Scientia Marina, Vol 67, No S1 (2003)

Recruitment of Baltic cod and sprat stocks: identification of critical life stages and incorporation of environmental variability into stock-recruitment relationships


https://doi.org/10.3989/scimar.2003.67s1129

Friedrich W. Köster
Institute of Marine Sciences, Germany

Hans-Harald Hinrichsen
Institute of Marine Sciences, Germany

Dietrich Schnack
Institute of Marine Sciences, Germany

Mike A. St. John
Institute of Hydrobiologie and Fisheries Science, Germany

Brian R. Mackenzie
Danish Institute for Fisheries Research, Denmark

Jonna Tomkiewicz
Institute of Marine Sciences, Germany

Christian Möllmann
Institute of Marine Sciences, Germany

Gerd Kraus
Institute of Marine Sciences, Germany

Maris Plikshs
Latvian Fisheries Research Institute

Andrej Makarchouk
Latvian Fisheries Research Institute

Eeri Aro
Finnish Game and Fisheries Research Institute, Finland

Abstract


The recruitment processes of Baltic cod and sprat were analysed and critical periods were identified by addressing the major impact factors on individual early life history stages separately and relating observed abundance data between successive stages. For cod, recruitment appeared to be dependent on egg survival, with low oxygen concentration in dwelling depths and predation by clupeids as the major causes for egg mortality. Surviving egg production and larval abundance were weakly correlated, whereas larval abundance was significantly related to year class strength. This indicated that the period between the late egg and the early larval stage is critical for cod recruitment. A potential variable identified to affect this life stage was prey availability for larvae. For sprat, early and late egg stage production as well as late egg stage production and larval abundance were significantly related. However, year class strength was largely independent of larval abundance. Thus, the period between the late larval and early juvenile stage appeared to be critical for sprat recruitment. Potential variables identified to affect this life stage were ambient temperature and wind stress. Environmental factors showing statistically significant covariance with the survival of one of these critical life stages were incorporated into stock-recruitment models for individual spawning areas separately and for the Central Baltic combined.

Keywords


cod; sprat; Baltic; critical life stage; environment; stock-recruitment relationship

Full Text:


PDF


Copyright (c) 2003 Consejo Superior de Investigaciones Científicas (CSIC)

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.


Contact us scimar@icm.csic.es

Technical support soporte.tecnico.revistas@csic.es