scholarly journals The consequences of balanced harvesting of fish communities

2014 ◽  
Vol 281 (1775) ◽  
pp. 20132701 ◽  
Author(s):  
Nis S. Jacobsen ◽  
Henrik Gislason ◽  
Ken H. Andersen
Keyword(s):  
Fish Community ◽  
Trophic Structure ◽  
Juvenile Fish ◽  
Fish Communities ◽  
Maximum Sustainable Yield ◽  
Biomass Composition ◽  
Forage Fish ◽  
Sustainable Yield ◽  
Fish Community Structure ◽  
Total Maximum

Balanced harvesting, where species or individuals are exploited in accordance with their productivity, has been proposed as a way to minimize the effects of fishing on marine fish communities and ecosystems. This calls for a thorough examination of the consequences balanced harvesting has on fish community structure and yield. We use a size- and trait-based model that resolves individual interactions through competition and predation to compare balanced harvesting with traditional selective harvesting, which protects juvenile fish from fishing. Four different exploitation patterns, generated by combining selective or unselective harvesting with balanced or unbalanced fishing, are compared. We find that unselective balanced fishing, where individuals are exploited in proportion to their productivity, produces a slightly larger total maximum sustainable yield than the other exploitation patterns and, for a given yield, the least change in the relative biomass composition of the fish community. Because fishing reduces competition, predation and cannibalism within the community, the total maximum sustainable yield is achieved at high exploitation rates. The yield from unselective balanced fishing is dominated by small individuals, whereas selective fishing produces a much higher proportion of large individuals in the yield. Although unselective balanced fishing is predicted to produce the highest total maximum sustainable yield and the lowest impact on trophic structure, it is effectively a fishery predominantly targeting small forage fish.

Community changes of coral reef fishes in Bunaken National Park, North Sulawesi, Indonesia

2013 ◽  
Vol 1 (2) ◽  
pp. 117
Author(s):  
Fakhrizal Setiawan ◽  
Janny D Kusen ◽  
Georis JF Kaligis
Keyword(s):  
Reef Fish ◽  
National Park ◽  
Fish Community ◽  
Time Series Data ◽  
Coral Cover ◽  
Fish Communities ◽  
Reef Fishes ◽  
Series Data ◽  
Fish Community Structure ◽  
Reef Fish Community

In order to look at changes in coral and reef fish communities during the period of 2006 to 2013, this research was carried out at Bunaken National Park (BNP) with 26 observation sites. The existing data and information of reef fish communities in the park generally could not be used as representative for describing the whole region. Percentage of coral cover and fish abundance during the study period shows that Bunaken Island is more similar to other locations. Reef fish community structure as seen from ecological index (H' at all sites being categorized, E category labile and low category C) shows the condition of the reef fish community is still good. Changes in the structure of reef fish communities showed declining conditions compared to 2006, and coral cover continued to decrease compared to 1998 and 2007. Good overall reef fish and coral cover have decreased; it is thought to be related to the pressure in BNP. Some of the pressures in the region were (i) increasing numbers of domestic as well as foreign visitors, (ii) increasing number of residents in the region, as well as the burden of waste and trash from the Bay of Manado. Penelitian dilakukan di Taman Nasional Bunaken (Utara dan Selatan)   pada 26 lokasi  pengamatan untuk menganalisis perubahan struktur komunitas ikan karang melalui kajian dari suatu time series data dari beberapa penelitian sebelumnya. Data primer mengenai ikan-ikan karang diperoleh melalui visual sensus bawah air yang bersamaan dengan observasi terumbu karang menggunakan point intercept transect. Nilai persentase tutupan karang dan kelimpahan ikan menunjukkan bahwa pada lokasi pengamatan Pulau Bunaken paling baik dibandingan lokasi lainnya. Struktur komunitas ikan karang yang dianalisis dengan indeks ekologi menunjukkan indeks keanekaragaman (H’) di semua site masuk kategori sedang, indeks kesamaan (E) kategori labil dan indeks Dominansi (C) kategori rendah. Hasil penelitian ini menunjukkan bahwa kondisi komunitas ikan karang masih baik, sekalipun  perubahan struktur komunitas ikan karang menunjukkan kondisi yang menurun dibandingkan tahun 2006, begitu juga tutupan karang yang terus turun dibandingkan tahun 1998 dan 2007. Secara keseluruhan baik ikan karang maupun tutupan karang mengalami penurunan, hal ini diduga terkait dengan tekanan yang dialami kawasan TN. Bunaken. Salah satu tekanan terhadap kawasan adalah jumlah turis dari dalam maupun luar negeri yang semakin meningkat tiap tahunnya, penambahan jumlah penduduk di dalam kawasan, serta beban limbah dan sampah dari Teluk Manado.

scholarly journals Community structure and niche breadth of some fish in Pangelang Protected Lake, Kapuas Hulu District

2021 ◽  
Vol 21 (2) ◽  
pp. 105-115
Author(s):  
Sri Endah Purnamaningtyas ◽  
Dimas Angga Hedianto ◽  
Nurfiarini Nurfiarini
Keyword(s):  
Community Structure ◽  
Fish Community ◽  
Niche Breadth ◽  
Fish Communities ◽  
Food Preferences ◽  
Survey Method ◽  
Fish Community Structure ◽  
Regional Patterns ◽  
Weather Changes ◽  
Detritivorous Fish

Ecologically, weather changes cause local deviations from regional patterns in waters. So that there will be changes in fish types and food habits.The purpose of this study was to determine changes in fish community structure, food preferences, and area of niches for each type of fish in Pangelang Protected Lake. The research was conducted using a survey method in October 2016 (low tide), June 2018 (transition) and September (flood) 2018. The results obtained: 1. Fish communities in Lake Pangelang obtained a total of 12 families, 30 genera, and 37 species. In the low tide season, there are 21 species of fish caught, 17 species of transition season and 16 types of flood during low tide. 2. In the low tide season, the fish community in Pangelang Lake is dominated by detritivorous fish. In the transitional season, the fish community in Pangelang Lake experiences changes with an increase in the union of phytoplanktivore and insectivore fish. During the flood season, the fish communities in Lake Pangelang underwent a change again where the union of herbivores that used plants increased.

Particulate Organic Carbon Supply and Trophic Dynamics in a Mississippi Flood-Control Reservoir Dominated by Gizzard Shad (Dorosoma cepedianum)

1992 ◽  
Vol 49 (8) ◽  
pp. 1722-1733 ◽  
Author(s):  
Nicholas G. Aumen ◽  
Cindy L. Crist ◽  
Dawn E. Miller ◽  
Keith O. Meals
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
Fish Community ◽  
Flood Control ◽  
Gizzard Shad ◽  
Forage Fish ◽  
Fish Biomass ◽  
Dorosoma Cepedianum ◽  
Fish Community Structure ◽  
Phytoplankton Primary Production

Sources of particulate organic carbon (POC) and trophic–dynamic relationships were studied in a reservoir with low sportfish populations. Fish community structure and POC input from tributaries, phytoplankton primary production, and vascular vegetation on mudflats were estimated. Gizzard shad (Dorosoma cepedianum) averaged 39.8% of the total fish biomass in 1988, and as much as 94% of the total forage fish biomass was too large to serve as prey for most predators. Phytoplankton primary productivity averaged 1182 mg C∙m−2∙d−1 in 1987 and 1988, contributed 33.57 Gg POC∙yr−1 to the reservoir, and apparently was phosphate limited. POC inflow from tributaries contributed 60.00 Gg∙yr−1with 79% of POC <75 μm in size. Winter and spring stormflow was responsible for 92% of the total POC transported. Considering POC size fractions available to gizzard shad, POC input from tributaries, phytoplankton, and mudflats contributed 21, 54, and 25% of the total POC input, respectively. The trophic–dynamic analysis indicated that phytoplankton POC was adequate to support the reservoir fish community. A more efficient transfer of carbon in the food web might be accomplished by stocking with a smaller forage fish, such as threadfin shad (Dorosoma petenense), which are not common in the reservoir.

Spatial and temporal variability of fish communities of the Upper Mississippi River, USA

2009 ◽  
Vol 59 (1) ◽  
pp. 67-85 ◽  
Author(s):  
Ayhan Yildirim ◽  
Mark Pegg
Keyword(s):  
Life History ◽  
Community Structure ◽  
Mississippi River ◽  
Fish Community ◽  
Fish Communities ◽  
Morphological Characteristics ◽  
River System ◽  
Functional Composition ◽  
Upper Mississippi River ◽  
Fish Community Structure

AbstractFish community structure, morphological characteristics, functional composition, and life history attributes in relation to three aquatic habitats, backwater shoreline (BWS), main channel borders (MCB), and side channel borders (SCB) in Pool 4 of the Upper Mississippi River System (UMRS) were assessed. Fish communities were sampled annually using standardized electrofishing techniques from 1994 to 2004. We found significant differences in community composition and abundance, and the clearest pattern was that diversity and fish community structure in BWS were different from those in both MCB and SCB. We also found morphological characteristics, functional composition, and life-history differences among the habitats, with fish communities from BWS having a number of different characteristics from both MCB and SCB. Temporal changes in fish abundance, community structure, morphological, functional and life-history attributes from each habitat may reflect both human impact and environmental factors on the Upper Mississippi River System.

scholarly journals Investigating the recent decline in gadoid stocks in the west of Scotland shelf ecosystem using a foodweb model

2014 ◽  
Vol 72 (2) ◽  
pp. 436-449 ◽  
Author(s):  
Karen A. Alexander ◽  
Johanna J. Heymans ◽  
Shona Magill ◽  
Maciej T. Tomczak ◽  
Steven J. Holmes ◽  
...  
Keyword(s):  
Trophic Structure ◽  
Ecosystem Model ◽  
Maximum Sustainable Yield ◽  
Sustainable Yield ◽  
Fishing Pressure ◽  
Grey Seal ◽  
The West ◽  
Considerable Part ◽  
Seal Population ◽  
Key Driver

Abstract Abundance and biomass of cod, haddock, and whiting in the waters off of the west coast of Scotland (wcoS) have undergone large changes in recent years, most notably a recent decline. These three species contribute a considerable part of Scottish demersal landings from this area and as such it is important to understand why these stocks are behaving the way they are. A number of explanations for the decline have been proposed, including: seal predation, pressure from Nephrops trawls, and fishing pressure more generally. We used an ecosystem model of the wcoS continental shelf (&lt;200 m depth) to investigate whether these proposed explanations for declining gadoid stocks are feasible. Results suggest that the rise in the grey seal population over recent years has not led to the decline in gadoid stocks; there is insufficient bycatch by the Nephrops fleet to have a large impact on gadoid stocks; however, fishing, as a key driver of the west of Scotland shelf ecosystem, has impacted stocks and by decreasing fishing levels to maximum sustainable yield cod biomass may increase slightly though not returning to previous levels. Although this means we are little further forward in understanding the cause of recent gadoid declines in the area, the development of this model has enabled us to further our knowledge and understanding of aspects of trophic structure and the impacts of fishing on the wcoS.

scholarly journals Fish Community Structure in Seagrass Beds of Doreri Bay Manokwari Regency

2020 ◽  
pp. 17-29
Author(s):  
Wilhelmus Reinaldo Pattipeilohy ◽  
Thomas Frans Pattiasina ◽  
Simon Petrus Octavianus Leatemia ◽  
Selfanie Talakua
Keyword(s):  
Community Structure ◽  
Coastal Waters ◽  
Fish Community ◽  
Fish Communities ◽  
Seagrass Beds ◽  
Fish Community Structure ◽  
Fish Resources ◽  
Seagrass Ecosystems ◽  
Observation Times ◽  
Descriptive Method

One of the coastal ecosystems that has a high primary productivity, seagrass, makes it a places to find foods (feeding ground), spawn (spawning ground), and shelter for most fish. Whether the structure of fish communities on seagrass beds in the coastal waters of Doreri Bay based on day and night observation times is different from previous studies. This study aims to examine the structure of fish communities on seagrass beds in the coastal waters of Doreri Bay, between the time of observation and compared to previous studies. Data collection takes place during April-May 2019. The method used in this study is a descriptive method, using 1 and 1.5 inch gills net. The results of the study found that seagrass beds in Doreri Bay waters were more than in previous studies, which consisted of 10 species of seagrasses from 2 families (Hydrocharitaceae and Cymodoceaceae). The composition of fish is 56 species with a total of 91 individuals during the day and 189 individuals at night. Fish community structure in Doreri Bay waters has moderate diversity and uniformity while low dominance. Efforts should be made to protect seagrass ecosystems so that fish resources in the Doreri Bay region are maintained.

scholarly journals The importance of sponges and mangroves in supporting fish communities in degraded coral reefs in Caribbean Panama

2017 ◽  
Author(s):  
Janina Seemann ◽  
Alexandra Yingst ◽  
Rick D Stuart-Smith ◽  
Graham J Edgar ◽  
Andrew H Altieri
Keyword(s):  
Coral Reefs ◽  
Fish Community ◽  
Trophic Structure ◽  
Habitat Degradation ◽  
Human Impacts ◽  
Small Body ◽  
Fish Communities ◽  
Trophic Levels ◽  
Fish Biomass ◽  
Total Fish

Fish communities associated with coral reefs worldwide are threatened by overexploitation and other human impacts such as bleaching events that cause habitat degradation. We assessed the fish community on coral reefs on the Caribbean coast of Panama, as well as those associated with mangrove and seagrass habitats, to explore the influences of habitat cover, connectivity and environmental characteristics in sustaining biomass, richness and trophic structure in a degraded tropical ecosystem. Overall, 94 % of all fishes across all habitat types were of small body size (≤11 cm), with communities dominated by fishes that usually live in habitats of low complexity, such as Pomacentridae (damselfishes) and Gobiidae (gobies). Moreover, total fish biomass was very low, small fishes from low trophic levels were over-represented, and top predators were under-represented relative to other Caribbean reefs. For example, herbivorous/omnivorous/detrivorous fishes (trophic level 2-2.7) comprised 37 % of total fish biomass, with the diminutive parrotfish Scarus iseri comprising 72 % of the parrotfish biomass. However, the abundance of sponges and proximity of mangroves were found to be important positive drivers of reef fish richness, biomass and trophic structure on a given reef, presumably by promoting functional processes of ecosystems. The masked goby (Coryphopterus personata) was a strong indicator of reef degradation, apparently benefiting from the reduced density of large predators on local reefs. The damselfish Abudefduf saxatilis was more common on reefs with high sponge cover, and also to proximity to mangroves. Our study suggests that a diverse fish community can persist on degraded coral reefs, and that the availability of habitat forming organisms other than corals, including sponges and mangroves, and their arrangement on the landscape, is critical to the maintenance of functional processes in these ecosystems.

Influence of Tributary Spatial Position on the Structure of Warmwater Fish Communities

1992 ◽  
Vol 49 (4) ◽  
pp. 671-681 ◽  
Author(s):  
Lewis L. Osborne ◽  
Michael J. Wiley
Keyword(s):  
Species Richness ◽  
Community Structure ◽  
Fish Species ◽  
Fish Community ◽  
Fish Communities ◽  
Drainage Area ◽  
Physical Habitat ◽  
Drainage Network ◽  
Fish Community Structure ◽  
Stream Size

We found a significant and positive relationship between fish species richness and four measures of stream size (drainage area, stream order, link magnitude, and downstream link) in three Illinois drainage basins. Downstream link (incorporating both stream size and size of stream at the next downstream confluence) explained the greatest portion of the variance. This suggests that downstream processes significantly influence the structure of fish communities inhabiting warmwater streams. Significantly higher numbers of fish species were collected from tributary streams (< 259 km2 drainage area) located lower in a drainage network and connected to a main channel system than from similarly sized streams located in the headwaters of a drainage network. The difference in species richness among station treatments was not due to a difference in the number of individuals collected among treatments. We were unable to accept or reject the hypothesis that differences in fish species richness were due to differences in physical habitat. The immigration–extinction hypothesis appears to provide a plausible explanation for the observed pattern in fish community structure within a drainage. The location of a stream channel within a network may provide a general template for fish community structure in warmwater drainages by regulating potential species richness.

scholarly journals The importance of sponges and mangroves in supporting fish communities in degraded coral reefs in Caribbean Panama

2017 ◽  
Author(s):  
Janina Seemann ◽  
Alexandra Yingst ◽  
Rick D Stuart-Smith ◽  
Graham J Edgar ◽  
Andrew H Altieri
Keyword(s):  
Coral Reefs ◽  
Fish Community ◽  
Trophic Structure ◽  
Habitat Degradation ◽  
Human Impacts ◽  
Small Body ◽  
Fish Communities ◽  
Trophic Levels ◽  
Fish Biomass ◽  
Total Fish

Fish communities associated with coral reefs worldwide are threatened by overexploitation and other human impacts such as bleaching events that cause habitat degradation. We assessed the fish community on coral reefs on the Caribbean coast of Panama, as well as those associated with mangrove and seagrass habitats, to explore the influences of habitat cover, connectivity and environmental characteristics in sustaining biomass, richness and trophic structure in a degraded tropical ecosystem. Overall, 94 % of all fishes across all habitat types were of small body size (≤11 cm), with communities dominated by fishes that usually live in habitats of low complexity, such as Pomacentridae (damselfishes) and Gobiidae (gobies). Moreover, total fish biomass was very low, small fishes from low trophic levels were over-represented, and top predators were under-represented relative to other Caribbean reefs. For example, herbivorous/omnivorous/detrivorous fishes (trophic level 2-2.7) comprised 37 % of total fish biomass, with the diminutive parrotfish Scarus iseri comprising 72 % of the parrotfish biomass. However, the abundance of sponges and proximity of mangroves were found to be important positive drivers of reef fish richness, biomass and trophic structure on a given reef, presumably by promoting functional processes of ecosystems. The masked goby (Coryphopterus personata) was a strong indicator of reef degradation, apparently benefiting from the reduced density of large predators on local reefs. The damselfish Abudefduf saxatilis was more common on reefs with high sponge cover, and also to proximity to mangroves. Our study suggests that a diverse fish community can persist on degraded coral reefs, and that the availability of habitat forming organisms other than corals, including sponges and mangroves, and their arrangement on the landscape, is critical to the maintenance of functional processes in these ecosystems.

scholarly journals Early evidence of a shift in juvenile fish communities in response to conditions in nursery areas

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Sanja Matić-Skoko ◽  
Dario Vrdoljak ◽  
Hana Uvanović ◽  
Mišo Pavičić ◽  
Pero Tutman ◽  
...  
Keyword(s):  
Fish Community ◽  
Juvenile Fish ◽  
Early Period ◽  
Fish Communities ◽  
Taxonomic Composition ◽  
Littoral Fish ◽  
Early Evidence ◽  
Community Information ◽  
Adriatic Coast ◽  
Community Data

AbstractA multivariate analysis of juvenile fish community data, sampled at two nursery sites at an interval of 17 years (2000—early, and 2017—late), was conducted to elucidate the trends of change in littoral juvenile fish communities along the eastern Adriatic coast. Fishing, trophic and taxonomic composition to the community data were analysed for possible causality. The ichthyofaunal composition differed significantly for Site, Period and all interactions. According to the mMDS ordination plot, four groups of communities were defined, with clear cyclicity. No patterns were found in species composition between sites in the early period, while the observed community changes were governed by the same pattern at both sites in the late period. The species that contributed most to the observed changes were non-commercial, small, benthic resident fishes, such as gobiids and blennids, or those associated with canopy alga for shelter and feeding. The analysis correctly allocated samples based on community information to Sites and Periods. The data obtained provided an invaluable opportunity to test for the generality of potential patterns of change in littoral fish communities, suggesting that significantly modified juvenile fish communities may be the result of constant human embankment and marine infrastructure construction along the coast in recent decades, rather than climate change or fishing pressure, as generally considered.

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