Original provider: Blue Whale Study Inc. Dataset credits: Blue Whale Study Inc. Abstract: Wind-forced cold water upwelling occurs seasonally along the continental shelf of south-east Australia, where pygmy blue whales aggregate to forage. Seasonality and variability are apparent for both blue whale encounter rates and upwelling, within and between seasons. Here we quantify upwelling variability over 11 seasons (2001/02 to 2011/12) and relate it to blue whale encounter rates. Two indices, cumulative wind stress (Intensity) quantifying physical forcing, and surface chlorophyll-a (chl-a) quantifying the ocean’s biological response, revealed variability in upwelling at a variety of temporal scales. Within seasons, upwelling Intensity peaked during February, and chl-a during February–March. Blue whale encounter rate from 52 aerial surveys was modelled against upwelling indices and the climate signal SAM (Southern Annular Mode), at individual survey- and aggregated season-levels, using General Additive Models (GAMs). Survey-level GAMs showed that encounter rate increased with increasing chl-a, and with increasing upwelling Intensity to a point beyond which further increases in Intensity resulted in declining encounter rates. This indicated the importance of productivity, as well as relaxation of upwelling, in producing optimal blue whale foraging conditions. In exploratory season-level models, a strong influence of SAM was apparent, with higher encounter rates associated with positive SAM during the preceding 12 months. Including chl-a improved the model, indicating that both broad-scale climatic signals inherently incorporating environmental variability and uncertainty, as well as more proximal regional factors may influence blue whale occurrence in the study area. Measuring the complex relationships between whale occurrence and upwelling is complicated by the fact that the population of blue whales using the Bonney Upwelling is open, and moves between alternate foraging areas. The findings were interpreted in the context of blue whale foraging ecology in this system. Purpose: Relate variability in blue whale relative abundance to variability in upwelling off southern Australia
The data in this occurrence resource has been published as a Darwin Core Archive (DwC-A), which is a standardized format for sharing biodiversity data as a set of one or more data tables. The core data table contains 87 records.
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How to cite
Researchers should cite this work as follows:
Gill, P. 2015. Blue Whale Study aerial surveys, southern Australia, 2007-2012. Data downloaded from OBIS-SEAMAP (http://seamap.env.duke.edu/dataset/1281) on yyyy-mm-dd.
Researchers should respect the following rights statement:
The publisher and rights holder of this work is OBIS-SEAMAP. This work is licensed under a Creative Commons Attribution (CC-BY 4.0) License.
This resource has been registered with GBIF, and assigned the following GBIF UUID: 424d81c1-d67a-4791-8a89-f445b9569abe. OBIS-SEAMAP publishes this resource, and is itself registered in GBIF as a data publisher endorsed by Ocean Biodiversity Information System.
Occurrence,Marine Animal Survey,Marine Biology,Marine mammals,Visual Sighting,Aircraft; Observation; Occurrence
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|Bounding Coordinates||South West [-39.41, 139.52], North East [-37.531, 143.364]|
Scientific names are based on the Integrated Taxonomic Information System (ITIS).
|Subspecies||Balaenoptera musculus brevicauda (Pygmy blue whale)|
|Start Date / End Date||2007-11-09 / 2012-03-28|
No Description available
|Title||Blue Whale Study aerial surveys, southern Australia, 2007-2012|
The personnel involved in the project:
Method step description:
|Parent Collection Identifier||OBIS-SEAMAP|
marine, harvested by iOBIS
|Purpose||Relate variability in blue whale relative abundance to variability in upwelling off southern Australia|