A New Species of Late Early Miocene Cetorhinus (Lamniformes; Cetorhinidae) from the Astoria Formation of Oregon, and coeval Cetorhinus from Washington and California

Welton, Bruce J.

doi:10.5962/p.241294

Cited by 5 publications

(1 citation statement)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Given the intense historic climate changes that have occurred in the 100 million years since Cetorhinidae split from Lamnidae (Sorenson et al, 2014), it is perhaps reasonable to assume the species will weather coming changes. However, the extinction of Cetorhinus piersoni, C. huddlestoni, and Keasius parvus during the late Oligocene to middle Miocene during climatic cooling are evidence that climatic transitions have impacted Cetorhinidae before and may do so again (Hovestadt and Hovestadt-Euler, 2012;Welton, 2015).…”

Section: Discussionmentioning

confidence: 99%

Highly variable basking shark (Cetorhinus maximus) diving behavior in the lower Bay of Fundy, Canada

Siders

Westgate²,

Bell³

et al. 2022

Front. Mar. Sci.

View full text Add to dashboard Cite

Diving behavior in basking sharks, the largest obligate ram filter feeding planktivore, is highly dependent on their location. In the Bay of Fundy, where basking sharks congregate in the boreal summer and autumn, the sharks’ copepod prey are located deep in the water column, below 100 m, in dense but scattered patches. We used time-depth recorders to examine how the vertical movements of basking sharks adapt to such a prey field and captured 4,138 hours of diving behavior from 42 sharks in the boreal summer from 2008 to 2020. Using finite mixture models, we split the time series into surface and subsurface movement blocks and used dynamic time-warping to cluster subsurface movements into seven modes based on their shapes and lengths, with mostly V-shaped subsurface movements (85%) and a minority that were U-shaped (14%). Across sharks, five overall strategies of vertical movement behavior were identified. The strategies split broadly by the ratio of V-shaped movements to U-shaped movements in a deployment and whether the majority of subsurface movements were above or below 100 m. A majority of basking sharks (64%) were reverse diel vertical migrators but none altered their time-allocation across tidal periods. During more thermal stratification, sharks dove deeper, longer, and less frequently while during less thermal stratification sharks dove shallower, shorter, and more frequently. Overall, we show that basking sharks exhibit considerable inter- and intra-individual variability in their diving behavior, and therefore presumably also in foraging modes. Some of this variability relates to time of year and tidal phase, unsurprising in this highly tidally-driven system; however, the majority of the variability remains unexplained without more information on the distribution, composition, and abundance of the copepod prey field. The technique presented is extendable to other species and, unlike many dive classification techniques, requires few subjective delineations of diving behavior.

show abstract

Section: Discussionmentioning

confidence: 99%