Stone fish traps are among the most ancient of structural harvesting techniques. The fact that the oldest known manmade structure on the planet is a fish trap should tell you something about their ability to provide protein.
A series of hand laid stone barriers and ponds have been dated back to a period of 40,000 years ago. The traps stretch across a bend of the Barwon River near Brewarrina in New South Wales and were in use until 1968. A concrete weir was put in place to create a reservoir of water for the local area, which was prone to drought. It did prevent drought but it also put an end to the travel of fish upstream, and that stopped the regular catching of fish in the traps.
Finally, in 2012 a fish ladder was installed that allowed the weir to be bypassed by spawning fish, and once again the traps are in use, allowing locals to harvest perch, Murray cod, black bream and other species.
Traps are frequently repeated. River weirs or traps require shallow water. If a shallow stretch of river occurs, you might as well make the best of it. See the image below.
This image from the Darling River in New South Wales provides a different example of multiple trap placement.
In the image above, fish enter from the upstream side and are funnelled down into the narrow catchment area to the left or downstream end of the trap.
Stone fish traps come in different types and styles. Those found on rivers or shallow areas in lakes typically serve the purpose of funnelling fish into smaller and smaller areas where they can be grabbed, netted or speared.
One of the most unique stone fish traps of the world is to be found in Penghu County, Taiwan.
Designed to take advantage of the daily changing tides, with this trap it is easy to see how fish coming ashore with the rising tide are funnelled into the catch area and can be much more easily be harvested as the water recedes. It is only necessary to visit the stone trap at specific times of the day to take advantage of it’s working.
The stones form a broad walkway over a meter wide and can handle the daily tide change and even heavy seas.
It is not uncommon for a narrow strait to separate two sections of land. When the tides flow into and out of the strait, depending on the rise or fall of the land, simple weirs can provide traps to catch ocean creatures.
It is not hard to extract principles of operation from these examples. Using moving water to assist in concentrating fish numbers into smaller areas or to strand them completely makes it far easier to harvest them. All that is required is access to shallow stretches of water or tidal flats and portable stones.
Of course, fish traps can be made in multiple ways. In future posts I will cover both older and contemporary techniques of fish trap manufacture. Check back again for more info. Fish Harvesting
