Did you know that there is a shark that has got a spine in front of each of his two dorsal fins secreting a mild venom? This is the spiny dogfish, also called cape shark or spurdog. It is a bottom-dweller with breath holes behind its eyes. These are used to actively breathe while lying in the sand – without breathing in and coughing up sand by breathing through the mouth and without the need to swim constantly.
Spiny dogfishes mature at around 11 years of age -male- or 18–21 years -female-, growing up to 100 cm (3.3 ft) -male- or 159 cm ( 5.22 ft) – female- in length and 10 kilogram in weight. After internal fertilization, the eggs are surrounded by thin shells called “candles”, the young hatch, being still in the mother’s body. The gestation period lasts up to 2 years (the probably longest gestation period in the animal kingdom), at the end the female bears normally 6 or 7 live young. This shark is known to live 100 years and more and was to be found in shallow waters and further offshore (normally in 50 to 150 m) in really giant shoals all around the world, segregated by size and sex.
Sadly, that is not true anymore. Human are well on their way to eradicate the once most abundant shark species in the world. They are on the IUCN Red List of threatened species as critically endangered in the Northeast Atlantic, endangered in the Northwest Atlantic and Mediterranean and vulnerable worldwide.
Despite having a toxic amount of methyl mercury in their bodies and their meat, resulting in allowable daily portions of spiny dogfish meat of 10 g – for an adult of 70 kg, the spiny dogfish or rather its parts Schiller’s curl and sea eel are a well known and popular food fish in Germany, as well as in Belgium and France (under the name small salmon – saumonette). In Great Britain it is (under the name Rock Salmon) an important part of the classic fish and chips dish. It is also used as fertilizer, pet food and dissection specimen in high schools and universities and its fins needles for cheap shark fin soup and cartilage or liver oil for medicinal purposes.
Since 2011, targeted fishing of spiny dogfish has been prohibited in EU waters. After protests of fisherman, accusing the spiny dogfish of depleting their Northwest Atlantic fisheries (despite, proven by longtime stomach analysis, most groundfish like cod or haddock are not common in their diets), the US opened up the fishery of spiny dogfish again to meet European demand, claiming the rebuilt status of the spiny dogfish stock in the Northwest Atlantic in 2010.