Category Archives: Hauraki Gulf conservation

Seachange Tai Timu Tai Pari Launched

The first marine spatial plan for New Zealand, which applies to the Hauraki Gulf was launched last night at an event in Auckland. The plan has been developed by a collaborative stakeholder working group, representing key interests, and provides a roadmap for restoring the Gulf to a healthy, abundant and productive marine area.

At the heart of the plan is the need to restore healthy habitats and water quality to support abundant marine life including fisheries as well as taonga, such as seabirds and marine mammals. The plan includes several initiatives to achieve this, including:

  • Transitioning trawling, dredging and Danish seining out of the Hauraki Gulf Marine Park. These fishing methods can cause additional damage to seabed habitats, they remobilise sediment, and they prevent recovery from historic loss.
  • Setting catchment-based sediment and nutrient limits and deploying a range of tools to modify land use and re-engineer natural systems so that they can be met.
  • Removing harvest pressure from some areas through the establishment of Type 1 MPAs and seabed-damaging activities from additional areas through Type 2 MPAs.
  • Scaling up efforts to actively restore marine habitats including through shellfish and seaweed restoration, habitat creation and the like.

The plan also supports increased abundance of marine life through a series of actions such as reviewing harvest levels of priority species, protecting vulnerable species from over-harvesting, decreasing mortality of under-sized fish, reducing pressures on threatened species and addressing marine biosecurity risks.

The plan provides support for marine-related industries including Aquaculture, through the provision of suitable marine space for growth; Commercial Fishing, through support for a high value, low impact industry; and Tourism and Recreation, through improved abundance, access, place-based management and visitor strategies. In particular, the plan supports Recreational Fishing through increasing the abundance and local availability of fish.

In addition, the plan seeks to inspire local communities through engaging hearts and minds, embracing volunteering and expanding marine education.

Underpinning the plan is the need for strengthened management and governance arrangements. These include the establishment of:

  • Ahu Moana local management areas, jointly managed by mana whenua and local communities.
  • Fisheries Management Area for the Hauraki Gulf Marine Park and a Multi-stakeholder Fisheries Advisory Group to provide recommendations directly to the Minister.
  • A new overarching Governance Entity that embraces co-governance and will champion the Hauraki Gulf Marine Park and the implementation of the plan.

Further details on the plan can be found here.

Sediment kills marine life

The removal of indigenous forest cover from most of the land draining into the Hauraki Gulf has resulted in around five times more sediment entering the marine area. After heavy rain it is common to see plumes of sediment billowing out from river mouths where they meet the sea.

Harvested forest behind kawakawa bay
Forestry harvesting can release large quantities of sediment into the sea while the soil is exposed. Shown here are recently harvested hills behind Kawakawa Bay.

Current major causes of sediment are earthworks, forestry harvesting and grazing of steep erodible land. Erosion of river banks is another significant source.

Earthworks at Snells Beach
Earthworks can generate a large amount of sediment which can be washed into waterways and the sea when it rains.

This increase in sediment has been accompanied by the expansion of mangroves in many estuaries around the Hauraki Gulf and most markedly in the Firth of Thames.

Mangroves at Meola Creek
An increase in sediment entering the marine area has resulted in the expansion of mangroves in many estuaries. Shown here are mangroves in Meola Creek.

High levels of sedimentation can fundamentally change the marine environment. Sediment reduces water clarity and can result in the loss of species reliant on photosynthesis such as seagrass and seaweeds.

Murky water can make it harder for juvenile fish such as snapper to find prey and reduce their ability to survive. The sediment can also cause their gills to deform.

Particles in the water can make it difficult for filter feeders such as cockles, pipi and scallops to feed efficiently and it reduces the survival chances of larvae and juvenile shellfish.

Scallops at Otata
Sediment in the water, makes it difficult for filter feeders such as scallops shown here, to survive.

Overall, high levels of sedimentation reduce the abundance and diversity of species and the ability of the marine system to support productive fisheries.

“I’ve seen water going past the Whitianga wharf yellow with clay from what appeared to be forestry runoff.”

“Every time we have a Coromandel downpour, if you stand up on Shakespeare Cliff, you see an enormous brown plume coming down the Purangi and Whitianga rivers and flowing right out into the bay.”

Juvenile snapper have an ‘ecological bottleneck’

Scientists have identified an ‘ecological bottleneck’ in the ability of juvenile snapper to survive into adulthood. Research has shown that young snapper prefer three-dimensional habitats on the seafloor, particularly seagrass meadows but also horse mussel and sponge beds. It is not known why these areas are preferred, but it is thought that they provide a good source of food, protection from predators and shelter from seawater currents (reducing the need to expend energy to swim against them).

Seagrass Cavalli Islands
Seagrass meadows provide important habitat for juvenile snapper and other small fish and increase their changes of surviving into adulthood.

If there is not sufficient area of these habitats available, particularly in places close to important spawning areas, then this creates an ‘ecological bottleneck’ and the survival rate of juvenile snapper is likely to be lower. This has a flow on effect for fish stocks as it reduces the number of snapper that are recruited into the fishable adult population.

In the Hauraki Gulf, the majority of these habitats have been lost over the past 170 years, through a combination of increased levels of sediment and other pollutants entering the marine area from land, and direct damage from reclamation, harbour works, trawling and dredging. Habitat loss is still occurring in important fish nursery areas such as the Mahurangi Harbour.

Mahurangi Harbour
Habitat of importance to juvenile fish is still being lost in the Mahurangi Harbour, as a result of high levels of sediment coming from the land, including horse mussel beds.

Loss of seagrass

The Waitematā harbour was once host to enormous seagrass  (Zostera) beds which played a crucial role in providing habitat for juvenile fish. However the extensive harbour works, including port development and reclamations, had considerably reduced the seagrass beds by the 1930s. Then the remaining areas were virtually wiped out during the 1940s by an outbreak of fungal slime.

Waitemata harbour bridge
Port and waterfront development in the Waitematā harbour has contributed to the loss of extensive seagrass beds in the area.

The Tāmaki Strait was also an area with hosted seagrass beds. The steam trawler Doto, chartered by the government to do exploratory trawling in the Hauraki Gulf during 1901, found a net they hauled up after trawling along the Tāmaki Strait full of ‘grass and weeds’, indicating the extensive seagrass beds in the area.

Tamaki Strait looking from Waitawa Regeional Park
There is evidence that in 1901 there were extensive seagrass beds in the Tāmaki Strait, shown here from Waitawa Regional Park.

A major cause of seagrass loss is sediment from land development washing into the sea. When the health of a harbour or estuary deteriorates, seagrass is one of the first things to be lost. And with the seagrass beds goes part of the ability of the marine system to produce fish.

“If the sub tidal seagrass is lost, then juvenile fish production goes with it. It has a cascade effect.”

One of the few places with remaining seagrass beds in the Gulf is Huruhi Harbour at Great Mercury Island.

Huruhi Harbour, Great Mercury Island
One of the few places sub tidal seagrass beds can now be seen in the Hauraki Gulf is at Great Mercury Island.

 

 

 

 

 

 

 

Snapper at risk?

Snapper is the predominant fish species in the Hauraki Gulf and it is also one of the most widely studied fish species in New Zealand. Snapper are slow growing and long lived, potentially reaching up to 60 years of age and 17 kilograms in weight.

The adult fish are extremely productive. They spawn many times over the warm summer months, with smaller fish producing tens of thousands of eggs and larger fish producing several million eggs, each season. The older fish are therefore important for their spawning potential. As well as producing many more eggs, their eggs are larger, which likely improves the survival and growth of their offspring.

Recent research has identified a significant difference between snapper that live around shallow rocky reefs and those that live further afield. The reef-based snapper appear to be largely residential and therefore they are susceptible to being fished out of local areas. In contrast, snapper that live over soft areas of seabed range much larger distances and are therefore more resilient to localised depletion. This suggests that fishing off reefs should be undertaken with care.

Snapper in kelp Leigh marine reserve
Snapper that live around rocky reefs are largely residential and therefore are easily fished out and slow to replenish.

One of the most direct threats to a healthy snapper population in the Gulf is overfishing. It is thought that harvesting reduced the snapper population to as little as 10 per cent of its original size in 1988, before it increased to around 24 per cent in 2010, and then again went into decline.

snapper in slurry
Overharvesting by recreational and commercial fishers is one of the biggest threats to the snapper population in the Gulf.

Habitat degradation from sedimentation and bottom disturbing fishing practices such as trawling have also likely affected the ability of the snapper population to rebound. This is due to the loss of habitats such as sea grass, shellfish beds and sponge and coral gardens which enable juvenile fish to survive into adulthood.

Sediment from earthworks in Beachlands
Sediment from earthworks, as shown here in Beachlands, degrades the marine environment and reduces its ability to produce harvestable sized fish.

Hunting humpback whales

Humpback whales used to regularly pass through the Hauraki Gulf during their migrations from Antarctica to the tropics and back. Whalers named them ‘humpback’ because of the way the animals arch their back before diving, which profiles the hump around their dorsal fin.

The relative abundance of whales in the Gulf led to the establishment of a shore whaling station in Whangaparapara Harbour, Great Barrier Island, in 1956. Two specially-built petrol-engined chasers, fitted out with harpoons, were used to catch the whales. The whales were then towed back to the factory and cut up into hunks to be boiled down. The oil was skimmed off the top of the liquid for sale and the solids were processed into blood and bone fertiliser. The baleen was dumped at sea. Some of the higher quality whalemeat was sold to restaurants in Auckland.

The 1960 season proved the most profitable with 135 whales caught. But then the population crashed and the whaling station was closed 2 years later.  As well as being hunted in the Gulf and elsewhere around New Zealand the whales had been targeted in Antarctica by Japanese, Russian and Norwegian factory whaling ships. The remains of the old whaling station can still be seen in Whangaparapara harbour.

Whangaparapara whaling stationIt was many years before humpback whales were seen around New Zealand’s coasts in any numbers. But now that the hunting of the whales has stopped, we are likely to see many more of these magnificent animals frequenting the Gulf again.

 

 

Recreational Fishing Park for the Gulf a good idea?

Read a Dialogue piece in today’s NZ Herald by Sue, Rod and Zoe Neureuter, the family who acts as guardians of the Noises Islands. Sue Neureuter’s personal Story of the Gulf features in The Story of the Hauraki Gulf.

“Creating a fishing park in a region in such alarming decline brings division where the opposite is required write Sue, Rod and Zoe Neureuter.”

Sue Neureuter on her boat at the Noises Islands
Sue Neureuter on her boat at the Noises Islands.

Hauraki Gulf’s special whales

A group of Bryde’s whales have chosen the Hauraki Gulf as a place to live all year round and as somewhere to bring up their calves. This is unusual for a whale species, as most migrate from the tropics to the polar regions each year. We are very lucky to have a population of whales right on Auckland’s doorstep and we need to look after them.

View this fantastic drone video of the Bryde’s whales in the Gulf taken by AUT scientists.

Bryde’s whales are small baleen whales that can often be seen feeding amongst seabirds and dolphins in large ‘boil ups’ of fish in the Hauraki Gulf. The population is considered to be threatened, being listed by the Department of Conservation as “nationally critical”.

The whales used to be hunted, with 19 animals being taken at the whaling station at Whangaparapara, Great Barrier Island during the 1960s. However, Bryde’s whales do not produce much oil so they were not targeted in the same way that humpback whales were.

Old Whangaparapara Whaling Station
19 Bryde’s whales were taken at the Whangaparapara whaling station on Great Barrier Island during the 1960s. The remains of the old whaling station, shown here, can still be seen in the harbour.

The biggest risk the whales now face is being hit by the large ships that transit the Gulf to enter the Port of Auckland. The shipping lanes cut right across the areas where the whales spend much of their time, and if they are hit by the large hulls travelling at high speed, the whales have little chance of surviving. A total of 18 whales are known to have died from ship strike in the Hauraki Gulf since 1996.

Container ship leaving the Port of Auckland
Large ships are a risk to whales if they travel at fast speeds transiting through the Hauraki Gulf. If the ships slow down to 10 knots or less that risk is significantly reduced.

Responding to this issue, in 2013, Ports of Auckland issued a voluntary protocol that advised ships to reduce speed, where possible, when transiting through the Gulf. At speeds of 10 knots or less there is a much higher chance that the whales will survive a collision. Since the release of the protocol, speeds have been reducing and are now on average less than 11 knots. There has only been one recorded whale death from ship strike, on 12 September 2014, since the protocol was put in place.

Bryde's whale Transit Protocol page 1 Bryde's whale Transit Protocol page 2

‘Goat Island’ Marine Reserve World First

The marine reserve surrounding Goat Island near Leigh, called the Cape Rodney-Ōkakari Point Marine Reserve, was the first no-take marine reserve in the Hauraki Gulf, in New Zealand and probably in the world. It was established in 1975 after a long campaign by scientists at the Leigh marine laboratory.

The idea was first mooted in 1965 by Professor Valentine Chapman who suggested that the scientists needed a place where their scientific equipment was protected and where the fish weren’t eaten.

Leigh marine reserve from teh north
Goat Island was chosen as the site for the first marine in reserve in the Hauraki Gulf in 1975.

Chapman wrote to the then Marine Department suggesting that a marine reserve should be established. But they showed no interest in taking action on the basis that there was no legislation on the statute books enabling government to establish a reserve in the sea.

Leigh glass bottom boat
The marine reserve at Leigh attracts thousands of visitors each year and supports local business such as the glass bottom boat.

But Chapman wasn’t put off. He simply escalated the issue. He wrote to the Marine Department every month and obtained support from Ngāti Manuhiri, the Marine Sciences Association and the New Zealand Underwater Association. He also held public meetings and addressed school groups. In the end the government passed the Marine Reserves Act 1971 and created the new reserve in 1975.

The marine reserve has been an outstanding success. The abundance of fish has increased substantially and hundreds of thousands of visitors visit each year. It is a place where parents can take their children to see underwater life. It is also a great tourist attraction for visitors to New Zealand.

Bill Ballantine
The late Bill Ballantine was a fearless promoter of marine protection and he was the first Director of the Leigh Marine Laboratory.

The reserve has served as inspiration for other marine reserves around the Gulf, throughout the country and overseas. The late Bill Ballantine was a strong advocate for the reserve and he was the driving force behind the Leigh Marine Laboratory for many years.

 

 

Seachange Tai Timu Tai Pari

The Seachange Tai Timu Tai Pari initiative is in the process of preparing a marine spatial plan for the Hauraki Gulf. The plan is being developed by a Stakeholder Working Group which has been tasked with developing ‘a spatial plan that will achieve a Hauraki Gulf that is vibrant with life and healthy mauri, is increasingly productive and supports healthy and prosperous communities.’

Fixing the Gulf, Boating NZ, 27 July 2016

Listen to author and SWG member Raewyn Peart talk about Seachange

Nature’ article identifies marine spatial planning as a way of bringing fishers and conservationists together to address ecosystem issues.

The Group is focused on identifying ways, to turn around the degradation that has happened over the last century or so, within the next generation. It is committed to achieving this through adopting a holistic approach to solutions based on mātauranga Māori as well as western science.

Seachange Haruaki Plains wide
Participants in Seachange Tai Timu Tai Pari have gone out into the field to investigate the drivers of ecological decline in the Hauraki Gulf. Shown here is a trip to the Hauraki Plains to look at the drainage infrastructure.

The Seachange process is being sponsored by the Auckland Council, Waikato Regional Council, Department of Conservation and Ministry for Primary Industries. It is expected that these organisations will implement the marine spatial plan.

Seachange members visiting the Whangapoua forest
Seachange participants visited the Whangapoua Forest on the Coromandel Peninsula to look at management approaches to reducing sediment runoff as a result of forestry harvesting and earthworks.

The plan is scheduled to be completed later in 2016. The Story of the Hauraki Gulf has been written to help support the implementation of the spatial plan through communicating the issues to a broader audience.