The Hauraki Gulf is on the verge of collapse according to a new report “State of the Gulf 2020.”
The report warns little progress has been made since the Hauraki Gulf Marine Park was established 20 years ago. Destructive commercial fishing methods, more people, more coastal development and climate change give no reason for optimism and reversing the downward trend.
The report said the balance was tipped in favour of “development and utilisation” rather than the environment.
Decades of destructive fishing methods have depleted the fishing biomass today to 50 percent of 1925’s level while destroying the habitat and pushing large areas towards becoming “kina” wastelands.
Fish numbers are a fraction of past levels. Trevally numbers are 86 percent from original “virgin biomass” levels, snapper 83 percent, sharks 86 percent and dolphins a staggering 97 percent.
Sediment now muddies the clear water, smothering shellfish and invertebrates with silt.
Dredging has devastated the seafloor of all its mussel beds – crucial for filtering the water – reduced scallops to alarmingly low levels while crayfish are rated “functionally extinct”.
The report highlights the ecological food chain and flow-on effects with declines in crayfish and snapper – predators of kina – leading to an increase in the “kina barren”.
Kina eat kelp and other algae and when no longer “controlled” by predators, multiply and strip kelp forests to bare rock.