Estuarine use and movement patterns of seven sympatric Mugilidae fishes: The Tatu Creek estuary, central western Taiwan

By combining the spatio-temporal distribution of fish abundance and their size structure, and a detailed lifetime Sr/Ca ratio analysis in their otoliths, this study delineates the estuarine use and the movement patterns of seven sympatrical occurring adult mullets in the Tatu Creek estuary, central western Taiwan. In the estuary Mugil cephalus are the most dominant species, whereas Liza subviridis, Liza macrolepis and Liza haematocheilus are common, and Liza affinis, Liza dussumieri and Valamugil seheli are rare. They have adapted a size-related salinity preference. A mean Sr/Ca ratio of (7.5–10.2) × 10−3 in the otolith cores demonstrated that all seven mullet species spawned in the sea. After recruiting to the estuary (mean ratios of (3.6–6.4) × 10−3 at the estuarine check in the otoliths), the ratios fluctuate between (0.1–3.5) × 10−3 and (9.5–19.5) × 10−3 indicating that the mullet shared a common movement between marine and brackish waters and probably even freshwater habitats. However, the profiles fluctuated substantially among individuals. There was high intra-specific variation among M. cephalus and L. subviridis, intermediate intra-specific variation among L. macrolepis and L. affinis, and relatively little among L. haematocheilus, L. dussumieri and V. seheli. Persistent residency in high or low saline environments was found to vary among species, and the extent of their catadromy is discussed.