Section 1: The Current Situation 24 This section outlines the current situation of New Zealand seaweeds by providing the best available information across the SOIs three broad outcomes: ♦ Health of the aquatic environment is protected ♦ Best value is able to be realized ♦ Credible fisheries management 25 Most seaweeds belong to one of three groups based on colour: the browns (phaeophytes), reds (rhodophytes), and the greens (chlorophytes). 26 The brown seaweeds are the largest and most conspicuous of the three seaweed groups and include kelps. Green and red seaweeds are typically smaller, and more frilly and delicate in structure. Conflict – one plural, one singular - 27 Seaweeds generally comprise of three main parts: a holdfast, a stipe, and blades (or fronds) – refer to Figure 2 for illustration of each seaweed part and lifecycle. The stipe can be of considerable length to enable the blades to reach shallower water where light intensity is greater. Stipe is usually unable to support the weight of the blades out of the water. Green and red seaweeds are typically more filamentous or sheet-like in structure. 28 The life history comprises two main phases – the predominant (conspicuous) sporophyte phase (stage that produces asexual zoospores) and the inconspicuous gametophyte phase (stage that bears sexual gametes). There are species-specific variations in life history. Figure 2: A stylised diagram of the life history of a seaweed (illustration obtained from NIWA website at www.niwascience.co.nz) 9 HEALTH OF AQUATIC ENVIRONMENT PROTECTED 29 An understanding of the nature, diversity, stability, productivity, and the extent of New Zealand’s seaweed resources provides information to address fishing and non-fishing impacts on the aquatic environment. 30 Seaweeds are structurally important components of the aquatic environment. They play a vital role in the ecology of the aquatic ecosystems giving structure and complexity; providing substrate, food and shelter to many marine organisms; and contributing to the nutrient cycling of both beaches and the surrounding coastal waters. Seaweeds are critical for the recruitment, dispersal and protection of many commercially important fisheries such as rock lobster, paua and mussel spat. Managing the Effects of Fishing 31 The activity of fishing can impact the aquatic environment in a variety of ways. For example, bottom impacting fishing methods (eg, trawling and dredging) can alter the structure of the seafloor and impact associated plants and animals, and fishing nets or lines can inadvertently capture or injure marine mammals or seabirds. The Fisheries Act 1996 outlines several environmental principles that must be considered when making decisions relating to the use or sustainability of fisheries resources like seaweeds. These include: ♦ maintaining biological diversity (biodiversity) of the aquatic environment ♦ protecting habitats of particular significance for fisheries management. ♦ maintaining associated or dependant species above a level that ensures their long- term viability 32 In addition, in 2005 the Government launched its Strategy for Managing the Environmental Impacts of Fishing (SMEEF) The SMEEF proposed the development of a set of standards for defining acceptable limits of effects of fishing on the aquatic environment. The development of these performance standards is now underway. The following sections examine seaweed fisheries in relation to the environmental principles and linked performance standards. Fishing impacts on the seafloor (benthic impacts) are discussed as a separate topic as these impacts span both biodiversity and habitats of particular significance to fisheries management. Biological diversity Performance standard: Draft standard is to identify and maintain biodiversity in the aquatic environment. 33 Section 9 of the Fisheries Act 1996 outlines several environmental principles that all persons exercising or performing functions, duties, or powers under the Act, in relation to the utilisation of fisheries resources or ensuring sustainability, shall take into account. One of these environmental principles is to maintain biological diversity of the aquatic environment. 34 New Zealand’s marine biodiversity is to be protected by establishing a network of marine protected areas that is comprehensive and representative of New Zealand’s marine habitats and ecosystems. 10 35 The Government aims to achieve a “target” of 10% of New Zealand’s marine environment protected by 2010. MFish and the Department of Conservation are jointly responsible for developing and implementing marine protected area policy to achieve this target. There are a number of marine protected areas throughout New Zealand, including various closed areas and 31 marine reserves. 36 New Zealand has an extensive marine algal flora of about 1 000 species. Exposed reefs, channels and pools have the greatest diversity of seaweed species. Harbours, fiords, and sounds share some of this rich flora. Sheltered lagoons, mangroves, inlets and estuaries where the salinity is reduced by freshwater have a very different seaweed flora. In many of these habitats, a flowering plant commonly called seagrass ( Zostera spp.) may be very extensive. Each of these natural habitats has a typical association of seaweed species that commonly vary in composition from north to south. 37 Seaweeds are critical for the recruitment and protection of many commercially important finfish and shellfish fisheries. Attached seaweeds are structurally important components of the marine environment and support high biodiversity by providing habitat, shelter and food, as well as affecting wave flow and energy. Many important finfish (eg, butterfish, moki) and shellfish (eg rock lobster, paua, kina) species generally associate with reef areas that predominate with large kelp forests. However, the interactions and associations between seaweeds and higher-order species are not well understood. 38 Free floating seaweeds play an important role in the recruitment and dispersal of other organisms. Beach-cast seaweeds provide habitat and food for a diverse ecology of marine and terrestrial organisms, as well as being key sources of nutrient cycling within the aquatic environment. It is estimated that up to 25% of the annual kelp production may become beach-cast, and, when not removed from the beach environment, this material can play a significant role in coastal ecosystems. 39 Each of the three seaweed states has different key implications on biodiversity. These key implications are set out in Figure 3. 40 The invasive Japanese seaweed Undaria pinnatifida is found in many parts of New Zealand (mainly restricted to parts of the southern North Island and throughout the South Island). This seaweed is known to displace many native seaweed species and has the potential to have negative implications for biodiversity of both seaweeds and non-seaweed species. There is presently a prohibition on the commercial harvest of Undaria . Biosecurity New Zealand, however, is to review this prohibition in 2007 and some commercial harvest may be allowed in the future. In some areas, regional authorities are taking limited measures to control the spread of this species. 11 Figure 3: Key characteristics of the three seaweed states and implications for biodiversity States Attached Free Floating Beach-cast Biological life-cycle Biodiversity ECOLOGICAL CANOPY FORMING CAN STILL BE IMPORTANT FOOD ROLE GROWING AND SOURCE AND REPRODUCING SHELTER FOR CRITICAL HABITAT INVERTEBRATES IMPORTANT FOR AND SHORE BIRDS RECRUITMENT OF DISPERSAL OF MANY SPECIES SPECIES NESTING MATERIALS FOR STRUCTURAL SETTLEMENT SEABIRDS/WADERS IMPORTANCE SURFACE FOR MODIFYING WAVE MUSSEL SPAT FLOWS AND POTENTIAL BEACH ENERGY BUILDING REFUGE AREAS MATERIAL FOR JUVENILE AND LARVAL FISH Habitats of particular significance to fisheries management Performance standard: Draft standard is to identify and protect habitats of particular significance for fisheries management. 41 Protecting habitats of particular significance to fisheries management is one of the environmental principles outlined in s 9 of the Fisheries Act 1996. 42 Seaweeds are found in all habitats of significance, including spawning and nursery areas, estuaries, and areas of particularly high biodiversity. Associated or dependent species Performance standard: Draft standard is to identify and maintain associated and dependent above a level that ensures their long-term viability 43 Maintaining associated or dependent species above a level that ensures their long-term viability is one of the environmental principles outlined in the Fisheries Act 1996. 44 Associated or dependent species means any non-harvested species taken or otherwise affected by the taking of any harvested species. This can include protected species such as marine mammals, seabirds, and reptiles. 12 Protected species 45 There are no direct associations between seaweed harvesting and fishing-related mortality of protected species. However, there are indirect associations between seaweed harvesting and several protected species, as presented below. Seabirds and reptiles 46 A wide range of invertebrates (eg, amphipods, isopods, copepods) are found living on beach-cast seaweeds. These invertebrates are an important food source for some protected birds and reptiles. For example, kiwi on Stewart Island are often found foraging for amphipods and isopods amongst beach-cast seaweeds. Although there are no quantitative New Zealand studies on the use of seaweeds by birds, overseas