My goodness, that fish swam a long way from California! Is it true that they get over 45kg down under? In California, an 18kg yellowtail is considered huge.
I think alot of Texans would look at your fish and say it was an amberjack ... and our kingfish is very closely related to your narrow-barred mackerel (although you folks also call narrow-barred mackerel by the name 'spanish mackerel', and spanish mackerel out here are little bitty fish ...). Then again, y'all call grouper by the name of 'coral trout' and I don't know what names you use for real trout.

Regardless, thats a very nice catch & it looks like loads of fun on the jetski!!