I REFER to Mr Jonathan Gray's letter headlined, ''Go catch the big fish'', which was published in the South China Morning Post, on January 4.
Whilst it may not be commonly perceived by the public that in many parts of the territory, fish are actually reared in waters heavily polluted by their own excretions, it is nevertheless clear that mariculture activities do cause significant pollution tothe waters of Hong Kong.
The 1990 consultancy study commissioned by the Environmental Protection Department (EPD) on the assessment of the environmental impact of marine fish culture in Hong Kong clearly concluded that apart from problems such as littering, noise and visual impact, the major pollution problems of mariculture are increased levels of nitrogen and phosphorus, oxygen depletion, blanketing of the sea bed, destruction of benthic fauna and increased ammonia toxicity.
These pollution problems are particularly serious for fish culture zones located in enclosed water bodies such as Tolo Harbour and Port Shelter.
Whilst it may be tempting to treat fish farmers as victims of pollution caused by dredging and dumping activities rather than polluters themselves, it is important that these two issues be treated separately.
Environmental problems associated with the many extensive operations presently taking place all over the territory for the future development of Hong Kong are undoubtedly of our concern.
Indeed, one of our pressing tasks is to ensure that the environmental impact caused by these activities is mitigated as far as possible.
