On a day when the waters not too rough, wait for a wave to break. As the water recedes you may notice bumps in the sand. Immediately dig at one of those spots. There is a special net you can purchase but I feel that it is unnecesary.
hey there snoekvoel, i've learnt to catch sealice by looking for a V shape as the water is receeding along the beach. Once i see the V shape, i quickly use my hands to dig. When i say dig its more like 1 scoop of sand, done by pushing your finger tips into sand.
One could also use a sort of triangular sealice net, place net in water along shoreline, once water is receeding, drive you heels into sand by moving heel left to right. The recedding water will carry and sealice into the net.
you need a licence last time i checked.
To catch them you use a Triangle shaped contraption covered in chicken Wire Its sort of like a Pyramid cut in half that is about 50cm high with a base of about 50 cm
Method to catch is spot an area likely to have lice, and run in on a receding wave 10-40cm deep. Plant the sealice catcher thingy and bury your feet into the sand so that the backwashing wave washes the sand you "dig" up with your feet through the catcher. It acts as a sluice and the sealice get caught up in the chicken wire. its possble to get a few at a time with this, and a LOT easier than chasing 1 at a time. Will try find a link to a picture of the Sea lice catcher.