Before I get into what I saw, I figure it's useful to list what was happening with the water. I've seen plenty of people cancel a dive because the visibility looked low, or the temperature was down or the currents were strong, and in reality, all of these conditions effect where the fish go as well. So if we know what happens when those conditions turn up, and what it means for finding different underwater life, we, as divers can decide if it's a good thing, or a not so good thing, and chance our luck.
One of the persistent comments I hear when ever I'm diving in low visibility, and I use this very subjectively (as anyone who has learned to dive in a quarry will tell me 3-5m vis is good vis) is that they wish the visibility was better. In retort, the go-to expression used by most habitual low visibility divers is "Good visibility is great.... if you like looking at rocks" and sometimes I agree.
Temperature: 19 degrees, which is getting toward the cooler side of the annual range at this site.
Current: Running "reverse" or from the south to the north, along the deeper parts of the dive site, which is uncommon here. The surface water was warmer and running in the usual north to south direction.
Visibility: Where the surface water hit the Julian Rocks, an area of clean warmer (20 degree) water created localised 8-10m visibility. The deeper areas with cooler reverse current had approximately 4-5m visibility.
Swell: A 3-4ft swell created whitewash over parts of the shallower sections, surge was apparent at shallower (-10m) areas.
Ok, now that we have that out of the way, we get to the interesting part!
Those who have dove Julian Rocks many times will recount that, during the winter months, there are large numbers of snapper (Pagrus Auratus) and grey nurse sharks (Carcharhinus Taurus) and today certainly didn't disappoint that expectation. As well as the smattering of wobbegong sharks, surgeon fish, yellow and blue fusiliers that we saw; on the currents lee side (the northern side) there was a distinct absence of jewfish from the 'cod-hole' (Agryosomus japonicas) although I suspect they may shifted to the current front.
These were the highlights from a hydrological perspective: We had schools of pearl perch, really active in 12-14m. Along side them were venus tuskfish (Choerodon venustus) and my absolute favourite (and second ever sighting at Julian Rocks) a 3-4kg rusty jobfish. I usually find these fish far deeper than the 14m mark, however I've noted before that the cold reverse currents often bring the venus tuskfish into these areas. I had previously associated the rusty jobfish with more tropical waters, so it was also really interesting to see it at this latitude, this depth and this temperature. Looking forward to getting some pictures up, hopefully that should happen soon!