Monday 12 May 2014

That Recent Sonar Image

Okay, so the recent sonar image from Jacobite Cruises was five years old. I updated the article to reflect that shortly after, but it seems the real image has been published in what was deemed a cock up. Original article here.




The image was taken off Urquhart Bay on the 27th April 2014. A zoom in of the screen grab is somewhat indistinct, but it seems to be showing a target hit at about 30 feet down which has a crescent shape that is reminiscent of the crescent shape we see for smaller fish all the time. Note that in the case of fish such as charr or salmon, it is the swim bladder that registers the strongest echo. The crescent shape is caused by the relative motion of the fish to the sonar.




This sonar image is not a small fish. What it is on an initial inspection is difficult to say and I have seen various strange sonar hits from nearly all the cruise companies now. The normal answer from them is to say it is anomalous and I guess that is where I will have to leave it myself!


16 comments:

  1. Is this a lot bigger than the normal fish echo ? Any idea of a size?

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    1. Well, I would say it was bigger. I presume what we see echoed back is in feet rather than inches.

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  2. Interesting. Im no expert on sonar but there is plenty of contacts been made and the people who understand it claim they are big targets.

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  3. Geordie Sceptic13 May 2014 at 09:04

    Could be a seal.

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    1. Well, I would not discount the seal explanation in general. But unlike Nessie, seals are not shy of advertising their presence in the loch and ending up with a bullet by the fishery folk.

      If a seal was reported in the area, then fine. If not, it is to be assumed this is not one of their rare trips up the river Ness into the loch.

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    2. Just curious about your 'seal/bullet' statement...do local fishermen do that? If not, does an agency? Seems severe to me, but I imagine seals could eat a lot of salmon. If there are seals in the Loch, do they remain there long?

      richard

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    3. Shooting seals is illegal in Scotland, but owners of fish farms (of which there is one on Loch Ness, just by Dores) can apply for a licence to cull seals if they feel their fisheries are threatened by rogue seals. The criteria to get such a licence is pretty stringent though.

      Seals are very rare on Loch Ness as they have to negotiate 4 miles of fast flowing river to gain entry to the loch. Otters are relatively more common. There are otters living on Ness Islands at the moment. I am pretty sure a lot of Nessie sighting over the years have been otters.

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    4. I spoke to one chap who does it who runs a cruise. You have to be licensed to do it.

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  4. Ive never seen a seal in loch ness so it cant be that common. But my good friend who lives there says he has seen 3 seals over the years. He says they dont stay long.

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  5. I hear the Royal Scot cruise boat picks up regular large sonar contacts, any thoughts on this GB ?

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  6. Three years ago we were aboard the Royal Scot and got into a conversation with Richard MacDonald, the skipper. He told us that they had several hundred large contacts over the previous few years and admitted that although many could be explained away as anomalies of some kind this couldn't possibly account for all of the hits they got. I am no sonar expert so I'm not sure what to make of this other than, as the old saying goes, "There ain't no smoke without fire". Have you heard any of this from Richard yourself GB.

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    1. He showed me one or two old images, so I guess there is an archive of old, ambiguous hits resident with many of the cruise operators.

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  7. I saw him on a programme on the LNM and he said he got regular sonar hits on his cruise boat.

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  8. I know Richard quite well. Good guy but definitely heavy on the patter when he's in tour guide mode.

    I think 'several hundred large contacts' must be a bit(!) of an exaggeration, especially when you consider it doesn't take much to get a sonar contact into the media as the last couple of weeks has shown.

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  9. Well i have been on his cruise and obviously he exaggarates the whole thing for the tourists but he has definetley had large sonar contacts and is a big believer in nessie.

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  10. We need more HQ underwater infrared cameras..
    Come on you Scottish millionaires.

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