The single Offshore zone includes all offshore waters within the Wet Tropics NRM marine region. The Offshore zone extends east from the boundary of the mid-shelf water to the boundary of the Great Barrier Reef Marine Park, and is bordered north and south by the Wet Tropics NRM marine region.

Water quality in the Offshore zone is less affected by plumes of sediments, nutrients and pesticides from river discharge than the inshore zones due to its distance from the land. The closest point on the mainland to the offshore zone boundary is Cape Kimberley, just north of the Daintree estuary, at a distance of approximately 14 km, whilst the boundary is typically a minimum of 20 km from the mainland.

The Offshore zone includes numerous coral reefs, 15 of which are included in the offshore coral surveys for the Report Card. Unlike the inshore zone where coral reefs often occur in the shallow fringing waters of continental islands, the coral reefs in the Offshore zone predominantly grow on limestone platforms that are relics of past phases of reef growth. These coral reefs provide habitats for an immense diversity of organisms including hard and soft coral species, ascidians, bryozoans, molluscs, fish, turtles and marine mammals.

Scroll down for further detailed results for each indicator group.



very good








very poor

insufficient data

Confidence surrounding the data used in the circle diagrams has been assessed using a multi-criteria framework.


Water quality

Hover over each segment for indicator scores and data confidence.

The overall water quality grade in 2015-16 for the offshore zone is ‘very good’.

Water quality grades are based on water quality guideline trigger values established for the waters of the Great Barrier Reef Marine Park that, if exceeded, identify the need for management responses. The guidelines are not targets or assessments of pollutant loads entering the marine environment. The results are from remote sensed water quality indicators of offshore waters sourced from the eReefs Marine Water Quality dashboard provided through the Bureau of Meteorology.

The sediment score of 99.1 (‘very good’) in the Offshore zone is comprised of a total suspended solids (TSS) score.

The chlorophyll a score in the Offshore zone is 99.7 (‘very good’).

These grades have remained consistent with those of 2014-15 and very little change in the scores have occurred.


Hover over each segment for indicator scores and data confidence.

The overall coral grade in 2015-16 for the Offshore zone is 65 (‘good’).

The coral grade is comprised of the density of juvenile hard corals score of 93 (‘very good’), the coral cover score of 51 (‘moderate’) and the coral change score of 53 (‘moderate’).

The scores are very similar to those from 2014-15. The coral grade for 2015-16 is ‘good’ since surveys occurred before major bleaching events occurred. 2016-17 will include effects of bleaching. Coral juveniles are less susceptible to bleaching so whilst some decrease in coral cover can be expected this may not impact the number of juveniles. Following a coral bleaching event it will take several months to determine if recovery is possible, since bleached coral can remain alive.


Hover over each segment for indicator scores and data confidence.

The fish index is currently under development and will be available in future report cards.


Further information on the methods used to produce the scores and grades and detailed results can be found here.