Joewolfjfyi on some biological matters - the higher temperatures...

Joewolf

jfyi on some biological matters

- the higher temperatures in August is a positive in fact. Temperatures in the range of 14 deg/c - 18 deg/c biologically puts Atlantics in "the zone" where FCR and SGR are optimal.

Problems however arise when temperatures are above 18 deg/c and substantially arise when above 20 deg/c - can be catastrophic if not managed well. Dissolved or available oxygen is a function of temperature - decreasing the higher the temperature. Oxygen requirement is a function of fish size and fish size and farm biomass in the main are largest over the summer months.

The gill ameoba that Tasmanian Atlantics are affected by, whilst ever present proliferates most rapidly in higher temperatures. This gill ameoba seriously impacts the fishes ability to respire etc etc. So high temperatures, low DO, large fish, heavy on farm biomass and gill ameoba are the issue.

Feed the fish and their oxygen demand increases - if the oxygen availablity is already marginal, as a consequence of high temperatures, and you feed them then you have an O2 debt which causes death - magnified by the level of AGD infection they carry. Don't feed them and they lose condition - therefore shrink - which directly effects FCR.

These are not the only issues the higher top end temperatures promote.

I think you will find that the breeding program is targeting AGD resistant stock with a few other favourable traits as a bonus.

Note though that the farms in Macquarie are AGD free due to the brackish nature of the estuary however IMO this region is at risk of being pushed in the short term giving rise to other disease issues - which may already be apparent.

I recognise that TASSAL have significant 'warm' climate expertise - it is where they farm. Organise temps between 14 - 18 year round and they will be laughing.

I personally am unsure that an evolutionary cold climate fish can be selectively bred to be reliable warm climate stock in only a few generations.

I am also unsure that TGR can achieve worlds best cost of production - per Norway (seems to have been waved around for ever). They will have to change their farming infrastructure to achieve that. They will however be competative.

All IMO

Cheers

Waterfront