Predation rates by North Sea cod (Gadus morhua) — predictions from models on gastric evacuation and bioenergetics

• Main Authors: Sture Hansson, Lars G. Rudstam, James F. Kitchell, Mikael Hildén, Barry L. Johnson
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1996
• Subjects: Key words; cod; Gadus morhua; North Sea; food consumption; predation
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.595.8632; http://icesjms.oxfordjournals.org/content/53/1/107.full.pdf

We compared four diVerent methods for estimating predation rates by North Sea cod (Gadus morhua). Three estimates, based on gastric evacuation rates, came from an ICES multispecies working group and the fourth from a bioenergetics model. The bioenergetics model was developed from a review of literature on cod physiology. The three gastric evacuation rate models produced very diVerent prey consumption estimates for small (<0.5 kg) and large (>2 kg) fish. For most size and age classes, the bioenergetics model predicted food consumption rates intermediate to those predicted by the gastric evacuation models. Using the standard ICES model and the average population abundance and age structure for 1974–1989, annual prey consumption by the North Sea cod population (age §1) was 840 kilotons. The other two evacuation rate models produced estimates of 1020 and 1640 kilotons, respectively. The bioenergetics model estimate was 1420 kilotons. The major diVerences between models were due to consumption rate estimates for younger age groups of cod.