Differences in growth and survival between cod Gadus morhua and herring Clupea harengus early stages co-reared at variable prey concentrations

• Published in: Journal of Fish Biology
• Main Authors: Folkvord, Arild, Vollset, K. W., Catalán, Ignacio Alberto
• Other Authors: Institute of Marine Research (Norway), Ministerio de Educación y Ciencia (España), University of Bergen
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Blackwell Publishing 2015
• Subjects: Competition; Zooplankton; Larvae; Juveniles; Feeding; Bergen; Gadus morhua
• Online Access: http://hdl.handle.net/10261/132268; https://doi.org/10.1111/jfb.12783; https://doi.org/10.13039/501100005036

It was hypothesized that the survival and growth strategies of herring Clupea harengus, displaying a flexible reproductive activity, are adapted to coping with longer periods of prey deprivation (i.e. more variable prey availability), in contrast to cod Gadus morhua, which are adapted to match growth and survival at high prey concentrations. Experimental larval growth and survival data for the two naturally co-occurring species reared either in separate tanks or in combination are presented to test this hypothesis. Natural zooplankton was supplied either ad libitum or in a periodically restricted manner to mimic natural suboptimal conditions. Periodically restricted feeding significantly reduced initial growth of G. morhua larvae co-reared with C. harengus, while no such initial effect was seen for co-reared C. harengus. Overall survival of G. morhua was higher when reared together with C. harengus (32 v. 24%), while C. harengus had higher survival without the presence of G. morhua (59 v. 44%), indicating that both species were affected by higher densities of G. morhua larvae. Furthermore, the final survival in G. morhua was inversely related to average final size, while in C. harengus an opposite trend was observed. How potential behavioural interactions may drive the present results are discussed and contended that a better insight into field vital rates may be gained from further exploration of co-rearing experiments. This work was funded by the University of Bergen and the Institute of Marine Research (KILO project). I.A.C. was partially supported by a José Castillejo research mobility grant, from the Spanish Ministry for Education and Science Peer Reviewed