[MARMAM] Cetacean blubber/ muscle shearing in context of intramuscular tags - new paper

Michael Moore mmoore at whoi.edu
Thu Oct 19 09:24:18 PDT 2017


Colleagues - There is a new paper in JEB at: 
http://jeb.biologists.org/content/220/20/3717

Moore MJ, Zerbini AN (2017) Dolphin blubber/axial muscle shear: 
implications for rigid transdermal intramuscular tracking tag trauma in 
whales. The Journal of Experimental Biology 220:3717-3723

Abstract
Whale tracking tags often penetrate semi-rigid blubber, with 
intramuscular sharp tips and toggling barbs under the subdermal sheath 
to reduce premature shedding. Tag sites can show persistent regional 
swellings or depressions. Fibroelastic blubber grips a tag, so if muscle 
shears relative to blubber during locomotion, the tag tip could cavitate 
the muscle within overall shearing distance. We modeled shearing of 
blubber relative to muscle, within the dorsal-ventral peduncular 
movement range of four common dolphin (/Delphinus delphis/) cadavers 
(mean length 186 cm). The net change in angle and hence tip distance 
moved was calculated with dorsal and ventral flexion, and compared 
between 1.5 mm diameter needles inserted into blubber only and through 
blubber into muscle. The greatest shearing value was 3.6 cm, and 
shearing was most pronounced in the areas ventral and caudal to the 
dorsal fin. Scaled dummy tags were also inserted and the animal 
cyclically flexed dorsally and ventrally for 18 h. Tag sites were 
dissected and cavities around the tag tips documented. If this shearing 
is comparable in large whales, depressions and regional swellings 
observed with intramuscular tracking tags are likely the result of 
tissue loss and repair, respectively. Placing tags para-sagittally 
anterior to the dorsal fin would cause the least trauma, but pain from 
such tags remains a concern.

Michael Moore
mmoore at whoi.edu
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