DataSheet_1_Vocalizing humpback whales (Megaptera novaeangliae) migrating from Antarctic feeding grounds arrive earlier and earlier in the Perth Canyon, Western Australia.docx

Migratory species undertake seasonal, long-distance travel between feeding and breeding grounds, and time their arrivals with high-quality resources. The Breeding Stock D population of humpback whales (Megaptera novaeangliae) migrates from Antarctic to Western Australian waters every austral winter. Based on 16 years (2002-2017) of passive acoustic recordings in the Perth Canyon, Western Australia, the hourly presence/absence of humpback whale vocalizations was used as an indicator of inter-annual changes in migration timing. A trend of earlier arrivals in the Perth Canyon by 1.4 days/year during the northward migration and possibly earlier departures from the Perth Canyon during the southward migration was observed. A distance-based linear model and a generalized linear model (GLM) both identified sea surface temperature (SST) as the most significant predictor for acoustic presence in the Perth Canyon. A 1 °C increase in SST corresponded to a decrease in humpback whale acoustic presence by 4.4 hours/day. Mean SST at the peak of the humpback whale season in the Perth Canyon was 19 °C. Exploratory analysis of the metocean environment of the Antarctic feeding grounds suggested that whales were leaving the Antarctic at the end of the austral summer, as sea ice concentration (SIC) increased and SST decreased. Further research should investigate whether changes in the metocean conditions on Australian breeding grounds correspond to changing departures from the Perth Canyon during the southward migration. If environmental conditions on breeding and feeding grounds change out-of-sync, migrating whales might be unable to arrive at either ground during optimal conditions.

洄游物种会在觅食地与繁殖地之间开展季节性长距离迁徙，并会将抵达时间与优质资源的可获取时段相匹配。座头鲸（Megaptera novaeangliae）的D繁殖种群每至南半球冬季，便会从南极海域迁徙至西澳大利亚水域。本研究基于2002至2017年共16年在西澳大利亚珀斯峡谷获取的被动声学监测数据，以座头鲸鸣唱信号每小时的出现或缺失情况作为迁徙时间年际变化的指示指标。研究观测到，北迁过程中座头鲸抵达珀斯峡谷的时间呈现出每年提前1.4天的趋势，且其从珀斯峡谷南迁的时间可能也有所提前。基于距离的线性模型与广义线性模型（Generalized Linear Model, GLM）均显示，海表温度（Sea Surface Temperature, SST）是影响座头鲸在珀斯峡谷声学信号出现情况的最显著预测因子。海表温度每升高1℃，座头鲸的声学信号日出现时长会减少4.4小时。珀斯峡谷座头鲸活动高峰期的平均海表温度为19℃。对南极觅食地海洋气象环境的探索性分析显示，随着海冰浓度（Sea Ice Concentration, SIC）升高与海表温度下降，座头鲸会在南半球夏季末离开南极海域。后续研究应探究澳大利亚繁殖地的海洋气象环境变化是否与座头鲸从珀斯峡谷南迁的出发时间变化存在关联。若繁殖地与觅食地的环境变化不同步，迁徙中的座头鲸可能无法在最优环境条件下抵达任一栖息地。