4. Potential Opportunities for Development of Marine Resources (Continued)
As previously discussed, fish, shellfish and crustacean species of commercial value are present in the waters surrounding Tai Tokerau. On the eastern coast there are ports providing suitable bases for commercial fishing activities (e.g. Houhora, Whangaroa, Mangonui and Whangarei Harbours, and Opua (in the Bay of Islands)) as well as a variety of smaller areas. Sand bars, and the high level of wave exposure at the entrances to Parengarenga Harbour and those on the western coast mean that these harbours are less suited as ports.
The potential for fishing to contribute to sustainable economic development is dependent upon sustainable management of fish stocks. Sustainable fishing can be defined as ‘ fishing activities that do not cause or lead to undesirable changes in biological or economic productivity, biological diversity, or ecosystem structure and functioning from one generation to the next ' (National Research Council 1999). The desired levels of biological and economic productivity are based on values decided by society.
Currently, commercially fished stocks in New Zealand are managed by the Ministry of Fisheries through the Quota Management System (QMS) on a ‘single species' basis. The QMS was introduced in 1986. It controls the total commercial catch from all the main fish stocks found within New Zealand's 200-nautical mile Exclusive Economic Zone (EEZ). The quantity of fish that can be taken for each fish stock by both commercial and non-commercial fishers is known as the Total Allowable Catch (TAC). An allowance is then made to provide for recreational fishing and customary Mäori uses. The remainder is then made available to the commercial sector as the Total Allowance Commercial Catch (TACC). This is the total quantity of each fish stock that the commercial fishing industry can catch that year. Quota are now a percentage of the TACC for each species and not a fixed tonnage.
Ecosystems are complex, linked, interactive systems in which organisms, habitats, and external factors (such as weather) act together to shape communities and regulate population abundances. Fishing is a major activity that can selectively remove large portions of animal populations and also significantly alter interactions between organisms at different levels of the community. For example, over-fishing of a predator species can result in an increase in abundance of the species on which it preys. Fishing also alters the age and size structure of populations. It may also alter the genetic structure of populations. For example, minimum fish size limits may result in disproportionately greater survival of smaller, early maturing, slower-growing fish, i.e. genetic selection for small size, early maturity and slow growth. As stated above, commercial fish stocks in New Zealand are currently managed on a ‘single species' basis. However, there is increasing interest being expressed by environmental groups in having fisheries managed on an ecosystem basis, that is, for the interactions within the marine ecosystem to be considered in setting quota for individual species. Ecosystem-based management has been described as: ‘ an approach that takes major ecosystem components and services, both structural and functional, into account in managing fisheries. It values habitat, embraces a multispecies perspective, and is committed to understanding ecosystem processes ' (National Research Council 1999). While this would no doubt have much merit, the currently poor level of understanding of the complex interactions within marine ecosystems is unlikely to effectively support such a system.
Mäori have unique fishing rights protected by the Treaty of Waitangi. The settlement of claims relating to these rights has resulted in Mäori becoming very significant participants in the commercial fishing industry in New Zealand. The potential for sustainable Maori economic development in Tai Tokerau arising from commercial fishing depends very much upon the way in which the assets owned by Mäori are managed. While the fisheries assets of Mäori in Tai Tokerau will increase as a few new species are brought into the QMS, the fish stocks are finite in quantity. Unless stocks are artificially enhanced (see below), a significant increase in the quantity that can be sustainably harvested is unlikely. Growth can thus be achieved only through strategies that increase the economic benefit from existing resources.
However, one method of increasing the harvest from wild fisheries is through reseeding juveniles into their natural environment to artificially enhance the stock levels. This is most likely to be relevant to species that are relatively sedentary, (or in the case of salmon, return to the same river in which they were bred) since otherwise the recapture of reseeded stock is not possible. Stock enhancement through reseeding has been very successful in the Challenger scallop fishery in Tasman and Golden Bays in the north of the South Island, where reseeding operations are funded jointly by the scallop fishermen in the area through a production levy. A similar operation could potentially improve the productivity of the scallop fishery in Tai Tokerau also. Scallop reseeding is based on collection of scallop spat (juvenile scallops) from the wild, and holding them in an environment that significantly reduces their natural mortality, prior to redistributing them back onto the sea-bed. By utilising the habit of larval scallops of settling out of the plankton onto foliose seaweed (i.e. seaweed with very fine, branching leaves), scallop spat can be collected on artificial materials that resemble their natural settlement surfaces in ‘spat bags' that protect them from predators. These bags are hung off sub-surface long-lines in the summer months in areas where scallop larvae are abundant. Once collected, scallop spat are left to grow in the bags until they are a suitable size for seeding out, at which time they are removed from the bags and released onto the sea-bed at a density to provide optimal growth. The areas into which they are seeded are left un-harvested until the scallops reach market size 1-2 years later. The development of a scallop enhancement programme would require a co-operative approach across all existing fishermen in the scallop fishery. Resource consents to use space on the sea-bed to catch scallop spat, and (under current legislation) a spat-catching permit are required to undertake spat-catching activities.
The potential for artificial enhancement of scallops in Northland has recently been reviewed by Morrison and Cryer (2003). Initial trials in northern New Zealand have identified problems in variability in spat catch, and handling stress and significant levels of predation of juvenile scallops once they are reseeded onto the sea-bed. Areas with consistently high levels of spat each year are not known in Tai Tokerau, and trials would need to be run across a range of geographically spread areas to identify areas suitable for spat collection. There is likely to be a range of areas that are suitable for reseeding scallops – these may include areas where scallops are not currently found in large numbers due to hydrographic conditions that limit larval supply. Thus the areas of scallop production may be increased through reseeding. Morrison and Cryer (2003) suggest that the most suitable areas would be Rangaunu Bay and Bream Bay, but other areas could include Doubtless Bay, the area between Bream Tail and Cape Rodney, and the area around Little Barrier Island (Hauturu). They also estimate that enhancement of scallop beds could result in an increase in scallop production in the Northland fishery from 100 tonnes to 750 tonnes per year, which would directly support more than 300 jobs. However, they also note that several years of trials and experiments are required to assess the feasibility of large-scale commercial reseeding operations, and to address potential problems in spat supply and juvenile survival. They suggest that this would require a financial investment of several hundred thousand dollars.
Maori can potentially benefit economically from the extraction of sand, either through commercial utilisation of the resources themselves, or through receipt of royalties from companies utilising the resources. There are several regions in Tai Tokerau where the quality of sand is suitable for commercial use. Sand is primarily utilised as a fine aggregate in the production of concrete products, but may also be used in glass manufacture, or to provide sand for beach replenishment projects.
The following basic criteria have been suggested as guidelines for assessing mineral resources (Applied Geology Associates 1982):
• The naturally occurring material can, with or without treatment, satisfy the physical requirements set by the market for the mineral product.
• There is sufficient volume of accessible material to warrant the capital investment in land and plant.
• That it is possible to gain access by licence or private agreement to remove the material.
• That it is economically possible to extract, process, and transport the mineral product to the market at a competitive price.
There are a variety of different sand types found on the coast of Tai Tokerau, including some of specific commercial interest. The sand at Kokota Spit at the head of the Parengarenga Harbour is the only coastal source of silica sand with very few impurities (<2 per cent) in New Zealand, and is suitable for the manufacture of glass (Van Dam et al. 2003). On the southwestern coast of Tai Tokerau, south of the Kaipara Harbour, the sand from the beach contains titanomagnitite, a source of iron for steel manufacture, with the heavy mineral content increasing rapidly from 1 per cent at the Kaipara Heads to 41 per cent at Muriwai (Applied Geology Associates 1982).
Sand to be used for concrete has the most rigid specification for grading and cleanliness. The sands which satisfy the physical requirements for concrete occur in the nearshore zone off the beaches from Cape Rodney to Ocean Beach, and also in the dune sands at Pakiri, and the dune and underlying coarser relict beach sands in Bream Bay. The raw material for fibreglass needs to contain alumina, usually in the form of feldspar. Sand suitable for fibreglass is found at Pakiri. The highly feldspathic sands in the recent dunes, on the beach, and near the shore from Takatu Point to Marsden Point are suitable for the manufacture of ceramics (Applied Geology Associates 1982). The proximity of some of these resources to Auckland, and the quantity apparently available, means that the exploitation of these resources is potentially commercially attractive.
Sand mining has occurred commercially in Tai Tokerau since the mid 1900s. In 2001, there were 5 resource consents for the extraction of sand in Tai Tokerau. These were for areas within the Kaipara Harbour (2), at the entrance to Mangawhai Harbour (2), and at the entrance to Parengarenga Harbour (1). At present, the consents for sand extraction in the Parengarenga Harbour entrance and Pouto Point in the Kaipara Harbour are not being exercised. Sand extraction has also previously been undertaken at Tokerau Beach. Sand is currently being extracted from the nearshore zone (in 4-10m water depth) off the Pakiri/Mangawhai embayment, and from within the Kaipara Harbour.
Sand extraction is a controversial issue amongst Maori, both due to cultural concerns (for example, the potential uncovering of taonga in areas of the Kaipara Harbour), financial concerns (disputes about who owns the resources) and concerns regarding potential environmental impacts. Sand extraction from the coastal marine environment in New Zealand, i.e. below Mean High Water Spring Tide Level (MHWS) is controlled by Regional Councils in conjunction with the Minister of Conservation, under the framework of the Resource Management Act. It is difficult to generalise regarding the specific environmental impacts of sand extraction, as the degree of potential impact depends on the extraction site, volumes taken, and extraction methods used. However, one key issue is relevant to the sustainability of sand extraction – whether the sediment system is ‘open' or ‘closed'. In an open system, extracted sand may be replaced naturally from outside the area. In a closed system, extraction may cause shoreline erosion, although the effects may be localised (Hume et al. 1998). Hume et al. (1998), in the introduction to the report on their study of Mangawhai-Pakiri sand resources, comment that ‘ Generally sand extraction is not sustainable in a closed system in the long-term because extraction will eventually deplete the resource to zero and/or cause severe beach erosion. However, extraction may be permitted over shorter time periods if the extraction rate is small compared to the total resource, sound economic or other benefits accrue from the extraction, and adverse effects can be avoided, remedied or mitigated ' .
On the western coast of Tai Tokerau, the action of the southwesterly swells delivers sediment onto the coast. The orientation of the coastline perpendicular to the swell effectively reduces long-shore movement of sediment, thus resulting in accretion of sediment. On the eastern coast, the lower energy regime, wave climate variability, and the highly irregular coastal outline, with promontories that effectively impede sediment transport results in less movement of sediment both onto and along the coast. This means for example, that recovery from the erosion of beaches during storms is relatively slow. Similarly, although some areas on the eastern coast are more sensitive than others, the physical impacts of sand extraction are likely to be less significant on the western coast of Tai Tokerau than on the eastern coast.
In addition to physical impacts resulting from extraction, ecological impacts may also occur as a result of mining activities. Likely impacts include those resulting from disturbance to the substrate and the associated benthic (seafloor) ecosystem, and a localised increase in turbidity, which may also affect marine organisms nearby.
While the commercial potential of the sand resources within Tai Tokerau depends on business considerations, whether or not these resources should be further exploited also depends heavily on social and cultural values that determine the acceptability of potential impacts, balanced against the needs of society for the resource materials.
Power can be generated from the sea using tidal flows or wave action. The technology for both types of power generation is still in the early stages of development, and worldwide there are few generation sites. While the tidal flows in and out of most of the harbours in Tai Tokerau are considerable and could potentially be used as a renewable power source, it is unlikely that the technology developed to date (using tidal barrages) would be suited to these areas as the entrances to the harbours are required to remain navigable, and many of the harbours (particularly those on the western coast) are extremely exposed to wave action.
Power generation from wave action has received more research attention than tidal power generation, and several model generation systems have been developed (Ross 1990). One study done in New Zealand suggested that the prime site for an oceanic wave power device would be the western and southern coast of the South Island, where wave energies are extremely high (Hornstra 1983). Wave power generation systems need to be built to withstand wave action, including freak 20-year waves. This is expensive. While the waves off the western coast of Tai Tokerau undoubtedly contain much energy, the technology to harness this energy cost-effectively is in its infancy. The high cost of power generation using both tidal flows and wave action (mainly due to the high capital costs in construction) suggest that this may not be a viable use of resources until more competitive technology is developed. The attractiveness of these options may change in the future with the development of new technology, the increase in energy demand with increasing population, and the increasing reliance on sources of energy alternatives to fossil fuels (which are of finite supply). Tidal and wave energy thus represent potential marine resources for the future.
Resource management needs to take account not only of the way in which various activities within the marine environment impact on each other and on marine ecosystems in general, but also the way in which land-based activities may impact on the sustainability of marine resources, along with associated social and cultural impacts. Understanding and consideration of these inter-relationships is essential to sustainable utilisation of marine resources. In the previous section we briefly mentioned the kinds of environmental and ecological impacts that might occur with different options for resource utilisation. While the physical and environmental characteristics of an area may offer several different opportunities for development, incompatibility of these activities may act as a constraint to development. This may occur when the utilisation of one resource coincidentally removes or impacts on the potential to utilise another. For example, sand extraction would be incompatible with a scallop fishery, and the utilisation of the marine waters as a receiving environment for the discharge of untreated or partially treated sewage is incompatible with shellfish farming, customary gathering of shellfish, and commercial and non-commercial harvesting of shellfish. We note however that it is possible for different industries to work together in utilising common resources. One example of this is the promotion of aquaculture as a tourist attraction.
Maintenance of environmental quality is fundamental to the long-term survival of most commercial activities based on marine resources (for example, fishing, aquaculture, tourism), as well as the sustainability of non-commercial activities (such as customary and non-commercial harvest of kaimoana, marine-based recreational activities etc.). Discussions with Mäori throughout the course of our study indicate that there is a very high level of concern regarding the current degradation of marine resources. This concern relates both to over-fishing and pollution of the marine environment, primarily from land-based activities and the discharge of effluent from sewage treatment systems. The increasing urbanisation of the coastline in Tai Tokerau is increasing the risk of degradation of marine resources. In an ecosystem approach to the use of marine resources, natural resources cannot be regarded as ‘free gifts of nature'. There is a cost to replenishing non-renewable or over-harvested resources. Similarly the use of a resource may impose costs on the use of other resources in that ecosystem (Grima and Berkes 1989). Ignoring this cost results in degradation of resources.
The close proximity of the marine environment to most areas in Tai Tokerau, and the variety of marine and coastal ecosystems, enhance the potential for development of marine resources. This presents significant opportunities for Mäori, who have traditionally had very close links with the marine environment. The extent to which marine resources contribute to the sustainable economic development by Mäori in Tai Tokerau in the future is likely to be dependent on the quality of resource management strategies implemented in the area. This is contingent on there being a good scientific understanding of the resources and the impacts of the activities associated with their utilisation (embracing both traditional Mäori knowledge and western based science), an holistic approach to resource management, the incorporation of true co-management inclusive of all stakeholders, and a desire on the part of the Tai Tokerau community as a whole to support sustainable management of marine resources.
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