Preparing fresshwater crayfish for market
In order to obtain the best price for freshwater crayfish, you must ensure the best quality. How live crayfish are handled to prepare them for the market is of utmost importance in ensuring their survival during transport. Some important points to remember are listed below.
Gill washing
When crayfish are lifted from the water, they clamp the cover of their gills shut. This traps muddy bottom-water in the gill chamber that is loaded with bacteria that can pass across the gills and cause infections.
To remove this water, the crayfish must be held for two to three minutes in clean water to allow them time to relax their breathing and clear the gill chamber. Gill washing can be performed by either holding the crayfish in the upper layers of dam water (at least six inches below the surface if the dam is clear and the top layer is warm), or by placing them in a tub of clean dam water.
Damaged or unsightly shells
Freshwater crayfish harvested from dams can suffer imperfections that are often unacceptable to the consumer. Crayfish with missing limbs, stains or blemishes on the shell can be sold as seconds.
Grade the fish carefully and do not mix the damaged ones with the top quality product. If seconds are not required, return the lower grade animals to the dam, where they can moult and regenerate new limbs. Crayfish that have just moulted have soft shells and these should also be returned to the dam to avoid damage or death during transport.
External fouling organisms
It is not uncommon for freshwater crayfish to have small parasites living on their shell (see section on Epistylis and Temnocephala).
Aeration should be provided and rinse the crayfish in freshwater after treatment. However, salt water bathing will not remove the eggs of these parasites and if the crayfish still look unsightly, return them to the dam and leave them to moult.
Purging
It is important that crayfish be purged to remove any food from their gut that might affect their taste, or their ability to survive transportation. The animals should be left in clean flow-through tanks for a minimum of 48 hours, during which time they are not fed.
Flow-through systems have an advantage over recirculating systems, as the water carries the waste away and this prevents build up of toxic substances that may cause mortalities or alter the flavour of the crayfish. Biological filtration systems can be used when water is not readily available but caution should be exercised ( see notes on biological filtration).
Please note
It is preferable that all procedures carried out when preparing freshwater crayfish for the market, such as trapping, gill washing and purging, be performed in the coolest part of the day to minimise temperature stress on the animals. Care should be taken to shade the crayfish from direct sunlight, to avoid eye damage.
These are just a few tips that, if followed, may help you successfully transport your crayfish and minimise losses. It is up to the individual to ensure that the product he or she is marketing is of the highest possible quality and in this way ensure the continued success of the industry.
It is important to handle your animals gently; they are living creatures, not lumps of rock, and are just as susceptible to stress and injury as the people farming them.
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