A1 Journal article – refereed
Occurrence of two-year cyclicity, "saw-blade fluctuation", in vendace populations in Finland
List of Authors: Marjomäki Timo J., Auvinen Heikki, Helminen Harri, Huusko Ari, Huuskonen Hannu, Hyvärinen Pekka, Jurvelius Juha, Sarvala Jouko, Valkeajärvi Pentti, Viljanen Markku, Karjalainen Juha
Publisher: FINNISH ZOOLOGICAL BOTANICAL PUBLISHING BOARD
Publication year: 2021
Journal: Annales Zoologici Fennici
Journal name in source: ANNALES ZOOLOGICI FENNICI
Journal acronym: ANN ZOOL FENN
Volume number: 58
Issue number: 4-6
Number of pages: 15
ISSN: 0003-455X
DOI: http://dx.doi.org/10.5735/086.058.0408
The tendency towards two-year cyclicity is considered typical of many Fennoscandian vendace populations, especially in fluctuation of recruitment, based on time series of individual lakes. We used two robust indicators to identify and quantify two-year cycles in vendace population proxy time series at different life-stages - spawning stock biomass (SB), density of newly hatched larvae (LD) and recruitment (REC) - from 22 Finnish lakes. Then we applied Fisher's meta-analytical test to assess the adequacy of the evidence to support the hypothesis that vendace population dynamics include two-year cyclicity. The results supported this hypothesis for REC but not for SB or LD. Yet. the indicators and test are conservative and time-series of SB and LD are shorter than those for REC. The appearance of cycles in REC is associated with high post-recruitment mortality, consequently practically only one spawning per cohort. Cycles may be typical for the recovery period from low abundance period also. Still, some populations with moderate post-REC mortality and non-cyclic SB abundance exhibited cycles in REC. Such dynamics presuppose the existence of more complex regulation based on the interaction of different life stages.
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