Association of Environmental Factors in the Taiwan Strait with Distributions and Habitat Characteristics of Three Swimming Crabs

Abstract

Information regarding the oceanic environment is crucial for determining species distributions and their habitat preferences. However, in studies on crustaceans, especially swimming crabs, such information remains poorly utilized, and its effects on crab communities in the Taiwan Strait (TS) has not been well documented. The purpose of this study was to understand the relationship between the catch rates of three swimming crab species and environmental factors in the TS. We fitted generalized additive models (GAMs) to logbooks and voyage data recorder data from Taiwanese crab vessels (2011-2015), developed a species distribution model, and predicted catch rates for these three swimming crab species based on the GAM output. The chlorophyll-a(Chl-a) concentration was related to the high catch rates ofChrybdis feriatusandPortunus sanguinolentus, whereas bottom temperature (BT) was related to high catch rates ofPortunus pelagicus. The variance percentages for each crab species indicated that high catch rates ofC. feriatusandP. sanguinolentusoccurred in a Chl-aconcentration > 0.5 mg/m(3), whereasP. pelagicuscatch rates exhibited negative correlations with BTs > 25 degrees C. The model predicted high catch rates ofC. feriatusin the north of the TS during autumn and winter, whereasP. pelagicuswas observed to the south during summer and autumn.P. sanguinolentuswas predicted to be widely distributed around the TS and distributed further to the northern area during autumn and winter. These findings revealed that each species responds to spatiotemporal environmental variations. Understanding the distributions and habitats of these three crabs is vital in fisheries resource management and conservation planning.