Trophic decoupling of mesozooplankton production and the pelagic planktivores sprat Sprattus sprattus and herring Clupea harengus in the Central Baltic Sea

Abstract The pelagic-fish fauna in the Gulf of Finland, Baltic Sea was sampled by trawling and hydroacoustics in September 2002. Spatial and size/age-dependent patterns in the diets of herring (Clupea harengus), sprat (Sprattus sprattus), and the three-spined stickleback (Gasterosteus aculeatus) were explored. At night the fish concentrated at thermocline depth but at dawn they scattered over a larger depth range. All three fish species fed on mesozooplankton but nektobenthos, for example, was scarce. In the eastern Gulf of Finland, where there is a strong freshwater inflow, the cladoceran Bosmina longispina was the dominant prey item, but it was also abundant in the diets of young-of-the-year (total length <10 cm) clupeids in the western Gulf of Finland. In these more saline western areas, calanoid copepods, especially Eurytemora affinis, were the most important prey for large (≥10 cm) clupeids. The large clupeids in particular, also fed on Temora longicornis. The diet of three-spined stickleback overlapped with that of the clupeids. However, Cercopagis pengoi, a recent arrival to the area, was much more abundant in the diet of stickleback than in the diet of clupeids.

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Synoptic survey of pathological symptoms in herring (Clupea harengus) and sprat (Sprattus sprattus) in the Baltic Sea

ICES Journal of Marine Science ◽

10.1006/jmsc.1999.0467 ◽

1999 ◽

Vol 56 (2) ◽

pp. 169-174 ◽

Cited By ~ 5

Author(s):

W Grygiel

Keyword(s):

Baltic Sea ◽

Clupea Harengus ◽

The Baltic Sea ◽

Sprattus Sprattus ◽

The Baltic

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Forage fish quality: seasonal lipid dynamics of herring (Clupea harengus L.) and sprat (Sprattus sprattus L.) in the Baltic Sea

ICES Journal of Marine Science ◽

10.1093/icesjms/fst106 ◽

2013 ◽

Vol 71 (1) ◽

pp. 56-71 ◽

Cited By ~ 28

Author(s):

Maria C. Røjbek ◽

Jonna Tomkiewicz ◽

Charlotte Jacobsen ◽

Josianne G. Støttrup

Keyword(s):

Fatty Acids ◽

Baltic Sea ◽

Lipid Content ◽

Clupea Harengus ◽

Forage Fish ◽

The Baltic Sea ◽

Sprattus Sprattus ◽

Fish Size ◽

Lipid Dynamics ◽

The Baltic

Abstract Røjbek, M. C., Tomkiewicz, J., Jacobsen, C., and Støttrup, J. G. Forage fish quality: seasonal lipid dynamics of herring (Clupea harengus L.) and sprat (Sprattus sprattus L.) in the Baltic Sea. – ICES Journal of Marine Science, 71: . This study investigates lipid content and fatty acid composition of two important forage fish, sprat (Sprattus sprattus) and herring (Clupea harengus) in the Baltic Sea ecosystem. Seasonal variation in lipids was studied during three periods following the annual reproductive cycle considering potential differences relating to fish size, sex, and reproductive status. The isopod Saduria entomon, being at times an important prey for predatory fish, was included for comparison. In both sprat and herring, lipid content and absolute contents of essential polyunsaturated fatty acids (PUFAs) varied seasonally with high levels towards the end of the annual zooplankton production cycle, succeeded by a decline. Lipid content and fatty acid composition differed significantly between sprat and herring. Sprat lipid content was higher than herring, increasing with fish size and characterized by large proportions of monounsaturated fatty acids. Herring lipid content was related to the reproductive cycle and proportions of PUFAs were high compared with sprat. Levels of essential PUFAs were high in S. entomon compared with clupeids rendering it a valuable alternative prey species in the Baltic Sea ecosystem. The lipid dynamics of forage fish and benthos, combined with changes in availability and abundance, will affect growth and reproduction of their predators.

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