Have scientists have changed the name of the Lesser-spotted dogfish to Small-spotted catshark?

The world of animal and plant taxonomy is a tumultuous one, in a nigh-constant state of flux as new discoveries and improvements in genetic techniques change our understanding of how species are related. In recent years I have a number of times come across comments, often on the BBC’s Springwatch programme, that scientists have changed the name of a very familiar member of Britain’s shark fauna, the lesser spotted dogfish (Scyliorhinus canicula). Such statements are typically followed by a stir on their Facebook page. In short, however, no - scientists haven’t changed anything.

When early naturalists such as Carl von Linné (aka Linnaeus) started classifying animals in the eighteenth century, they began by clumping similar species together in big groups. In these early days, almost all sharks, from dogfish to great white sharks, were grouped together in the Squalus genus, squalus being the Latin word for shark.

When this shark was first described, in 1825, it was put with all the other sharks in the Squalus genus. In the early 1900s, however, when biologists realised that Squalus needed sorting, this species, along with several others, was moved into the Scyliorhinus (catshark) genus.

Line drawings of the Small-spotted catshark (Scyliorhinus canicula), often called the "Lesser spotted dogfish", and the Spiny dogfish (Squalus acanthias), a true member of the dogfish family (Squalidae). Notice how the shape of the head and position of the fins are different for the dogfish and catsharks. In catsharks (Scyliorhinidae family) the dorsal (back) fins are shifted towards the rear, the caudal fin (tail) prostrate and there are three sets of ventral (belly) fins: from front to back, pectoral, pelvic and anal. In dogfish, the dorsal fins are spaced more widely, the caudal fin more erect and there are only two sets of ventral fins: pectoral and pelvic. There are various other anatomical features that separate the families, including tooth and dermal denticle (scale) shape, but the external appearance provides the simplest guide. - Credit: Food & Agriculture Organization of the UN (Fisheries & Aquaculture Department)

The first major attempt to comprehensively classify all the sharks known to science happened in 1984, when South African ichthyologist (fish scientist) Leonard Compagno published the first of his two-volume tome Sharks of the World. Compagno reserved the Squalus genus for the dogfish and agreed with the early naturalists that Scyliorhinus canicula indeed was a catshark, based on their tooth arrangement and body anatomy, particularly the shape of the tail and the position of their fins. Hence, Compagno endorsed the idea that it was incorrect to call a member of the catshark family a lesser-spotted dogfish.

The issue comes, however, because fishermen had the understandable habit of referring to any common/abundant sharks as “dogfish”, regardless of their actual classification, and that name stuck in many circles. Consequently, people got used to calling them dogfish, even though technically this shark has been considered a catshark for at least the last 100 years. The recent pushing of the correct vernacular name of small-spotted catshark appears to be an attempt to correct this historical ‘dogma’. After all, to quote Confucius:

The beginning of wisdom is to call things by their proper name.”