salmonids, while protecting important public and private works and thus helping to balance the needs of man and nature. Credit for invention The design of the dolos is usually credited to the South African Eric Mowbray Merrifield, one-time East London Harbour Engineer (from 1961–1976). In the late 1990s the claim of Aubrey Kruger gained more prominence. Kruger's claim is that he and Merrifield had considered the shape of concrete blocks to be used to protect East London's extensive breakwaters for the City's non-natural harbour, following a major storm in 1963. Merrifield wished to design a block that did not break up or shift when struck by the sea; that was cheap; and that did not require precise placement. He said in later years that he wanted a block designed in such a way that it could be "sprinkled like children's jacks". Kruger stated that he went home for lunch, cut three sections from a broomstick, and fastened them with nails into an H-shape with one leg turned through 90 degrees to create the distinctive dolos shape. Merrifield was intrigued by the object and had Kruger draw a plan. Kruger never formally received credit for the invention. Merrifield won the Shell Design Award and the Associated Science and Technology Societies of South Africa's Gold Medal. The death of Merrifield (in 1982) has put this controversy beyond proof either way. Aubrey Kruger died in East London on 19 July 2016. Design protection The design of the dolos is not protected by any form of patent. Merrifield did not take the necessary steps to protect the concept. The reason for this is uncertain. Two reasons for this have been put forward: one by Merrifield; the other by Kruger. Merrifield stated that he did not protect them as he wished them to benefit humanity. Kruger alleges that Merrifield received incorrect legal advice: to wit, that as the blocks had been designed during office hours while he was employed by the State (South African Railways and Harbours Administration), he was unable by law to protect their design. Origin of name The name is derived from the Afrikaans word dolos- plural dolosse. This word has two given derivations. states it to be a contraction of 'dobbel osse', or 'gambling' (Afrikaans) 'bones' (from Latin). Boshof and Nienaber state it to be a contraction of 'dollen os', or 'play' (old Dutch) 'oxen' (Afrikaans). The first is a meaning-shifted