The European anchovy (Engraulis encrasicolus) increase in the North Sea

K.E. Raab

Research output: Thesisinternal PhD, WU

Abstract

Small pelagic fish such as anchovy are of high socio-economic importance worldwide. They are known for strong fluctuations in abundance, for which the mechanisms are not always understood. European anchovy (Engraulis encrasicolus) increased its population in the North Sea starting in the mid-1990s while previously it was found in more southern waters in Europe. Changed food availability (resulting from plankton changes) or changed habitat availability (due to warmer waters) seemed likely candidate explanations for this increase, based on understanding of the species’ general ecology.

In order to compare the two likely explanations, first, the food of anchovy in the North Sea had to be determined. Analysing the contents of anchovy stomachs and comparing the results with other similar fish (herring and sprat), it appeared that anchovy was a generalist feeder. Observed patterns of anchovy distribution in fisheries surveys were compared to relevant environmental factors related to food availability and temperature. This showed that temperatures experienced by anchovies in the first  months after birth was a better explanation for how many anchovy were caught than any measure of food availability was. Modelling their body growth in those months showed that during the past decades, the conditions for juvenile growth improved, probably leading to better overwinter survival.

This doctoral thesis contributed to an increased understanding of the ecology of anchovy in the North Sea, and the insights gained can support studies of small pelagic fish in other systems of the world where fisheries scientists wish to integrate more ecological understanding into their management practice.

Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Wageningen University
Supervisors/Advisors
  • Rijnsdorp, Adriaan, Promotor
  • Dickey-Collas, Mark, Co-promotor
  • Nagelkerke, Leo, Co-promotor
Award date10 Oct 2013
Place of PublicationS.l.
Publisher
Print ISBNs9789461736826
Publication statusPublished - 2013

Fingerprint

food availability
pelagic fish
fishery survey
ecology
habitat availability
warm water
generalist
plankton
management practice
environmental factor
temperature
fishery
food
fish
modeling
sea
water

Keywords

  • anchovies
  • engraulis
  • feeding behaviour
  • population growth
  • population dynamics
  • fishery biology
  • marine ecology
  • north sea

Cite this

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title = "The European anchovy (Engraulis encrasicolus) increase in the North Sea",
abstract = "Small pelagic fish such as anchovy are of high socio-economic importance worldwide. They are known for strong fluctuations in abundance, for which the mechanisms are not always understood. European anchovy (Engraulis encrasicolus) increased its population in the North Sea starting in the mid-1990s while previously it was found in more southern waters in Europe. Changed food availability (resulting from plankton changes) or changed habitat availability (due to warmer waters) seemed likely candidate explanations for this increase, based on understanding of the species’ general ecology. In order to compare the two likely explanations, first, the food of anchovy in the North Sea had to be determined. Analysing the contents of anchovy stomachs and comparing the results with other similar fish (herring and sprat), it appeared that anchovy was a generalist feeder. Observed patterns of anchovy distribution in fisheries surveys were compared to relevant environmental factors related to food availability and temperature. This showed that temperatures experienced by anchovies in the first  months after birth was a better explanation for how many anchovy were caught than any measure of food availability was. Modelling their body growth in those months showed that during the past decades, the conditions for juvenile growth improved, probably leading to better overwinter survival. This doctoral thesis contributed to an increased understanding of the ecology of anchovy in the North Sea, and the insights gained can support studies of small pelagic fish in other systems of the world where fisheries scientists wish to integrate more ecological understanding into their management practice.",
keywords = "ansjovissen, engraulis, voedingsgedrag, populatiegroei, populatiedynamica, visserijbiologie, mariene ecologie, noordzee, anchovies, engraulis, feeding behaviour, population growth, population dynamics, fishery biology, marine ecology, north sea",
author = "K.E. Raab",
note = "WU thesis 5567",
year = "2013",
language = "English",
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publisher = "s.n.",
school = "Wageningen University",

}

Raab, KE 2013, 'The European anchovy (Engraulis encrasicolus) increase in the North Sea', Doctor of Philosophy, Wageningen University, S.l..

The European anchovy (Engraulis encrasicolus) increase in the North Sea. / Raab, K.E.

S.l. : s.n., 2013. 207 p.

Research output: Thesisinternal PhD, WU

TY - THES

T1 - The European anchovy (Engraulis encrasicolus) increase in the North Sea

AU - Raab, K.E.

N1 - WU thesis 5567

PY - 2013

Y1 - 2013

N2 - Small pelagic fish such as anchovy are of high socio-economic importance worldwide. They are known for strong fluctuations in abundance, for which the mechanisms are not always understood. European anchovy (Engraulis encrasicolus) increased its population in the North Sea starting in the mid-1990s while previously it was found in more southern waters in Europe. Changed food availability (resulting from plankton changes) or changed habitat availability (due to warmer waters) seemed likely candidate explanations for this increase, based on understanding of the species’ general ecology. In order to compare the two likely explanations, first, the food of anchovy in the North Sea had to be determined. Analysing the contents of anchovy stomachs and comparing the results with other similar fish (herring and sprat), it appeared that anchovy was a generalist feeder. Observed patterns of anchovy distribution in fisheries surveys were compared to relevant environmental factors related to food availability and temperature. This showed that temperatures experienced by anchovies in the first  months after birth was a better explanation for how many anchovy were caught than any measure of food availability was. Modelling their body growth in those months showed that during the past decades, the conditions for juvenile growth improved, probably leading to better overwinter survival. This doctoral thesis contributed to an increased understanding of the ecology of anchovy in the North Sea, and the insights gained can support studies of small pelagic fish in other systems of the world where fisheries scientists wish to integrate more ecological understanding into their management practice.

AB - Small pelagic fish such as anchovy are of high socio-economic importance worldwide. They are known for strong fluctuations in abundance, for which the mechanisms are not always understood. European anchovy (Engraulis encrasicolus) increased its population in the North Sea starting in the mid-1990s while previously it was found in more southern waters in Europe. Changed food availability (resulting from plankton changes) or changed habitat availability (due to warmer waters) seemed likely candidate explanations for this increase, based on understanding of the species’ general ecology. In order to compare the two likely explanations, first, the food of anchovy in the North Sea had to be determined. Analysing the contents of anchovy stomachs and comparing the results with other similar fish (herring and sprat), it appeared that anchovy was a generalist feeder. Observed patterns of anchovy distribution in fisheries surveys were compared to relevant environmental factors related to food availability and temperature. This showed that temperatures experienced by anchovies in the first  months after birth was a better explanation for how many anchovy were caught than any measure of food availability was. Modelling their body growth in those months showed that during the past decades, the conditions for juvenile growth improved, probably leading to better overwinter survival. This doctoral thesis contributed to an increased understanding of the ecology of anchovy in the North Sea, and the insights gained can support studies of small pelagic fish in other systems of the world where fisheries scientists wish to integrate more ecological understanding into their management practice.

KW - ansjovissen

KW - engraulis

KW - voedingsgedrag

KW - populatiegroei

KW - populatiedynamica

KW - visserijbiologie

KW - mariene ecologie

KW - noordzee

KW - anchovies

KW - engraulis

KW - feeding behaviour

KW - population growth

KW - population dynamics

KW - fishery biology

KW - marine ecology

KW - north sea

M3 - internal PhD, WU

SN - 9789461736826

PB - s.n.

CY - S.l.

ER -