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Freshwater Species

Most of the freshwater species in Borneo belong to the genus Macrobrachium in the family Palaemonidae, sometimes called long-legged or marsh shrimp, and are characterized by long, developed claws in the dominant male, adult shrimp. These shrimp are true shrimp, and some species (such as Macrobrachium rosenbergii) are harvested for commercial consumption. Some species also become quite large, with freakishly huge claws, but these are not those species. If there were any like those in Latak stream or in the Maliau's streams, they were too big for my traps. (That's what I like to think happened at Maliau.)

Detail of a map of Lambir Hills National Park
From the Sarawak Forestry website
The shrimp were caught with simple bottle traps consisting of a large water bottle with its top cut off and reattached so the mouth of the bottle was inverted to make a funnel pointing toward the inside of the bottle. (Traditionally people used bamboo traps similar in design but much bigger.) Cord attatched to these traps were used to secure the traps to the river/stream bank. Greg and Min-Sheng assisted me in making these, coming up with bait concoctions, and setting them up. The bait consisted of bread or crackers mixed with rotting fish/shrimp/squid and/or cheese and/or peanuts. These were set overnight in various areas of Lambir Hills National Park (none so far were found in traps at Maliau Basin, where small fish rather than shrimp seem to dominate as scavengers within the Basin, especially at Ginsing Camp).

Although the traps easily caught many shrimp extremely quickly (frighteningly easily, in fact) the most immediate scavengers seemed to be juvenille shrimp, which were hard to identify.
If traps were left out longer, the juvenille shrimp, which are territorial, would kill each other and become bait for larger, more mature shrimp. These mature shrimp would also end up killing each other, and if the traps were left out for even longer, the decaying shrimp would attract various fish species for Greg's taxon. Because of the limitations of using a trap to catch the mature shrimp, I have limited notes on their behavior and territory.
According to Iwata et al. (2003), Macrobrachium species seem to prefer different microhabitats within the same river, and there are at least three Macrobrachium species residing in freshwater streams in Sarawak, Borneo(1). However, because I could not find the characteristics of these species (M. neglectum, M. trompii, and M. pilimanus), I couldn't figure out which was which. "Wood Shrimp", or shrimp of the genus Atyopsis (distinguished by a different body shape and carapace form) also apparently reside in the same area, but I did not find them.

Last updated August 2008. Contact Justine at jschow88[AT]gmail.com.