Feeding opportunities of larval and juvenile cod (Gadus morhua) in a Greenlandic fjord: temporal and spatial linkages between cod and their preferred prey

Rasmus Swalethorp, Sanne Kjellerup, Evandro Malanski, Peter Munk, Torkel Gissel Nielsen

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Feeding of fish depends on a spatial and temporal match with prey, and since larval and juvenile feeding can be highly selective, their preferences for given prey sizes and taxa should be considered when quantifying the actual availability of potential prey. We investigated the diet and prey preferences of the early-life stages of Atlantic cod (Gadus morhua) to quantify the availability of prey during
a spring-summer season in a West Greenlandic fjord. We hypothesized that abundances of larval and juvenile cod at size were synchronized to optimal availability of preferred prey in space and time. The present analysis is based on
nine cruises each covering 5 stations visited between 24 May and 5 August 2010 comparing zooplankton abundance, cod gut content and distribution patterns. Cod 4–25 mm in length preferred prey of about 5 % of their own length. During ontogeny, their preferences changed from calanoid nauplii towards Pseudocalanus spp. and Calanus spp. copepodites. The larvae/juvenile had an exceptionally high dietary contribution from cladocerans, which were highly preferred by cod larger than 9 mm, while the abundant Metridia longa and the non-calanoid copepods contributed less. These findings stress the importance of
focusing on abundance of preferred prey when assessing the actual prey availability to young fish. We found a spatio-temporal overlap between cod and their preferred prey, and observations suggest that advection of both zooplankton and cod contributed to this overlap. Hence, the larval
feeding opportunities might be sensitive to climate-related changes affecting the circulation patterns in this fjord
Original languageEnglish
JournalMarine Biology
Volume161
Issue number2
Pages (from-to)2831-2846
ISSN0025-3162
DOIs
Publication statusPublished - 2014

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