March 21st – The last couple of days have seen sharks afoot – though I can’t say that the encounter ended well for the sharks:
“A large shark followed the ship, & was first struck by a harpoon; after this he was hooked by a bait & again being struck broke the hook & escaped. — Such an adventure creates great interest all over the whole ship.” (Mar 20)
“The greatest event of the day has been catching a fine young shark with my own hooks: It certainly does not require much skill to catch them, yet this no way diminishes the interest. — In this case the hook was bigger than the palm of the hand & the bait only a bit of salted pork just sufficient to cover the point. Sharks when they seize their prey turn on their backs; no sooner was the hook astern, than we saw the silvery belly of the fish & in a few moments we hauled him on deck. ” (Mar 21)
Sharks, along with rays and skates, belong to the class Chondrichthyes (these fish all have a skeleton made of cartilage, rather than bones like the much more common group of “bony fish”, the Osteichthyes. There are more than 440 species of sharks living today. Unfortunately, with over 88 species in Brazilian waters, it is impossible to tell what species Darwin encountered. (The only sharks listed in his Zoological Notebook are dogfish (Squalus) – so it is possible it is was some type of dogfish.)
Spiny Dogfish – possibly similar to what Darwin caught? (from SharkCentral.blogspot.com)
As a geologist, one of the things I have to point out about sharks is that as a group of organisms they have been around for a long time – I mean a really long time. The oldest shark fossil – currently identified as Doliodus problematicus is over 410 million years old. Since that time the individual species have changed, but sharks as a whole have survived – living through the Permian extinction which is estimated to have whipped out over 90% of marine life on Earth! Some of these species were quite unusual, such as the Helicoprion shark that lived about 250 million years ago and had a “buzz saw”-like round of teeth in its lower jaw (from Wikipedia Commons)
The sad truth about sharks is that after making it for 400 million years, they are not doing so well today. Of the 440+ species, 201 are currently listed on the IUCN “Red List” of endangered and threatened species. This ratio is similar in Brazil where Sea Sheppard reports that 43% of Brazilian shark species are endangered. The major threat to sharks comes from overfishing, and of that, much if it is for harvesting shark fins. (This cruel process requires the “fisherman” to cut the fin off the living shark, after which they throw the shark back into the sea to die.) The primary market for these fins is the affluent delicacy “shark fin soup”. It has been estimated that over 100 million sharks are killed to feed the “soup” market each year.
It is depressing to think that one of the oldest groups of organisms on the Earth – a species that have survived the greatest mass extinction in Earth’s history (plus three other “smaller” mass extinctions) – is shuffling off into oblivion in the name of soup. It is times like these that I feel like we, as a species, have lost our perspective. Darwin killed his fair share of animals in his day, but I suspect he too would be disappointed in us. (RJV)