FMU History and Land Use
The climate of the Te Hoiere/Pelorus FMU is characterised by the highest annual rainfall in Marlborough, with annual rainfall across the FMU having been recorded as high as 2,650mm. Winters are generally cold and wet in the valleys with frosts, though the hills are warmer, while summer months are warmer but often still wet. The mean annual rainfall for the Te Hoiere/Pelorus FMU is 1,500 to 2,700mm and average monthly temperatures can range from below 5oC to above 20oC.
Geology and soils
Tectonic activity in the wider Marlborough Sounds area has had a significant influence on the Te Hoiere/Pelorus area. Tectonic tilting northwards of the Wairau Fault resulted in the uplifting of the Richmond Ranges and regional subsidence in the Marlborough Sounds area. For the Te Hoiere/Pelorus FMU, the consequence of the tilting has been the reversal of ancient river drainage patterns with the present-day Te Hoiere/Pelorus and Kaituna Rivers originally being tributaries of the Wairau River.
The Richmond and Bryant Ranges are comprised of greywacke and schist with argillite basement rocks, with greywacke in the valleys which has been overlain by alluvial sediments. These formed as outwash glacial terrace surfaces, which were subsequently excavated in the warmer Post Glacial period and have formed the modern-day floodplain system. These soils are highly erodible, with clay content up to 60 percent.Tectonic activity in the wider Marlborough Sounds area has had a significant influence on the Te Hoiere/Pelorus area. Tectonic tilting northwards of the Wairau Fault resulted in the uplifting of the Richmond Ranges and regional subsidence in the Marlborough Sounds area. For the Te Hoiere/Pelorus FMU, the consequence of the tilting has been the reversal of ancient river drainage patterns with the present-day Te Hoiere/Pelorus and Kaituna Rivers originally being tributaries of the Wairau River.
The Richmond and Bryant Ranges are comprised of greywacke and schist with argillite basement rocks, with greywacke in the valleys which has been overlain by alluvial sediments. These formed as outwash glacial terrace surfaces, which were subsequently excavated in the warmer Post Glacial period and have formed the modern-day floodplain system. These soils are highly erodible, with clay content up to 60 percent.
Bodies of water
The Te Hoiere/Pelorus River is the longest river in the FMU rising in the Richmond Ranges in the southwest of the FMU and flowing in a north-easterly direction until its confluence with its major tributary, the Rai River, just to the east of Pelorus Bridge. The Rai River is situated in the north-eastern part of the FMU and flows directly south from its northern tributaries, the Ronga, the Tunakino and the Opouri Rivers which rise in the Bull Range. The Te Hoiere/Pelorus River then takes a more easterly path towards its entry into Te Hoiere/Pelorus Sound at the Motuweka/Havelock Estuary, with the Wakamarina River joining it at Canvastown.
To the southeast of the FMU, the Kaituna River flows north from its source near Mt Riley in the Richmond Range to its entry into Motuweka/Havelock Estuary to the eastern side of the Havelock township.
Flora and fauna habitats
The Te Hoiere/Pelorus FMU has high freshwater biodiversity values where 14 species of native freshwater fish have been recorded, including two ‘Threatened’ and seven ‘At Risk’ species. Several species of ‘Threatened’ and ‘Data Deficient’ freshwater invertebrates have also been recorded in the catchment. A population of the endemic long-tailed bat resides within the Te Hoiere/Pelorus catchment, and Forest and Bird have been actively involved in securing their protection for several years through an intensive predator control project centred at Pelorus Bridge.
The valley floors contain several important alluvial forest remnants – large podocarp and beech forests with a rich understory of broadleaf species. Several important and rare plants and animals are present throughout the catchment, including shovel mint, the Pygmy Button Daisy and giant land snails. The wetlands and estuary margins are home to an array of wetland birds, such as the banded rail and fernbird. The estuary is a wintering site for black-billed gulls and provides significant areas of seagrass habitat. Key threats to biodiversity values, ecosystems and taonga species include predation, weed incursion, habitat loss, land modification and climate change.
Land use and cover
Originally, the entire Pelorus valley was heavily forested in mixed beech and podocarp forest. Māori lived in coastal settlements in Te Hoiere/Pelorus Sound and would visit the area, camping on the riverbanks while hunting, undertaking some clearing for farming activities, exploring for stone materials, and travelling across the Marlborough – Nelson/Tasman region.
Large amounts of original forest remain in the upper, remote reaches of the catchment. Lower reaches were extensively felled by early Pakeha settlers in the late 1800s and valley floors were burned and converted into pasture for sheep and cattle grazing.
Canvastown emerged from the short-lived gold rush in 1864, which lasted about a year. Although Havelock had been mapped out years before, it was the same gold rush which truly established the area. Rai Valley towards the north of the catchment was established in the early 1900s in response to dairy farming in the area and nearby Carluke around a sawmill around the same time.
Dairy farming commenced on the valley floors in the early 1900s with the first dairy factory opening in 1909. By the 1930s, farming of the hillsides declined due to erosion and soil fertility issues. Farms were converted to pine plantations, or the land was left to regenerate to native forests. Similarly, later years saw a brief resurgence in farming activities, but by the early 1980s widespread regeneration to native forest, or conversion to pine plantations occurred throughout the area. Similar to other areas of the region, exotic plantation forestry accelerated through the 1970s-1990s and many areas of the catchment are now in Pinus Radiata.
Today, open space dominates most of the territory in this FMU, around 80% of the total area. This is predominantly upper catchment areas including steep mountain ranges and conservation areas. The second largest land use is plantation forestry at 10% and pastoral use closely following on 9%. The pastoral use is mainly dairy farming in this FMU with a number of medium scale units in the Rai and Okaramio valleys. Viticulture is a minor land use in this FMU, as the high rainfall climate is less sought after for this production system.
The below FMU map shows up to date land use/land cover classes in this area, which supports the smaller amount of viticulture, dairying use on the valley floors, and prevalent forestry.
The Land Air Water Aotearoa (LAWA) website shows the combined changes in land cover and use in the Te Hoiere/Pelorus and Kaituna catchments between 1996 and 2018, summarised in the chart below. Most of both catchments are in forestry which encompasses plantation and native bush. The next most predominant cover is grassland. Viticulture shares a very small portion of the overall cover, as described above in the small area of plantings.
Several small townships are located within the Te Hoiere/Pelorus FMU, the largest of which is Havelock at the head of the Motuweka/Havelock Estuary.
Today, this town provides services to dispersed communities within the Te Hoiere/Pelorus Sound, tourists, and the local rural areas, with a marina, green lipped mussel processing factory and several cafes and restaurants. Continuing along State Highway 6 towards Nelson, the small centres of Canvastown and Rai Valley provide services to the wider dispersed rural communities.
Māori history in the area
The council has an ongoing work stream with local iwi to identify their visions, values, and aspirations for freshwater in the FMU. These will be collated with views from the wider community.