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!