Estimating Baltic sprat (Sprattus sprattus balticus S.) population sizes from egg production

Kraus, Gerd and Köster, Friedrich W. (2004) Estimating Baltic sprat (Sprattus sprattus balticus S.) population sizes from egg production Fisheries Research, 69 (3). pp. 313-329. DOI 10.1016/j.fishres.2004.06.005.

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The sprat (Sprattus sprattus balticus S.) population size in the Bornholm Basin, one of the major spawning areas of the species in the Baltic Sea, was estimated with the daily egg production method. Egg abundance, stock structure, sexual and gonadal maturation, spawning frequency and the batch fecundity of sprat throughout the sprat spawning season were simultaneously investigated to obtain an estimate of the population size at spawning time. The results confirmed the population estimate from a hydroacoustic survey, but contrasted spatially down-scaled results from an area dis-aggregated stock assessment model applying fisheries statistics. Conflicting results from both latter methods have previously hampered quantitative studies on recruitment processes of sprat and cod, for example the estimation of predation pressure on cod eggs by sprat. The egg production method did not allow an estimation of the population size of sprat in the entire assessment area larger than the Bornholm Basin, i.e. ICES sub-division 25. This failure is caused by sprat spawning activity outside the Bornholm Basin, not covered by the standard egg surveys and has consequences for the general applicability of available egg abundance time series to retrospectively estimate sprat stock development.

Document Type: Article
Keywords: Baltic sprat; Sexual and gonadal maturation; Spawning frequency; Batch fecundity; Daily egg production method
Research affiliation: OceanRep > GEOMAR > FB3 Marine Ecology > FB3-EV Evolutionary Ecology of Marine Fishes
Refereed: Yes
DOI etc.: 10.1016/j.fishres.2004.06.005
ISSN: 0165-7836
Projects: STORE
Date Deposited: 16 Mar 2009 15:52
Last Modified: 09 Jan 2017 13:40

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