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Tseng, C-T., Su, N-J., Sun, C-L., Punt, A. E., Yeh, S-Z., Liu, D-C., and Su, W-C. 2013. Spatial and temporal variability of the Pacific saury (Cololabis saira) distribution in the northwestern Pacific Ocean. – ICES Journal of Marine Science, 70: 991–999.Logbook data for the Taiwanese Pacific saury fishery and multi-sensor satellite images for 2006–2010 were used to characterize the habitat of Pacific saury (Cololabis saira) in the northwestern Pacific (NWP). An empirical cumulative distribution function (ECDF) approach identified that high cpue (catch per unit of effort) of Pacific saury occurred when sea surface temperature (SST) ranged from 14 to 16°C, chlorophyll-a concentration (Chl a) ranged from 0.4 to 0.6 mg m−3, and net primary production (NPP) ranged from 600 to 800 mg C m−2 d−1. A generalized additive model (GAM) and spatial non-stationary geographically weighted regression (GWR) were applied to predict the habitats of Pacific saury in the NWP. The spatial distributions of Pacific saury in the NWP estimated using the two approaches were similar and matched the nominal cpue distributions and those inferred from preferred habitat ranges based on ECDF. The density of Pacific saury is higher in coastal waters close to the island of Hokkaido and near the southern Kuril Islands than in the open sea. SST, Chl a, and NPP were substantially higher in the fishing grounds for Pacific saury during the main fishing season (September and October), corresponding to a high cpue for Pacific saury (23.1 t fishing day−1). The GAM explained more variability in spatial distribution (35.7%) than GWR (20.5%) VGPM (Vertically Generalized Production Model). Results derived from this study could improve our understanding of Pacific saury habitat distributions, which could be used to forecast fishing grounds and to develop fishery management advice based on oceanographic conditions that might be impacted by climate change. [ABSTRACT FROM PUBLISHER]

Su, N.-J., Sun, C.-L., Punt, A. E., Yeh, S.-Z., DiNardo, G., and Chang, Y.-J. 2013. An ensemble analysis to predict future habitats of striped marlin (Kajikia audax) in the North Pacific Ocean. – ICES Journal of Marine Science, 70: 1013–1022.Striped marlin is a highly migratory species distributed throughout the North Pacific Ocean, which shows considerable variation in spatial distribution as a consequence of habitat preference. This species may therefore shift its range in response to future changes in the marine environment driven by climate change. It is important to understand the factors determining the distribution of striped marlin and the influence of climate change on these factors, to develop effective fisheries management policies given the economic importance of the species and the impact of fishing. We examined the spatial patterns and habitat preferences of striped marlin using generalized additive models fitted to data from longline fisheries. Future distributions were predicted using an ensemble analysis, which represents the uncertainty due to several global climate models and greenhouse gas emission scenarios. The increase in water temperature driven by climate change is predicted to lead to a northward displacement of striped marlin in the North Pacific Ocean. Use of a simple predictor of water temperature to describe future distribution, as in several previous studies, may not be robust, which emphasizes that variables other than sea surface temperatures from bioclimatic models are needed to understand future changes in the distribution of large pelagic species. [ABSTRACT FROM PUBLISHER]

Chang, Y.-J., Sun, C.-L., Chen, Y., Yeh, S.-Z., DiNardo, G., and Su, N.-J. 2013. Modelling the impacts of environmental variation on the habitat suitability of swordfish, Xiphias gladius, in the equatorial Atlantic Ocean. – ICES Journal of Marine Science, 70: 1000–1012.We developed a habitat suitability index (HSI) model to identify the optimal habitats of swordfish (Xiphias gladius) in the equatorial Atlantic Ocean. Environmental variables, including sea surface temperature (SST), mixed layer depth (MLD), chlorophyll-a concentrations, and sea surface height anomaly, as well as catch and effort data from Taiwanese longline fisheries, were used. The geometric mean model including all the above environmental variables was identified as the most parsimonious model for yielding HSI predictions coinciding with productive fishing grounds with high fishing effort. Swordfish mainly aggregated in the northwest region during March–May and spread southeast thereafter in response to seasonal shifts in oceanographic conditions. There was annual variation in the distribution of habitat patches, and the habitat quality was reduced in the northwest region of the equatorial Atlantic Ocean during 2005. The apparent spatial shifts in optimal habitats might be linked to reduced MLD and elevation in sea surface height, which might be related to climate variability (e.g. Niño-Southern Oscillation and/or Northern Atlantic Oscillation). Because environmental data regarding climate change scenarios are becoming readily available, we can utilize the proposed HSI models to evaluate possible changes in habitat suitability resulting from climate change and provide scientific advice for the development of management regulations. [ABSTRACT FROM PUBLISHER]