Despite the iconic pictogram sign telling all that fishing was not permitted, it seems as if there is a lot of fishing going on along the Kranji Nature Trail.
Singapore's Northern shores harbour some very small stretches of surviving mangroves ecosystems which are the last refuge of many critically endangered flora and fauna. The section of shore seen in the clip is part of a short section where wooden stakes have been driven at intervals into the shore forming an enclosed area for a small mangrove tree nursery.
Abandoned fishnets have often been found along this area adjacent to the
Sungei Buloh Wetland Reserve. The long gill nets are usually set up in the shallows over a stretch of 50 meters or longer depending on the length of the net. The wonders of plastic are such that these gill nets are made very long and light and can be bundled up into a small grocery bag ensuring great portability. However, they also last a very long time...perhaps forever.
The floats in the nets ensure that a virtual wall is set up to cover not only the surface of the water but right down in the water to a depth of about 1.2 to 1.5m depth. Depending on where the nets are set up, they could drape over the mudflat floor catching anything within the water column or on the mudflat coming into contact with it. Fish are the obvious target but these nets do also trap other animals unintentionally.
The clip shows two foreign workers arriving by bicycle at the Kranji end of the trail. One of them carries a gillnet bundle onto the shore whilst the other looks for a wooden stake to prop up the net. They walk into the shallows and promptly set up the net. All this takes about 10 minutes and the net is left to the forces of the tides for a few hours or overnight to do their magic in catching fish.
Improperly secured nets can become dislodged and float unrestrained over the mudflat getting caught in fallen trees or even on coral where there is a coraline shore. Such nets are difficult if not impossible to retrieve without cutting up large holes in them rendering them all but useless and so the fishermen leave then where they lie rarely if ever bothering to do the right thing by taking the time to extricate and remove the net. As a consequence, the nets survive in a tangled state and can do so for decades before they may be covered up by sand or mud.
The long nets continue to trap crabs and even birds (and sometimes even
the odd crocodile). Many
horseshoe crabs are caught in this way. Nets which have gotten loose from their moorings continue to sweep the floor of the shore trapping animals such as the horseshoe crabs. The Northern mudflats are one of the last refuges in Singapore for horseshoe crabs. The mudflats are an important feeding and breeding ground for these ancient creatures.
A recent mangrove survey at the nearby Mandai mangroves found horseshoe crab eggs with living embryos in them. This shows how important our Northern mudflats are. This not forgetting that the mudflats are a well known transitory stopover for migrating shore birds. The Sungei Buloh Wetland Reserve which is adjacent to the Kranji Nature Trail does have a brood of resident otters as well and it is forseeable that these otters may get trapped in the nets as well much like the hapless
crocodile.
Hopefully, with the ongoing plans for the expansion of the
Sungei Buloh Wetland Reserve to cover the Kranji Nature Trail, the incidence of fishing by gill nets will disappear...at least from this small corner of Singapore.
Links :
About horsehoe crabs :
1. From WildSingapore.com -
http://www.wildsingapore.com/wildfacts/arthropoda/limulidae/limulidae.htm
2. From WildSingapore.com -
http://wildshores.blogspot.com/2009/05/results-of-horseshoe-crab-survey-by.html (results of the Nature Society's survey)
3.
A paper on the Mangrove Horseshoe Crab population by Nature Society of Singapore volunteers
4. From
Fiona Hong's blog :
On the distribution of horsehoe crabs in Singapore - a 2004 research paper
5. From Habitatnews.nus.edu.sg - r
escuing Horsehoe crabs trapped in 'ghost' nets
6. From WildSingapore.com -
about the Nature Society's horseshoe crab rescue programme
