Fish Farming Enigma.

When the first human beings appeared on this planet they adopted a " hunter gathering " lifestyle.  Food was where they could find it and they often went hungry.  It took centuries before they managed to domesticate some animals and learn to plant seeds to replicate crops. Gradually they learned to farm the land and hence agriculture became the corner stone of life as we knew it.

The other great food source was the sea. Those dwelling near the coastline learned how to catch fish and eventually how to build boats that would take them far from land.  In todays world giant fishing boats from a variety of nations roam the oceans and there is a fear that what they are catching is exceeding sustainability levels. Nations enjoy protected fishing rights in the waters immediately adjacent to their shoreline - but the high seas have no owner.

It was probable inevitable that the farming methods used on land would eventually spread to the sea.  Some clever people discovered how to farm fish by keeping them in giant cages in sheltered offshore waters and this is now a growing industry in most parts of then world.  Here it is particularly prevalent in Tasmania.

Salmon are an ideal fish for this type of farming.  Giant metal cages are established offshore with a double outer perimeter to ward off predators and these are stocked with " fingerlings " which quickly grow in size.  These growing fish are fed a diet which usually consists of offal from slaughterhouses and the waste catch from the regular fishing industry.  There is a high density of fish in these cages and their waste settles on the ocean bottom, requiring the cages to be moved to new locations on a regular cycle.


Unfortunately when animals of any type are massed in close proximity to each other this proximity is an incubator for many types of disease and this is prevented by regularly treating them with an antibiotic.  In fact, agriculture in all its forms absorbs a vastly greater amount of all the antibiotics produced than used in the treatment of humans.

Alarm bells are ringing because this over use of antibiotics is allowing many diseases to gain immunity and we are in danger of having superbugs emerge that will be beyond our ability to control. Diseases that were once fatal but long under control may reappear and a mere scratch that is of little consequence today could become life threatening.  It is imperative that we reduce this mass use of antibiotics in agriculture.

Statistics from the fish farming industry in Tasmania are alarming.   The biggest salmon company quadrupled its use of antibiotics between 2012 and 2015.   It used 301 kilograms in total, which represented 9.8 grams per tonne of fish.   This is in contrast to other fish farms which managed to reduced the amount of antibiotics as a control measure.


The company reports that use fluctuates from year to year, depending on what the fish require to be kept healthy.  Some diseases are seasonal and wax or wane according to weather conditions.  It seems that these intensive farming methods are not sustainable without such measures to keep disease under control.

Ensuring that salmon and many other delicacies are reliably and consistently on sale in the food markets comes at a price.  We can only hope that drug research can fill the gap as the old antibiotic standbys become ineffective for humans.