Modelling Present and Climate- Shifted Distribution of Marine Fishes and Invertebrates

Global climate change is recognized as an important determining factor for the future distributions of marine organisms, notably fishes and invertebrates. Shifting of distribution range may affect global marine fisheries and have large socio-economic implications. However, globalscale evaluation of the impact of climate change on marine species is lacking. In this paper, we develop a dynamic bioclimate envelope model to predict the effect of climate change on the distributions of marine species with emphasis on commercially exploited fishes and invertebrates. First, the model infers, for various species, bioclimate envelopes based on their current distribution. Bioclimate envelopes are defined by sea water temperature, bathymetry, habitats and distance from sea ice. Secondly, the model predicts the shifting of the bioclimate envelopes induced by changes in climate variables. Simultaneously, following the shifting of the bioclimate envelopes, the model simulates movement of relative abundance through changes in population growth, mortality, larval dispersal and adult movement. We test the model with several commercially exploited fish species with widely different biogeography. The model provides reasonable and robust predictions of future distribution ranges of the four species under different scenarios of sea water warming. Moreover, the predictions are robust to major model assumptions and parameter uncertainty. Using realistic climate change predictions from the NOAA/GFDL Coupled Model, this model will be used to evaluate impacts of climate change on global marine fisheries. INTRODUCTION There is ample evidence from empirical observations and climate models indicating that mean global temperatures have been increasing over the last 100 years (IPCC 2007). Global temperature has increased by over 0.6 oC since 1900 and it may continue to increase at a rate of around 0.2 oC per decade (IPCC 2007). Biological responses to this change have been observed in both terrestrial and marine biomes (Murawski 1993; Hughes 2000; McCarty 2001; Parmesan & Yohe 2003; Perry et al. 2005; Hobday et al. 2006). The responses include changes in physiology (e.g. productivity), geographic range and phenology at population, species, community and ecosystem levels (Hughes 2000; McCarty 2001). For instance, nearly two-thirds of marine fishes in the North Sea shifted in mean latitude or depth or both over 25 years as sea temperature increased (Perry et al. 2005). During the last century, annual growth rates for the juveniles of eight long-lived fish species in the southwest Pacific increased in shallow waters and decreased in deep waters where ocean warming and cooling occurred, respectively (Thresher et al 2007). This agrees with the quantitative model of fish physiology, which predicts increasing growth performance and fecundity in higher latitude and the converse in lower latitude as sea 1 Cited as: Cheung, W.W.L., Lam, V.W.Y., Pauly, D. 2008. Dynamic bioclimate envelope model to predict climate-induced changes in distribution of marine fishes and invertebrates, p. 5-50. In: Cheung, W.W.L, Lam, V.W.Y., Pauly, D. (eds.) Modelling Present and Climate-shifted Distribution of Marine Fishes and Invertebrates. Fisheries Centre Research Report 16(3). Fisheries Centre, University of British Columbia [ISSN 1198-6727].