Home Warning Hook event The law
Interaction between cables and fishes
Cable ships in operation
Signals given by Cable ships in operation

Interaction between cables and fishes

One might imagine that fish might congregate in cable zones as they are relatively protected with less trawling gear and other fishing equipment than elsewhere.

In fact, this is not true.

Fish movements are conditioned by many different factors which interact with each other.
Two of these are, however, of primary importance :

  • Food,
  • spawn.
For these two activities conditioning the survival of the species, some parameters are intangible.
These are :
  • currents
  • salinity
  • the temperature of the water as habitat,
  • availability of food (which depends in turn on the preceding factors)
  • the ocean floor
  • protection
  • the absence of pollutants.
To these physical parameters can be added other influences. Certain types of fish coexist with, or reject, other marine species. There can be competition for food, causing the exclusion of certain species.

There can also be significant predatory activity because of the presence of particularly carnivorous fish, and this may also cause some species to migrate.

The phenomenon of fish migration is common amongst all species, and can cause deserticication of vast zones of ocean tract for long periods of time.

Some fish species seek food and protection close to wrecks. These are, generally speaking, gadides (coley and pollack, ling, cod). Others browse and feed on rock bottoms (hake and "St Pierre" ).
Some particularly well-stocked sites serve as nurseries for young fish, which gather there in abundance.

In the near vicinity of cables fish find neither food nor protection.
These areas are therefore not very attractive places for the various fish species to congregate.

To think that more fish would be found in these areas is erroneous as they would move about according to fluctuations in the supply of the foods they like the most, or as a function of concentrations of spawn.

It is therefore in your interests to avoid taking pointless risks, and avoid trawling too close to cables.


Cable ships in operation

If you meet a cable ship, it is advisable to check if they are in operation. If they are, they will emit the regulationary signals, and you should respect them.

The ships may be conducting surveys of the sea bottom to research future cable routes.
. In this case, they will be towing a probe at a distance of more than one mile. You should avoid passing in front of these ships, as it will disturb their progress.
You should avoid, likewise, cutting in too close behind them, because of the length of the towing gear.
If you do, Cable ship may snag on the towing line or the probe itself.

You would be at fault with respect to sea transport regulations. Moreover, expensive equipment may be damaged or lost, and the cost of replacing it would fall to your charge.


Depending on the depth of the water, a long length of cable is suspended behind the ship. You need to make a grand detour to avoid snagging on the cable. If you are fishing, it is best to bear away even more, so the warps or panels do not come into contact with the equipment being towed behind the cabling ship.
Maintenance and Repair
The same precautions should be taken as described above, for the same reasons.

Signals given by Cable ships in operation


  • By day, it will display two black spheres with a black rhombus (nipple) inserted.
  • By night, it displays two red lights with a white light between them.
These marks are visible on every horizon.
These ships have priority over fishing vessels, which should give them a wide berth.

Extracts from the international code for preventing collisions at sea

Rule 3 - Paragraph G
The current legislation defines a "ship with restricted manoeuvering capability " as any ship whose capacity to manoeuvre is limited because of the nature of its work, and which therefore cannot deviate to avoid the course of another ship.

The "ships with restricted manoeuvering capability " include ships laying or recovering a buoy, a cable, or a submarine pipeline.

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