scholarly journals Occurrence and distribution of fish in rivers of Latvia

2011 ◽  
Vol 65 (3-4) ◽  
pp. 57-66 ◽  
Author(s):  
Jānis Birzaks ◽  
Ēriks Aleksejevs ◽  
Māris Strūgis
Keyword(s):  
Fish Species ◽  
Field Research ◽  
Life Cycles ◽  
Freshwater Species ◽  
Species List ◽  
Fishery Data ◽  
Distribution Of Fish ◽  
New Fish Species ◽  
Lamprey Species ◽  
Diadromous Species

Occurrence and distribution of fish in rivers of Latvia This publication is a review of data on fish and lamprey species found in 435 of Latvia's rivers and related reservoirs. A total of 43 fish species and three lamprey species, whose life cycles are, at least in part, associated with rivers, have been recorded. These can be divided into freshwater species and diadromous species. Differences between chronologically older publications and records collected since 1990 on fish occurrence are examined. Since 1990, the intensity of study of Latvia's rivers has increased, which is the reason for changes in the conception of the distribution and occurrence of fish species. The authors propose a new fish species list for Latvia's rivers, based on the newest field research and fishery data. The species included in list were caught in research trips during the period 1990 - 2010, or their capture was confirmed by an expert.

scholarly journals A survey of the ichthyofauna in the Noetsie Estuary, Western Cape Province, South Africa

Koedoe ◽  
2018 ◽  
Vol 60 (1) ◽  
Author(s):  
Martin K.S. Smith ◽  
Demi Rodrigues ◽  
Bianca Currie
Keyword(s):  
South Africa ◽  
Fish Species ◽  
Late Summer ◽  
Marine Species ◽  
Ecological Condition ◽  
Estuarine Fish ◽  
Freshwater Species ◽  
Western Cape ◽  
Species List ◽  
Estuarine Resident

The fish assemblage in the Noetsie Estuary, a temporarily open and closed estuary on the southern coast of South Africa, was sampled using multiple gears. A total of 12 species from 8 families were recorded. Collectively, estuarine-dependent marine species dominated seine net catches numerically and in terms of biomass for both sampling seasons. Estuarine round herring (Gilchristella aestuaria) was numerically the dominant species in late summer, while juvenile Mugilidae dominated catches in winter. Size class distributions of various fish species indicate that the estuary both serves a nursery function for important euryhaline marine species and supports estuarine resident taxa. Application of the Estuarine Fish Community Index indicates the ecological condition of the estuary to be ‘good’. This study contributes to the species list for the estuary while also reporting the presence of an alien invasive freshwater species, Gambusia affinis. Recommendations include the development of a management plan and the formalisation of an estuarine management committee.Conservation implications: The Noetsie Estuary serves a nursery function for important euryhaline marine species, while supporting healthy populations of estuarine resident taxa. The presence of one alien invasive fish species is documented with potential implications for the conservation of biodiversity in the estuary.

Reproduction

2017 ◽  
Author(s):  
Derek Burton ◽  
Margaret Burton
Keyword(s):  
Reproductive Behaviour ◽  
Life Cycles ◽  
Freshwater Species ◽  
Adult Fish ◽  
Reproductive Patterns ◽  
Cell Divisions ◽  
Early Stages ◽  
External Cues ◽  
Neural Factors

Interspecific fish reproductive patterns, outputs and life cycles display the greatest variability within the vertebrates. Early stages of oogenesis can be repeated in adult fish, contrasting with mammals; the pre-set sequence of cell divisions in gametogenesis is otherwise similar and is described in detail. Most fish deposit much yolk (vitellogenesis) in developing eggs. Migrations, beach-spawning and mouth-brooding are some of the interesting variations. Fertilization is predominantly external but is internal in some groups such as chondrichthyans. The omission of annual reproduction is well established in some freshwater species and the idea that this may also be the case for marine teleosts is gaining acceptance. This should be taken into account for intensively fished species. The possible roles of external cues, hormones, pheromones and neural factors acting as ‘switches’ and coordinators in gametogenesis and reproductive behaviour are discussed.

Diversity and abundance of cichlids in Ikere Gorge Reservoir, Iseyin, Oyo State, Nigeria

2021 ◽  
Vol 18 (1) ◽  
pp. 52-56
Author(s):  
S.O. Ajagbe ◽  
R.O. Ajagbe ◽  
O.S. Ariwoola ◽  
F.I. Abdulazeez ◽  
O.O. Oyewole ◽  
...  
Keyword(s):  
Fish Species ◽  
Riparian Forest ◽  
Abundant Species ◽  
Freshwater Ecosystems ◽  
Freshwater Species ◽  
Fishing Villages ◽  
Gorge Reservoir ◽  
Commercially Important ◽  
Sarotherodon Galilaeus ◽  
Fish Species Diversity

Cichlids are highly abundant and commercially important fish in freshwater ecosystems in Nigeria. This study examined the diversity and abundance of cichlids in Ikere Gorge Reservoir. Four fishing villages were randomly selected from 12 fishing villages in Ikere Gorge Reservoir as sampling sites. Cichlids were sampled randomly and examined from fishermen catch in each selected fishing village; were identified with appropriate keys; the weight and abundance of the catches were recorded. The data obtained was subjected to descriptive statistical analysis using SPSS (Version 20.0) software to determine the abundance of fish species. Fish species diversity was carried out by using Palaeontological Statistics (PAST). Eight species of cichlids were sampled in Ikere Gorge but Sarotherodon galilaeus was the most abundant species while the least abundant species was Pelmatolapia mariae. It was observed that, cichlids were  abundant in rainy season than in the dry season. Likewise, cichlids were abundant in Ikere-gorge reservoir but they have low diversity. This may be as a result of unsustainable fishing pressure and deforestation of riparian forest and sedimentation in Ikere-gorge reservoir. Therefore, to maintain sustainable fishing activities and improve cichlids population in Ikeregorge reservoir, unsustainable activities in and around Ikere Gorge reservoir should be put under control. Keywords: Cichlidae; freshwater species; dominant; Sarotherodon galilaeus; Pelmatolapia mariae.

scholarly journals The hydraulic management of the Barra Bonita reservoir (SP, Brazil) as a factor influencing the temporal succession of its fish community

2007 ◽  
Vol 67 (3) ◽  
pp. 433-445 ◽  
Author(s):  
ML. Petesse ◽  
M. Petrere Jr. ◽  
RJ. Spigolon
Keyword(s):  
Fish Species ◽  
Fish Community ◽  
Abundant Species ◽  
Anthropogenic Stress ◽  
Reservoir Level ◽  
Species List ◽  
Adaptation Capacity ◽  
Reproductive Structures ◽  
Temporal Succession ◽  
Reproductive Compensation

The temporal succession of fish communities allows evaluating the environmental conditions and the adaptation capacity of the fish species to anthropogenic stress in reservoirs. The fish community at Barra Bonita reservoir was sampled in two different periods of the year (dry and rainy) and in three different areas of the reservoir (fluvial, transition, and lentic). The species list was compared to another four lists, trying to detect the transformations of the fish community for the last 15 years. In order to evaluate the adaptation of the present fish community to the hydraulic management of reservoir, the trophic and reproductive structures were studied. Temporal succession analysis shows little change in fish richness of the communities. The number of fish species varies between 23 and 39 for a total of 68 registered species. From this, 27 can be considered constant, 14 accessory and 27 accidental; the main differences observed were for Anostomidae, Loricariidae and Characidae families. In relation to the hydraulic management, we found a fish community stabilized and adapted to environmental stress. This is characterized by the dominance of small-sized fish species of opportunistic diet and high reproductive compensation (r-strategists). The overlap of biological cycles of the most abundant species with the reservoir level fluctuations points to the period from September to March-April as critical for reproductive success and only the species with partial reproductive strategy or parental care are best succeeded. These results, interpreted in the context of the reservoir aging process, indicate that Barra Bonita reservoir is entering a transition phase, between the colonization and aging stages.

scholarly journals The contribution of environmental factors to fish assemblages in the Río Acahuapa, a small drainage in Central America

2017 ◽  
Vol 15 (3) ◽  
Author(s):  
Francisco S. Álvarez ◽  
Wilfredo A. Matamoros ◽  
Francisco A. Chicas
Keyword(s):  
Fish Species ◽  
Habitat Structure ◽  
Fish Assemblages ◽  
Species Abundance ◽  
Main Channel ◽  
Estuarine Fish ◽  
Species Origin ◽  
High Temperature Water ◽  
Distribution Of Fish ◽  
Temperature Water

ABSTRACT The ichthyofauna of the Río Acahuapa was analyzed sampling 17 sites that included the basin main channel and its tributaries. Fish were collected using dip-nets, seine-nets and electrofishing. Fish standard length and species abundance were recorded. Species origin and salinity tolerance criteria were used to classify fish species. Water physicochemical variables, habitat structure and sampling sites elevation were recorded. A total of 33 fish species were registered, 12.1% are primary, 45.5% are secondary and 42.4% are of marine derivation. Fish species richness declined with increase of elevation (R2=0.55, p=0.0006). Two assemblages of fishes were identified: the first one associated to sites of low elevations (19-184 masl), composed mainly of secondary and marine-estuarine fish species related with high temperature, water velocity, river width, dissolved oxygen and low sand and silt substrate cover; the second one associated to sites of middle and higher elevations (185-519 masl), composed by primary and secondary freshwater fishes related with high pH, logs and rocks substrate cover. In summary, elevation and environmental variables contributed to the composition and distribution of fish in the Río Acahuapa.

scholarly journals Population and biological parameters of selected fish species from the middle Xingu River, Amazon Basin

2015 ◽  
Vol 75 (3 suppl 1) ◽  
pp. 112-124 ◽  
Author(s):  
M. Camargo ◽  
T. Giarrizzo ◽  
VJ. Isaac
Keyword(s):  
Fish Species ◽  
Growth Rates ◽  
Amazon Basin ◽  
High Growth ◽  
Life Cycles ◽  
Biological Parameters ◽  
High Productivity ◽  
Xingu River ◽  
Biological Yield ◽  
Belo Monte

Abstract This study estimates the main biological parameters, including growth rates, asymptotic length, mortality, consumption by biomass, biological yield, and biomass, for the most abundant fish species found on the middle Xingu River, prior to the construction of the Belo Monte Dam. The specimens collected in experimental catches were analysed with empirical equations and length-based FISAT methods. For the 63 fish species studied, high growth rates (K) and high natural mortality (M) were related to early sexual maturation and low longevity. The predominance of species with short life cycles and a reduced number of age classes, determines high rates of stock turnover, which indicates high productivity for fisheries, and a low risk of overfishing.

scholarly journals Fish, Marmelos Conservation Area (BX044), Madeira River basin, states of Amazonas and Rondônia, Brazil

Check List ◽  
2007 ◽  
Vol 3 (4) ◽  
pp. 291 ◽  
Author(s):  
Mauricio Camargo ◽  
Tommaso Giarrizzo
Keyword(s):  
River Basin ◽  
Fish Species ◽  
Ecological Assessment ◽  
Aquatic System ◽  
Species List ◽  
Conservation Area ◽  
Madeira River ◽  
Northern Brazil ◽  
Rapid Ecological Assessment ◽  
Madeira River Basin

The present study provides a species list of fish from the Marmelos River Area – BX044 in the states of Amazonas and Rondônia in northern Brazil. During a Rapid Ecological Assessment (REA) performed in October and November of 2003, 133 fish species from six orders and 24 families were recorded. The most diverse families were Characidae (47 species), Cichlidae (15 species), Loricariidae (12 species) and Pimelodidae (7 species). 23 fish species were common to the entire river basin and 4 were endemic to the aquatic system studied.

scholarly journals Effects of climate change in the seas of China: Predicted changes in the distribution of fish species and diversity

2022 ◽  
Vol 134 ◽  
pp. 108489
Author(s):  
Wenjia Hu ◽  
Jianguo Du ◽  
Shangke Su ◽  
Hongjian Tan ◽  
Wen Yang ◽  
...  
Keyword(s):  
Climate Change ◽  
Fish Species ◽  
Distribution Of Fish

scholarly journals Keanekaragaman Jenis Ikan di Hilir Sungai Sekadau Kalimantan Barat

2019 ◽  
Vol 8 (2) ◽  
Author(s):  
Kristoforus Slamet Suryadi Junardi, Tri Rima Setyawati
Keyword(s):  
Data Collection ◽  
Fish Species ◽  
Environmental Conditions ◽  
West Kalimantan ◽  
Gill Net ◽  
Distribution Of Fish

Diversity of fish species is important  known to determinate river. The purpose of this study was to determine the diversity and distribution of fish also environmental conditions in the lower reaches of the Sekadau River, West Kalimantan. Data collection is conducted from March to May 2018 using posat and gill net. The results showed that the most common Cyprinidae family was found in Rasbora argyrotaenia  and Osteochilus microcephalus with dominance value  0.72 and 0.70 respectively.

Insights into fish-anthropogenic pressures relationships using machine learning techniques: the case of Castilla-La Mancha (Spain)

2021 ◽  
Author(s):  
Carlotta Valerio ◽  
Graciela Gómez Nicola ◽  
Rocío Aránzazu Baquero Noriega ◽  
Alberto Garrido ◽  
Lucia De Stefano
Keyword(s):  
Machine Learning ◽  
Fish Species ◽  
Conservation Status ◽  
Boosted Regression Trees ◽  
Machine Learning Techniques ◽  
Freshwater Species ◽  
Anthropogenic Pressures ◽  
La Mancha ◽  
Learning Techniques ◽  
Starting Point

<p>Since 1970 the number of freshwater species has suffered a decline of 83% worldwide and anthropic activities are considered to be major drivers of ecosystems degradation. Linking the ecological response to the multiple anthropogenic stressors acting in the system is essential to effectively design policy measures to restore riverine ecosystems. However, obtaining quantitative links between stressors and ecological status is still challenging, given the non-linearity of the ecosystem response and the need to consider multiple factors at play. This study applies machine learning techniques to explore the relationships between anthropogenic pressures and the composition of fish communities in the river basins of Castilla-La Mancha, a region covering nearly 79 500 km² in central Spain. During the past two decades, this region has experienced an alarming decline of the conservation status of native fish species. The starting point for the analysis is a 10x10 km grid that defines for each cell the presence or absence of several fish species before and after 2001. This database was used to characterize the evolution of several metrics of fish species richness over time, accounting for the species origin (native or alien), species features (e.g. pollution tolerance) and habitat preferences. Random Forest and Gradient Boosted Regression Trees algorithms were used to relate the resulting metrics to the stressor variables describing the anthropogenic pressures acting in the rivers, such as urban wastewater discharges, land use cover, hydro-morphological degradation and the alteration of the river flow regime. The study provides new, quantitative insights into pressures-ecosystem relationships in rivers and reveals the main factors that lead to the decline of fish richness in Castilla-La Mancha, which could help inform environmental policy initiatives.</p>

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