Dusky smooth-hound time to induce tonic immobility in smooth dogfish was 32.5 seconds. The mean duration of the tonic immobility was 61.9 seconds. Sharks that had the “limp” response also exhibited tonic immobility. The “limp” response is a criterion for the onset of tonic immobility. Dusky smooth-hound The dusky smooth-hound ("Mustelus canis"), also called the smooth dogfish or the dog shark, is a species of houndshark in the family Triakidae. This shark is an olive grey or brown in color, and may have shades of yellow or grayish white. Females live to 16 years and males have a lifespan of 10 years.
Humpback smooth-hound the three species it is the humpback smooth-hound that is the main target of the tollo fishery in Peru. Landings averaging 11,000 tons of tollo per year were made in that country between 1965 and 1989, but quantities caught diminished thereafter. A minimum size requirement of was set in 2001 but was pitched so low as to have limited conservation effect. The International Union for Conservation of Nature (IUCN) has rated the status of the humpback smooth-hound as being "vulnerable" and considers more should be done to publicise and enforce the size limit. Humpback smooth-hound The humpback smooth-hound ("Mustelus whitneyi")