Restoring Shellfish Reefs in Pumicestone Passage.

Transcription

1 Restoring Shellfish Reefs in Pumicestone Passage. Anglers and community working together for fish habitat WRFC8 18 Jul 2017 Victoria, Canada. Ben Diggles, PhD 1

2 Co-authors Fred Palin, (Joondoorburi Elder, Traditional owner) Philip Kraus, Kerry Jones (Traditional owners) Carlo Sain, (Pumicestone Passage oyster grower) John Daley, Mark Higham, (Pumicestone Passage Restocking Association (Fishing club) Joel Bolzenius, Susie Chapman (Healthy Waterways and Catchments) Jaquie King, (Banksia Beach State School) Rob King (Sunfish local recreational fishing representative group) Neil Tindale (University of the Sunshine Coast) 2

3 Shellfish in Moreton Bay East Coast GBR Brisbane Moreton Bay 3

4 Moreton Bay Pumicestone Passage Subtropical Moreton Bay Brisbane embayment (27-28 S) 100 miles nth-sth 1523 km2 (1/7 Chesapeake) Catchment >75% cleared since 1823 Pop n >3x106 4

5 Shellfish in Moreton Bay - History Thousands of years of sustainable use by coastal indigenous groups including culture of Sydney rock oysters (Saccostrea glomerata) in Moreton Bay. After European settlement in 1823, shell from indigenous middens (discard piles) used to make road base or burnt for lime to make mortar for buildings in early Brisbane. By end of 1880s Moreton Bay oyster industry was intensifying by enhancing oyster banks and subtidal reefs with spat from central QLD. 5

6 Shellfish in Moreton Bay - History Intertidal bank, Toorbul Point,

7 European exploitation First problems with dredge sections occurred after multiple floods during LaNina period of Peak of production in 1891 (21,000 sacks, approx 1890 tonnes). Subtidal oyster reefs smothered by silt mudworm disease outbreaks problematic by Production of dredge oysters declined to 0 by 1940 s, bank oysters down to < 10% of peak by 1981, and have not recovered. 7

8 Decline began in early 1890s 8

9 Changing ecosystems in SE QLD Intertidal bank, Toorbul Point, Pumicestone Passage 1906 vs , prolific oyster recruitment on clean intertidal rocks , algal turfs trap resuspended sediment, preventing oyster recruitment 9

10 Case study Pumicestone Passage 10

11 Case study Pumicestone Passage Historically, Sydney rock oysters were massively abundant in Pumicestone Passage. Early settlers in the mid 1800 s described subtidal oyster reefs down to 12 feet below low tide and intertidal reefs 300 yards long. But today subtidal oyster reefs are extinct and around 96% of oyster zonation has been lost. Investigations suggest underlying cause is due to recruitment failure from poor water quality and habitat change. Disease (QX) is the symptom, NOT the cause. Increased mud = increased disease risk. 11

12 SRO in Pumicestone Passage Pale digestive gland, gill lesions S. glomerata clumps Ningi Creek, 2011 Heavy QX infections 12

13 SRO in Pumicestone Passage Legacy oyster furniture, Ningi Creek,

14 Changing ecosystems in SE QLD Subtidal shellfish reefs functionally extinct in SE QLD (Beck et al 2011, Diggles 2013) Evidence from middens and remnant reefs suggests reef forming shellfish species historically included: Sydney Rock Oyster (SRO, S. glomerata) Hairy Mussel (Trichomya hirsuta) Pearl oysters (F. Pteriidae) including Leaf oysters (Isognomon ephippium) Pinctada spp., including P. albina sugillata 14

15 Southern QLD species Sydney Rock Oysters Saccostrea glomerata bank and remnant subtidal reef, Ningi Creek,

16 Southern QLD species Hairy Mussels Trichomya hirsuta, amongst SRO clumps, Sandstone Point

17 Southern QLD species Family Pteriidae Leaf oysters Isognomon ephippium on rocks in Pacific Harbour canal,

18 Southern QLD species Family Pteriidae Juvenile pearl oyster Pinctada albina on experimental reef module,

19 What can be done about it? Obviously catchment management that reduces inputs of sediments, nutrients and urban pollutants is important - working with Catchment managers. Recreational fishing groups want to contribute on the water working with oyster growers on proof of concept micro-trials. Results: Natural SRO recruitment still occurs in subtidal areas if appropriate substrates provided. These data suggest restoration of subtidal shellfish reefs is feasible in Pumicestone Passage if appropriate interventions/innovations are made. 19

20 Why restore shellfish reefs? Assimilate 283% more nitrogen than mud or sand banks Generate 1300% to 10,000% more fish and crabs than mud banks 20

21 Why restore shellfish reefs? Snapper (Pagrus auratus) (Sparidae) 21

22 Why restore shellfish reefs? Anglers learning where their fish come from. 22

23 Shellfish Reef Restoration in Australia Following 20+ years behind efforts overseas, shellfish reef restoration efforts finally started in Australia in A National Shellfish Reef Restoration Network is established. Projects in all states. 23

24 Shellfish Reef Restoration in Australia 24

25 Local community support Pumicestone Passage Restocking Association (recreational fishing club) has been looking for ways to improve fisheries in Pumicestone Passage for over a decade. Initial emphasis on restocking fingerlings. Now habitat restoration is the aim, support has come from traditional owners, local environment groups, catchment management groups and local and State governments. 25

26 Financial support Pumicestone Passage Restocking Association committed $30,000 towards shellfish reef restoration, matched by grant monies and dollar for dollar funds from local government. 26

27 Preliminary Trials

28 Preliminary Trials SRO recruitment onto shell substrate placed subtidally increased with depth below low tide mark % more invertebrates and 1000 s of fish embryos deposited onto SRO shell substrate placed subtidally compared to intertidal controls. 28

29 Preliminary trials /16 29

30 Preliminary trials / Recorded 2600% more invertebrates in shell substrate placed subtidally vs intertidally s of fish larvae again deposited onto SRO shell substrate placed subtidally 30

31 Preliminary trials = Promising results 31

32 Developed a Project Progress website. Trial restoration sites identified. 32

33 Project Progress Bathymetric surveys completed. Video transects completed. Reef design and engineering underway (site 1). 33

34 Related projects - Oyster gardening 34

35 Related projects - Oyster gardening Australia s first oyster gardening initiative is underway in Bribie s canal systems. Aim is to grow live oysters to add to trial restored reefs template for success from overseas. 35

36 Related Projects - Oyster shell recycling Recycling oyster shells to reclaim from landfill for eventual use as shellfish reef substrate. Involvement with local restaurants and schools. 36

37 Related Projects - Oyster shell recycling Local and State Government Support 37

38 Restoring shellfish reefs Recreational fishers behind all of these projects working with local communities to restore lost fish habitat. Questions? 38