Tēnā koe e te Minister Parker,

We want to thank you for your proactive and prudent decision to protect most of the last of New Zealand’s scallop beds from continued overfishing. It’s shameful that we’ve reached this point and that you must take these actions to clean up the mess caused by decades of decline and mismanagement under the Quota Management System (QMS).

The purpose of this letter is to highlight the critical importance of the scallop beds which remain open for harvest in the Colville Channel and off Little Barrier Island.

We have examined the advice you were given to leave these areas open and found only a general (and cursory) reference to their potential as spawning sites. These areas are vital to the recovery of scallop populations around the wider Hauraki Gulf, the Eastern Coromandel Peninsula and the Bay of Plenty.

Scallops are broadcast spawners, with external fertilisation of eggs which drift in the prevailing currents for four to seven weeks before dissipating to the ocean floor where, using fibrous threads, they attach themselves to seafloor objects. Rapid growth occurs and they can reach commercial size within 18 months, although this varies between areas. Although adult scallops can move around, in Hauraki Gulf populations it is known they do not move large distances, mostly remaining sedentary. The biological characteristics of scallops mean: the more scallops that spawn at the same time in proximity, the higher the likelihood of successful fertilisation and subsequent recruitment.

It is well documented that there are “sink” populations that receive spat but do not have much influence on increasing biomass, and “source” populations that produce spat which drift on the currents before settling in sink and source beds.

Exploiting a source population can therefore have a hugely detrimental effect on down current “sink” populations.

There is little research on the scallop density required to make this reproduction process effective. A recent study of the Hauraki Gulf’s scallop dispersal patterns indicates the scallop beds in the areas of the Colville Channel and off Little Barrier Island could be source populations for sink beds in the wider Hauraki Gulf, off the Coromandel Peninsula and even the Bay of Plenty (see appendix 1).

In fact, one of the reasons for the rapid current depletion of scallops in the Hauraki Gulf Marine Park could be the short-term extensive dredging of scallops in the Colville Channel bed which saw commercial harvest peak in 2013 at 337% of their pre-season allowances, consequently making an abundant source of scallops discovered in 2011 a severely depleted scallop bed some 3 years later, contributing to rapid depletion of surrounding sink beds. It is also important to consider the effects of resuspension of marine sediments caused by trawling which occurs year round, and from dredging scallops during the open season.

While TACC has been reduced, so has the total biomass. Therefore, the consequences of continued harvest from these critical beds in the Colville Channel and off Little Barrier Island could be far reaching.

While some may argue population decline is only due to land-based sedimentation, this does not explain why the issue is so widespread and includes offshore islands where there is no increased runoff. It is also important to consider the effects of resuspension of marine sediments caused by trawling which occurs year-round, and from dredging scallops during the open season.

Minister, there is little reason to leave these essential beds open. Indeed, there is substantial justification to prioritise their protection as they prove vital to the recovery of the overall biomass. We urge you to continue your conservative decision making for the following reasons.

1. A decline of scallop biomass from 776 tonnes to 52 tonnes in 10 years is alarming.
2. Dredging is a destructive fishing technique that, together with seabed disturbance, sedimentation and runoff, has brought an end to a traditional New Zealand summer delicacy.
3. When scallop populations recover, we endorse the use of low impact, innovative harvest techniques such as Underwater Breathing Apparatus, but only if adopted in conjunction with removal of scallop dredging
4. Ngāti Manuhiri have placed a rāhui tapu on scallop harvesting in these waters. Your decision to allow dredging of scallops in these waters, when the rāhui tapu was a direct response to observed increased scallop dredging activity and undermines the primary objective of the rāhui which is to protect and restore tipa.

Even though sustainability is referred to frequently, clearly the QMS has failed this species and we urge you to now focus on rebuilding scallop populations.

Please Minister, on behalf of the undersigned, close the remaining two beds and give all of the Gulf a chance to recover quickly and reopen one day.

Nā mātou noa, nā,

Appendix 1:

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