Speckled smooth-hound seabed on the continental shelf at depths of between . Reports of this fish occurring in the Atlantic Ocean off the coast of Argentina are thought to be erroneous, and are likely to refer to the narrownose smooth-hound ("Mustelus schmitti"), another shark that is speckled with white spots. The speckled smooth-hound is ovoviviparous with eggs that develop within the female and hatch into juvenile fish which are about at birth. Litter sizes are typically seven. Along with the humpback smooth-hound ("Mustelus whitneyi") and the spotted houndshark ("Triakis maculata"), this fish is known to local fisheries as "tollo" and is caught
Slender smooth-hound pups, one per uterus. The International Union for Conservation of Nature (IUCN) has assessed the slender smooth-hound as Least Concern; it is taken as fishery bycatch but not in great numbers, and furthermore large portions of its range see minimal fishing activity. The first known specimen of the slender smooth-hound was a long adult male collected by the trawler "Maimai" in December 1953, at a depth of off Cape Palliser on New Zealand's North Island. It was preserved by the crew as a curiosity and given to ichthyologist Jack Garrick, who described it in a 1954 issue of the scientific