The Elasmobranch Husbandry Manual

This is here partly for NaNo use, and partly because I just want to know:  how fragile are spiny dogfish (Squalus acanthias)?  There was one particular individual we caught while conducting mark-and-recapture trawling for English sole in … 1992?  1993?  It was surrounded by the net and other fish.  I was removing it to let it go.  It was twisting its tail and wagging its head.  I felt its muscles tear under the skin and have wondered about it ever since; I just want to know, you know?