UPON reading an article in Fisho recently on frozen bait (December 2022 edition), I was struck by how times have changed. Twenty to thirty years ago around 80% of the seafood you could buy in the shops was locally produced in Australia. However, today, due to globalisation of trade, around 80% of seafood in supermarkets is most likely imported from various international locations. This situation has several consequences, particularly for biosecurity. Products which have been cooked are generally OK and pose little biosecurity risk because the high temperatures tend to kill or inactivate microbial disease agents like bacteria and viruses. However, if the product is uncooked, the chilling or freezing process tends to preserve, not kill, microbial disease agents.
These preserved microbes may remain viable after long periods of freezing, and even after one or two freeze thaw cycles, which makes them a biosecurity threat at their destination. Indeed, it is widely accepted that frozen imported seafood has caused several disease incursions into Australian waters in the past. The huge pilchard kills that occurred along Australia’s entire southern coastline in 1995 and 1998 were probably due to a herpesvirus that was introduced into Australia with frozen pilchards imported to feed tuna in South Australia. More recently, the incursion of White Spot Syndrome Virus (WSSV) into South East Queensland followed a biosecurity breach at the international border where greedy unscrupulous seafood importers circumvented quarantine regulations liberating thousands of tonnes of heavily infected frozen prawns into Australian supermarkets.
Having diseased imported uncooked prawns on retail sale is one thing, but it gets worse. From there, surveys have shown that between 20 and 25% of recreational anglers in SE Queensland use supermarket bought frozen uncooked prawns as bait. This means they were placing the infected imported prawns directly into our local waterways. In the case of Moreton Bay it appears that this is the most likely process by which white spot disease outbreaks emerged in not only aquacultured prawns, but also wild prawns and crabs sampled along the Logan River and in Moreton Bay.
Clearly these poignant lessons show that use of any frozen imported seafood as bait is potentially dangerous for our environment, fisheries and aquaculture industries. This is due to risks from not only WSSV, but several other known and new/emerging diseases of fish and crustaceans that we do not have in Australia at present.
What makes things difficult for recreational anglers is that the consumer is seldom, if ever, properly informed that the product sold in the supermarket is only intended for human consumption and should not be used as bait. Also, country of origin labelling at the retail point of sale in supermarkets is notoriously unreliable and can depend on which staff are rostered on for any given day.
Current biosecurity risk analysis by the Australian Federal Government is also technically inadequate – unfortunately we can’t rely on them to keep out a range of new aquaculture diseases which continue to emerge overseas. The contrast between the situation with imported seafood and the rapid Federal Government response to the recent foot and mouth outbreaks in Indonesia is stark.
All of these factors mean that, if readers can take home just one message from all of this, it is please do not use any supermarket bought frozen seafood as bait. Purchase your bait from local bait suppliers, or even better, collect your own before or during your fishing trip.
Pic. The massive 1995 and 1998 pilchard kills along Australia’s southern coastline were due to a herpesvirus which probably arrived in Australia in imported pilchards. If you care for our marine environment, please not use any supermarket bought frozen seafood as bait.
