Antarctic krill fishery effects over penguin populations under adverse climate conditions: Implications for the manageme
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RESEARCH ARTICLE
Antarctic krill fishery effects over penguin populations under adverse climate conditions: Implications for the management of fishing practices Lucas Kru¨ger , Magdalena F. Huerta, Francisco Santa Cruz, Ce´sar A. Ca´rdenas
Received: 27 October 2019 / Revised: 18 March 2020 / Accepted: 18 August 2020
Abstract Fast climate changes in the western Antarctic Peninsula are reducing krill density, which along with increased fishing activities in recent decades, may have had synergistic effects on penguin populations. We tested that assumption by crossing data on fishing activities and Southern Annular Mode (an indicator of climate change in Antarctica) with penguin population data. Increases in fishing catch during the non-breeding period were likely to result in impacts on both chinstrap (Pygoscelis antarcticus) and gentoo (P. papua) populations. Catches and climate change together elevated the probability of negative population growth rates: very high fishing catch on years with warm winters and low sea ice (associated with negative Southern Annular Mode values) implied a decrease in population size in the following year. The current management of krill fishery in the Southern Ocean takes into account an arbitrary and fixed catch limit that does not reflect the variability of the krill population under effects of climate change, therefore affecting penguin populations when the environmental conditions were not favorable. Keywords Antarctic Peninsula Chinstrap penguin Gentoo penguin Population growth rate Southern annular mode
INTRODUCTION The western Antarctic Peninsula (WAP) is one of the areas most affected by climate change. Fast warming in the last Electronic supplementary material The online version of this article (https://doi.org/10.1007/s13280-020-01386-w) contains supplementary material, which is available to authorized users.
decades (Cook et al. 2016; Moffat and Meredith 2018) and the southward input of warmer waters are decreasing the seasonal sea ice extent and duration (Stammerjohn et al. 2008; Moffat and Meredith 2018). Climate change effects have also been observed in different macro-scale atmospheric phenomena, such as the southern oscillation index (SOI) and the Southern Annular Mode (SAM; Stammerjohn et al. 2008; Moffat and Meredith 2018). Specifically, warming in the WAP has been related to strengthening a positive trend in the SAM, which describes atmospheric circulation patterns associated to the belt of westerly wind surrounding Antarctica (Clem et al. 2016). The SAM has a strong influence in the inter-annual variability around the WAP, driving changes in sea ice formation and melting and the injection of meteoric water (combination of glacial discharge and precipitation) to the Southern Ocean (Moffat and Meredith 2018). Current climate change has had significant effects in the Antarctic ecosystem, particularly for sea ice-dependent species, such as the Antarctic krill Euphausia superba. Several studies have shown dramatic changes in Antarctic krill populations, inclu
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