Code of Conduct for clam digging activities

Shui Hau Wan has become so popular over the years that the entire shore area on weekends and holidays is teeming with hundreds of visitors, primarily there to collect clams. But unregulated recreational clam-digging will lead to overharvesting, causing disturbance to both habitat and animals, and ecological consequences1, including:
  • substrate disturbance altering seabed topography
  • reduction in the number of clam species and reproduction opportunities
  • changes to the community structure along the food chain
  • hamper ecological services provided by the habitat. Clams and other associated animalsare key species tofilterand clean upseawater
To reduce impact on the environment, WWF has worked with academics and Shui Hau residents to develop a self-disciplinary code of conduct for clam-digging activities. The rules and how they help preserve the ecology are listed below:
1 Set the small ones free –Give them a chance to grow and reproduce (please use our handy clam gauge).
  • Small clams have yet to reach sexual maturity. Release them to grow and reproduce – so sustain the clam communities
  • Different clam species have a different size of maturity. Please refer to the clam gauge which includes several species.
2 Happiness consists of contentment – Collect clams for your own consumption, not too many, not for others
  • Overharvesting causes clam population decline
  • Don’t waste clams - if you cannot consume all collected clam, why not just leave them?
3 Use less destructive equipment, such as hand-held shovels for clam digging
  • Small hand-held shovels have a smaller impact to the mudflat ecology than some large, commercial digging equipment
4 Backfilling your clam holes – try to restore the original state of the mudflat after clam digging
  • Backfilling ensures the disturbed substratum can recover more quickly. It also prevents overturned organisms being exposed to and hunted by predators, or killed under heat stress
  • Make sure you return boulders as you found them before you leave to lower the disturbance to the organisms on/ under the boulders
  • Prevent injury to other mudflat users from tripping over the holes
5 Don’t dig in the mangrove area and rivers
  • Mangrove stands and rivers support a high biodiversity. Stay away from these ecologically sensitive areas to avoid disturbing or injuring the organisms
  • You may damage the aerial roots of mangroves while walking in the mangrove areas. If you step on the mangrove propagules they may not be able to survive
6 Respect lives – do not hurt or disturb horseshoe crabs and other marine creatures
  • The Shui Hau mudflat is one of the few remaining horseshoe crab habitats in Hong Kong. It serves as the important spawning and nursery ground. Their numbers have been decreasing and more protection is needed to help them to cope with increasing threats
  • Show your respect while observing marine life. Walk carefully on the mudflat, and do not touch or hunt them
7 Watch out when tide rises - for the sake of your own safety, be alert when tide rises
  • Check tidal charts when planning your trip to the mudflat
  • It could be very dangerous to explore mudflats during rising tide, the water level could go up in a very short period of time. Spare enough time to tidy up and return to shore
8 Leave no trace – take all your belongings and litter home
  • Anything you leave on the mudflat will become marine litter. It can cause wildlife entanglement, and will block the animal’s digestive tract once ingested
  • Marine litter, especially plastics, break up slowly. They will continue to threaten marine life for decades or even longer.
1Gaspar, M.B.; Barracha, I.; Carvalho, S.; Vasconcelos, P. Clam Fisheries Worldwide: Main Species, Harvesting Methods and Fishing Impacts. In Clam Fisheries and Aquaculture; Da Costa González, F., Ed.; Nova Science Publishers: Hauppauge, NY, USA, 2013; pp. 291–327.