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Crayfish following the swallow route?  Rate Topic 
 
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 Posted: Thu Jan 8th, 2009 06:48 pm
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1st Post
Hendre
Senior Member


Joined: Mon Dec 31st, 2007
Location: Durbanville, Cape Town, South Africa
Posts: 275
Equipment: AFAW Rods, Shimano Trini 30,
Best Catch: 48kg Bronzie;Galjoen: 1.6kg;Yellowtail, 4kg; Trout, 2kg
Favorite Fishing Spot: Hermanus Walker Bay, Macassar, Stilbaai
Boat: Skicraft 16'
Club: WP536
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Mana: 
Hi Guys

Just an observation. I usually dive at Sandbaai near Hermanus and usually got my quota of crays every time I went diving. I have been struggling the past 2 years to get any and this past December only saw a few while diving.

Now, we have debated why this is happening and came to some sort of conclusion:

First the background:

About 20 years ago there were no crayfish to be found in Sandbaai/ Hermanus and we only dived for Perlemoen and Alikreukel. We never even saw a crayfish. There was also a lot of "pampoentjies"(sea urchins) and I remember lying on my back at night with my mom trying to pick out the thorns with a needle.

Then, about 15 years ago crayfish started to appear in small numbers, the pampoentjies got less and this trend carried on until about 2 years ago where Sandbaai / Hermanus / Onrus etc was regarded as a crayfish 'hotspot' (this is at least when I noticed it). Most people will say that it still is a mecca for getting crayfish, especially from a boat with crayfish nets. Anyway- from about 2 years ago the pampoentjies started to return and the crayfish are getting less.

Now with some debating and a bit of research I came to the following conclusion:

We know perlemoen can basically be taken out of the equation with all the poaching in recent years BUT:

The spawn of perlemoen and the little perlemoen themselves lives inside pampoentjies for the first part of their lives. It is known that crayfish eat pampoentjies, so the natural habitat was destroyed where the perlemoen lived the first few years. I remember diving not seeing any pampoentjies at all, where in earlier years I couldn't put my feet down for fear of stepping on them. I think this is at least a very small part of why there are no perlemoen left with the obvious being the poachers playing a very big part.

To get back to the crayfish: from the time I noticed more pampoentjies, the less crayfish I see. So the question is why?

One can argue that there was less pampoentjies and therefore less food for the crayfish. But where do the crayfish go then?

My conclusion is that crayfish have migratory patterns and that the West Coast crayfish migrate between the West Coast, around Cape Point up to the Hermanus areas. I think they might be migrating back to the West Coast side and that this process takes a few years, hence the fewer crayfish I see.

Anyway, these are my thoughts and any critisism, feedback and discussions are welcomed!

Cheers

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 Posted: Fri Jan 9th, 2009 10:12 am
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ICTHYES
Senior Member


Joined: Fri Mar 23rd, 2007
Location: CPT, South Africa
Posts: 969
Equipment: HMG Slim /6 ,HMG Custom /6,BMT53, Waft Mako, Torium & ...
Best Catch: 94Kg Black Pylie
Favorite Fishing Spot: Kerkies
Boat: n/a
Club: 4 Oceans AC
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Mana: 
Intresting observation Hendre would like the hear what the experts got to say about this...will pay close att to the above if i go Crayfishing...

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 Posted: Sun Jan 11th, 2009 10:16 am
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156
Member


Joined: Mon Feb 18th, 2008
Location: Cape Town, South Africa
Posts: 275
Equipment: Penn, Int, LD, 49 more Penns & handlines
Best Catch: Next weekend
Favorite Fishing Spot: False Bay
Boat: 23 Buttcat- Masai, Kayak
Club: SAMTC
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Mana: 
I spoke to one of the researchers at MCM and he confirmed that they also suspect the conclusion drawn by Hendre. They are also investigating the inshore/ offshore migration patterns of the West Coast rock lobsters where lobsters tagged at Rocky Bank have been returned from Hangklip. Obviously any of these hypotheses can only be supported by collection of data and this takes time effort and money. It seems that all tagging is carried out by the MCM scientists and that they get a return of around 15% of the tagged specimens, mostly from the commercial fishermen. At around R25/ tail for the returns to MCM you can see why there are not many returns from the artisinal or recreational fishers. Incidentally only legal take sizes are tagged. MCM should maybe have spent less on the big red vessels gracing the quays and more on their scientists who are doing some very valuable work on our fish stocks and their exploitation.

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 Posted: Wed Jan 14th, 2009 06:36 pm
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Hendre
Senior Member


Joined: Mon Dec 31st, 2007
Location: Durbanville, Cape Town, South Africa
Posts: 275
Equipment: AFAW Rods, Shimano Trini 30,
Best Catch: 48kg Bronzie;Galjoen: 1.6kg;Yellowtail, 4kg; Trout, 2kg
Favorite Fishing Spot: Hermanus Walker Bay, Macassar, Stilbaai
Boat: Skicraft 16'
Club: WP536
Status: 
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Mana: 
Thanks 156! Seems there's something to it...

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