Abandoned driftnet with lots of horsehoe crabs, Kranji (25 Jul 2012)

A long abandoned driftnet with many horseshoe crabs trapped in it was seen at Kranji mudflats during a trip with the Bivalve Workshop.

We rescued those that were still alive and removed as much as the net as we could.

It was Ivan who showed me the abandoned. Yen-ling came by to help us pull out the net and rescue the animals trapped in it. The driftnet is quite long, we pulled out about 50m of it. The rest seem to be laid across the stream and was too deep and embedded to pull out.

Lots and lots of Mangrove horseshoe crabs (Carcinoscorpius rotundicauda) were trapped in the net. Many of them were still alive and we managed to rescue about 40 of them. Including the dead ones, I estimate there were about 80 animals trapped in the net. We had to work fast as the trip was ending so I couldn't take proper photos or keep count.

Besides horseshoe crabs, there were also some crabs. The problem with an abandoned driftnet is that scavenging animals such as horseshoe crabs and crabs are attracted to the animals that get trapped and die in the net. These scavengers also get trapped and die and attract more scavengers. In a never ending tragedy as the nets do not biodegrade.

Another crab trapped in the net. Most of the crabs appear to be Stone crabs (Myomennipe hardwicki).

There was also the remains of some kind of animal with a granulated skin. Possibly a small Malayan water monitor (Varanus salvator), but more likely a Banded file snake (Acrocordus granulatus). Sigh.

The rest of the team came by to help remove the entire net and put it into the dustbin not very far from the shore. If only the fisherman who laid the net could do this before it had killed so many harmless creatures. Sadly, this is not an uncommon event. Sivasothi shared about how 300 horseshoe crabs were found trapped in an abandoned net at Mandai. The Nature Society (Singapore) has a programme to track horseshoe crabs in another part of Kranji and does work on horseshoe crab populations in Singapore.

On the high shore, we saw three large bundles of driftnets hanging from the mangrove trees.

I must find time to come back to Kranji with the Project Driftnet team to remove nets and properly document their impact. Hopefully, with more data, we can encourage some movement to control the use of these nets.