I thought the Lee orcas were lost and/or dying. Fair point though about the scottish pod. My point is that these animals seem to pass by Ireland on their way to somewhere else. Why are there no resident populations?
It turns out that sea turtles have always been reasonably well known to local fishermen around the SW coast during summer, even though the sightings were rarely recorded. These unfortunately go belly up very quickly being a warm water species. You can't say that because an animal has been sighted, that therefore they "live" here.
Resident populations when talking about Orca, and GWs for that mater, is a very vague term.
A resident pod of Orca could take in an area that stretches from say the coast off of Cork to the coast off of Southampton in England. So the chances of seeing them on even a weekly basis is slim. As their food moves, so do they.
Also Orca are broken into a few groups, with the resident types being only one term.
There are off shore Orca too and transients. The latter grouping has had tagged whales seen in California, then found off of our coast and later found up around greenland, so they do not stay in the one area for long spells.
Plus resident Orca, even in Ireland, are not normally feeding so close to shore that the naked eye can see them. They are normally a number of miles off shore. So unles you know that they are in the area and you take a boat out at exactly the right time, you will not see them.
Which leads to people thinking that they are not there at all, and that if they are spotted, that it is a rare thing that they are in Irish waters.
Take the Farallon Island area that I mentioned in an earlier post.
It is known as one of the most heavily populated areas for great whites on the planet, and is known for resident Orca. Yet there are spells each year where a great white may not be sighted by researchers for weeks and even months on end, and the same goes for their Orca population, despiet both groups being known as resident in the area.
Basically all it boils down to is the supply of food. The prey moves and the predators follow, and giving that both prey and predator are less constrained in terms of range than their terrestrial counterparts, then the range at which they can travel, and still be regarded as resident, is considerably larger.
As stated earlier in this thread, Atlantic Great Whites are not known to predate on seals to any great degree, they specilize on fish prey, with the deep swimming six gill shark being one of their main prey species. So why would they be seen near the surface or near the shore?
The Orca pods around Ireland and Britain have long been known to be mainly fish hunters also, so why would they follow the totally different behavioural traits of Orca that prey primarily on marine mammals.
You seem to be working on the assumption that the large predators that are in Irish waters, and the large predator that may come into Irish waters are feeding and hunting in a manner that Atlantic Orca and Atlantic great whites do not do, which is predate mainly on marine mammals.
If we were discussing Orca and indeed great whites off the West Coast of America for example, then what you are saying would stand up, as both species there prey mostly on marine mammals, and as such get seen much closer to shore, and much nearer the surface.
Just as an example of the size of a six gill shark compared to a seal, here is a picture of a six gill caught off of the Clare coast earlier this year. Plenty of eating in these guys, and as said earlier they live in deep water, and are known to be one of the main and preferred species that the Atlantic Great whites prey upon.
Also this year another species that the Atlantic GW preys upon was found in large numbers off of the Kerry coast, and it is another member of the cow shark family, the seven gill shark. This discovery is the one that has drawn the interest of marine biologists, as it is the most common cow shark, and everywhere else on the planet where it is in numbers, the great white shark has been found.
Just to correct you on something you said about the bottlenose dolphin. You called the dolphin in the Shannon estuary transient. That is incorrect, the bottlenose dolphin there are the ONLY known resident bottlenose dolphins in Irish waters, they are not transient at all.
Plus they are not preyed upon by the Orca in Irish waters and have often been seen swimming together. Fish eating Orca do not pose a threat to Dolphin unless the Orca is literally starving.
Cagediving...hmmm, Those who dive regularly with sharks, and its something I used to do, abhor this activity and place it firmly in the Steve Irwin category of sport science...i.e. prodding animals and placing them in unnatural situations and unsurprisingly getting a nervous reaction from them. Cage diving is considered to be behaviour modifying in an unquantifiable manner to sharks. Of course, it is a trade off with the awareness of the species raised by the activity and funding,support for research etc. raised also.
Its still hard to consider it though if you've ever had the pleasure to dive with hundreds of sharks, uncaged. Diving with sharks, even the imperial predator, the great white, is not so risky, and quite a rewarding experience to enter their environment in an unobtrusive manner.
I would not go as far as to say that I abhor cage diving, but I do agree that it is seen as a crass money making business.
Personally I do think it brings more positives than negatives, as it does highlight the animals in question, and it does raise awareness of them.
If it is done in a proper manner by responsibe operators, than I think the pros outweigh the cons.
I would suggest that if you ever get the chance that you try the cage diving setups at the Farallon islands.
They are quite unlike the set ups in Africa, and things like chumming etc are not allowed, as the Islands are nature reserves and the operators have to follow the strict guidelines as set by those authorities.
Also feediving or scubadiving with the sharks is illegal in the waters around the Farallon Islands, due to the population numbers of GWs there, plus the average water temp there makes it quite uncomfortable to be underwater there for too long.
Free diving with a GW is an ambition of mine as I have dived with whale and smaller shark. But the waters I cage dive in are generally waters that have large populations of pinnipeds, so freediving is a big no no in those areas.
Have you gone diving with GWs around? If so, I would love to hear about your experiences and if I may, could I ask where you did so?
I don't think there are GWS here, With the amount of fishing effort going on around the coast there would have been accidental catches before now, Salmon driftnetting,Wecknetting Pelagic trawling for Tuna and in years gone by the Tuna Driftnet fishery in the Porcupine basin/West coast, I find it hard to believe that they could be present in any numbers and not show up as bycatch.
The furthest north they have been recorded is Concarneau/Brittany and that was one shark a long time ago.
I tend to think they are creatures of habit, they follow set routes and do not deviate from them. They are relatively common in the Med but do not seem to make any efforts to increase their range North.
Those Six and Seven gill sharks would make those kind of bites on a dolphin, not to mention the Greenland sleeper shark which also occur in cold waters and around here.
I would say that without doubt GW do occasionally frequent Irish waters. I was surfing in Donegal about 20 years ago and the biggest 'momma' swam directly under me. It was massive, about 15 ft. Cant say for sure if it was a GW as it swam directly under me at a depth of about 4 ft. I can only think that, whatever it was, just came in for a look as there were about four people in the water. No seals around, and the area is not renowned for seals anyway. there are whales and dolphins mind.
There have been sightings further north of GWs and I believe there was a recorded GW attack in thurso, Scotland in the 70's. Thurso is about 58 degrees north and icy!
I would agree that they feed in the deeper water when migrating through Irish waters but on occasion they may follow prey items closer to shore, though infrequently.
I don't think anyone is saying that they could be in Irish waters in any great numbers. Even in parts of the world that are well known for Great white populations, you could go some time without spotting them.
As for how far north they go or how cold a water temp that they will swim in.
They have been recorded much further north than Brittany and in far colder waters.
papachango has mentioned the scottish attack in the 1970's and the waters that I have seen the most in, near the Farallons is extremely cold and much further north than Brittany also. With water temps of 52 to 56 degrees F. Those temps are colder than Irish waters, and that cold area is the biggest known breeding area for great whites on the planet.
If there is a popultaion that passes through Irish waters on a regular or semi regular basis, we may only be talking about numbers that would be between one and ten sharks as a rough estimate, and they most likely would not be in our waters at the same time. So trying to spot one deep feeding GW wheich could be anywhere off of our coast would be next to impossible, and the odds of it turning up in a trawler's net off of coast would be just as tiny.
Think about the other large sharks that are off of our coast like the six gill and the greenland sleeper shark, they are there in larger numbers than a great white could be, yet how often do we hear of them being caught in trawler's nets? Very rarely.
If we have them, and there is no reason why we would not as it is not as though they don't have a healthy and large population of known prey fish here, then they will not be specialist seal hunters like in warmer waters, they will be specialist fish hunters like the other great whites which have been found and tagged in the Atlantic, so they will be deep water feeders.
I do think we have them in our waters from time to time, but their numbers will be very small.
You could have become the Irish version of Rodney Fox.
Although he was spearfishing when hit.
Not to disbelieve you but there is a big difference between seeing a GWS and positively ID'ing one.
Porbeagles look similar and can grow to 15ft and inhabit all coastal waters in Ireland and further north.
What I am saying is that with all the fishing effort around here there is no recorded catches of GWS.
Thurso is actually quite warm considering it's latitude, it is still part of the Gulf stream effect, I have been up there a few times on commercial fishing vessels.
I just find it hard to believe that if GWS were here that they would not have been caught by now. Fishermen chase fish and use gears that target concentrations of fish which is where you would expect the sharks to feed, Many other types of sharks and mammals have been recorded as bycatch but never a GWS except for the solitary specimen from a commercial gill net vessel in La Rochelle in May 1977.
Until someone proves it beyond doubt then I am afraid I am a non-believer.
I can see where you are coming from, and without positive proof it can be hard to say whether an animal is there or not.
Humour me by letting me show you a map of the North East Atlantic, where Great Whites have been studied and also have been caught by commercial nets. Plus it is the one part of the planet where sharks are most endangered due to commercail fishing. The map I found online but it is useful for what I am trying to say.
In the parts numbered I, II, IV, and V, great whites have been found, recorded and caught by commercial fishermen. The Irish waters are marked as number III.
The EU have put the Great White, amongst others, as on the endangered list for those areas, and have marked it as a protected species with legal action to be taken against any commercial firm that brings one in. So it would be in the interests of the commercial fishermen to simply throw the dead fish back.
The two links I put up are just for your reading. They do not prove that Ireland has Great whites, but they do confirm that the North East Atlantic has them, which is the water off of our coasts from Kerry to Donegal.
I don't think we have resident great whites in our waters, but I do think that we have transient great whites who pass in and out of the Irish waters on that map. As I said earlier it may be one fish a year, it may be up to ten fish a year, but I do firmly believe that they have been in Irish waters. The fact that they are a species that lives and has been found everywhere else on the map I showed you would suggest that they at least pass through our waters, but until, like you have said, one gets caught and officially reported in our waters, then there is no definitive proof of them there.
I think you are incorrect with that map, The northernmost record of GWS in European waters is from the Loire and that was from a set of jaws.
The only confirmed and documented case was the fish caught off La Rochelle.
there has never been a confirmed documented GWS from the North Sea AFAIK.
even in the Mid Atlantic there is no records of GWS from Japanese longline vessels which routinely catch Mako, Blue and other large sharks.
I am not saying that it is not possible that they occur here but the total absence of any kind of catch records would indicate that they simply don't come up here.
I tend to believe that they are programmed from the time they are born to occupy certain areas, in other words they have a genetic memory from millions of years ago and that the Nth East Atlantic was not a part of their traditional range and therefore they don't travel here.
Fishermen can not be prosecuted for catching one as bycatch, and I know that most would land one as a curiosity if it was caught.
I really hope it's not the shark that did this:
Even going back tens of thousands of years, ocean conveyer belts, ice ages etc have modified conditions, timescales are small in this context, depending which scientific paper you read eevn as small as 40 - 60 years for a significant change to affect a species distribution.
Could Great Whites' ranges be becoming amplified? Sure! Could we come close to proving this? Not likely just yet! We know next to nothing about distribution ranges for species such as these, even if they turned up in bycatch, this is incidental and science likes far harder data figures.
Leading nicely on from this, to answer your question Kess, I was working in Galápagos off Ecuador, assisting tagging of hammerhead, galápagos and whale sharks in efforts to know more about their ranges to assist protection measures in the future. It is only recently we have some definites about their range in the +1000km context. It is common and easy to dive and snorkel, uncaged with hundreds of hammerhead, whitetip and galápagos sharks there.