Cormorant predation overlaps with fish communities and commercial-fishery interest in a Swedish lake

2017 ◽  
Vol 68 (9) ◽  
pp. 1677 ◽  
Author(s):  
M. K. Ovegård ◽  
K. Öhman ◽  
J. S. Mikkelsen ◽  
N. Jepsen
Keyword(s):  
Water Quality ◽  
Fish Communities ◽  
Common Species ◽  
Predatory Fish ◽  
Commercial Fishery ◽  
Phalacrocorax Carbo ◽  
Phalacrocorax Carbo Sinensis ◽  
Gill Net ◽  
Pike Perch ◽  
Main Factor

The increase of the fish-eating cormorant (Phalacrocorax carbo sinensis) in Europe has resulted in conflicts with fisheries. In Lake Roxen, Sweden, cormorants are blamed for causing a decrease in fishery catches. To study and describe the potential effects that cormorants may have had on fish in the lake, their diet was analysed in relation to fish catches in gill-net surveys and fishery catches. Estimates of predation were achieved by ‘tag and recovery’ on eel, pike-perch and perch. Cormorants predated on the most common species and sizes, which were mainly smaller perch, ruffe and roach (mean sizes of 9, 8 and 13cm respectively). Tag recoveries from perch, eel and pike-perch detected predation estimates of 14, 7 and 15% respectively. From a highly eutrophic state, the lake has shown improvements in water quality and a development towards larger predatory fish was expected, but the results from gill-net surveys did not show this. Results indicated that cormorants and fisheries may both be responsible, but because cormorants remove more fish, they may be the main factor for the lack of recovery of large predatory fish. Their predation keeps recruitment high, but the number of fish that reach large sizes remains low.

CHARACTERISTICS OF FREE-RADICAL PROCESSES IN THE ORGANISMS OF SOME PREDATORY FISH SPECIES IN DIFFERENT SEASONS OF THE YEAR

2017 ◽  
pp. 117-123
Author(s):  
Nikolay Aleksandrovich Pudovkin ◽  
Peter Vladimirovich Smutnev
Keyword(s):  
Fish Species ◽  
Catalase Activity ◽  
Perca Fluviatilis ◽  
Selenium Concentration ◽  
The Body ◽  
Predatory Fish ◽  
Volga River ◽  
Silurus Glanis ◽  
Average Value ◽  
Pike Perch

The authors of the article have studied the content of the elements of anti-oxidant system (malondialdehyde, catalase, selenium) in tissues of the internal organs (gills, intestine, muscles, liver, swimbladder, scales) in some species of predatory fish (pike Esox lucius (L., 1758), perch Perca fluviatilis (L., 1758), pike-perch Sander lucioperca (L., 1758), catfish Silurus glanis ) widespread in the basin of the Volga river in the Saratov region. The lowest concentration of malondialdehyde in organisms of the studied fish species is observed in fall and winter; the highest - in spring and summer. Catalase activity in gills tissue of a pike raised in 11.8%, cat-fish - 9.1%, pike-perch - 7.5%, perch - 7.8%. In fall (compared to winter) enzyme activity lowering in gonads of pike-perch makes 16.3%, in gonads of perch - 14.4%. In other tissues there were not observed any evident changes of catalase activity. Fish species under consideration are listed according to the average value of selenium concentration in organisms, µg/g: pike (0.208) > catfish (0.207) > pike-perch (0.196) > perch (0.178). According to the average value of the selenium accumulation in the body in different season all the studied species can be placed in the following order, µg/g: winter-pike (0.132) > pike-perch (0.136) > perch and catfish (0.142); spring - pike-perch (0.190) > perch (0.191) > pike (0.208) > catfish (0.209); summer - perch (0.186) > pike-perch (0.190) > catfish and pike (0.203); autumn - perch (0.193) > pike-perch (0.268) > > catfish (0.274) > pike (0.289).

scholarly journals Hydrochemical characteristics and water quality evaluation of shallow groundwater in Suxian mining area, Huaibei coalfield, China

2020 ◽  
Vol 7 (4) ◽  
pp. 825-835
Author(s):  
Hao Yu ◽  
Herong Gui ◽  
Honghai Zhao ◽  
Meichen Wang ◽  
Jun Li ◽  
...  
Keyword(s):  
Water Quality ◽  
Major Ions ◽  
Shallow Groundwater ◽  
Mining Area ◽  
Water Quality Evaluation ◽  
Groundwater Samples ◽  
Silicate Dissolution ◽  
Huaibei Coalfield ◽  
Main Factor

AbstractThe aim of this study is to evaluate the hydrogeochemical characteristics and water environmental quality of shallow groundwater in the Suxian mining area of Huaibei coalfield, China. The natural formation process of shallow groundwater in Suxian is explored using Piper trilinear charts and Gibbs diagrams, and by examining the ratios between the major ions. United States Salinity Laboratory (USSL) charts, Wilcox diagrams, and the water quality index (WQI) are further employed to quantify the differences in water quality. The results reveal that the main hydrochemical facies of groundwater are HCO3–Ca, and that silicate dissolution is the main factor controlling the ion content in shallow groundwater. The USSL charts and Wilcox diagrams show that most of the water samples would be acceptable for use in irrigation systems. The WQI results for each water sample are compared and analyzed, and the quality of groundwater samples around collapse ponds is found to be relatively poor.

scholarly journals Estimating the mortality caused by great cormorant predation on fish stocks: pikeperch in the Archipelago Sea, northern Baltic Sea, as an example

2016 ◽  
Vol 73 (1) ◽  
pp. 84-93 ◽  
Author(s):  
Outi Heikinheimo ◽  
Pekka Rusanen ◽  
Katja Korhonen
Keyword(s):  
Age Groups ◽  
Total Mortality ◽  
Sensitivity Analyses ◽  
Fish Stock ◽  
Great Cormorant ◽  
Phalacrocorax Carbo ◽  
Fish Stocks ◽  
Archipelago Sea ◽  
Phalacrocorax Carbo Sinensis ◽  
The Impact

Estimates of the mortality rates caused by cormorants are needed to assess the impact on fish stock dynamics and fisheries. In this study, we calculated the annual instantaneous mortality caused by great cormorants (Phalacrocorax carbo sinensis) on young pikeperch (Sander lucioperca), using data from Archipelago Sea, southwestern coast of Finland. The pikeperch are vulnerable to cormorant predation mainly at the ages 2–4. The annual instantaneous mortality caused by cormorants was between 0.04 and 0.13, and the estimated effect on the pikeperch stock size at recruitment to the fishery ranged from 4% to 23%, respectively. The average annual cormorant-induced mortality accounted for 5%–34% of the total mortality in these age groups. The sensitivity analyses proved that the rates of mortality from other sources largely affect the estimated mortality from cormorant predation. In cases with strong fluctuations in the abundance of the prey fish stocks, ignoring the size and density dependence of the natural mortality may lead to overestimation of the importance of cormorants as competitors of fisheries.

Indexes of Lipid Metabolism in Fish from the Zaporizke Reservoir

2017 ◽  
Vol 64 ◽  
pp. 10-16 ◽  
Author(s):  
Tamila Ananieva
Keyword(s):  
Muscle Tissue ◽  
Total Lipid ◽  
Iodine Value ◽  
Liver Tissue ◽  
Predatory Fish ◽  
Contamination Level ◽  
European Perch ◽  
Tissue Samples ◽  
Lipid Contents ◽  
Pike Perch

The total lipid contents and iodine value of fats had been determined in fish from two sections of the Zaporizke Reservoir (Ukraine) with different contamination levels. Research was conducted using the muscle and liver tissue samples from pike-perch (Sander lucioperca), european perch (Perca fluviatis), prussian carp (Carassius gibelio), roach (Rutilus rutilus) and rudd (Scardinius erythrophthalmus). Obtained data showed that at the contaminated zone, the total lipid contents were significantly (p ≤ 0.05) reduced in muscle tissue of pike-perch and european perch in comparison with the samples from “conventionally clean” lower section of the reservoir. Increased iodine value of fats in muscle tissue and liver tissue were detected in the predatory fish and both fish groups respectively. The research results could be used for estimation of the adaptation processes in freshwater fish as well as for indication of environmental contamination level in the natural and artificial reservoirs.

scholarly journals Using stable isotopes to unravel and predict the origins of great cormorants (Phalacrocorax carbo sinensis) overwintering at Kinmen

2008 ◽  
Vol 22 (8) ◽  
pp. 1235-1244 ◽  
Author(s):  
Yuan-Mou Chang ◽  
Kent A. Hatch ◽  
Tzung-Su Ding ◽  
Dennis L. Eggett ◽  
Hsiao-Wei Yuan ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Phalacrocorax Carbo ◽  
Phalacrocorax Carbo Sinensis ◽  
Great Cormorants

Expansion of the Cormorant (Phalacrocorax Carbo Sinensis) Population in Western Lithuania

2002 ◽  
Vol 12 (3) ◽  
pp. 283-287 ◽  
Author(s):  
Ramunas Žydelis ◽  
Gediminas Gražulevič ◽  
Jūratė Zarankaitė ◽  
Romas Mečionis ◽  
Mindaugas Mačiulis
Keyword(s):  
Phalacrocorax Carbo ◽  
Phalacrocorax Carbo Sinensis
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