Sustainable shellfish
Our commitment to harvesting shellfish in sustainable way
A commitment to sustainably harvesting shellfish and reducing any environmental impact is part of the central ethos of Southern Rainbow and its parent company Southern Clams.
For this reason, we develop and continue to use the manual body dredge system, rather than switching to a less labour-intensive machine dredging system. The body dredge system has the harvester pull what looks like the metal lattice of a supermarket trolley through the upper-levels of the substrate, harvesting clams which are big enough to take, while letting the juveniles pass through the bars of the dredge. Other clam harvesting systems in New Zealand involve using a machine dredge to suck up the substrate, separating the clams and ejecting the substrate out the side. We believe our method is the best at minimising our disturbance to the marine environment.
After the clams are machine and hand sorted at our factory in Dunedin any seaweed, empty clam shells and juveniles that have been inadvertently taken are returned to the same harvest ground where it was taken from. We believe that this helps to restore the substrate to the way it was before, maintaining ecosystem integrity.
While all harvesting is ‘to order’, when demand exceeds supply it remains unfilled as the supply level is set by The Ministry of Fisheries. We deliberately adopt a conservative approach to harvesting, as we have sought to increase its knowledge of managing the resource. The company believes that as humans, we all modify our environment. The important thing is to be careful about how we do it.
Managing stock
Managing the large stock of clams has been at the forefront of our thinking as the company has grown as a shellfish supplier in NZ and overseas. The company has developed a systematic rotational harvest method, to ensure the long-term sustainability of the clam stock. To achieve this, we continue to research and refine our harvest planning system, making use of GPS location data of each day’s harvest area, combined with the proportion of each size-grade of clams and the overall harvest weight. As well as this, we work in collaboration with higher education facilities, both domestically and internationally, to continue research into all facets of the business.
Another sustainability practice that we have taken on has been using cardboard chilltainers instead of polystyrene boxes where possible to transport clams (including both the New Zealand and export markets). Polystyrene takes a large amount of energy to produce and the boxes are essentially single use. By changing to the leak proof cardboard chilltainers, we not only save money on both the purchasing of the packaging and the cost of shipping, but we have a recyclable product, reducing our environmental impact. The clams are densely packed, so there is enough thermal mass to negotiate the travel.
Carbon credits
Southern Clams invested into its own forestry venture in 2011. Around 92 hectares of bio-diverse forestry has been planted to this point in old gold-mining hill country at Livingstone, in the Waitaki District. This forest is planted in around 12 different species of tree, and most will not be fully mature until around 50 years of age. The carbon credits surrendered from this forest mean that clams sold in New Zealand are carbon neutral to the first point of sale. The company’s decision to grow its own forest rather than buying carbon credits on the open market is an investment in economic stability. By owning our own carbon generating mechanism we are insulating the company from the volatility of the carbon credit market.
