The Transparent Goby, Aphia MinutaReview of Biology and Fisheries of a Paedomorphic European Fish

The transparent goby, Aphia minuta, is one of the few pelagic species of the family Gobiidae. Its geographic range covers the eastern Atlantic Ocean, from Gibraltar to Norway and the Mediterranean basin including the Azov and Black seas. However, it does not occur along the north African coasts. The species is characterized by a unique larval morphology and precocious sexual maturation, i.e. a type of heterochrony known as progenesis. The transparent goby is an annual species that lives less than 1 year, with a maximum size of less than 60 mm. The breeding season is quite long and spawning takes place at least twice during its short lifespan. Just after spawning, all breeders quickly die probably as a consequence of the degeneration of the intestinal epithelium by apoptosis, marking the end of the entire cohort. Spending most of its life in the water column, it is a planktotrophic feeder, relying mainly on small copepods. In turn the transparent goby is preyed on by several species of fish and larger cephalopods. During ontogenesis, t hree phases characterize the species: a “pelagic phase”, composed of larval stages hatched from demersal eggs that inhabit shallow coastal waters; an “aggregated phase”, composed of juveniles that gather in schools in shallow waters during winter; finally, a “demersal phase”, composed of adults that in spring migrate offshore with a more dispersed distribution in proximity of the bottom. Despite its small size, this species is largely exploited by local small-scale fisheries developed mainly in the western and central Mediterranean. The fishing fleets, harboured in several sites in Spain and Italy, are generally composed of small vessels. Most of them use very selective gear such as purse-seine nets to catch schools of the transparent goby during winter. For these artisanal fisheries, the transparent goby represents, although seasonally, a very important source of income, yielding locally up to more than 100 tons per fishing season and 75 kg/vessel/day. This review critically examines the published literature on the biology and fisheries of the transparent goby, aiming to provide useful tools for appropriate management and for a sustainable exploitation of this important resource.