# What are these lines in sea off Normandy coast? **URL:** \ **Category:** Factual Questions\ **Created:** [August 4, 2023, 2:01am UTC](https://boards.straightdope.com/t/what-are-these-lines-in-sea-off-normandy-coast/988033 "2023-08-04T02:01:10Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Walken\_After\_Midnight](https://avatars.discourse-cdn.com/v4/letter/w/b487fb/32.png) [@Walken\_After\_Midnight](https://boards.straightdope.com/u/Walken_After_Midnight)\ **Post date:** [August 4, 2023, 2:01am UTC](https://boards.straightdope.com/t/what-are-these-lines-in-sea-off-normandy-coast/988033/1 "2023-08-04T02:01:10Z")
What are these lines in the sea off the coast of Normandy, France? [![](https://i.imgur.com/8prDRlI.png) ](https://i.imgur.com/8prDRlI.png) [Location on Google Maps](https://www.google.com/maps/@49.3917256,-1.0955518,4847m/data=!3m1!1e3?entry=ttu). I thought they might be a photographic glitch and not actually there, but they’re also visible in 2007 historical images in Google Earth. I’m guessing they’re to do with fishing. While we’re on the Normandy coast, [here’s the location of the remains of the temporary Mulberry B harbor](https://www.google.com/maps/place/49%C2%B020'43.0%22N+0%C2%B034'18.0%22W/@49.3502752,-0.6239564,3056m/data=!3m1!1e3!4m4!3m3!8m2!3d49.345278!4d-0.571667?hl=en&entry=ttu) from the Normandy Landings of World War II on Gold Beach. There are more of the lines in the sea in question to the east of here. ---
**Author:** ![Johnny\_Bravo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_bravo/32/493_2.png) [@Johnny\_Bravo](https://boards.straightdope.com/u/Johnny_Bravo)\ **Post date:** [August 4, 2023, 2:20am UTC](https://boards.straightdope.com/t/what-are-these-lines-in-sea-off-normandy-coast/988033/2 "2023-08-04T02:20:41Z")
It’s labeled “Peche interdite,” which Google Maps calls a seafood farm. ---
**Author:** ![md-2000](https://avatars.discourse-cdn.com/v4/letter/m/9d8465/32.png) [@md-2000](https://boards.straightdope.com/u/md-2000)\ **Post date:** [August 4, 2023, 2:23am UTC](https://boards.straightdope.com/t/what-are-these-lines-in-sea-off-normandy-coast/988033/3 "2023-08-04T02:23:06Z")
Isn’t peche interdite meaning “no fishing”? Zoom in, definitely some sort of lines of construction. I’m guessing shellfish farming or something, since a seafood farm is usually an enclosure, not strings of construction? ---
**Author:** ![Walken\_After\_Midnight](https://avatars.discourse-cdn.com/v4/letter/w/b487fb/32.png) [@Walken\_After\_Midnight](https://boards.straightdope.com/u/Walken_After_Midnight)\ **Post date:** [August 4, 2023, 2:23am UTC](https://boards.straightdope.com/t/what-are-these-lines-in-sea-off-normandy-coast/988033/4 "2023-08-04T02:23:27Z")
“Peche interdite” means “Fishing prohibited”. ---
**Author:** ![Walken\_After\_Midnight](https://avatars.discourse-cdn.com/v4/letter/w/b487fb/32.png) [@Walken\_After\_Midnight](https://boards.straightdope.com/u/Walken_After_Midnight)\ **Post date:** [August 4, 2023, 2:27am UTC](https://boards.straightdope.com/t/what-are-these-lines-in-sea-off-normandy-coast/988033/5 "2023-08-04T02:27:31Z")
> [@md-2000](#): > > I’m guessing shellfish farming or something, since a seafood farm is usually an enclosure, not strings of construction? That’s what I was thinking it might be. Lobster pots: [![](https://t4.ftcdn.net/jpg/00/97/46/21/360_F_97462107_60r7SM9nZDrQg1HvFED7o2RyBfbs1yty.jpg) ](https://t4.ftcdn.net/jpg/00/97/46/21/360_F_97462107_60r7SM9nZDrQg1HvFED7o2RyBfbs1yty.jpg) ---
**Author:** ![Johnny\_Bravo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_bravo/32/493_2.png) [@Johnny\_Bravo](https://boards.straightdope.com/u/Johnny_Bravo)\ **Post date:** [August 4, 2023, 2:27am UTC](https://boards.straightdope.com/t/what-are-these-lines-in-sea-off-normandy-coast/988033/6 "2023-08-04T02:27:45Z")
I’m just reporting on what Google maps says, which is literally: Peche interdite Seafood farm I suppose meaning “don’t fish here because it is a seafood farm.” After some more googling, I believe it is an aquaculture business called Douesnard Ludovic. An image search for the name will pull up some photos of whatever those enclosures are. ---
**Author:** ![Fish\_Cheer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fish_cheer/32/17179_2.png) [@Fish\_Cheer](https://boards.straightdope.com/u/Fish_Cheer)\ **Post date:** [August 4, 2023, 3:38am UTC](https://boards.straightdope.com/t/what-are-these-lines-in-sea-off-normandy-coast/988033/7 "2023-08-04T03:38:01Z")
Yes, it’s for oysters. More photos [here](https://www.normandie.fr/huitres-de-normandie-5-crus-de-qualite-de-gouville-veules-les-roses). ---
**Author:** ![pjd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pjd/32/3009_2.png) [@pjd](https://boards.straightdope.com/u/pjd)\ **Post date:** [August 4, 2023, 8:24am UTC](https://boards.straightdope.com/t/what-are-these-lines-in-sea-off-normandy-coast/988033/8 "2023-08-04T08:24:34Z")
In that Mulberry B map … there’s a convenience store in the middle of the sea !? wtf ! ---
**Author:** ![SanVito](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sanvito/32/2805_2.png) [@SanVito](https://boards.straightdope.com/u/SanVito)\ **Post date:** [August 4, 2023, 9:22am UTC](https://boards.straightdope.com/t/what-are-these-lines-in-sea-off-normandy-coast/988033/9 "2023-08-04T09:22:06Z")
What are you seeing that I’m not? ---
**Author:** ![hibernicus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hibernicus/32/2802_2.png) [@hibernicus](https://boards.straightdope.com/u/hibernicus)\ **Post date:** [August 4, 2023, 10:21am UTC](https://boards.straightdope.com/t/what-are-these-lines-in-sea-off-normandy-coast/988033/10 "2023-08-04T10:21:45Z")
I am very familiar with this as I usually spend my annual holidays in areas of the west coast of France where this kind of “ostréiculture” (oyster farming) and is practised. It is a huge industry with millions of tonnes produced every year. The thing to understand is that these coasts have some of the most extreme tides in the world (tidal ranges in excess of 10 metres). That means that twice a day, vast areas of seabed are exposed, often stretching a couple of kilometres out from shore. So the image that you are seeing where the squares are underwater will look very different six hours later. At low tide, it is possible for vehicles including vans and tractors to drive out to tend the oyster farms and for pedestrians or private cars to cross the sand to visit islands and fortifications that are inaccessible at high tide. ---
**Author:** ![pjd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pjd/32/3009_2.png) [@pjd](https://boards.straightdope.com/u/pjd)\ **Post date:** [August 4, 2023, 11:01am UTC](https://boards.straightdope.com/t/what-are-these-lines-in-sea-off-normandy-coast/988033/11 "2023-08-04T11:01:21Z")
In the second link in the OP (“temporary Mulberry B harbour”), i’m seeing a flag about 3.5km north off the coast labelled “Villemandeur” which it says is a convenience store. ETA: [![](https://i.ibb.co/Jrzg7BC/normandy-map.png) ](https://i.ibb.co/Jrzg7BC/normandy-map.png) ---
**Author:** ![FrenchDunadan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/frenchdunadan/32/5449_2.png) [@FrenchDunadan](https://boards.straightdope.com/u/FrenchDunadan)\ **Post date:** [August 4, 2023, 11:26am UTC](https://boards.straightdope.com/t/what-are-these-lines-in-sea-off-normandy-coast/988033/12 "2023-08-04T11:26:40Z")
For the first picture, yes oyster farm. There are wood pickets with nets on which the little oysters grow. The fishing nets will be caught on this pickets, hence the “no fishing” rule. For the second picture, Villemandeur is a town 300 km south of the coast… barring an extreme flood, I would say this one is a glitch. ---
**Author:** ![md-2000](https://avatars.discourse-cdn.com/v4/letter/m/9d8465/32.png) [@md-2000](https://boards.straightdope.com/u/md-2000)\ **Post date:** [August 4, 2023, 12:16pm UTC](https://boards.straightdope.com/t/what-are-these-lines-in-sea-off-normandy-coast/988033/13 "2023-08-04T12:16:49Z")
> [@hibernicus](#): > > That means that twice a day, vast areas of seabed are exposed, often stretching a couple of kilometres out from shore. So the image that you are seeing where the squares are underwater will look very different six hours later Yes, if you zoom in east of the D-Day harbour, the photo was obviously taken at low(er) tide. https://maps.google.com/maps?ll=49.3491367,-0.5490187&z=16&output=embed&dg=ntvb Zoom in as close as you can in photo mode. ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [August 4, 2023, 2:04pm UTC](https://boards.straightdope.com/t/what-are-these-lines-in-sea-off-normandy-coast/988033/14 "2023-08-04T14:04:24Z")
It took a bit of scrolling around, but I saw that too. Just a ghost in the machine, no doubt. ---
**Author:** ![Treppenwitz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/treppenwitz/32/3445_2.png) [@Treppenwitz](https://boards.straightdope.com/u/Treppenwitz)\ **Post date:** [August 4, 2023, 2:41pm UTC](https://boards.straightdope.com/t/what-are-these-lines-in-sea-off-normandy-coast/988033/15 "2023-08-04T14:41:50Z")
If you want to investigate these sorts of structures more closely, just along the coast at Cancale is the place to be. Oyster central. https://maps.google.com/maps?ll=48.6649328,-1.8398294&z=15&output=embed&dg=ntvb j ETA - don’t know what I did there - you have to click in the little square, bottom left ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [August 4, 2023, 3:26pm UTC](https://boards.straightdope.com/t/what-are-these-lines-in-sea-off-normandy-coast/988033/16 "2023-08-04T15:26:12Z")
Here’s what they look like close up: [![](https://en.normandie-tourisme.fr/wp-content/uploads/sites/3/2021/11/parc-huitres-baie-des-veys-Sabina-Lorkin.jpg) ](https://en.normandie-tourisme.fr/wp-content/uploads/sites/3/2021/11/parc-huitres-baie-des-veys-Sabina-Lorkin.jpg) ---
**Author:** ![Omar\_Little](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/omar_little/32/269_2.png) [@Omar\_Little](https://boards.straightdope.com/u/Omar_Little)\ **Post date:** [August 4, 2023, 4:20pm UTC](https://boards.straightdope.com/t/what-are-these-lines-in-sea-off-normandy-coast/988033/17 "2023-08-04T16:20:40Z")
Oysters…mmmmmmm yummy! ---
**Author:** ![The\_Stafford\_Cripps](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/the_stafford_cripps/32/7167_2.png) [@The\_Stafford\_Cripps](https://boards.straightdope.com/u/The_Stafford_Cripps)\ **Post date:** [August 4, 2023, 6:34pm UTC](https://boards.straightdope.com/t/what-are-these-lines-in-sea-off-normandy-coast/988033/18 "2023-08-04T18:34:44Z")
> [@Walken\_After\_Midnight](#): > > That’s what I was thinking it might be. > > Lobster pots: Those are for catching wild lobsters, nothing to do with seafood farming. From the air you’d just see a floating plastic buoy tied to the pot, and they would be very dispersed across an area of sea. ---
**Author:** ![Walken\_After\_Midnight](https://avatars.discourse-cdn.com/v4/letter/w/b487fb/32.png) [@Walken\_After\_Midnight](https://boards.straightdope.com/u/Walken_After_Midnight)\ **Post date:** [August 5, 2023, 12:08am UTC](https://boards.straightdope.com/t/what-are-these-lines-in-sea-off-normandy-coast/988033/19 "2023-08-05T00:08:42Z")
> [@Fish\_Cheer](#): > > Yes, it’s for oysters. Well discovered. > [@pjd](#): > > … there’s a convenience store in the middle of the sea !? > wtf ! Sounds more like an… inconvenience store! ---
**Author:** ![md-2000](https://avatars.discourse-cdn.com/v4/letter/m/9d8465/32.png) [@md-2000](https://boards.straightdope.com/u/md-2000)\ **Post date:** [August 5, 2023, 12:09pm UTC](https://boards.straightdope.com/t/what-are-these-lines-in-sea-off-normandy-coast/988033/20 "2023-08-05T12:09:40Z")
> [@Fish\_Cheer](#): > > Yes, it’s for oysters. > [@Walken\_After\_Midnight](#): > > > [@pjd](#): > > > > … there’s a convenience store in the middle of the sea !? > > wtf ! > > Sounds more like an… inconvenience store! She sells seashells by the seashore? How much should she sell them for? [Next page](https://boards.straightdope.com/t/what-are-these-lines-in-sea-off-normandy-coast/988033.md?page=2)