Sturgeon survives, but not for long, it seems
The worry about that most ancient of bony fish, the sturgeon, is that all the species left are endangered in their natural habitats. Even in the wilds of Canada and Siberia, few habitats have remained the same, leaving this magnificent, large and long-lived animal approaching a total extinction. The most recent death-knell has sounded in the Yangzi. This unfortunate river is dammed, polluted and rapidly emptying of life. The Chinese are trying to conserve species, but the loss of the Baiji dolphin there looks likely to be followed by this 5m (16 feet) monster, as well as the finless porpoise.
The report this week from the Chinese Academy of Fisheries Sciences is full of hope for artificial breeding, but the up-to-100-year-old Acipenser sinensis (the Chinese sturgeon) breed only 3-4 times in their lives , start breeding late in life and have only 1% success in reaching merely a small size. No wild sturgeon reproduced in the Yangzi this year, for the first time in 32 years. The young are normally swimming seaward right now, but none have been seen. 100 older fish are possibly still left.
140 million years ago, bony fish developed the famous bony scutes of the sturgeons' outer defence, but kept a (secondary) cartilaginous skeleton. Sine ten, the Methuselah of the fish world almost eclipses the coelocanth in retaining these distinct characteristics. All genera have the classic migrations and bottom living habit, with the giant size and 4 barbels you can see in the photograph. To look at sturgeons as one of the most primitive bony fish we have alive, this paper examined how the sturgeon's and other heads developed, early in vertebrate evolution in Getting a Head.