The University of Sunshine Coast Marine Science team led by Dr Ben Gilby has presented its final analysis of three years of fish monitoring on and around the Pumicestone Shellfish Habitat Restoration site near Bribie Island, and the results are showing that the restoration effort not only increases attraction of fish but contributes significantly to an increase in productivity of the fishery.
Particularly exciting for fish populations is that, for the first time, there is now robust data which shows the value of the restoration work being performed in the area. The Pumicestone shellfish restoration project is the only subtidal shellfish habitat restoration project yet to be approved in Queensland, so it is hoped the positive correlations clearly shown in the three-year monitoring study will strengthen the case for future restoration work to be approved.
Shellfish beds can offer a range of marine ecosystem services including water filtration, shoreline stabilisation, marine biodiversity, and fishery productivity.
When the major restoration project started in 2016, its main objective was to enhance fish stocks which had been put under stress by a range of pressures including poor water quality, loss of fish habitat and increasing fishing pressures.
Twenty reef units of six different unit types have been installed as part of the project, including shell patch reefs, crates of shells, and a biodegradable matrix (BESE).
The research team has measured fish abundance and species diversity using baited and unbaited underwater cameras at the one-hectare Pumicestone shellfish habitat restoration site and at 106 monitoring sites spread evenly across the seascape to detect any fish ‘attracting’ effects. Monitoring was undertaken every six months for 30 months.
The headline items in the scientific report show:
- Fish assemblages at the restoration site were 3.8 times more speciose and had 16.4 and 10.7 times more harvestable fish and total fish abundance, respectively, than before restoration.
- Over time, few differences in fish assemblages were identifiable between the six reef unit types, however, this may have been because of the abundance of fish at the reef site.
- There was no significant change in the distribution of fish assemblages relative to the restoration site over time, thereby indicating no attraction effect of the reef.
The findings support the concept that shellfish reef restoration enhances fish abundance and diversity at restoration sites and that this is not always caused by a centralisation of fish at restoration sites.
In this study, we show significant positive effects of shellfish reef restoration on fish and demonstrate quantitatively for the first time how this restoration effort has a broader positive impact on the carrying capacity of an entire seascape.
This project is supported by Healthy Land and Water, through funding from the Australian Government’s National Landcare Program, Pumicestone Passage Fish Restocking Association, Moreton Bay Regional Council, Boating Camping Fishing (BCF) through OzFish Unlimited, and Unitywater.
Significant in-kind support came from OzFish volunteers in their oyster gardening project, shell recycling, and invertebrate monitoring, the University of the Sunshine Coast, SunFish, Ngunda Joondoburri Land Trust and Kabi Kabi First Nation.
Article “Turning the tide on fishery productivity: final analysis confirms restoration efforts working” published 24 November 2020.
Full report added 18 December 2020.