Cetacean biodiversity, spatial and temporal trends based on stranding records (1920-2016), Victoria, Australia

Cetacean stranding records can provide vital information on species richness and diversity through space and time. Here we collate stranding records from Victoria, Australia and assess them for temporal, spatial and demographic trends. Between 1920 and 2016, 424 stranding events involving 907 individuals were recorded across 31 Cetacea species from seven families, including five new species records for the state. Seven of these events were mass strandings, and six mother and calf strandings were recorded. Importantly, 48% of the species recorded are recognised as data deficient on the IUCN Red List. The most commonly recorded taxa were Tursiops spp. (n = 146) and Delphinus delphis (common dolphins, n = 81), with the greatest taxonomic richness (n = 24) and highest incidence of stranding events documented within the Otways mesoscale bioregion. We found no seasonal stranding patterns anywhere in the state. While our findings improve understanding of the spatial and temporal patterns of cetacean diversity within Victoria, we suggest greater effort to collect demographic data at stranding events in order to better study state-wide patterns through time. We conclude with guidelines for minimum data collection standards for future strandings to maximise information capture from each event.鲸类搁浅记录可为揭示物种丰富度与多样性的时空分布特征提供关键科学依据。本研究汇编了澳大利亚维多利亚州的鲸类搁浅记录，并对其时间、空间及种群动态趋势展开系统性评估。1920年至2016年间，研究团队共记录到7个科下31种鲸目动物的搁浅事件共424起，涉及个体907头，其中包含该州此前未被记载的5个鲸类物种新记录。本次记录中7起为大规模搁浅事件，另有6起为母仔共同搁浅案例。值得注意的是，本次收录的物种中有48%在《世界自然保护联盟濒危物种红色名录》（IUCN Red List）中被列为数据缺乏（data deficient）等级。本次记录中最常见的分类群为宽吻海豚属（Tursiops spp.，n=146）与真海豚（Delphinus delphis，普通海豚，n=81）；奥特威中尺度生物地理区（Otways mesoscale bioregion）的鲸类分类丰富度最高（n=24），且搁浅事件发生频次亦居全州之首。研究未在维多利亚州全域范围内发现显著的季节性搁浅规律。尽管本研究结果提升了学界对维多利亚州鲸类多样性时空分布格局的认知水平，但我们建议未来应加大搁浅事件的种群数据收集力度，以更好地解析全州范围内鲸类多样性的长期动态趋势。最后，本研究提出未来鲸类搁浅事件的最低数据收集标准指南，以期从每一起搁浅事件中最大化获取有效科研信息。