Marine Research Findings of the VECTORS Project

This website provides access to the research results of the VECTORS project, which can be used to support marine management decisions, policies and governance as well as future research and investment. VECTORS was a large scale project that brought together more than 200 expert researchers from 16 different countries. It examined the significant changes taking place in European seas, their causes, and the impacts they will have on society.

Changes in behaviour of fish early life history stages

Vital rates during the early life history stages have a great influence on recruitment success of marine fish populations. Some of these characteristics (abundance, growth rate, survival and feeding behaviour) were studied in herring and non-commercial gobies Pomatoschistus spp. in the Gulf of Riga. External and internal ecosystem drivers, like hydroclimate and prey availability were used to describe/interpret the observed patterns.

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Early ice retreat (i.e. mild winters) results in a temporal mismatch between herring larvae and their first prey, copepod nauplii.

In the years of earliest ice retreat herring larvae appeared significantly earlier than copepod nauplii, resulting in the delayed feeding which likely facilitate high mortality rates amongst the first-feeding herring larvae that mostly prey on nauplii. Changes in prey availability can alter larval growth rates and consequently the duration of the pre-recruit period when larvae are particularly susceptible to predation mortality.

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Feeding activity of herring larvae was governed by different environmental variables and the relationships varied amongst the size classes of herring larvae.

The diet composition of all sizes of herring larvae was best described by the density of copepod nauplii. Feeding activity of small larvae appeared to be independent of any abiotic and biotic parameters investigated, while the feeding activity of medium larvae was mainly affected by water transparency and that of large larvae by a combination of water temperature, wind speed and the structure of local copepod community, respectively.

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Highly productive coastal area might function as a predation trap for fish larvae at high temperature conditions.

Daily growth rate and instantaneous mortality of the two dominating marine fish, herring and goby, were investigated in a coastal area of the Gulf of Riga. Despite of high growth rates, larval herring mortality was around one order of magnitude higher than reported elsewhere. High growth rates and elevated mortality may have resulted from rapid increase of water temperature observed during the investigation period.

References

Lead Author:

Timo Arula
(timo.arula@nospamut.ee)
Estonian Marine Institute (EMI-UT)
Date of research: May 2014

Related articles:

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Changes in herring larvae and environment 1957-2010

Ecological impact of a non-indigenous cladoceran 

Early life stage survival of Baltic cod

Fish distributions and spatial management measures 

Growth model for jellyfish Pelagia noctiluca 

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This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 266445
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