scholarly journals An experimental evaluation of the effect of escape gaps on the quantity, diversity, and size of fish caught in traps in Montserrat

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0261119
Author(s):  
Jason Flower ◽  
Andy Estep ◽  
Keinan James ◽  
Robin Ramdeen ◽  
Claire A. Runge ◽  
...  
Keyword(s):  
Fish Species ◽  
Diversity Index ◽  
Juvenile Fish ◽  
Fish Length ◽  
Small Fish ◽  
Mixed Effect ◽  
Fish Traps ◽  
Total Fish ◽  
The Mean ◽  
The Caribbean

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.

Fish population size, and not density, as the determining factor of parasite infection: a case study

Parasitology ◽  
2004 ◽  
Vol 128 (3) ◽  
pp. 305-313 ◽  
Author(s):  
A. M. BAGGE ◽  
R. POULIN ◽  
E. T. VALTONEN
Keyword(s):  
Species Richness ◽  
Population Density ◽  
Population Size ◽  
Fish Population ◽  
Host Population ◽  
Fish Length ◽  
Total Fish ◽  
Infection Parameters ◽  
The Mean

The diversity and abundance of parasites vary widely among populations of the same host species. These infection parameters are, to some extent, determined by characteristics of the host population or of its habitat. Recent studies have supported predictions derived from epidemiological models regarding the influence of host population density: parasite abundance and parasite species richness are expected to increase with increasing host population density, at least for directly transmitted parasites. Here, we test this prediction using a natural system in which populations of the crucian carp, Carassius carassius (L.), occur alone, with no other fish species, in a series of 9 isolated ponds in Finland. The ectoparasite communities in these fish populations consist of only 4 species of monogeneans (Dactylogyrus formosus, D. wegeneri, D. intermedius and Gyrodactylus carassii); the total and relative abundance of these 4 species varies among ponds, with one or two of the species missing from certain ponds. Across ponds, only one factor, total fish population size, explained a significant portion of the variance in both the mean number of monogenean species per fish and the mean total abundance of monogenean individual per fish. In contrast, fish population density did not influence either monogenean abundance or species richness, and neither did any of the other variables investigated (mean fish length per pond, number of fish examined per pond, distance to the nearest lake, and several water quality measures). In our system, proximity among fish individuals (i.e. host population density) may not be relevant to the proliferation of monogeneans; instead, the overall availability of host individuals in the host population appeared to be the main constraint limiting parasite population growth.

scholarly journals Diversity and Some Biological Aspects of Fishes in Lake Maybahr, Albuko Woreda, Ethiopia

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Gatriay Tut Deng
Keyword(s):  
Fish Species ◽  
Diversity Index ◽  
Good Health ◽  
Fish Diversity ◽  
Wet Season ◽  
Morphometric Measurements ◽  
Significance Level ◽  
Biological Aspects ◽  
The Mean ◽  
Number Of Individuals

Because fishes live in less-accessible habitats, their remarkable diversity is rarely appreciated. The fishery sector is growing rapidly worldwide with the intention of improving the livelihood in developing nations. Therefore, conservation and management of aquatic resources become eminent. Morphometric measurements of fishes are important tools in fish biology and fisheries assessment and conservation. Ethiopia is one of the developing countries with rich water resources. Although there are plenty of water bodies in the country, they are less explored for their ichthyofaunal documentation. Therefore, this study aimed to explore the diversity and some biological aspects of fishes in Lake Maybahr. The fish sample was collected from selected sampling sites using gill nets with varying mesh sizes. Fish identification was done in the field using relevant taxonomic keys. After identification, the total length (TL) and total weight (TW) of the specimens were measured to the nearest 0.1 cm and 0.1 g, respectively. After measurement, the samples were labeled and preserved in a 10% formalin solution. Two fish species were documented in the study area. The length-weight relationships indicated that both species (C. carpio and O. niloticus) exhibited allometric growth during the wet season. But C. carpio demonstrated an isometric growth in the dry season. The diversity index (H’ = 0.69) revealed that fish diversity in the current study is far less than the result reported in the other studies. The evenness index (J’ = 0.99) showed that each species is fairly represented by a number of individuals. The correlation coefficient value of length and weight parameters is statistically significant at a 1% significance level (s, R2 = 0.85). The mean FCF revealed that both fish species are in good health. Further study on local people’s perception, initiating fishing activities, and organizing and providing training to youth is recommended.

scholarly journals Patterns of small fish distributions in seagrass beds in a temperate Australian estuary

2007 ◽  
Vol 87 (5) ◽  
pp. 1297-1307 ◽  
Author(s):  
Jane E. Jelbart ◽  
Pauline M. Ross ◽  
Rod M. Connolly
Keyword(s):  
Fish Species ◽  
Fish Assemblages ◽  
Juvenile Fish ◽  
Small Fish ◽  
Seagrass Beds ◽  
Estuary Mouth ◽  
Seagrass Cover ◽  
Australian Estuary ◽  
Continuous Beds ◽  
Zostera Capricorni

Beds of the seagrass Zostera capricorni are an integral part of the estuarine landscape along the east coast of Australia, forming an important habitat for juvenile fish. Seagrass beds can vary in their size, shape and patchiness of seagrass cover as well as their distance from the estuary mouth. We tested for a correlation between these features and small fish assemblages in seagrass. Fifteen beds were selected from three size-categories (small, 980 to 2300 m2; medium, 3375 to 4090 m2; and large, 5335 to 6630 m2). We found that the size of beds, the patchiness of seagrass cover and location within the estuary (distance from estuary mouth) were all related to differences in fish assemblages. There were greater densities of fish species in small (10.3 ±0.79 species .net-1) compared to medium (7.6 ±0.6) and large (8.2 ±0.5) beds. This occurred regardless of bed placement within the estuary, its patchiness or time of sampling (day and night). The fish assemblages within seagrass beds also changed as bed distance to estuary mouth increased. Six species had greater densities in beds closer to the estuary mouth, while only two species were in greater densities far from the mouth. Fish assemblages were different between beds with patchy and continuous cover, although total densities of all fish species combined were similar. There were greater densities of four species in continuous beds compared to two species that were greater in patchy beds. Overall, an important finding was that even small patchy seagrass beds contain greater densities of small fish species than larger beds with continuous seagrass cover.

scholarly journals Population Aspects of Fishes in Geba and Sor Rivers, White Nile System in Ethiopia, East Africa

2017 ◽  
Vol 2017 ◽  
pp. 1-7 ◽  
Author(s):  
Simagegnew Melaku ◽  
Abebe Getahun ◽  
Mulugeta Wakjira
Keyword(s):  
Sex Ratio ◽  
Fish Species ◽  
Condition Factor ◽  
Diversity Index ◽  
Abundant Species ◽  
Fish Diversity ◽  
Reproductive Behaviors ◽  
Fish Samples ◽  
The Mean ◽  
White Nile

This study was carried out to assess the diversity, condition factor, length-weight relationship, and sex ratio of fishes in Geba and Sor Rivers located in Baro-Akobo Basin, White Nile system within Ethiopia. Fish samples were collected in one wet and one dry season. The length-weight relationships were fitted using power equation for the most abundant species. A total of 348 fish specimens were collected using gillnets and hooks. These were identified into eight species and one Garra sp. representing seven genera and four families. Family Cyprinidae was the most dominant with six species (66.7%). Labeobarbus intermedius, Labeobarbus nedgia, and Labeo cylindricus were the most abundant fish species, respectively, with 60.72%, 16.83%, and 14.66% index of relative importance (IRI). The diversity index was higher for Geba River (H′ = 1.50) than for Sor River (H′ = 1.10). All the three most abundant species had negative allometric growth. Seasonal variations in the mean Fulton condition factor (FCF) were statistically significant for L. cylindricus (p<0.05). There was variation in the sex ratio with the females dominating in all the three most abundant species. Further investigation into the fish diversity, food, feeding, and reproductive behaviors of fish species especially in the tributaries of these rivers and their socioeconomic aspects is recommended.

Spatial relationships and temporal variability in a littoral macrophyte fish assemblage

2004 ◽  
Vol 55 (6) ◽  
pp. 609 ◽  
Author(s):  
S. R. Balcombe ◽  
G. P. Closs
Keyword(s):  
Fish Assemblages ◽  
Temporal Dynamics ◽  
Juvenile Fish ◽  
Physical Structure ◽  
First Year ◽  
Small Fish ◽  
Spatial And Temporal Patterns ◽  
Emergent Macrophytes ◽  
Spatial And Temporal Dynamics ◽  
Fish Traps

The presence of macrophytes in lentic systems often exerts a large influence on the spatial and temporal dynamics of the small-bodied fish that inhabit them, particularly in the presence of piscivorous predators. To examine spatial and temporal patterns of fish abundance in macrophyte stands we sampled fish bimonthly with fine-meshed fish traps by day and night in giant rush habitats of a River Murray billabong between October 1995 and September 1996. Three native and three exotic species were found within these habitats during the study, however, catches were dominated by two species of native carp gudgeons (Hypseleotris spp.). Consistently higher numbers of gudgeons were trapped during the day than at night throughout the study period and there was a sustained decline in catch from spring in the first year to the following spring. The results suggest recruitment of juvenile fish spawned during the summer was insufficient for relative abundance to return to the high numbers found at the start of the study. Fine-scale distribution of carp gudgeons within emergent macrophytes was not generally explained by variability in either physical structure or physicochemical variability. This contrasts with many studies of small fish assemblages in macrophytes where piscivorous predators are present.

Association between juvenile reef fish and the Caribbean reef squid Sepioteuthis sepioidea on north-eastern Brazilian coastal reefs

2007 ◽  
Vol 87 (3) ◽  
pp. 761-762 ◽  
Author(s):  
José de Anchieta C.C. Nunes ◽  
Laís de C.T. Chaves ◽  
Rodrigo Maia-Nogueira ◽  
Cláudio L.S. Sampaio
Keyword(s):  
Reef Fish ◽  
Fish Species ◽  
Juvenile Fish ◽  
First Record ◽  
Squid Species ◽  
Caribbean Reef ◽  
North Eastern ◽  
Reef Fish Species ◽  
Juvenile Reef Fish ◽  
The Caribbean

This article reports on four different juvenile reef fish species, Polydactylus virginicus, Haemulon aurolineatum, H. steindachneri and Carangoides bartholomaei swimming along with schools of the caribbean reef squid Sepioteuthis sepioidea. Three different behaviours were observed. This is the first record of this squid species on Brazilian reef habitats. We suggest that this behaviour is mainly related to protection for juvenile fish against potential pelagic predators.

scholarly journals Changes in Pelagic Fish Community Composition, Abundance, and Biomass along a Productivity Gradient in Subtropical Lakes

Water ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 858
Author(s):  
Jinlei Yu ◽  
Wei Zhen ◽  
Lingyang Kong ◽  
Hu He ◽  
Yongdong Zhang ◽  
...  
Keyword(s):  
Fish Species ◽  
Fish Community ◽  
Yangtze River Basin ◽  
Small Fish ◽  
Fish Community Structure ◽  
Catch Per Unit Effort ◽  
Subtropical Lakes ◽  
Fish Catch ◽  
Total Fish ◽  
The Yangtze River Basin

How fish communities change with eutrophication in temperate lakes is well documented, while only a few studies are available from subtropical lakes. We investigate the fish community structure in 36 lakes located in the Yangtze River basin, covering a wide nutrient gradient. We found that fish species richness and total fish catch per unit effort (CPUE) increased significantly with chlorophyll a (Chla). Among the different feeding types, the proportion of zooplanktivores increased significantly with Chla, while the percentage of omnibenthivores showed no obvious changes; the CPUE of piscivorous Culter spp. increased with Chla, while their proportion of total catch decreased pronouncedly. Based on the index of relative importance (IRI), the most important and dominant fish species was the zooplanktivorous Sijiao (Toxabramis swinhonis), followed by the omniplanktivorous sharpbelly (Hemiculter leucisculus) and the omnibenthivorous crucian carp (Carassius carassius), a small-sized species belonging to the Cyprinidae family. The CPUE of these three species increased significantly with Chla. The focus has, so far, been directed at large fish, but as emphasized by our results, the abundant small fish species were dominant in our subtropical study lakes even in terms of biomass, and, accordingly, we recommend that more attention be paid to the population dynamics of these species in the future.

Linking fish and crustacean taxonomic composition with seasonal contrasts in the soft-bottom intertidal zone

2020 ◽  
Author(s):  
M. A. Gondal ◽  
S. Iqbal ◽  
U. Atique ◽  
N. U. Saher ◽  
N. A. Qureshi ◽  
...  
Keyword(s):  
Species Richness ◽  
Water Temperature ◽  
Fish Species ◽  
Diversity Index ◽  
Taxonomic Composition ◽  
Primary Objective ◽  
Negative Effect ◽  
Fish Species Composition ◽  
One Year ◽  
Sw Monsoon

Abstract The primary objective of this study was to investigate the seasonal fish and crustacean variations concerning taxonomic composition, species richness, and diversity in sandy beach habitat. For this purpose, we investigated the Sonmiani Hor lagoon area during four distinct seasons, i.e., northeast (NE) monsoon, pre-monsoon, south-west (SW) monsoon, and post-monsoon for one year. During each haul, the net was pulled about 100m along the beach in 0.5m depth. The results showed a strong linear correlation between the diversity index and equitability in fishes (r = 0.978). The diversity index was strong negatively correlated with the abundance and biomass (r = -0.978, -0.972, respectively). The physical attributes like sea surface water temperature and salinity showed a strong negative effect on species assemblages (r = -0.981 and -0.943, respectively). The mean air and water temperature illustrated approximately 3°C difference during NE and pre-monsoon seasons. However, salinity, pH, and electrical conductivity did not show any significant seasonal variabilities. Under the ecological indices, the fish species displayed higher diversity (H’ = 3.19) during SW monsoon, whereas the lowest diversity was observed during pre-monsoon (H’ = 1.58). The equitability and species richness, however, remained more noticeable during SW monsoon (J’ = 0.81). The total number of individuals of fish and crustaceans reached 4799 with 3813 fish individuals and 986 individuals of crustaceans. A total of 27 families of fish while five crustacean families comprising of 30 genera and 38 fish species while ten genera and 17 species of crustaceans were recorded. Liza subviridis displayed the highest abundance among the sampled fish species. In conclusion, fish species constituted a significant part of the coastal fauna in the study area. The seasonal variations displayed distinct variations in fish species composition and diversity.

scholarly journals Coverage Increases of Porites astreoides in Grenada Determined by Shifts in Size-Frequency Distribution

Diversity ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 288
Author(s):  
Ryan G. Eagleson ◽  
John S. Lumsden ◽  
Lorenzo Álvarez-Filip ◽  
Christophe M. Herbinger ◽  
Ryan A. Horricks
Keyword(s):  
Coral Community ◽  
Scleractinian Corals ◽  
Area Measurement ◽  
Coralline Algae ◽  
Measurement Tool ◽  
Size Frequency Distribution ◽  
Point Count ◽  
Porites Astreoides ◽  
The Mean ◽  
The Caribbean

Despite coral community collapse, the mustard hill coral (Porites astreoides) is a species currently experiencing success throughout the Caribbean. The inshore reefs of Grenada were selected to study the influence of benthic factors on the abundance, size, and coverage of P. astreoides colonies. Surveys of reef communities along established 30 m transects were conducted at eight sites in 2014 and 2017 using a 0.5 m² quadrat. Coral Point Count was used to annotate the images, estimating the coverage of scleractinian corals, sponges, algae, and benthic substrates. Coverage, size, and abundance of P. astreoides colonies were quantified using the area measurement tool in ImageJ standardized against the quadrats. There were significant differences in benthic community assemblages between islands, selected sites, and between years. From 2014 to 2017 there was a significant decrease in the mean abundance of P. astreoides colonies and significant increases in mean colony size and coverage. The presence of P. astreoides colonies was significantly correlated with: rubble (−), sand (−); pavement (+); macroalgae (−); coralline algae (+); sponges (varying response); gorgonians (−); massive corals (+); and branching corals (−). P. astreoides follows similar recruitment patterns as other scleractinian corals. Observed changes in P. astreoides populations appear to indicate a recovery event following a disturbance, potentially tropical storm Chantal in 2013.

Kidney function decline is associated with an accelerated increase in plasma homocysteine in older adults: a longitudinal study

2021 ◽  
pp. 1-21
Author(s):  
Hui Zhang ◽  
Yi Li ◽  
Meng Hao ◽  
Xiaoyan Jiang ◽  
Jiucun Wang ◽  
...  
Keyword(s):  
Kidney Function ◽  
Repeated Measurements ◽  
Baseline Survey ◽  
Mixed Effect ◽  
Pronounced Increase ◽  
Crude Model ◽  
The Mean ◽  
Kidney Function Decline ◽  
Over Time

Abstract Background: Few studies have been conducted to investigate the association of kidney function decline with the trajectories of homocysteine (Hcy) over time, using repeated measurements. We aimed to investigate the association of kidney function with changes in plasma Hcy levels over time. Methods: Data were collected from the Rugao Longevity and Ageing Study. In detail, plasma Hcy and creatinine levels were measured in both waves (waves 2, 3 and 4) during the 3.5-year follow-up (N = 1135). Wave 2 was regarded as the baseline survey. The estimated glomerular filtration rate (eGFR) was calculated based on creatinine. Subjects were categorized into four groups according to quartiles of eGFR at baseline. Linear mixed-effect models were used to investigate the association of eGFR with subsequent plasma Hcy levels. Results: The mean eGFR at baseline was 90.84 (11.42) mL/min/1.73 m2. The mean plasma Hcy level was 14.09 (6.82) at baseline and increased to 16.28 (8.27) and 17.36 (10.39) μmol/L during follow-ups. In the crude model, the interaction between time and eGFR at baseline was significant (β = −0.02, 95% CI: −0.02 to −0.01, p = 0.002). After adjusting for confounding factors, a significant relationship remained (β = −0.02, 95% CI: −0.02 to −0.01, p = 0.003), suggesting that kidney function decline at baseline was associated with a faster increase in Hcy levels. Conclusion: Kidney function decline is associated with a more pronounced increase in plasma Hcy levels. Further studies with longer follow-up periods and larger sample sizes are needed to validate our findings.

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