MEPS 480:277-287 (2013)  -  doi:10.3354/meps10308

Population growth across heterogeneous environments: effects of harvesting and age structure

Joël M. Durant1,*, Manuel Hidalgo1,5, Tristan Rouyer1,6, Dag Ø. Hjermann1,7, Lorenzo Ciannelli2, Anne Maria Eikeset1, Natalia Yaragina3, N. C. Stenseth1,4

1Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, PO Box 1066 Blindern, 0316 Oslo, Norway
2College of Earth, Ocean and Atmospheric Sciences, Oregon State University, 104 COAS Administration Building, Corvallis, Oregon 97331-5503, USA
3Knipovich Polar Research Institute of Marine Fisheries and Oceanography (PINRO), 6 Knipovich Street, Murmansk 183038, Russia
4Institute of Marine Research, Flødevigen Marine Research Station, 4817 His, Norway
5Present address: Instituto Español de Oceanografía, Centre Oceanogràfic de les Balears, Moll de Ponent s/n, 07015 Palma, Spain
6Present address: Laboratoire Ressources Halieutiques de Sète, Ifremer, Station de Sète, Av. Jean Monnet, BP 171 - 34203 Sète Cedex, France
7Present address: Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, 0349 Oslo, Norway

ABSTRACT: Population growth is affected by several factors such as climate, species interaction and harvesting pressure. However, additional complexity can arise if fishing increases the sensitivity to environmental variability. To predict the effects of fisheries and climate on marine populations, there is a need for improved understanding of how they affect key ecological processes such as population growth. In this study, we used a comparative approach investigating commercially fished species across different ecosystems: the Norwegian Sea-Barents Sea (Northeast Arctic cod), the North Sea (North Sea cod), the Atlantic Ocean (European hake), the Mediterranean Sea (European hake), and the Gulf of Alaska and Bering Sea (walleye pollock). Our objective was to compare the effects of commercial fisheries, age structure and environmental variability on population growth rate. We show that although all stocks experienced a decline in abundance, only 3 of them showed a concomitant decreasing trend in generation time (South Atlantic hake, North Atlantic hake and Northeast Arctic cod), suggesting a fishing-induced erosion in their age structure. Intra-specific analysis shows that changes in generation time triggered an increase in the relative contribution of recruitment to population growth. Furthermore, the contribution from recruitment to population growth changes due to large-scale climate indices or regional-scale environmental covariates, such as sea temperature. This study illustrates how and where the interaction between large-scale ecological patterns and regional/short-scale processes are important for designing management regulations.


KEY WORDS: Barents Sea · Mediterranean Sea · Bering Sea · Cod · Gadus morhua · European hake · Merluccius merluccius · Pollock · Theragra chalcogramma · Leslie matrix · Fisheries


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Cite this article as: Durant JM, Hidalgo M, Rouyer T, Hjermann DØ and others (2013) Population growth across heterogeneous environments: effects of harvesting and age structure. Mar Ecol Prog Ser 480:277-287

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