cichlidae in the inshore water habitat (P Bagridae and Centropomidae were caught only in the inshore and bottom water habitats while the other families were caught from all habitats and showed no habitat preference. The dominance of primary and secondary consumers indicates high fish production potential under adequate management. Journal of Applied Sciences and Environmental Management Vol. 9(1) 2005: 93-97

Mass-marking Young Salmonids with Fluorescent Pigment

Abstract Jackson (1959) introduced a technique for mass-marking fish that entails forcing fluorescent pigment into the dermal tissue with compressed air from a small sandblast gun. The technique is faster and less expensive than existing marking methods and is particularly useful in short-term studies of the dynamics and distribution of fish populations. Several experiments were conducted to define the best pigment size and air pressure for marking young salmonids, viz., pink, coho and sockeye salmon (Oncorhynchus gorbuscha, O. kisutch, and O. nerka) and rainbow trout (Salmo gairdneri), ranging in length from 30 to 120 mm. Two pigment sizes were used: powder, which was less than 20 µ in diameter, and granular pigment, which varied from 30 to 350 µ in diameter. The granular pigment was retained significantly better (55.0–100.0%) than the powder (6.1–89.0%) in test periods ranging up to 130 days. Mark retention among the experimental groups was comparable at air pressures between 80 and 160 psi. Mortality d...