Recent letters concerning shark fin have shown unquestioning acceptance of a dogma.
There is a refusal on the part of correspondents to consider opposing viewpoints when dealing with those they consider to be the unenlightened.
Joan Miyaoka's letter ("Tuna being wiped out through greed", January 8) sees the diversity of the oceans crumbling, because the greedy "educated and wealthy" do not share her view that Chinese people should refuse to eat sharks and tuna.
Self-proclaimed "thinking people" such as Laurence Mead ("Time to stop defending the indefensible", January 11) see seafood drying on rooftops as akin to cage homes for the elderly - his logic, not mine - with no place in civilised society.
Outside of their views lies the uncivilised "la-la land" in which people are unaware that the amount of food required to feed today's human population is more than it was 150 years ago. This is a profound insight. Their mantra is not new. The [early Christian] author Tertullian said that "we weigh upon the world; its resources hardly suffice to support us. As our needs grow larger, so do our protests that already nature does not sustain us". But nature has sustained us, and with rational management will continue to do so.
Biodiversity losses in the oceans are trivial relative to those that have occurred in the swamps, rivers, forests and savannahs degraded for centuries to feed, clothe and shelter people.
If we followed Ms Miyaoka's logic, eating rice, cereals, vegetables, beef and farmed shrimps should cease, because it is clearly more damaging to biodiversity than the consequences of eating tuna or sharks. There is no more greed among consumers of seafood or fishermen than there is in humans involved in any other endeavour.
People just value marine resources for different reasons than your correspondents do, which they are quite entitled to do. Organisations such as the Commission for the Conservation of Atlantic Tunas reflect the fishing industry's determination to improve sustainability. The dogma that devaluing seafood products will automatically reduce fishing pressure is naive. As the price of a by-product like shark fin declines, the fishermen get less money, but more than if they had to discard the fins. The same numbers of fins enter trade, at a lower price, feeding more people.
Mr Mead hopes his Chinese friends will forgive him for his strong views. I suspect they have been politely doing so for some time.
Charlie Lim, chairman, conservation and management committee, Marine Products Association