The Marine and Coastal Managements brochures and website indeed does state that 5 is the daily limit. They also dont mention any area restrictions, apart from those that are in Marine Protected Areas, where no collection of any bait is allowed.
I think the NPB's restrictions on bloodworm is to do with these facts. Bloodworm (Arenicola Loveni Loveni) only spawn once a year , and only once the worm is at a mature age (2-3 years). The reason the restrictions of Natal and the Cape differed is to do with this next fact. The bloodworm's new born larvae have a higher survival success rate in water temperatures of between 15-18 C,which is in the range of the Cape waters during summer. The waters of Natal are quite a few degrees higher in summer and therefore lower the survival rate of the larvae, which lessens the ability of the worms to recover from bait collection. So in other words the worms population recovery from bait collection in Natal is much less than in the Cape. Saying that, the worm is also heavily exploited here and needs to be protected.
So we can see from these facts above how important it is to stick to those bag limits, especially for the guys in Natal.
Class dismissed...