After reading some of the posts in Lethals- Crays for Africa, got me thinking about what the hell are they really up to? Ive heard the usual tales that they all line up and walk this mighty journey around NZ and off to Oz, but why?
Have any of you got some hard evidence of what they are doing or some out there theories, or is it a case of you have to be a crayfish to know what the f**k's up with it all? One of Mother Natures great acts for sure!!
I was under the belief that its was the Packhorse crays that marched, not the reds.
Paul, what does the video say. Were they reds or packies ?
Well,
When crays allround the country and in oz shake their tails and release their eggs, they basically mostly all end up off the Eastern coast of NZ a few hundred miles in a big eddy.
The reason for this is that the currents between Oz and around NZ all end up in this place.
The eggs turn into little swimmer things that don't look like crays at all, and they start swimming west ending up mostly around the gisborne-Wairarapa area but actually all onlong the eastern coast of NZ.
They put these little test traps out and found the largest concentrations around Gisborne down to the wairarapa and through the cook straight.
After several years, and it doesn't happen every year, the crays, that actually remember where they were released from (Pretty amazing ) march going down NZ around stuart Island then up as far as Greymouth and some split off and go back to Aussie and the others continue up around the top of NZ .
From personal experience this explains why the cook staright is full of baby crays, literally nearly every crack in some places have hundreds of these. While up around Kapiti Ive only ever found larger crays, never a nest of babies.
Obviously there will be exceptions but for the main part this is what the crays do. Also not all of them march. Like a built in homing instinct in a percentage of the population to ensure a good gene pool mix. Thats why in general most crays are found in that Gizzy to Wairarapa area, and thats why we in Wellington can consistantly catch good crayfish 5 minutes from central wellington.
Saw on TV a few years back that the theory behind them marching in a line was so they could cover a distance quicker in the currents like cyclists do in the wind.
P.C.
In the good old days, there columns were up to 100 meters wide in places.
The spotter planes thought it was an oil slick when they saw them.
Dont spose anyone was watching Prime at around 1930-2000hrs last night??? there was a prog on ocean killers and they had some cool footage of crayfish doing exactly that...
Apparently when the water cools down to a certain level they start to think about the march and when the next full moon comes they start... They walk single file non stop untill they reach their destination. It was very cool footy and it showed trigger fish (leatherjackets) attacking the crayfish that had strayed from the pack. As you can imagine they are rather vulnerable on a sandy sea bottom.
also on this programme they had the most incredable footage of Striped Marlin herding fish into a meatball. This was all under water footage and was the best I have seen. According the the programme Striped Marlin use the stripes to communicate to each other, in particular whose turn it is to charge the meatball... (hmmm... I doubt that is the primary function of the stripes, but what would I know)
surly someone else watched this last night???
lalandi..... those were Painted crayfish which they have over seas they are vegetarians...... ours tend to march in a pointed arrow head fashion and even climb over each other because they are that dense in numbers......
Bushie..... both packies and spinies march here in NZ....... had a mate come across a Packhorse march and they filled the 10ft tinny up till they could not get in themselves none of these crays where under 12lb......
I hired the blue plannet from the library, what an awsome set that is.
How about them Bluefin. Massive.
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