Section 1: The Current Situation

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1 Section 1: The Current Situation 32 This section sets out some key information held by the Ministry of Fisheries on the current situation of key shellfish fisheries on the west coast of the North Island. The information is set out in a format which follows the Ministry s three broad outcome goals for New Zealand s fisheries: health of the aquatic environment is protected best value is able to be realised, and credible fisheries management. AQUATIC ENVIRONMENT Statement of Intent Outcome: The health of the aquatic environment is protected 33 If the aquatic environment is to support our fisheries for current and future generations, the ecosystem must remain healthy. In addressing fishing and non-fishing impacts on the aquatic environment, it is essential to have a good understanding of: the nature (composition, diversity, stability and productivity) of the stocks the ecosystem of the west coast of the North Island, and the effects of fishing and other activities on the stocks and the aquatic environment. General Features of the North-West Coast Environment The North-West Coast Aquatic Region 34 The west coast of the North Island includes the harbours of Whangape and Herekino, Hokianga, Kaipara, Manakau, Raglan, Aotea and Kawhia. Gravel sands and iron sands occur offshore. Areas of special interest include offshore islands such as the Sugar Loaf Islands and Gannet Island. The coastline is characterised by open, exposed sand and iron sand beaches interspersed by stretches of rocky platforms, bluffs and outcrops. 35 Bathymetry (the contours of the sea bed), the width of the continental shelf, substrate types, hydrology, temperature, salinity, oxygen and light all help to determine the diversity and assemblages of marine species in coastal regions. The continental shelf at the north of the north-west coast is relatively narrow and extends km offshore out to a depth of 200m. There are many small canyons and trenches in this shelf edge that break the shelf margin as it drops into the depths of the New Caledonia basin. Further south, starting from the region of the Manukau Harbour, the shelf becomes progressively broader to a width of km in the northern Taranaki Bight where the continental margin extends on to the 9

2 deeper expanse of the Challenger Plateau. The sea bed of the northwest coastal shelf is mostly undulating with relatively few areas of reef or shoal. 36 Sub-tropical water surrounds New Zealand in the north temperatures range from C in the summer to C in the winter. The Western North Island near-shore biogeographic region is influenced by the northward flowing Westland Current and the southward flowing West Auckland Current, both of subtropical origin. These interactions play important roles in determining the distribution and abundance of marine species. Annual variations of these currents can determine the success of a season s spawning. Nutrients can be enhanced by upswellings and local freshwater inputs and planktonic productivity can develop in bays, where more complex communities and more abundant fish populations can develop. 37 The benthic environment of the sea-floor off the north-west coast is made up primarily of gravel and sand inshore with some mud and calcareous gravel as is shown in Figure 2. Further offshore, the sediment is almost entirely calcareous ooze. Figure 2: Sediments found on the substrate of the north-west coast of New Zealand Biodiversity 38 Biodiversity is defined as variability among living organisms, including the diversity within species, between species and of ecosystems. 39 New Zealand s isolation has meant that it has a particularly high proportion of endemic species (species which are unique to New Zealand and occur nowhere else in the world): 100% of triplefins, 90% of sponges, 86% of molluscs, 60% of bryozoans and 40% of 10

3 seaweeds in New Zealand are endemic. This is diversity worth protecting. New Zealand Biodiversity Strategy 40 The New Zealand Biodiversity Strategy developed by the New Zealand government has four key outcomes for marine biodiversity: natural marine habitats and ecosystems are maintained in a healthy functioning state a full range of marine habitats, and ecosystems of indigenous biodiversity is protected there are no human-induced extinctions of marine species, and marine biodiversity is appreciated, and any harvesting or marine development is done in an informed, controlled and ecologically sustainable manner. 41 One key part of the Biodiversity Strategy is to achieve a target of protecting 10% of New Zealand s marine environment by 2010 with a view to establishing a network of representative protected marine areas (areas that contribute to protecting marine biodiversity include marine reserves and world heritage sites). Protected Areas 42 There are also coastal and marine management tools under the Fisheries Act 1996 that contribute to protecting biodiversity. These include mätaitai reserves and taiapure-local fishery areas, marine area closures, seasonal closures and area closures to certain fishing methods. 43 As is shown in Figure 3 there are already some protected areas in FMA 8 and FMA 9: the area at Spirits Bay which is closed to trawling and dredging to protect sponges Kapiti and Parininihi marine reserves Tapuae marine reserve Sugarloaf Islands Marine Park the three protected seamounts, and the areas closed to fishing due to cables and pipelines. 44 Within these areas, shellfish species are now protected and cannot be taken by fishers. The seamount closures are offshore so do not affect inshore shellfish harvesting. 11

4 Figure 3: North-west marine reserves, seamounts, Sugar Loaf Islands Marine Park, Spirits Bay Restricted Area and cable and pipeline areas Spirits Bay Sponges 45 Research surveys in 1999 confirmed that the biodiversity of an area between North Cape and Cape Rëinga is unparalleled in known similar environments in New Zealand. The area is characterised by diverse sponge and bryozoan assemblages (218 and 170 species respectively identified to date), and corals, soft corals, gorgonians, black corals (probably) and a wide variety of subtropical invertebrates. 46 The survey report identified some potential effects of fishing. Several places surveyed between North Cape and Cape Rëinga were found to have either very few sponges or mainly unattached individual sponges. These tended to be in areas where scallop dredging had occurred, or where trawling had been reported. 12

5 47 Scallop fishers voluntarily agreed not to dredge in a substantial part of the area near Spirits Bay. MFish has since responded and dredging and trawling are both now prohibited in the shaded areas shown on figure 4. There have been no more recent surveys to assess the effectiveness of these measures. Figure 4: Restricted Trawl Area, Spirits Bay Importance of shellfish to biodiversity 48 All shellfish play a part in the food chain and interact with other organisms in complex ways which are not entirely understood. 49 By protruding above the seafloor, horse mussels modify their habitats considerably. They provide shelter and refuge for invertebrates and fish and act as substrata for settlement of sponges and soft corals. Many small invertebrates such as worms, shellfish and small crustaceans also live in the seafloor sediments in and around horse mussel beds. 50 Other filter-feeding shellfish such as tuatua, cockle and pipi play an important role in stabilising sandy beaches and banks by reducing the transport of finer sediment material and may assist in maintaining water quality through their filter-feeding activity. A reduction in biomass of these species may have implications on associated and dependent species, and on the physical aquatic environment, particularly if localised depletion of discrete populations occurs. 13

6 Fishery Information Habitats of Particular Significance to Fisheries Management 51 Habitat protection is essential for healthy productive fisheries. The government is committed to protecting habitat of particular significance to fisheries management. Table 2 below shows the habitats and locations of the species covered in this plan. Table 2: Shellfish species and their natural habitats Species Location Intertidal / Subtidal Blue mussel Rocky areas below low water in harbours and exposed open shores Subtidal Cockle Protected beaches / enclosed shores - down to 20m depth (though this is rare) Sheltered soft shore Intertidal Deepwater clam Depths of 5-25m in sand and mud off sandy ocean beaches Soft shore Subtidal Dredge oyster Found in harbours Soft shore Subtidal Green-lipped mussel (adult) From beach to over 50m depth on exposed rocky shores Intertidal / Subtidal Green-lipped mussel Attached to seaweed in shallow water near or on Ninety-Mile Beach Intertidal / Subtidal Horse mussel Muddy-sand in the lowest intertidal and subtidal shallows of mainly sheltered waters Soft shore Subtidal Kina Waters less than 10m deep Rocky shore Subtidal Knobbed whelk In sand, silt and mud from low water to a depth of 600m Soft shore Subtidal Mud snail On high tidal mud-flats Intertidal Octopus From low water to a depth of 400m Subtidal / Intertidal Pacific oyster Lower, intertidal, areas of estuaries. Mainly attached to rocks or debris Intertidal Paddle crab Off sandy beaches, in harbours and estuaries, from intertidal zone to depth of 10m Soft shore Subtidal Pipi Protected beaches, bays and estuaries - from beach to depth of 7m+ Soft shore Intertidal Rock oyster Intertidal area, on rocks, in harbours or estuaries to depth of 50m Intertidal Scallop Mainly in semi-enclosed areas such as harbours Soft shore Subtidal Sea cucumber Between 5 and 40m in a wide range of habitats from rocky shores to sandy bottoms. Prefers sheltered coastline. Soft shore Subtidal Surf clam In and just beyond the surf zone on exposed sandy beaches, down to depths of 10m, although deepwater tuatua (PDO) and triangle shells (SAE) may extend to the midtide mark Exposed soft shore Subtidal, except for PDO and SAE. Mainly on Ninety Mile, Dargaville and Muriwai Toheroa Tuatua beaches Sandy and soft bottom habitats with other surf clam species Exposed soft shore Intertidal Exposed soft shore Intertidal / Subtidal 52 Many of the intertidal estuaries where some of the shellfish are harvested are important spawning and/or nursery areas for both finfish and shellfish. Damage that is done to the environment through fishing related activity can have consequences for the wider range 14

7 of aquatic life in these areas. 53 The estuarine plant of most significance is eel grass (Zostrea capricorni), a type of seagrass which grows mainly in the intertidal zone. It is found on many types of coast, from sheltered estuaries and coastal beaches to intertidal coastal reef platforms and subtidal bays around coastal islands. These are all areas that support the species covered in this plan. Seagrass meadows are known to play important ecological roles in estuarine and shallow water coastal eco-systems: they enhance primary production and nutrient cycling, stabilise sediments, elevate biodiversity, and provide nursery and feeding grounds for a range of invertebrates and fish. Productivity 54 Shellfish species have different rates of growth, reproduction and natural mortality, all of which affect their ability to withstand fishing pressure. Table 3 below shows the key productivity features, where known, for shellfish species found on the north-west coast. Table 3: Key biological characteristics of north-west shellfish species Species Mortality Fecundity Maturity age Maximum Growth rate (M) or length age or length Blue mussel 120mm Cockle mm Fast Deepwater (King) clam <61mm 34 years Fast initially, then slow Dredge oyster 0.1 Low 42-50mm 46 years Slow (Otago) Green-lipped High 40-50mm mussel Horse mussel 5-15 years Fast Kina 30-75mm 20 years + Moderate Knobbed whelk 50mm Mud snail 32mm Octopus High 1-5 years 3-5 years Fast Pacific oyster High 10 years Fast Paddle crab mm Fast Pipi High 40mm 10 years Fast approx Rock oyster 80mm Scallop Very High 60-70mm 6-7 years Fast Sea cucumber mm 5-15 years Surf clams Bassina yatei Dosinia anus Dosinia subrosea Mactra discors mm 58-82mm 41-68mm 63-95mm 15

8 Species Mactra murchisoni Paphies donacina Spisula aequilatera Mortality rate (M) Fecundity Maturity age or length Maximum age or length mm mm 39-74mm Growth Toheroa 1-2 years years Moderate Tuatua High 5 years + Fast Sustainability Indicators 55 Only limited biomass surveys have been carried out for north-west shellfish stocks. Fairly regular surveys have been carried out on toheroa abundance on Ninety Mile and Dargaville Beaches. Intertidal shellfish surveys focusing on cockle and pipi beds on beaches in the Auckland area, including Mill Bay and Raglan, have provided some information on biomass at a local level. Assessments of biomass have been carried out for surf clam populations on Foxton Beach. 56 Those stocks that are assumed to be above B MSY 3 such as sea cucumber and surf clams are those which have not, to date, been heavily harvested. Catch trends can be shown for stocks fished commercially (see charts in Use and Values section of this document, pages 30-32). Information Status 57 There is a significant number of north-west shellfish stocks for which the stock sustainability and biomass is unknown and insufficient information is available to make confident decisions on sustainable harvest levels. TACs have therefore been set at conservative levels or, where catches are not declining, at levels consistent with previous use. Research 58 MFish contracts research providers to carry out projects which provide information on the status of certain stocks and species around New Zealand. Table 4 below shows how some north-west shellfish stocks are assessed, any recent and current research and requirements for the future. There has also been some research done on stocks elsewhere in New Zealand and, although those stocks are not part of this plan, the information found may be relevant. For example, yield assessments have been made for scallops and cockles on the north-east coast of the North Island. 3 The weight (biomass) of a group of fish necessary to produce the maximum sustainable yield (MSY). MSY is the level at which the stock is most productive as older unproductive fish are fished out of the population and smaller, faster growing fish produce higher yield but not the maintenance of a higher biomass. 16

9 Table 4: The Inshore Shellfish Fisheries Medium Term Research Plan (as applied to north-west shellfish stocks) Fishstock COC 9 PPI 9 Assessing stock status Current Monitoring of intertidal shellfish populations at selected beaches. PZL 8-9 Comparison of annual landings against TACC. GLM 8-9 Comparison of annual landings against TACC. HOR 8-9 Comparison of annual landings against TACC. SUR 8-9 Recorded annual landings for all North Island FMA stocks from 1983 to QMS introduction October Comparison of annual landings with TACC. KWH 8-9 Comparison of annual landings against TACC. PAD 8-9 Comparison of annual landings with the TACC. SCC 8-9 Comparison of annual landings against TACC. Surf clams BYA 8-9 DAN 8-9 DSU 8-9 MMI 8-9 MDI 8-9 SAE 8-9 PDO 8-9 Comparison of annual landings against TACC. TUA 8-9 Comparison of annual landings against TACC. TOH 9 Estimations of abundance of populations on Ninety Mile and Dargaville beaches. Recent & Current research AKI2006/01 Intertidal shellfish monitoring on specified beaches in the Auckland Fisheries Management Areas Biomass estimates of surf clams on Foxton Beach were conducted in There is no current research. Estimation of distribution and abundance of toheroa on: - Ninety-Mile Beach, 2006, - Dargaville Beach, 2006/07 Research Requirements 2008/09 Ongoing monitoring. The scope of this project may extend beyond the Auckland FMA (as separate project/s) with increasing interest by customary fisheries managers of monitoring populations shellfish and other species in selected areas 2007/08 - No research requirements fisheries would require research. 2007/08 - No research requirements fisheries would require research. 2007/08 - No research requirements fisheries would require research. 2007/08 No research requirements fisheries would require research component. 2007/08 - No research requirements fisheries would require research. 2007/08 No research requirements identified. Further development of these fisheries would require a research component. 2007/08 No research requirements fisheries would require research. 2007/08 - No research requirements fisheries would require research. 2007/08 - No research requirements fisheries would require research. 2007/08 Assessments of distribution and abundance of toheroa on specified beaches. 17

10 Managing the Effects of Fishing Total allowable catch 59 The main measure within the QMS used by MFish to ensure fisheries are sustainable is the Total Allowable Catch (TAC). The TAC is set as an upper limit on the catch of species from each Quota Management Area. When setting a TAC, a number of provisions of the Fisheries Act 1996 are taken into account. In particular, these include: The maximum sustainable yield (MSY) of the stock; The level of the stock s long term viability; Interdependence of stocks; Social, cultural and economic factors; Environmental principles; Information principles; International obligations; The Treaty of Waitangi (Fisheries Claims) Settlement Act 1992; Effects on the aquatic environment; Relevant services; and Other Crown statutory plans, policy statements, and management strategies. 60 Total Allowable Commercial Catches (TACCs) were set under the QMS for the first time in 1986, although not for any shellfish stocks except squid. TACs were first set under the Fisheries Act 1996, providing for a TACC plus allowances for customary and recreational catches and other fishing-related mortality. The first stocks covered by this plan to have TACs set were Paddle crab in FMAs 8 and 9 in Since then, 36 stocks covered by this plan have had TACs set (see table 5). TACs for all these stocks have been unchanged since they were first set. 61 Stocks within the QMS can be managed under section 13 or section 14 of the Fisheries Act Stocks managed under section 13 must be maintained at or above a level that can produce the maximum sustainable yield (MSY) for that stock. Most stocks within the QMS in New Zealand are managed under section 13. Stocks managed under section 14 are those which the Minister of Fisheries has decided would be better managed outside of the requirement to be at or above B MSY. The only stock in this plan managed under section 14 is green-lipped mussel in FMA 9. This is because the green-lipped mussel fishery is for spat which are washed onto, or just off, Ninety Mile Beach and would die if they were not harvested. Therefore the harvesting of mussel spat has no impact on the sustainability of green-lipped mussel in that area. 18

11 Table 5: The state of the north-west shellfish stocks in relation to maximum sustainable yield, the date they were introduced to the quota management system and the current TAC levels. Species Cockle Deepwater (King) clam Oyster Green-lipped mussel Horse mussel Kina Knobbed whelk Paddle crab Pipi Scallop Sea cucumber Surf clams Tuatua Stock Introduced to QMS TAC (tonnes) At MSY? COC Unknown COC Unknown Above MSY (near virgin PZL biomass) Above MSY (near virgin PZL biomass) OYS 8A Unknown OYS Unknown GLM Unknown Not relevant (for spat GLM collection) HOR 8 1 April Unknown HOR 9 1 April Unknown SUR Unknown SUR Unknown KWH Unknown KWH Unknown PAD Unknown PAD Unknown PPI Unknown PPI Unknown SCA 8A Unknown SCA 9A Unknown SCC 8 1 April Unknown SCC 9 1 April Unknown DSU, BYA, DAN, PDO, MMI, MDI & Above MSY (near virgin SAE 8 1 April biomass) DSU, BYA, DAN, PDO, MMI, MDI & SAE 9 1 April TUA 8 TUA Unknown Unknown Above MSY (near virgin biomass) 62 TACs for COC 8 and 9, PPI 8 and 9, SCA 8A and 9A, TUA 8 and 9, GLM 8 and 9, OYS 8A and 9 and SUR 8 were set on the basis of catch history of the fisheries. These TACs 19

12 were set conservatively to ensure sustainability. 63 TACs were set for SCC 8 and 9, PAD 8 and 9 and SUR 9 to provide for estimated catch history and enable some development of the fishery. The paddle crab TACs were set recognising that the abundance of the fishery was cyclical and that there was a level of unreporting of catches. 64 TACs were set for HOR 8 and 9 to provide for any bycatch taken by other fisheries. 65 TACs were set for surf clams in FMAs 8 and 9 based on a maximum constant yield assessment (for Foxton beach, extrapolated across the areas) and an estimate of recreational and customary catch for deepwater tuatua. 66 TACs were set for KWH 8 and 9 and PZL 8 and 9 to reflect the biological characteristics of the stocks and the absence of stock assessment information, while still providing for some development opportunities for the fisheries. Benthic impacts 67 Benthic impacts are defined as: impacts on the animals and plants living on or attached to the bottom of the sea or lake, from high water mark down to the deepest levels (i.e. animals or plants of the benthos). 68 Some of the fishing methods used to take shellfish on the west coast of the North Island involve the use of equipment that comes into contact with the seabed. Some of the methods, particularly dredging, use equipment that is heavy enough to leave furrows through soft sediment and dislodge harder material. Such impacts in turn can harm bottom dwelling organisms. Like most of the shellfish fishing on the west coast of the North Island, dredging mainly occurs in the harbours where conditions are calmer. 69 The key commercial target fisheries on the west coast of the North Island are handgathering (using spades) of green-lipped mussel on Ninety Mile Beach, dredging for tuatua in the mouth of the Kaipara (although not in the last two fishing years) and taking paddle crab on the Manawatu coast by pots set on sandy/muddy bottoms beyond the surf zone. Potting and hand-gathering have limited impact on the benthos. 70 Tangata whenua of the Ninety-Mile Beach area have expressed concerns that vehicle movement on the beach, particularly the tractors and trucks used to harvest mussel spat, have a significant adverse impact on the survival of the shellfish and other infauna of the beach such as tuatua and toheroa. However, recent research, on the use of a tractor to harvest mussel spat, have found that the impact of the tractor is likely to be minimal. 71 Kina is taken by divers (use of UBA is prohibited) from rocky reef environments, this does not have a significant impact on the benthos. 72 If surf clam fishing proves to be economically viable, hydraulic dredges will be used to harvest surf clams. The immediate impact of dredging for surf clams is not discernable a few hours after dredging. This is because the surf zone is a high-energy environment subjected to frequent natural disturbance and high sand mobility and this environment tends to recover faster from disturbance than environments in deeper water. Widespread and intensive hydraulic dredging, however, may have the potential to adversely modify the 20

13 environment. 73 Recreational fishing methods probably have less impact on the environment than some commercial methods. Shellfish are mainly hand-gathered by recreational fishers. An exception is scallops, which can be targeted by dredge. Associated or dependent species 74 MFish is committed to maintaining associated or dependent species above a level that ensures their long-term viability. Associated or dependent species is a term defined in the Fisheries Act 1996 as any non-harvested species taken, or otherwise affected, by the taking of any harvested species. 75 In some areas shellfish abundance has declined, either through over-harvesting or environmental change. The potential effects of this on seabirds and other species which feed on shellfish are unknown. Protected Species 76 Maui s dolphin, other dolphins, whales, seabirds and white sharks are all found in the west coast of the North Island. However, none of these species are believed to be affected by shellfish fishing activities in the area. Most fishing for shellfish is done by dredge or handgathering and these methods are not a significant risk to Maui s dolphin. Some shellfish is taken by bottom trawl, which may be a risk to Maui s dolphin, however all shellfish caught in this way is bycatch only and is not the target of the fishing activity. 77 Black coral can be damaged by dredging for shellfish. However, black coral is found offshore in deeper water and outside of west coast harbours, so fishing for the shellfish stocks covered by this plan is unlikely to pose a significant risk to black coral. Other Impacts on Fishery Resources 78 Regional and District Councils manage the impacts of land and some water based activities on the aquatic environment. These councils also manage both the establishment of marine farming and its ongoing operation. 79 The Ministry of Economic Development manages oil and mineral extraction. Oil extraction occurs in Taranaki, iron sand extraction south of Kawhia and sand extraction inside the entrance to the Kaipara Harbour. These activities close areas to fishing and reduce the overall area available for fishing. In the Kaipara, there is a 99% mortality rate of shellfish sucked up by the dredge used in the sand extraction. 80 There is displacement of fishing effort around the Trans Tasman cable that runs offshore from Muriwai Beach (see Figure 3, above). This is because fishing is prohibited out to the 12 mile limit of the Territorial Sea in the vicinity of the cable closure. 81 Regional Councils have been considering establishing aquaculture management areas in the Kaipara Harbour and there is an application for a sizable oyster farm there. If these proposals proceed they would displace fishing from those parts of the harbour. The actual impact on fisheries depends on whether the areas have any habitats of special significance to 21

14 fisheries and/or special qualities that make them especially good places to fish. Offshore sea conditions are such that it is very unlikely that the extensive mussel farms proposed for parts of the east coast, that could also displace fishing effort, would be viable on the west coast. 82 From a fishery perspective, activities that affect the important habitats for fisheries described previously are at least as potentially harmful in their impacts on fisheries as these other uses of the marine environment. On the west coast the most harmful activities may be those with effects such as sedimentation coming from land use activities. Sedimentation is the cause of siltation in harbour estuarine areas and this can have significant detrimental effects on shellfish species. 83 There has been an ongoing community effort around the Raglan Harbour to control such effects by planting harbour margins. It is probably not possible to measure to what extent this has improved harbour fisheries there. 84 Through filter feeding, shellfish can become contaminated from pollution in the water. This does not necessarily harm the shellfish, but it would harm any humans who eat polluted shellfish. 22