Zing
Well-Known Member
It’s never too late, just the bloodshed increases.
Orca attack
- Thread starter Sailfree
- Start date
Boathook
Well-Known Member
ducked
Well-Known Member
OTOH if you are attacked on that route you are a long way out. and distant from required assistance.
Form convoys under escort?
geem
Well-Known Member
There have been zero attacks a fraction of that distance out. Look at orcas.pt for locations and timing
Baggywrinkle
Well-Known Member
For an attack, you need an orca and a boat .... question is, are the orcas going to the boats, or ar the boats running into orcas?
I would imagine the orcas are primarily following their prey, and boats become collateral damage if found in their hunting grounds.
ergo, go where there is no orca prey. What we need is a real-time seasonal migration map of Atlantic bluefin tuna, because that is where you are most likely to find orcas, and I wonder how closely the incidents on orcas.pt map to that migration pattern?
My other question is, do the orcas prioritise feeding or boats? When hungry they would probably prioritise hunting for food, so that may be another factor to think about in relation to the location of the tuna, the proximity of orcas and therefore their likeliness to engage with boats.
billskip
Well-Known Member
I think most animals can become aggressive at feeding time, try taking back food from your pet dog, even crocodile can be sleepy with a full belly, so adding the the food availability, feeding time and an intrusive rudder, could spark aggressive behaviour...but that said they might just be bored, and playing...
ducked
Well-Known Member
Well that'd be zero so far. I dunno how many boats have been taking the pelagic route. By your own account, there have been "several" problem free transits, but orca have been sighted. Strikes me as quite a lot less than guaranteed, especially in a developing situation
geem
Well-Known Member
There are orcas all over the world. Even spotted off Ireland and the south coast of England. They are not necessarily the same group chewing rudders off the Spanish and Portuguese coast. These have all been close in where all attacks have been logged on the Orcas.pt website.
By my account, we have met several boats doing the route I described, because they are anchored next to me and I have spoken to them. Others may have continued directly to the Canaries.
Nothing in life is guaranteed. You way up the odds and risks and make decisions. Just like a whole host of issue you are likely to face in life.
If I took your attitude, I would never leave my home port.
ducked
Well-Known Member
Certainly you would express less certainty about the inherently uncertain.
ducked
Well-Known Member
IIRC Dylan Winter suggested, I think in his film featuring the sand bar at the mouth of the Tay, that seal and dolphin werent generally capable of catching Mackerel in open water, but needed to use "terrain", and its associated currents and turbulence, for tactical advantage, ambush predator stylee.
IF this is true (he isnt a biologist but hes a pretty good observor) then the same might apply to Orca, and they might be mostly therefore feeding inshore, where the terrain provided cover.
Bummer if thats where your home port is, of course.
ducked
Well-Known Member
https://www.sciencedirect.com/science/article/abs/pii/S0006320715301774
Dynamics of killer whale, bluefin tuna and human fisheries in the Strait of Gibraltar
Contrary to my speculation above, this study suggests they can and do chase Tuna down in open water, (an “endurance-exhaustion” technique, with accelerations in excess of 3g recorded) but also take them off hooks, which is energetically a lot more efficient and allows them to catch bigger fish. Also says the prey population is in decline due to industrial overfishing by seine netters, and that the Orca population studied are under pressure, with low reproductive success.
This implies conflict with artisanal Spanish and Morroccan line fishermen, confirmed by this study
firmm's report on Orcas
“They try to drive the Orcas away by all means, according to some of our mariners since this season, among other things, with the devices that are used to stun the tuna with electric shocks.”
Perhaps yachties are collateral damage victims in an inter-species resource war.
(I wonder if those tuna shockers actually work. IIRC I suggested something along those lines for yacht rudder defense up-thread somewhere. Should be non-lethal, but OTOH might piss them off A LOT)
OTOH there is apparently a more-or-less-separate Eastern population of Tuna that is recovering, and moving in to new areas, including the English Channel, according to Annual migrations, vertical habitat use and fidelity of Atlantic bluefin tuna tracked from waters off the United Kingdom - Scientific Reports
Annual migrations, vertical habitat use and fidelity of Atlantic bluefin tuna tracked from waters off the United Kingdom
which I suppose Orca populations (and fisheries) would eventually be expected to (over?) exploit.
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Wansworth
Well-Known Member
The fellow who I recently bought my boat from recounted he was visited by two Orcas off the islas Berlinga,off Portuguese coast about three years ago ,put the fear of Christ up him!….He said he followed the instructions ,stopping the engine lowering 5he sails.Orcas continued to cruise about so he fired off a rocket into the sea and they buggered off.
ducked
Well-Known Member
Electrical Shock Device (Stun Gun) - TUNA SHIP SUPPLY
I'd guess thats an aid to deck handling and it doesn't seem very likely to be usable against Orca in the water without significant modification.
Perhaps it could be hooked up to cables trailed in the water, or even, in the line-fishing context, to a wire hook-trace.
I suppose a TAZER might work unmodified though
I'd guess thats an aid to deck handling and it doesn't seem very likely to be usable against Orca in the water without significant modification.
Perhaps it could be hooked up to cables trailed in the water, or even, in the line-fishing context, to a wire hook-trace.
I suppose a TAZER might work unmodified though
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E39mad
Well-Known Member
ducked
Well-Known Member
I THINK my rudder is stainless steel. but its going to be difficult to electrify it in such a way as to give a biting Orca a shock, because its immersed in seawater, a conductive electrolyte, which would be an alternative current path to the whales body.
It MIGHT be possible with another electrode cable in direct contact with the whale, but even then, unless embedded, the whales blubber seems likely to be more resistant than the seawater.
Plus there seems to be a risk of electrolytically damaging the rudder, though I suppose driving it negative with impressed current against a sacrificial anode might minimise that.
It MIGHT be possible with another electrode cable in direct contact with the whale, but even then, unless embedded, the whales blubber seems likely to be more resistant than the seawater.
Plus there seems to be a risk of electrolytically damaging the rudder, though I suppose driving it negative with impressed current against a sacrificial anode might minimise that.
greeny
Well-Known Member
https://www.sciencedirect.com/science/article/abs/pii/S0006320715301774
Dynamics of killer whale, bluefin tuna and human fisheries in the Strait of Gibraltar
Contrary to my speculation above, this study suggests they can and do chase Tuna down in open water, (an “endurance-exhaustion” technique, with accelerations in excess of 3g recorded) but also take them off hooks, which is energetically a lot more efficient and allows them to catch bigger fish. Also says the prey population is in decline due to industrial overfishing by seine netters, and that the Orca population studied are under pressure, with low reproductive success.
This implies conflict with artisanal Spanish and Morroccan line fishermen, confirmed by this study
firmm's report on Orcas
“They try to drive the Orcas away by all means, according to some of our mariners since this season, among other things, with the devices that are used to stun the tuna with electric shocks.”
Perhaps yachties are collateral damage victims in an inter-species resource war.
(I wonder if those tuna shockers actually work. IIRC I suggested something along those lines for yacht rudder defense up-thread somewhere. Should be non-lethal, but OTOH might piss them off A LOT)
OTOH there is apparently a more-or-less-separate Eastern population of Tuna that is recovering, and moving in to new areas, including the English Channel, according to Annual migrations, vertical habitat use and fidelity of Atlantic bluefin tuna tracked from waters off the United Kingdom - Scientific Reports
Annual migrations, vertical habitat use and fidelity of Atlantic bluefin tuna tracked from waters off the United Kingdom
which I suppose Orca populations (and fisheries) would eventually be expected to
Don't electrons flow the other way?
KevinV
Well-Known Member
Don't be boring - I'm looking forward to hearing what happens to his electronics when he wires a 20kv electric fence energizer to his boat earth - or, should he be successful, how a 2 ton orca reacts to being poked with a cattle prod
veshengro
Well-Known Member
Between 1996 and 2013 I made 7 return voyages to the Med, basically leaving Falmouth between early May or at latest mid July on a couple of occasions due to 'orrible weather. Single handed my destination was always about 10 Degrees 30 West with Finisterre abeam to Port. That position put me at least 50+ miles off Cape Finisterre which for a single hander has a number of benefits. Clear of inshore shipping and coastal Fishermen, sea room in the event of bad weather and usually, but not always as I got a couple of batterings, the sea state while rough is less confusing or more regular at least. 10-30 West is well to seaward ( 25-30 ? odd miles or so from memory ) of the Shelf where the soundings rapidly decrease.
Voyages homeward the next summer after wintering in the Med were always NW from Cape St Vincent on the Azores route until I found a favourable wind. Never got anywhere near the Azores as I always seemed to be lucky and get a South Westerly ( ish) after a few days, so I was well clear of their (current) hunting grounds anyway.
I only post this in the Orca discussion to support anyone thinking of the off shore route to the Med. I never saw an Orca in all those voyages on that route..although I'm aware that the rudder nibbling and unwelcome visits from Willie seem to have started in more recent years., which might be the case, as I never saw or had a visit from them even when cruising the Portuguese coast from Faro East and round to Gibraltar.
ducked
Well-Known Member
I doubt one can tell, though I cant claim to be a conoisseur of electric shock, and IIRC have only really had AC ones, (including electic fences, which I think are AC) where it all seemed to happen rather quickly
ducked
Well-Known Member
Think I acknowledged that above with "(I wonder if those tuna shockers actually work. IIRC I suggested something along those lines for yacht rudder defense up-thread somewhere. Should be non-lethal, but OTOH might piss them off A LOT)"Don't be boring - I'm looking forward to hearing what happens to his electronics when he wires a 20kv electric fence energizer to his boat earth - or, should he be successful, how a 2 ton orca reacts to being poked with a cattle prod
OTOH fishermen have reportedly (and successfuly) been doing something along these lines (which I suggest MIGHT be the origin of this behaviour) though their boats are perhaps robust enough to better get away with it.