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A Dutch beam trawler caught an unusual black dogfish whilst operating in German waters but was it a dogfish or another species?
A Dutch trawler caught an unusual carbon black dogfish whilst operating in German waters recently.
The surprise catch was boarded by the beam trawler Meijert Smid N-350 and the crew of the boat were curious as to how the dogfish got its colour.
EMK Vissers tweeted “Does anyone have any idea what could be the cause of this discolouration?”
“We have never seen an almost completely black dogfish before,” said the skipper of Meijert Smid (N-350).
And in case anyone is concerned with what happened to the dogfish the skipper replied, “The shark was very much alive and went straight back into the sea after the photo.”
So, what made the dogfish black?
Well, according to Ecomare, a Dutch nature museum and seal sanctuary the dogfish isn’t a dogfish. It is a catshark but it’s not that long ago when this species was better known as the lesser-spotted-dogfish until it was recategorised.
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“A message from the biologists of Ecomare: it is a young catshark. The anal fin ends at the center of the second dorsal fin. In the dogfish, the anal fin ends before the start of the second dorsal fin. The cause of the colour remains partly melanism.
“This appears to be a case of partial melanism. Melanism occasionally occurs in all kinds of animals, apparently also in dogfish. It is a genetic disorder in which the animal produces too much of the pigment melanin.”
The catshark is commonly referred to as a dogfish but there are differences.
Catsharks are ground sharks of the family Scyliorhinidae are more closely related to the Great White Shark. Dogfish, also known as spurdogs, are of the species Squalidae.
Black coloured dogfish are widespread in temperate Atlantic. Eastern Atlantic from Greenland and Norway, along the Atlantic Slope, to Sierra Leone, and Namibia to South Africa, Western Atlantic from Greenland to northern Gulf of Mexico but are not usually found in the North Sea.