DTAG studies of blue whales (Balaenoptera musculus) in the Gulf of Corcovado, Chile

Abstract

A joint effort between WHOI and the Melimoyu Ecosystem Research Institute (MERI) sought to gain a better understanding of a population of blue whales (Balaenoptera musculus) in the Gulf of Corcovado, Chile. A cruise in March 2014 resulted in the deployment of 5 DTAGs, which are miniature sound and orientation recording tags that are attached via suction cups. A total of five tag deployments on four individual whales were achieved, totaling 21 hr 11 min. Dives were predominantly between 10 and 50 m in depth, with a maximum of 139 m. Sloughed skin found on the suction cups of recovered tags and fecal samples were preserved to be used for genetic, dietary and pollutant analyses. Acoustic data on the tags revealed numerous calls from distant blue whales, and an apparent call exchange was recorded between a tagged juvenile whale and a distant animal. Photo-identification images and acoustic recordings of all marine mammal species encountered were obtained whenever possible; these included humpback whales (Megaptera novaeangliae), Peale's dolphins (Lagenorhynchus australis), Chilean dolphins (Cephalorhynchus eutropia), and bottlenose dolphins (Tursiops truncatus). Continuation of this collaboration has great potential to provide information to policy makers regarding how to protect the unique habitats in this region.

Characterizing Chilean blue whale vocalizations with DTAGs: a test of using tag accelerometers for caller identification

“…A number of previous research efforts in this important feeding ground for Chilean blue whales have focused on their ecology (Branch et al, 2007a;Williams et al, 2011), genetics (LeDuc et al, 2007, acoustic behavior (Buchan et al, 2014(Buchan et al, , 2015, and potential for anthropogenic impacts (Colpaert et al, 2016). We used noninvasive digital acoustic recording tags (DTAGs; Johnson and Tyack, 2003) outfitted with hydrophones, accelerometers, magnetometers and depth sensors to study communication and diving behavior of individual whales (Bocconcelli et al, 2016).…”

“…DTAGs were attached to the dorsal regions of blue whales using an 8 m carbon fiber pole and were held on with four suction cups (Johnson and Tyack, 2003;Bocconcelli et al, 2016). DTAGs were programmed to release after periods of up to 24 h. Tags were equipped with very high frequency (VHF) transmitters to track the whales during deployments and to retrieve the tag post-release.…”

Diel differences in blue whale (Balaenoptera musculus) dive behavior increase nighttime risk of ship strikes in northern Chilean Patagonia

“…to monitor the status of blue whales in northern Chilean Patagonia, increasing knowledge of their ecology (Branch et al 2007;Williams et al 2011), genetics (LeDuc et al 2007, morphology (Durban et al 2016), acoustic behavior (Buchan et al 2010(Buchan et al , 2014Bocconcelli et al 2016;Saddler et al 2017), and potential anthropogenic noise impacts (Colpaert et al 2016).…”

“… 2010 , 2014 ; Bocconcelli et al . 2016 ; Saddler et al . 2017 ), and potential anthropogenic noise impacts (Colpaert et al .…”

Detection of blue whale vocalisations using a temporal-domain convolutional neural network

“…Our case study focuses on the Chilean blue whales from the Chiloé-Corcovado region, Chile [4], [5]. This area is a relevant feeding ground that hosts approximately 300 blue whales, a relatively large population discovered in 1993 which has been the subject of a number of researchers lately.…”