Characteristics of integrated mangrove-shrimp farming systems in Ben Tre Province, Vietnam: preliminary findings for organic shrimp production certification

Thao, Huynh Van; Cong, Nguyen Van

doi:10.1590/2675-2824071.22117hvt

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Original articles • Ocean Coast. Res. 71 • 2023 • https://doi.org/10.1590/2675-2824071.22117hvt copy

Characteristics of integrated mangrove-shrimp farming systems in Ben Tre Province, Vietnam: preliminary findings for organic shrimp production certification

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Mangrove forests play a critical role in natural disaster resistance and provide meaningful livelihoods for local communities, especially integrated mangrove shrimp farming (IMSF) systems. Organic shrimp certification actually increases the value chains of shrimp farming in addition to ameliorating mangrove–forest management. Identifying technical issues and assessing environmental risks are the leading concerns when considering organic shrimp production certification. In this study, the technical practices of 30 households were investigated, and surface water and sediment samples were collected in the IMSF models and adjacent rivers in the Thua Duc Forest Management Board area, Ben Tre Province. Data collected from shrimp farming ponds and the environmental background were referred to both the Naturland and National Standards. The results showed that the average mangrove forest and shrimp pond ratio was 56.90:42.70 (%). Two technical issues were highlighted: (i) the use of rotenone, known as a toxin to kill undesirable fish before stocking shrimp, and (ii) annual shrimp pond regeneration causing increased pollution. The data showed that higher concentrations of TSS and P-PO4 3- were detected in surrounding rivers, while surface water in either IMSF ponds or adjacent rivers slightly surpassed the permissible levels of total Fe concentration. All parameters—including heavy metals; toxic and persistent parameters; oil and grease and coliforms analysed in surface water, and sediment samples—were lower than the detection and permissible levels. The results provided evidence that the IMSF’s practices and environmental characteristics were suitable for recommending the Naturland Standards. Recommendations and technical interventions for farmers are necessary to help reduce Fe levels and the safe use of rotenone in IMSF systems. An environmental quality monitoring programme at the target area should be applied when launching organic shrimp production.

Descriptors:
Mangrove forest; Water and sediment quality; Shrimp farming practices; Vietnamese Mekong Delta

Sample	Parameters	Analytical methods
Water	TSS	SMEWW 2540.D:2012
	N-NH ₄+	SMEWW 4500-NH3.F:2012
	P-PO43-	SMEWW-4500P.E:2012
	F-	SMEWW 4500-F -B:2012
	CN-	SMEWW 4500CN- C:2012
	As, Cd, Pb, Cu, Zn and Cr	SMEWW 3120 B:2012
	Cr6+	SMEWW 3500-Cr.B: 2012
	Mn and Fe	SMEWW 3111.B:2012
	Hg	SMEWW 3112.B: 2012
	Aldrin, Dieldrin, Benzene hexachloride (BHC), dichlor o-diphenyl-trichloroethane (DDT), Heptachlor and Heptachlorepoxide	EPA (1998)
	Total phenol	ISO 6439:1990
	Oil and Grease	SMEWW 5520.B:2012
	Total coliform	SMEWW 9221.B:2012
Sediment	As	ISO (2007)
	Cd, Pb, Zn, total Cr, and Cu	ISO 11047:1998
	Hg	ISO, 2004
	Chlordane, DDT, dichlorodiphenyldichloroethylene (DDE), dichlorodiphenyldichloroethane (DDD), Dieldrin, Endrin, Lindane, total Polychlorinated Biphenyl (PCB) and Heptachlor epoxide	ISO 10382: 2002

Variable	Unit	Value
Total mean area of interviewed farmers	ha household ^-1	5.62 (1.30 – 12.15)
Mangroves forest area	ha household ^-1	2.40 (0.40 – 5.50)
Shrimp pond area	ha household ^-1	0.28 (0.89 – 6.60)
Forest:pond ratio	%	56.90:42.70
Households maintained the ratio at 70:30	%	10.00
Households maintained the ratio at 60:30	%	66.67
Households maintained the ratio at 50:50	%	23.33
Annual shrimp-pond regeneration schedule (lunar calendars)
July	%	21.00
August	%	70.00
September	%	9.00
The height of sediment layer excavated
≤0.5 m	%	10.00
0.5 – 1.0 m	%	44.00
≥ 1.0 m	%	46.00
Stocking density
≤ 30,000 shrimp ha ^-1 yr ^-1	%	20.18
30,000 - 50,000 shrimp ha ^-1 yr ^-1	%	50.54
≥ 50,000 shrimp ha ^-1 yr ^-1	%	29.28
Harvest frequency	time per month	2
Shrimp yield	kg ha ^-1 yr ^-1	172.4 (120 - 260)
Net profit†	million VND ha ^-1 yr ^-1	55.42 (35 - 70)

Parameter	Unit	Pond	River	Standard†
Total Fe	mg L ^-1	1.36±0.63a	0.82±1.82b	0.5
Cu	mg L ^-1	<DL	<DL	0.2
Zn	mg L ^-1	<DL	<DL	0.5
F-	mg L ^-1	0.90±0.08a	0.80±0.79b	1.5
CN	mg L ^-1	<DL	<DL	0.01
As	mg L ^-1	<DL	<DL	0.02
Cd	mg L ^-1	<DL	<DL	0.005
Pb	mg L ^-1	<DL	<DL	0.05
Hg	mg L ^-1	<DL	<DL	0.001
Cr6 +	mg L ^-1	<DL	<DL	0.02
Total Cr	mg L ^-1	<DL	<DL	0.1
Mn	mg L ^-1	0.28±0.05a	0.18±0.21b	0.5
Aldrin	µg L ^-1	<DL	<DL	0.1
Benzene hexachloride (BHC)	µg L ^-1	<DL	<DL	0.02
Dieldrin	µg L ^-1	<DL	<DL	0.1
Total DDTs	µg L ^-1	<DL	<DL	1
Heptachlor and heptachlor epoxide	µg L- 1	<DL	<DL	0.2
Total phenol	mg L ^-1	<DL	<DL	0.03
Oil and grease	mg L ^-1	<DL	<DL	0.5
Total coliform	MPN 100mL ^-1	9.00±5.61b	93±29.75a	1000

Parameter	Unit	Shrimp pond	Standard†
As	mg kg ^-1	<DL	41.6
Cd	mg kg ^-1	<DL	4.2
Pb	mg kg ^-1	<DL	112.0
Hg	mg kg ^-1	0.04±0.01	0.7
Total Cr	mg kg ^-1	17.97±0.76	160.0
Cu	mg kg ^-1	10.41±0.93	108.0
Chlordane	µg kg ^-1	<DL	4.8
DDT	µg kg ^-1	<DL	4.8
DDE	µg kg ^-1	<DL	374.0
DDD	µg kg ^-1	<DL	7.8
Dieldrin	µg kg ^-1	<DL	4.3
Endrin	µg kg ^-1	<DL	62.4
Heptachlor epoxide	µg kg ^-1	<DL	2.7
Lindane	µg kg ^-1	<DL	1.0
Total PCB	µg kg ^-1	8.00±0.00	189.0

Instituto Oceanográfico da Universidade de São Paulo Praça do Oceanográfico 191, CEP: 05508-120, São Paulo, SP - Brasil, Tel.: (11) 3091-6501 - São Paulo - SP - Brazil
E-mail: diretoria.io@usp.br

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[1] ^* Corresponding author: nvcong@ctu.edu.vn