scholarly journals Feeding preferences of herring (Clupea harengus) and sprat (Sprattus sprattus) in the southern Baltic Sea

2004 ◽  
Vol 61 (8) ◽  
pp. 1267-1277 ◽  
Author(s):  
Michele Casini ◽  
Massimiliano Cardinale ◽  
Fredrik Arrhenius
Keyword(s):  
Baltic Sea ◽  
Entire Range ◽  
Field Studies ◽  
Clupea Harengus ◽  
Feeding Preferences ◽  
Southern Baltic Sea ◽  
Mysis Mixta ◽  
Temora Longicornis ◽  
Southern Baltic ◽  
Autumn And Winter

Abstract No field studies have been performed on the selectivity of herring and sprat in the southern Baltic Sea in relation to their entire range of prey. Accordingly, we tested in the field the following hypotheses: (i) sprat and herring are selective feeders and (ii) sprat and herring selectivity is size- and season-dependent. The results show that (i) smaller herring and all size classes of sprat are strictly zooplanktivorous, selecting principally Temora longicornis and Bosmina maritima during the autumn and Pseudocalanus elongatus in winter; (ii) larger herring are essentially nektobenthos feeders, predating on Mysis mixta during the autumn and amphipods and polychaetes during the winter; and (iii) herring and sprat seem to avoid Acartia spp. in both autumn and winter. During the autumn, herring are zooplanktivorous up to 18–20 cm, whereas in winter herring feed on nektobenthos starting from 14–15 cm. Selectivity was not an absolute process but it was related to prey relative abundance in the sea and, possibly, to prey profitability (e.g. size, conspicuousness, and reaction time).

Diet composition of herring (Clupea harengus L.) and cod (Gadus morhua L.) in the southern Baltic Sea in 2007 and 2008

2011 ◽  
Vol 40 (4) ◽  
Author(s):  
Diana Dziaduch
Keyword(s):  
Baltic Sea ◽  
Diet Composition ◽  
Gadus Morhua ◽  
Clupea Harengus ◽  
The Baltic Sea ◽  
Commercial Fish ◽  
Southern Baltic Sea ◽  
Starting Point ◽  
Southern Baltic ◽  
The Baltic

AbstractDiet composition of two commercial fish species, herring and cod, were studied in some regions (mainly Gda’nsk and Bornholm Basins, and the Polish coast) of the southern Baltic Sea in 2007 and 2008. Herring is the dominant zooplanktivorous species in the ecosystem of the Baltic Sea, but apart from mesoplanktonic organisms it also eats macroplanktonic and benthic species in considerable amount. The diet of cod consists of fish and crustaceans from pelagic, hyperbenthic and benthic habitats. The feeding preferences of fish indirectly reflect changes in the whole food chain in the Baltic Sea. This research focuses specifically on these invertebrate species, which are eliminated from the environment by most of the ichthyofauna of this region. The aim of this research is to examine the role of invertebrate organisms belonging to Crustacea in the diet of herring and adult cod to supply updated results about feeding of these fish as little data have been collected since the 1990s. The present study is a preliminary survey and results can not be considered conclusive. The restricted numbers of analyzed stomachs of fish and selected seasons of the year addressed in this paper are a starting point for further studies with a larger scope. In this study, 20 to 90% of herring had empty stomachs. Mesozooplankton dominated the diets of small and large herring. Mysidacea, which were historically important prey for herring, are now scarce and have been replaced by planktonic Amphipoda. In the case of cod, consumption of Mysidacea has never been as low as in this study. As for other invertebrate prey, the benthic isopod Saduria and Crangon shrimp achieved the highest amount by number and weight. These results show distinct changes in diet when compared to previous investigations and require verification at a larger spatial scale.

Reference organisms for assessing the impact of ionizing radiation on the environment of the southern Baltic Sea

2012 ◽  
Vol 41 (4) ◽  
pp. 1-7 ◽  
Author(s):  
Tamara Zalewska ◽  
Maria Suplińska
Keyword(s):  
Ionizing Radiation ◽  
Baltic Sea ◽  
Benthic Fauna ◽  
Clupea Harengus ◽  
Assessment System ◽  
Ecological Niches ◽  
Hediste Diversicolor ◽  
Southern Baltic Sea ◽  
Southern Baltic ◽  
The Impact

AbstractAssessing the impact of ionizing radiation on the marine environment requires a well-defined methodology, which includes, among other elements, the analysis of exposure and effects. One of the most important components of the assessment system is the choice of reference organisms specific for the assessed area that fulfill requirements such as radioecological sensitivity, widespread distribution, and amenability to research and monitoring. The following species specific to the southern Baltic Sea that represent diversified ecological niches were proposed as reference organisms. Polysiphonia fucoides was proposed as a representative of macroalgae. Pelagic and benthic fauna were represented by Crangon crangon (crustacean), Saduria entomon (crustacean), Hediste diversicolor (polychaete), and Mytilus trossulus (mollusc). Fish were represented by Clupea harengus (pelagic planctotrophic fish), Gadus morhua (pelagic carnivorous fish), and Platichthys flesus (benthic fish). Activity concentrations of 137Cs were determined in reference biota as well as in seawater, as required for the total dose-rate evaluation, and relevant concentration factors were calculated.

scholarly journals Assessing the performance of statistical classifiers to discriminate fish stocks using Fourier analysis of otolith shape

2020 ◽  
Vol 77 (4) ◽  
pp. 674-683 ◽  
Author(s):  
Szymon Smoliński ◽  
Franziska Maria Schade ◽  
Florian Berg
Keyword(s):  
Machine Learning ◽  
Fourier Analysis ◽  
Baltic Sea ◽  
Clupea Harengus ◽  
Fish Stock ◽  
Fish Stocks ◽  
Otolith Shape ◽  
Southern Baltic Sea ◽  
Statistical Classifiers ◽  
Southern Baltic

The assignment of individual fish to its stock of origin is important for reliable stock assessment and fisheries management. Otolith shape is commonly used as the marker of distinct stocks in discrimination studies. Our literature review showed that the application and comparison of alternative statistical classifiers to discriminate fish stocks based on otolith shape is limited. Therefore, we compared the performance of two traditional and four machine learning classifiers based on Fourier analysis of otolith shape using selected stocks of Atlantic cod (Gadus morhua) in the southern Baltic Sea and Atlantic herring (Clupea harengus) in the western Norwegian Sea, Skagerrak, and the southern Baltic Sea. Our results showed that the stocks can be successfully discriminated based on their otolith shapes. We observed significant differences in the accuracy obtained by the tested classifiers. For both species, support vector machines (SVM) resulted in the highest classification accuracy. These findings suggest that modern machine learning algorithms, like SVM, can help to improve the accuracy of fish stock discrimination systems based on the otolith shape.

scholarly journals The Interannual Changes in the Secondary Production and Mortality Rate of Main Copepod Species in the Gulf of Gdańsk (The Southern Baltic Sea)

2019 ◽  
Vol 9 (10) ◽  
pp. 2039
Author(s):  
Lidia Dzierzbicka-Głowacka ◽  
Maja Musialik-Koszarowska ◽  
Marcin Kalarus ◽  
Anna Lemieszek ◽  
Paula Prątnicka ◽  
...  
Keyword(s):  
Mortality Rate ◽  
Baltic Sea ◽  
Secondary Production ◽  
Developmental Stages ◽  
Mortality Rates ◽  
Gulf Of Gdańsk ◽  
Southern Baltic Sea ◽  
Temora Longicornis ◽  
Gulf Of Gdansk ◽  
Southern Baltic

The main objective of this paper was description of seasonal and interannual trends in secondary production and mortality rates of the three most important Copepoda taxa in the Gulf of Gdańsk (southern Baltic Sea). Samples were collected monthly from six stations located in the western part of the Gulf of Gdańsk during three research periods: 1998–2000, 2006–2007, and 2010–2012. Production was calculated based on copepod biomass and mortality rates estimated according to vertical life table approach. Redundancy analysis was used to investigate relationship between secondary production and environmental conditions. During the entire research period there was significant interannual and seasonal variability of secondary production, mortality rate, as well as abundance and biomass anomalies. Conducted analysis revealed positive correlation between increasing temperature and production of Acartia spp. and Temora longicornis developmental stages, while older copepodites of Pseudocalanus acuspes showed almost negative correlation with temperature. The mortality rate estimations obtained for Acartia spp. were the highest in summer, while Temora longicornis peaked in spring–summer period. The lowest mortality rate estimations were noted in autumn and winter for almost all stages of investigated taxa.

Modeling of egg production by Temora longicornis from the southern Baltic Sea including salinity

2013 ◽  
Vol 42 (3) ◽  
Author(s):  
Lidia Dzierzbicka-Głowacka ◽  
Anna Lemieszek ◽  
Maja Musialik ◽  
Iwona Żmijewska
Keyword(s):  
Baltic Sea ◽  
Egg Production ◽  
Food Concentration ◽  
Southern Baltic Sea ◽  
Matter Production ◽  
Wide Range ◽  
Temora Longicornis ◽  
Southern Baltic ◽  
The Baltic ◽  
June July

AbstractThe paper presents modeling of egg production (Egg — no. of eggs female−1 d−1) by Temora longicornis in the changing environmental conditions of the southern Baltic Sea (Gdańsk Deep). It is hypothesized that the food-saturated rate of egg matter production is equivalent to the specific growth rate of copepods. Based on the findings from the south-western Baltic Sea, Egg of T. longicornis is evaluated as a function of food concentration, temperature and salinity over a wide range of these parameters. Subsequently, the rate of reproduction during the seasons in the Gulf of Gdańsk is determined. According to our calculations, values of Egg reach ca 11 eggs per day in April and decline strongly in June-July, while the second smaller peak in reproduction occurs in September, ca 8 eggs per day. Our results suggest that egg production rates of T. longicornis depend not only on food concentration and temperature, but also on salinity, which is a masking factor in the Baltic Sea.

Contamination of the southern Baltic Sea waters by the residues of selected pharmaceuticals: Method development and field studies

2015 ◽  
Vol 94 (1-2) ◽  
pp. 62-71 ◽  
Author(s):  
Marta Borecka ◽  
Grzegorz Siedlewicz ◽  
Łukasz P. Haliński ◽  
Kinga Sikora ◽  
Ksenia Pazdro ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Method Development ◽  
Field Studies ◽  
Southern Baltic Sea ◽  
Southern Baltic
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