Last updated on 10 August 2016

SUMMARY

SUMMARY

IDENTIFICATION

SCIENTIFIC NAME(s)

Meretrix lyrata

SPECIES NAME(s)

Lyrate hard clam

COMMON NAMES

Hard clam

The Lyrate hard clam (Meretrix lyrata) or Ben Tre Clam fishery is a traditional source of food with a high nutritional value and provides employment for the local people living in coastal areas. Ben Tre Clam (Meretrix lyrata) is an abundant and valuable resource in large coastal areas stretching from Can Gio District (Ho Chi Minh City) to a number of provinces of the Mekong Delta including Tien Giang, Ben Tre, Tra Vinh, Bac Lieu and others, of which Ben Tre is the most important.

In Vietnam, the simplest traditional method of clam management in sand flat area is the bottom management system that is also called the broadcast, bottom sowing or relaying technique. Wild spat, or “clam seed”, at a size typically of 300-5000 clams/kg, is transferred to suitable “nursery” sand flat areas for a period of 10 – 12 months up to a size of 100 – 300 clams/kg, which are used for further relaying and ongrowing to adult size in dedicated “commercial management” sand flat areas (Luu et al 2009). This particular fishery was certified by the Marine Stewardship Council system in November 2009. Click here to link to the MSC fishery page and to learn more about the MSC fishery certification unit. This species also occurs along the coasts of Taiwan, the Philippines, and Southern China.


ANALYSIS

No related analysis

FISHSOURCE SCORES

Management Quality:

Management Strategy:

≥ 6

Managers Compliance:

≥ 8

Fishers Compliance:

≥ 8

Stock Health:

Current
Health:

≥ 6

Future Health:

≥ 8


RECOMMENDATIONS

CATCHERS & REGULATORS

1. Monitor fishery and management system for any changes that could jeopardize MSC re-certification.

RETAILERS & SUPPLY CHAIN

1. Support the sustainability achievements of this fishery by sourcing this product, and ensure that the producers are aware that sustainability certification played a role in your decision to source this product.


FIPS

No related FIPs

CERTIFICATIONS

  • Vietnam Ben Tre Clam Hand Gathered:

    MSC Recertified

Fisheries

Within FishSource, the term "fishery" is used to indicate each unique combination of a flag country with a fishing gear, operating within a particular management unit, upon a resource. That resource may have a known biological stock structure and/or may be assessed at another level for practical or jurisdictional reasons. A fishery is the finest scale of resolution captured in FishSource profiles, as it is generally the scale at which sustainability can most fairly and practically be evaluated.

MANAGEMENT UNIT FLAG COUNTRY FISHING GEAR
Ben Tre, Vietnam Viet Nam Hand implements

Analysis

OVERVIEW

RECOMMENDATIONS

Last updated on 28 July 2016

Improvement Recommendations to Catchers & Regulators

1. Monitor fishery and management system for any changes that could jeopardize MSC re-certification.

Recommendations to Retailers & Supply Chain

1. Support the sustainability achievements of this fishery by sourcing this product, and ensure that the producers are aware that sustainability certification played a role in your decision to source this product.

1.STOCK STATUS

STOCK ASSESSMENT

Last updated on 30 August 2016

Surveys that involved the counting and size classification of clams on a stratified – random basis along 24 transects during April and October – November 2000 in Ben Tre sand flat area were carried out by NTOI, 2001. It was found that there were large variations between differing areas, and also that distribution of the clams according to tidal height varied with season, with adults increasing in density at river mouths and subtidal areas during the dry season and increasing in density on the lower intertidal during the rainy season (Luu et al 2009).

On the basis of this stock assessment, an estimate of likely fishable biomass was made by the officers of the Institute. This took into account factors such as likely mortality and growth over the coming months, largely determined on the basis of field survey data and historical clam landings. An annual landing figure (quota) was then calculated by according to the methods of Gulland (1979).

The results obtained were as follows: the total potential sand flat area of 15,128 ha supported an estimated clam stock at that time of 216,000 – 465,000 tonnes, while the managed (at that time) area of 3,115 ha supported an estimated 47,000 – 102,000 tonnes. The likely fishable biomass for the two areas was estimated at 150,000 – 312,000 tonnes and 32,000 – 69,000 tonnes, respectively. Thus the estimated fishable biomasses represented 68 – 69% and 67 – 68% of clam standing stocks. These figures also indicate that the average density of clams in tonnes/ha in managed and non-managed areas may have been similar, although there is a high level of variation in the figures and hence a low level of confidence (Luu et al 2009).

SCIENTIFIC ADVICE

Last updated on 30 August 2016

Ben Tre Province has three coastal districts (Binh Dai; Ba Tri and Thanh Phu), all of which have clam resources and are involved in clam management. The province contains a total potential sand flat area of 15,128 ha that is suitable for clam protection and management. Since 2007, up to 24% has been used for clam management (Akroyd et al 2011 & 2013)​​.

Recommendations presented by Akroyd et al 2011 & 2013 :

 The DARD Ben Tre should establish some stations for environmental observation and measurement at the river mouth in order to mitigate the risk to clam resources as well as clams in management area.

 Implementation of a research project to determine on the reasons why mass mortality of clams in the sand flat areas during March/April period 2011 – 2013.

 The local government should support clam Co-ops in their efforts to stop clam illegal fishing.

 Besides, the recommendations on some aspects such as clam management, technology, financial, labor force and awareness of local people have been mentioned.

CURRENT STATUS

Last updated on 30 August 2016

Ben Tre Province has three coastal districts (Binh Dai; Ba Tri and Thanh Phu), all of which have clam resources and are involved in clam management. The province contains a total potential sand flat area of 15,128 ha that is suitable for clam protection and management. Since 2007, up to 24% has been used for clam management (Akroyd et al 2011 & 2013)​.

General status for this species is broadly presented by Tuan et al 1997.

2.MANAGEMENT QUALITY

MANAGEMENT

Last updated on 30 August 2016

The 15,128 ha of potential sand flat identified as being suitable for clams Meretrix lyrata have been divided into managed and non-managed areas (in which no harvesting is allowed) with the aim of limiting the amount of clams which can be harvested. This has been limited to no more than 35 – 40% of the fishable biomass, according to National Regulations. Under these regulations, the managed areas have to reach up to around 6,000 ha, representing 40% of the suitable clam area. Further surveys are planned, however, which may allow development of up to 70% or more of sand flats (Luu et al 2009).

Regulations applied in Ben Tre for clam management approved by the Department of Agriculture and Rural Development (DARD) of Ben Tre:

 Minimum landing size (implemented through a specified mesh size of usually 30 mm) to protect clams at the size of the first spawning; the mesh size has been 30 mm since September 1998.

 The harvest of clam seeds at a size smaller than 5,000 nos./kg (i.e. more than 5,000 nos./kg) for transplanting is fully banned. Only clam seed with a size of 5,000 nos./kg or larger may be harvested, whether for transplanting by the same co-operative or group or for selling on to other co-ops.

 Establishment of 10 clam co-operatives and 4 clam groups in three coastal districts to reasonably develop clam management systems and protect clam resources as well as sand flat area environment.

 No tractors are allowed on beaches to transport commercial clam harvested.

 Only hand collection with rakes and sieves is allowed for harvest of commercial clams and clam seeds.

 Temporary closure of clam sand flat area for fishery management purposes can be effected when it is necessary.

(Gascoigne et al. 2014)

COMPLIANCE

Last updated on 30 August 2016

The Ben Tre Clam fishery is a traditional source of food with a high nutritional value and provides employment for the local people living in coastal areas. Ben Tre Clam (Meretrix lyrata) is an abundant and valuable resource in large coastal areas stretching from Can Gio District (Ho Chi Minh City) to a number of provinces of the Mekong Delta including Tien Giang, Ben Tre, Tra Vinh, Bac Lieu and others, of which Ben Tre is the most important.

In Ben Tre, the traditional method of clam management in sand flat area is called the broadcast, bottom sowing or relaying technique. Wild spat, or “clam seed”, at a size typically of 300-5000 clams/kg, is transferred to suitable “nursery” sand flat areas for a period of 10 – 12 months up to a size of 100–300 clams/kg, which are used for further relaying and ongrowing to adult size in dedicated “commercial management” sand flat areas.

In order to manage the fishery resource efficiently and effectively and to protect and harvest of the clams resources in a sustainable manner, Ben Tre province have established 10 clam co-operatives and 4 clam groups. The Department of Agriculture and Rural Development (DARD) work closely with the members and assist with education, research, assessments and monitoring programs. The members have the responsibility to share all activities relating to clam protection and management (Akroyd et al 2013).

Moreover, during the harvest the larger clams are not taken but are left on the sand to re-bury, which they do rapidly. These adult clams are known to migrate in subsequent months down the beach to the subtidal area, although on occasion this is aided by the fishers physically relocating them. This development of ‘broodstock’ is a major feature of clam management in Ben Tre (Luu et al 2009).

Commerical harvesting takes place all year round, but the great majority takes place in the period April to October. A net to allow the return of small clams is used. In some cases the net is attached to the rake while in other cases the two are separate. The width of the rake and the mesh size on the net must abide by the regulations of management organizations. Interviews with members of Rang Dong co-operative carried out in March 2004 and August 2008 showed that the width of rake and mesh size were of 35 cm and 30 mm, respectively. With this mesh size only the commercial clams of typically 25 – 80 clams/kg are harvested and small sized clams can escape from the net.

The use of machines for harvesting clams is fully banned. Bags of clams are taken to a boat moored on the sand where they are checked, counted and weighed, and transport to markets or processors is normally by boat.

3.ENVIRONMENT AND BIODIVERSITY

BYCATCH
Other Species

Last updated on 30 August 2016

The harvests of clam seeds for transplantation and commercial clams for sale are carried out at low tide. At this time the majority of other species such as swimming crabs and other small crabs and various gastropod species have followed the ebb to the near shore subtidal waters. By–catch is therefore negligible. Some larger clam are left on the sandflats to provide future broodstock, but are not considered to be discard.

HABITAT

Last updated on 30 August 2016

There is no evidence that the fishery is having unacceptable impacts, based on a reasonable understanding of the fishery, although the issue has not been directly studied. The effects of the fishery on biological diversity, community structure and productivity have been considered and it can be demonstrated/justified that there are no unacceptable impacts. The effects of the fishery on biological diversity, community structure and productivity have been quantified and are within acceptable tested/justified limits. The effects of the fishery on sand flat community biological diversity, community structure and productivity have now been studied.

The results presented by Akroyd et al 2011 & 2013  shown that there are no unacceptable impacts on habitat structure.The effects of the fishery on biological diversity, community structure and productivity have been considered and it can be demonstrated/justified that there are no unacceptable impacts. This information, as a report, was presented to a workshop in October 2011 and the results have been quantified and appear to be within acceptable limits. If this report is published in a scientific journal the score would be 100.

FishSource Scores

SELECT SCORES

MANAGEMENT QUALITY

Different components of this unascertained score differently at the fishery level. Please look at the individual fisheries using the selection drop down above.

Different components of this unascertained score differently at the fishery level. Please look at the individual fisheries using the selection drop down above.

Different components of this unascertained score differently at the fishery level. Please look at the individual fisheries using the selection drop down above.

STOCK HEALTH:

Different components of this unascertained score differently at the fishery level. Please look at the individual fisheries using the selection drop down above.

Different components of this unascertained score differently at the fishery level. Please look at the individual fisheries using the selection drop down above.

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DATA NOTES

Last updated on 30 August 2016

Note
Quotas by area and year not publicly available.

Download Source Data

Registered users can download the original data file for calculating the scores after logging in. If you wish, you can Register now.

Fishery Improvement Projects (FIPs)

No related FIPs

Certifications

Marine Stewardship Council (MSC)

SELECT MSC

NAME

Vietnam Ben Tre Clam Hand Gathered

STATUS

MSC Recertified on 3 November 2009

SCORES

Principle Level Scores:

Principle Score
Principle 1 – Target Species 81.3
Principle 2 - Ecosystem 93.0
Principle 3 – Management System 89.8

Certification Type: Gold

Sources

Credits
  1. Akroyd, J., Li, D. 2011. Surveillance Report Ben Tre Hand-Gathered Clam Fishery. Intertek Moody Marine, November 2011. 14pphttp://www.msc.org/track-a-fishery/fisheries-in-the-program/certified/pacific/vietnam-ben-tre-clam-hand-gathered/assessment-downloads-1/82036_Second_Annual_Ben_Tre_Clam_Fishery_Surveillance.pdf

  2. Akroyd, J., Luu, T.T. 2013. Surveillance Report Ben Tre Hand-Gathered Clam Fishery. Intertek Moody Marine, April 2013. 15pphttp://www.msc.org/track-a-fishery/fisheries-in-the-program/certified/pacific/vietnam-ben-tre-clam-hand-gathered/assessment-downloads-1/20130509_SR_CLA125.pdf

  3. Gascoigne, J., Collinson, K., Phi Lai, T., 2014. MacAlister Elliott and Partners Ltd, April 2014. 13pphttp://www.msc.org/track-a-fishery/fisheries-in-the-program/certified/pacific/vietnam-ben-tre-clam-hand-gathered/assessment-downloads-1/20140430_SR_CLA125.pdf

  4. Luu. TT, Holt. T, Hough. A, 2009.Public Certification Report for Ben Tre Clam Fishery. Moody Marine Inc. http://www.msc.org/track-a-fishery/certified/pacific/vietnam-ben-tre-clam-hand-gathered/assessment-downloads-1/09.11.2009-ben-tre-clam-pcr.pdf

  5. Tuan, V.S. and Phung, N.H., 1997. Status of bivalve exploitation and farming in the coastal waters of South Vietnam. In 8. Tropical Marine Mollusc Programme, Phuket (Thailand), 18-28 Aug 1997.http://agris.fao.org/agris-search/search.do?recordID=TH2000003485

References

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    Lyrate hard clam - Ben Tre, Vietnam

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