Sablefish Is The New Salmon; Whales Appreciate The Trend

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Sablefish, heart healthy and buttery in texture, rivals salmon as a top choice for diet-conscious diners. It is loaded with omega-3 fatty acids, and because as adults it lives in the deep ocean it has an edge over salmon in that it is very low in toxins, such as mercury, dioxin, and PCBs. Also known as the more proletariat sounding name of black cod, this fish with the trendy name can live for 90 years or more in depths in excess of 9000 feet, and is found from Northern Mexico to Alaska. Clever humans have found ways to reach down to the abyss and snag these 4 foot long fish – from trawls and pots to longlines stretching down a mile or more, and the fishery appears to be well-managed. Because salmon is endangered by overfishing, pollution and habitat destruction, sablefish might turn out to be the panacea needed to give salmon a break.
Of course any relief for salmon is relief for the Southern Resident orca population which relies heavily on this food source, but they are not the only whale species that may find our increasing demand for sablefish to be a boon – in Alaska, a population of sperm whales enjoys a buffet as they pluck the fish off of the deep longlines, or like a revolving sushi track, the fish are thoughtfully pulled up to where the whales can snag them as they go by.
Needless to say, this makes the fishermen unhappy, so with a federal grant they worked with scientists to come up with yet another clever plan: they plan to attach acrylic beads down the length of the lines, hoping that they can trick the whales’ echolocation and disguise the fish. Presumably the beads are designed to mimic the echo of a fish bladder. Good plan, as long as the beads don’t wind up drifting with ocean debris somewhere. How likely is it to succeed?
Considering that 40 -60 foot long sperm whales are able to locate a 2 – 4 foot fish, 600 feet or more deep, in pitch black water…then carefully remove the fish from the hook (at times leaving just the lips behind) I’m guessing that the whales will know the difference between an acrylic bead and a fish. How they react will be more a question of how hard they want to work, and how long it takes them to sort out the new lines. Sperm whales have no teeth in their upper jaw, and the lower jaw is under slung below their massive heads. Their sonar (echolocation) is among the most sophisticated known in cetaceans, as illustrated in this animated video, which shows how the whales send a click then interpret the echo:

Here is video showing a whale taking a fish off a longline…wait for it…:

Who knows, long term, what our demand for sablefish will do the population of this long lived species. One can only hope that we have learned by now to be very cautious in their management, and that we accept that our lines are an intrusion into the ocean world where the sperm whales live and feed.
Fish Watch
AP article on beads

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