There were 2 principal fish faunas, one associated with the algal communities (average of 10.9 species per set) and the other with the open sandy seafloors (3.6 species per set). The silver trevally, Pseudocaranx dentex, the black-spot pigfish, Bodianus unimaculatus, and the comb wrasse, Coris picta, together tended to characterise the hard-bottom algal-dominated habitats. The Galapagos whaler shark, large stingrays (smooth, Dasyatis brevicaudata, black, D. thetidis, and blotched fantail, Taeniura meyeni) , and silver toadfish, Lagocephalus sceleratus, characterised the fauna on open sandy seafloors of deeper waters. These results are preliminary because of the small sample size. The majority of species had infrequent occurrence and as a consequence there were no clear species indicators recognised for the two groups recognised in this analysis.

Within these groupings, there were further, though reduced, differences with depth, although the lagoon site (L_2 with 3 species and 1 family not recorded elsewhere) was clearly separated on the depth gradient (Fig. 8). Twenty-five of the species recorded outside the lagoon were absent from the sandy, open seafloor compared with 10 species absent from the algal-dominated habitats on hard substrata. The Galapagos whaler shark, Carcharhinus galapagensis, was recorded from all sets and, on average, was also the most abundant taxa (average MaxN = 5 sharks per set). A maximum of 14 sharks was seen in one field of view when a large female Galapagos whaler scared the smaller ones off into the far field of view where they could be counted simultaneously.

Figure 8. Multivariate 2 dimensional biplot of MaxN abundance data from BRUVS sets. The fish communities were primarily identified as either associated with algae (closed circle) or not associated with algae (open circle), which were correlated with underlying substrata. The deeper (and sandy) sites supported different fish communities. The species shown were indicative of the respective fish communities. Note: 61% of the variation was explained by these 2 dimensions.

Ballina angelfish

One Ballina angelfish, Chaetodontoplus ballinae, was sighted NE of Balls Pyramid on a BRUVS set (BS3_5). The towed video imagery allowed identification of 12 individuals of this species from both Lord Howe and Balls Pyramid rises. It was seen inside the Commonwealth Sanctuary Zone (tow 10), the adjacent proposed State Sanctuary Zone (tow 9) and north of these abutting zones (tow 11). The Ballina angelfish was recorded in similar habitat NW of the island (tow 3) and South East Rock, SW of Balls Pyramid (tow 17). It occurred in the gorgonian gardens of the deeper waters SE of Lord Howe Island (tow 13), to the south of the island (tows 5 & 8 – 2 fish) and W of Balls Pyramid (tow 20 – 3 fish together) to a depth of 200m (Appendix 5). Coris bulbifrons and bluefish, Girella cyanea, were not abundant anywhere in the deeper waters and may be most common in shallow fringing reef areas not sampled by BRUVS.

This preliminary assessment of the fish faunas did not detect significant geographic variation in the fish assemblages. However, a number of species were restricted to one particular area. Most notably, the large red-throat emperor, Lethrinus miniatus, was sighted on 3 out of 4 BRUVS set to the west of the island, but nowhere else.

BRUVS sets in the Commonwealth Sanctuary Zone, east of Lord Howe Island, were made on hard substrata (BS2_2 & 2_5) and sand (BS2_6). A single set was made outside the northern boundary on hard substrata (BS2_1). The fish faunas from each showed affinities with those from elsewhere in the Marine Park. However, there was an apparent misclassification of station BS2_2, which was more closely associated with the sandy bottom communities. This was probably due to misrepresentation in the analysis of the surrounding habitat, as the species count (3) was exceptionally low for hard bottom communities found elsewhere.