MEPS 577:177-188 (2017)  -  DOI:

Age-structure, harvesting and climate effects on population growth of Arcto-boreal fish stocks

Joël M. Durant1,*, Dag Ø. Hjermann2

1Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, PO Box 1066 Blindern, 0316 Oslo, Norway
2Norwegian Institute for Water Research (NIVA), Gaustadalléen 21, 0349 Oslo, Norway
*Corresponding author:

ABSTRACT: We used a comparative approach investigating commercially fished species with contrasting life histories and trophic positions in an Arcto-boreal system, the Barents Sea. Our objective was to address the ecological consequences of harvesting on stock properties (stochastic growth rate; a property related to intrinsic growth rate) in relation to different external conditions (fishing pressure and climate). We used age-structured population matrices to calculate the transient elasticity of population growth with respect to recruitment (how much population growth depends on recruitment) over time. Using a generalized additive model (GAM) analysis, we found that the transient elasticity of population growth to recruitment overall depends mostly on age structure (which in turn is affected by fishing) but also on climate (temperature change or winter North Atlantic Oscillation). Our results indicate that under warmer conditions, population growth of high latitude stocks becomes increasingly dependent on recruitment, which makes the stocks more difficult to manage. In general, there was no effect of ongoing fishing pressure on elasticity after age structure had been taken into account, supporting the view that long-term fishing pressure affects the susceptibility of the population to climate indirectly, by changing the age structure of the stock. However, for most of the stocks we have studied here, populations have low elasticity to recruitment due to their life history, meaning that the health of the stock mainly depends on survival after the recruitment stage; i.e. fisheries management is more important than climate.

KEY WORDS: Fisheries effect· Climate effect · Recruitment · Comparative analysis · Matrix model · Fish · Barents Sea · Management

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Cite this article as: Durant JM, Hjermann DØ (2017) Age-structure, harvesting and climate effects on population growth of Arcto-boreal fish stocks. Mar Ecol Prog Ser 577:177-188.

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