Sea temperature rise over the period 2002-2020 in Pelorus Sound, New Zealand - with possible implications for the aquaculture industry

• Published in: New Zealand journal of marine and freshwater research 2021-01, Vol.55 (1), p.46-64
• Main Authors: Broekhuizen, Niall, Plew, David R., Pinkerton, Matt. H., Gall, Mark. G.
• Format: Article
• Language: English
• Subjects: Air temperature; Aquaculture; climate change; coastal sea warming; Effect of temperature on; Fishes; Forecasting; Freshwater fishes; mussel aquaculture; Ocean temperature; Oncorhynchus tshawytscha; Pelorus Sound; Physiological effect; Salmon; salmon farming; Satellites; Sea surface temperature; Slopes; Spring; Spring (season); Temperature; Temperature data; Time series; Water depth; Water temperature
• ISSN: 0028-8330; 1175-8805; 1175-8805
• DOI: 10.1080/00288330.2020.1868539

We assembled water-temperature data (1.0-15 m depth horizon) from several field studies (spanning 2003-2020) within Pelorus Sound to generate composite time-series of temperature at four locations. We also examined satellite-sensed sea-surface temperature records for the region (2002-2019). Time-series were deseasoned and Sen-slopes were calculated as measures of long-term trend. All of the in-situ slopes and most of the satellite slopes fell inside the range 0.2-0.4°C decade −1 . Within the in-situ data, warming appears to have been less rapid during the spring (September-November) quarter than in others. In the satellite data, warming was slower during both the winter and spring quarters. The satellite data indicate that warming has been less rapid inside the Sound than the nearby oceanic waters. Air temperatures inside the Sound have warmed at a rate similar to the nearby water (and a lesser rate than the oceanic ones) and riverine heat inputs have not changed appreciably. We infer that warming has been driven mainly by import of warming oceanic waters. We discuss the implications of future warming for the two marine crops grown in Pelorus Sound (Chinook salmon and Greenshell™ mussel) drawing upon literature concerning their responses to temperature.