I think the weights are given in kilos Alan (ie. HF was 1.396 kg - or 1396g) - the winning bag of 18 fish would have a hard time being size for 5.905lb but at 5.905kg (or about 13lb) it would seem to make sense. This would mean the winning fish was a whisker over 3lb.
I must admit the metric weights do my head in as well!
Gary