Coastal estuaries provide essential juvenile habitat for many commercially and recreationally important fish, which may move between estuarine and coastal environments throughout their life. Identifying the most important estuarine nurseries that contribute to the broader stock can support targeted management of juvenile and spawning populations. The objective of this study was to (1) compare chemical fingerprints within sagittal otoliths of juvenile Mulloway (Argyrosomus japonicus) sampled from putative south-eastern Australian nurseries, (2) assess their potential as natural tags to distinguish nursery grounds for the broader coastal Mulloway stock and (3) assess the viability of otolith chemistry as a fisheries management tool when limited to opportunistic, fisheries-dependant, otolith sample collection from by-catch. Otoliths from juvenile Mulloway (0 to 3 years, 4 to 44.8 cm total length) were obtained from 8 major estuaries and 2 inshore ocean locations along coastal south-eastern New South Wales, Australia, from April 2015 to July 2018. Concentrations of Sr, Ba, Mg, Mn and Li in the otolith region corresponding to the juvenile nursery stage were determined using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The element to Ca ratios of fish from coastal estuaries differed significantly among collection areas, based upon multivariate elemental fingerprints, with some exceptions. When the otoliths of fish were analysed in a multinomial logistic regression (MLR) classifier, there was an overall mean allocation success of 59% to the estuary of capture. This study highlights the use of otolith ‘fingerprints’ as natural tags in Mulloway, and contributes to progressive research in environmental reconstruction applications of otolith chemistry.

沿海河口为许多具有商业意义和娱乐意义的重要鱼类提供了重要的幼体栖息地，这些鱼类可能在一生中会在河口和沿海环境之间移动。确定最重要的河口育苗场有助于扩大种群的存栏，可以有针对性地管理少年和产卵种群。这项研究的目的是（1）比较少年穆罗威（Argyrosomus japonicus）矢状耳石内的化学指纹）从假定的东南澳大利亚苗圃中取样，（2）评估其潜力，以区别大范围沿海Mulloway种群的苗圃地，（3）评估耳石化学作为渔业管理工具的可行性，但仅限于机会性渔业-从副渔获物获得的耳石样本。2015年4月至2018年7月，从澳大利亚新南威尔士州东南部沿海的8个主要河口和2个近海位置获得了幼稚Mulloway（总长0至3年，总长4至44.8 cm）的耳石。使用激光烧蚀-电感耦合等离子体质谱法（LA-ICP-MS）测定了与幼稚期相对应的耳石区域中Ba，Mg，Mn和Li的含量。基于多元元素指纹图谱，沿海河口鱼类的元素钙比在采集区域之间存在显着差异，但有一些例外。在多项式逻辑回归（MLR）分类器中分析鱼的耳石时，捕获河口的总体平均分配成功率为59％。这项研究强调了耳石的“指纹”作为Mulloway中的天然标签的用途，并为耳石化学在环境重建应用中的进步研究做出了贡献。