Hoppers
The Australian trawl hopper is a container/tank on the back deck of a trawler that holds the catch prior to sorting in sea water. The device enables prawns and other target species to be sorted from by-catch naturally. For larger vessels some models use a conveyor belt to gather the prawns and deliver them to deck hands to be classed and packaged. In the case of hoppers for smaller vessels, conveyor belts are not always used and sorting is undertaken either manually or facilitated by moving the hopper tray bottom up as more product is sorted.
Hopper devices have arisen from industry innovation to enhance product-quality and cost-efficiency, with successful sea-trials in north Queensland. They contribute significantly to improving short-term by-catch survival, produce less mortality and discard by-catch to sea in the shortest time. Those who have already incorporated a hopper into their practices have reported a 5% to 10% increase in catch quality which is reflected in increased revenue per kilo of catch. Improved product quality is achieved as the catch is held in sea water, allowing prawns to rest, return to normal colour, be washed and remain fresh and lively. In addition, use of hoppers has proven to reduce the processing time and in many cases the number of crew required for processing.
Small Hopper Designs
The general perception of hoppers is that they are large, heavy auxiliary powered systems designed for vessels greater than 18 metres in length containing moveable trays, a large tank with hydraulic conveyor belt systems covering on average, 4.5 cubic metres. However, smaller hoppers have been successfully designed and trialled for small to medium vessels (12-18 m in length), and very small vessels (less than 12 m).
Movie - Small Hopper Example
See also: By-catch Project Queensland - Small Hopper Devices
OceanWatch and Fisheries Research and Development Corporation (FRDC) have produced a handbook for fishers detailing the design, operation and use of hoppers in trawl fisheries across Australia. Click on the following link to the Australian Natural Resources Data Library to download a copy of Hoppers in Australian Trawl Fisheries - A handbook for fishers (PDF)* or order a hard copy by visiting the OceanWatch web site or contacting the By-catch Project team.
* Requires Acrobat Reader
Last updated: 20 February 2009