Scientific name: |
Austrovenus stutchburyi |
Other names: |
hinangi, huangi, huuai, huangiangi tuangi (Maori), New Zealand littleneck clam (USA), clam, venus-shells, coque (Canada) |
Cockles collected by hand are a good seafood choice. Those that come from Otago or Nelson/Marlborough regions are the best choice.
A relatively short-lived but widespread shellfish species, found in soft mud to silty sand habitats in harbours and estuaries. The main commercial harvesting areas are at Whangarei, Nelson/Marlborough and the Otago Peninsula.
Cockles are either harvested by hand or by mechanical harvesting and digging at Tasman and Golden Bay. Concern over the fishery includes the effect of the harvesting technique (mechanical digger). Past depletion of stocks in Whangarei harbour, gaps between surveys and assessments of some areas that are more than 5 years old, the lack of a management plan, the uncertainty over stock size in relation to virgin biomass, and recruitment and BMSY in other areas are also of concern. The ecological effects of removing or killing this shellfish on wading birds that feed on them are unknown.
Not certified under any scheme.
Sold in New Zealand and in 2015 $1.365 million were exported, mainly to United States, with small amounts to Australia and the UK.
Asssessment output
Regional differences between Whangarei, Nelson/Marlborough and the Otago Peninsula were assessed. Collecting method either by hand or mechanical digger was also assessed. All hand-collected cockles are a good seafood choice and rated light green. There were small differences in scoring based on the regions, with Otago rating the highest, followed by Snake Bank in Whangarei, then Nelson/Marlborough region.
| Score: | Otago and Nelson/Marlborough – C, Whangarei – D |
| Population size: | Biomass was estimated to be about 35% of unfished biomass in COC 1A (Whangarei) in 2009. In COC 3A (Otago) adult cockles are just below 1992 levels in Waitati and Papanui Inlet. In COC 7A and B (top of South Island, Golden Bay, Marlborough) two of the three commercially fished areas have declined while the other has increased. |
| Annual catch limit: | Total catch limit set at 3,214 tonnes since 2007-08. |
| Recorded catch: | Reported commercial harvest of approximately 1,078 tonnes in 2014-15. There have been no reported landings in Whangarei since 2011-12. |
| Stock trends: | In Whangarei (COC 1), large cockles (greater than 35mm) have declined to about 5 % of 1982 levels in 2009. For Otago areas the biomass is likely to be at or above BMSY. In Tasman Bay-Golden Bay, the Pakawau Beach recruited population has declined by 60% since 2008, whereas Ferry Point and Riwaka-Tapu Bay cockle size and abundance had declined to 20% and 50% respectively up to 2008. In all fisheries the relationship between the spawning stock and recruitment is poorly understood. |
| MSY Status: | MSY or equivalent. Depleted for large cockles in Whangarei harbour. |
| The Ministry of Primary Industries assessment plenary report includes: |
For Whangarei Harbour (COC 1) that: “The stock status in 2009 was at 35% of Bo and has varied between 19 and 63% of Bo since 1988, following a decline from 1982-1991. It is very unlikely that overfishing is occurring.” For Nelson/Marlborough (COC 7A and B): The recruited biomass estimates of cockles from Pakawau beach have shown a general trend of increase, with the lowest value in 1992 and highest value in 2004. Ferry point recruited biomass estimates declined from 1996 to 2004-2008. Riwaka total biomass estimates decreased from 1991 to 2008. Fishing at present levels is very unlikely to cause declines below the soft (20%Bo) or hard limit (10%Bo). For Otago: “Biomass at Waitati Inlet has been stable and has never decreased below 85% of Bo. A Papanui Inlet biomass generally decreased to approximately 70% of Bo in 2004 but little commercial catch has come out of this inlet since. In Otago Harbour biomass has declined, but most of this occurred before havesting started.” (MPI, 2016, p 235-237, 176-181, and 186-191). |
| Score: | All regions – B |
| Distribution: | Widespread around New Zealand, including Stewart Island and the Chatham Islands, in harbours and estuaries from mean high tide level down to low tide. |
| Maximum age (years): | 8+ |
| Age at sexual maturity: | 1 |
| Growth rate: | Moderate |
| Reproductive output: | High to very high |
| Age exploited: | 2-5 |
| Ability to recover: | Moderate |
| Score: | Otago and Whangarei – A, Nelson/Marlborough – B |
| Fishing method(s): | Mechanical digging and raking of mudflats in Tasman Bay and Golden Bay, and hand harvesting in Whangarei harbour and Otago Peninsula. |
| Habitat damage: |
Mechanical digging: Mechanical digging and raking can kills small cockles and could impact on other species living within the sediment. Hand: Minimal impact from hand harvesting. |
| Habitat of particular significance: | hasn’t been defined in New Zealand. |
| Bycatch: | Impact of mechanical dredging on small shellfish and other sub-surface organisms. |
| Ecological effects: | Small cockles are an important part of the diet of some wading bird species. Removing or killing small cockles could reduce the amount of food available to wading birds, including South Island and variable oystercatchers, bar-tailed godwits, and Caspian and white-fronted terns. |
| Score: | All regions – A |
| Bycatch: | There is no reported bycatch of protected or threatened species. |
| Score: | Otago and Whangarei – A, Nelson/Marlborough – B |
| Management component: | Single species. There are uncertainties about stock boundaries and the stock structure. |
| Score: | Whangarei – B, Otago and Nelson/Marlborough – D |
| Quota Management Species: | Yes, since 2002 for four areas. |
| Catch limits: | Yes |
| Management plan: | There is no approved shellfish or inshore plan. |
| Stock assessment: | Surveys for stock assessments were carried out most recently in Whangarei in 2009, Otago (Papanui and Waitati) in 2011, Otago Harbour in 2012, Pakawau (Golden Bay) in 2014, Riwaka and Ferry Point in 2008. Initial quantitative assessments for most other areas are based on 1991-93 information. Annual surveys are required for CAY assessment. It is uncertain when the next surveys and assessments will take place. |
| Research: | Research has focused on yield assessments but several are over 5 years old. |
| Observer coverage: | Unobserved. |
Fisheries map
Taken from the Ministry for Primary Industries’ Plenary report for fisheries management.
References
Report from the Fishery Assessment Plenary, May 2009: stock assessments and yield estimates. Part 1: Alfonsino to Hake, Science Group, Ministry for Primary Industries; Ministry for Primary Industries (2016) Aquatic Environment and Biodiversity Annual Review 2015. Compiled by the Fisheries Management Science Team, Ministry for Primary Industries. 682p. The Guidebook to New Zealand Commercial Fish Species, 2007 Revised Edition, The New Zealand Seafood Industry Council Ltd. Seafood New Zealand, 2016. New Zealand Seafood Exports to December 2015. 133p.