Last updated on 30 November 2017

SUMMARY

SUMMARY

IDENTIFICATION

SCIENTIFIC NAME(s)

Portunus pelagicus

SPECIES NAME(s)

Blue swimming crab, Flower crab

Most of the information in this profile relates to the fishery in Kien Giang province, close to the border with Cambodia, as available information focuses on this area. No studies of the stock structure of the species in the region could be located and no regional assessment is conducted. Please refer to sections under the Kien Giang Management Unit to find the most detailed information.


ANALYSIS

Strengths
  • Three annual stock assessments have now been conducted
  • The most recent stock assessment (2015) indicated a small increase in the estimated biomass, and slight decrease in effort since the previous year (2014)
  • There is a fishery observer program and based on risk assessment, the fishing method appears to have minimal impact on most non-target species.
  • The management authority appears to be strong and sufficiently well resourced to undertake monitoring, control and surveillance activities.
  • There are already some government regulations including a minimum landing size, seasonal closures, and gear restrictions.
  • A community co-managment system is under development; an operational Crab Advisory Council (CAC) has already been established
  • Initiatives to improve stock assessment, managment, and fishery compliance are ongoing under the Kien Giang Blue Swimming Crab FIP 
Weaknesses
  • While fishing effort appears to have decreased slightly in the most recent assessment, it is still indicated to be over sustainable limits
  • Measures to limit effort are still not optimally implemented or effective, despite improvements
  • Chinese traps disproportionately exploit smaller, immature crab, and this gear is responsible for an increasing portion of the overall catch
  • Stock assessments are not yet robust enough to allow for an abundance based harvest control strategy
  • Based on a 2009 MSC Pre Assessment, the fishery was not recommended to proceed to full assessment.
  • Many key factors remain in need of resolution for the fishery to be able to undergo MSC assessment: signs of over-exploitation, a lack of precautionary management measures applied that would prevent a decline in the biomass, insufficient information available to allow for an assessment of impacts on other retained species, bycatch species, habitats and ecosystems; lack of a mechanism to limit expansion in fishing effort. Restrictions in place would require strengthening, and evidence of compliance.
  • While the fishery is indicated to have minor impacts on bycatch species, some interactions need to be carefully monitored (e.g. brownbanded bamboo shark which is "near threatened" according to the IUCN).
  • There is a need for increased publically available reporting on bycatch, habitat and ecosystem monitoring and evaluation.

FISHSOURCE SCORES

Management Quality:

Management Strategy:

≥ 6

Managers Compliance:

≥ 6

Fishers Compliance:

< 6

Stock Health:

Current
Health:

≥ 6

Future Health:

< 6


RECOMMENDATIONS

RETAILERS & SUPPLY CHAIN
  • Participate in and promote research to determine the stock structure throughout the Vietnam.
  • Develop and implement a stock assessment programme to assess all stocks based on the best available science, and develop appropriate stock-specific management advice.
  • Press regulators to fully implement the management plan (including a harvest strategy and reference points). The management plan should be sensitive to regional differences in the stocks, fisheries and socio-economic needs.
  • Implement product specifications and/or a Control Document to help address specific sustainability or compliance issues in the fishery (e.g. undersized crab and seasonal closures).
  • Encourage regulators to better enforce seasonal closures, demarcated areas for particular gear/vessel types, and the minimum landing size (10 cm carapace width).
  • Ensure regulators prohibit fishing gears that target or predominantly catch undersized crabs; and regulate for all other fishing gears to minimise the capture of crabs less that the minimum landing size.
  • Develop the existing observer programme into a comprehensive data collection programme that includes bycatch and non-target species catch (both ETP and non-ETP species), and initiate a data collection program for habitats and ecosystem.
  • Support ongoing efforts to foster local participation in developing responsible crab fishing, and encourage further localised management measures, including voluntary no-take zones and the protection of crab habitat (e.g. seagrass beds).
  • Implement the activities and milestones required in the FIP Action Plan, integrating changes and clarifying any areas of uncertainty identified during the FIP review meeting in December 2016.

FIPS

  • Vietnam blue swimming crab - bottom gillnet/pot/trap:

    Stage 5, Progress Rating A

CERTIFICATIONS

No related MSC fisheries

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
Vietnam Viet Nam Gillnets and entangling nets
Pots

Analysis

OVERVIEW

Strengths
  • Three annual stock assessments have now been conducted
  • The most recent stock assessment (2015) indicated a small increase in the estimated biomass, and slight decrease in effort since the previous year (2014)
  • There is a fishery observer program and based on risk assessment, the fishing method appears to have minimal impact on most non-target species.
  • The management authority appears to be strong and sufficiently well resourced to undertake monitoring, control and surveillance activities.
  • There are already some government regulations including a minimum landing size, seasonal closures, and gear restrictions.
  • A community co-managment system is under development; an operational Crab Advisory Council (CAC) has already been established
  • Initiatives to improve stock assessment, managment, and fishery compliance are ongoing under the Kien Giang Blue Swimming Crab FIP 
Weaknesses
  • While fishing effort appears to have decreased slightly in the most recent assessment, it is still indicated to be over sustainable limits
  • Measures to limit effort are still not optimally implemented or effective, despite improvements
  • Chinese traps disproportionately exploit smaller, immature crab, and this gear is responsible for an increasing portion of the overall catch
  • Stock assessments are not yet robust enough to allow for an abundance based harvest control strategy
  • Based on a 2009 MSC Pre Assessment, the fishery was not recommended to proceed to full assessment.
  • Many key factors remain in need of resolution for the fishery to be able to undergo MSC assessment: signs of over-exploitation, a lack of precautionary management measures applied that would prevent a decline in the biomass, insufficient information available to allow for an assessment of impacts on other retained species, bycatch species, habitats and ecosystems; lack of a mechanism to limit expansion in fishing effort. Restrictions in place would require strengthening, and evidence of compliance.
  • While the fishery is indicated to have minor impacts on bycatch species, some interactions need to be carefully monitored (e.g. brownbanded bamboo shark which is "near threatened" according to the IUCN).
  • There is a need for increased publically available reporting on bycatch, habitat and ecosystem monitoring and evaluation.
RECOMMENDATIONS

Last updated on 24 September 2018

Recommendations to Retailers & Supply Chain
  • Participate in and promote research to determine the stock structure throughout the Vietnam.
  • Develop and implement a stock assessment programme to assess all stocks based on the best available science, and develop appropriate stock-specific management advice.
  • Press regulators to fully implement the management plan (including a harvest strategy and reference points). The management plan should be sensitive to regional differences in the stocks, fisheries and socio-economic needs.
  • Implement product specifications and/or a Control Document to help address specific sustainability or compliance issues in the fishery (e.g. undersized crab and seasonal closures).
  • Encourage regulators to better enforce seasonal closures, demarcated areas for particular gear/vessel types, and the minimum landing size (10 cm carapace width).
  • Ensure regulators prohibit fishing gears that target or predominantly catch undersized crabs; and regulate for all other fishing gears to minimise the capture of crabs less that the minimum landing size.
  • Develop the existing observer programme into a comprehensive data collection programme that includes bycatch and non-target species catch (both ETP and non-ETP species), and initiate a data collection program for habitats and ecosystem.
  • Support ongoing efforts to foster local participation in developing responsible crab fishing, and encourage further localised management measures, including voluntary no-take zones and the protection of crab habitat (e.g. seagrass beds).
  • Implement the activities and milestones required in the FIP Action Plan, integrating changes and clarifying any areas of uncertainty identified during the FIP review meeting in December 2016.

1.STOCK STATUS

STOCK ASSESSMENT

A stock assessment of blue swimming crab (BSC) in the waters of Kien Giang Province in 2013 (Ha et al. 2014) marked the first study of its kind for the species in the Sea of Vietnam. Data for the study was collected from landing surveys, fisher logbooks, on board surveys, and random biological sampling of commercial catch data.  Biological data was used to estimate size distribution, size-weight relationship, size at first maturity, sex ratio, and spawning season. Fishery data was assessed to estimate total annual catch and catch per unit effort, as well as spatial and temporal distribution of catches, fleet and gear specific catch rates and bycatch statistics.  Biomass and fishing mortality (F) were estimated via length cohort analysis based on length frequency data, growth parameters, estimated natural mortality, and total annual catch. Fishing mortality reference points Fmsy and F0.1 were estimated via Yield per Recruit analysis (Beverton and Holt model).

Updated assessments of the stock condition in 2014 (Ha et al. 2015, report unavailable) and 2015 (Ha et al. 2016) have been conducted.  As of January 15, 2018, there were no more recently published stock assessments available. The 2013 stock assessment was reportedly reviewed by at least one independent scientist (Poseidon ARM Ltd. 2014).

Continued development and regular updating of stock assessments is a priority detailed within the Kien Giang Fishery Improvement Project (FIP) action plan (Poseidon ARM Ltd. 2017) .  Specific actions needed to strengthen the stock assessment include assessment of stock and fishery independence with surrounding fisheries, evaluation of how well management actions are achieving their objectives, re-assessment of the number of active fishing vessels in the fishery, development of the model to estimate fishery reference points and performance in terms of biomass rather than fishing mortality, incorporation of statistical error in the model, and consideration of error (statistical and otherwise) when developing harvest control rules.

SCIENTIFIC ADVICE

Scientific advice to date has been taken from stock assessments developed by scientists at the Research Institute for Marine Fisheries (RIMF) (Ha et al. 2016)(Ha et al. 2014)(Ha et al. 2016) .  As of the most recent stock assessment, there were only 3 years of biomass estimates available, and abundance based reference points had not yet been developed; thus objectives continue to be framed in terms of fishing mortality and effort management. Since the initial assessment, advice has focused on effort reduction strategies for meeting objectives for fishing mortality "F" or exploitation coefficient (exploitation ratio) "E" . 

The 2015 assessment specifically recommended the elimination of Chinese traps, which exploit large numbers of juvenile crab, as well as measures to avoid fishing on nursery grounds after peak spawning, in order to optimize potential regeneration and recovery of the stock (Ha et al. 2016) .

Reference Points

The 2013 stock assessment identified target (Fmsy = 0.8) and precautionary (F0.1 = 0.6) reference points, based on Yield per Recruit analysis (Ha et al. 2014) . The comparative fishing mortality estimate at the time, Fcurrent , was estimated to be 0.1. Updates to the YPR analysis have not been presented in subsequent stock assessments (Ha et al. 2016)(Ha et al. 2016) , which have reported the exploitation coefficient "E" from length cohort analyses as the relative indicator of fishing effort.

Viet Nam
Pots

The 2015 assessment specifically recommended the elimination of Chinese traps, which exploit large numbers of juvenile crab (Ha et al. 2016) .

CURRENT STATUS

The only published reference points for this stock relate to fishing mortality; biological reference points against which current biomass estimates can be directly compared are not available. Based on the 2013 stock assessment, the stock was overexploited, with Fcurrent exceeding Fmsy by 20%, and the exploitation rate "E" 14% over the assumed optimal rate of 0.5. The most recent available stock assessment (Ha et al. 2016) indicated that effort had since decreased to 10% over the optimal threshold, and biomass had increased from 5,200 tonnes in 2014 to 6,100 tonnes in 2015 (though still less than the 7,100 tonnes estimated in 2013).  It was noted in the 2016 FIP Action Plan (Poseidon ARM Ltd. 2017) that the status of the stock was now considered to be above the limit reference point. However, the specific benchmarks and statistics informing this determination are not explicit in FIP documents, or in the 2015 or 2016 stock assessment reports (Ha et al. 2016)(Ha et al. 2016) . A decreasing trend is observed in the proportion of immature versus mature crab in the stock biomass from 2013 to 2015 (Ha et al. 2016)

Trends

The fishery supports a workforce numbering in the dozens of thousands (Ha et al. 2016) . In 2009, it was estimated that there were 3,823 fishing vessels in the Kien Giang BSC fleet (Ha et al. 2014). A survey of the fleet in 2013 found there were 1,718 vessels registered for BSC fisheries.  

Size and catch rates of BSC vary by fleet, gear, area and time of year (BSC are exploited year round) (Ha et al. 2014)(Ha et al. 2016) .  In 2013, 53% of the catch by volume was taken by the 1,337 boat gillnet fleet, and 47% was captured by the 381 boat trap fleet.  Proportions were similar in 2015 (55% by gillnet, and 45% by trap). The average landing size of crab caught was shown to have increased overall from the 2015 to the 2016 stock assessment, though size composition varied greatly by gear type (Ha et al. 2016).  Relative to gillnets, traps ("normal" and Chinese) disproportionally exploit smaller size, immature crab. The majority of trap caught crab, and the smallest average size crab are taken by Chinese trap. In 2015, 57.5% of the individual crab were caught by Chinese trap, and of these 87% were immature. The overall portion of the catch in the Chinese trap increased by both number and volume from 2014 to 2015. 

A decline in the total catch from 11,300 tonnes in 2008, to 7,800 tonnes in 2013 was interpreted as an indication of decreased abundance due to overfishing (Ha et al. 2016). Catch volume continued to decrease in 2014 (6,200 tonnes) despite indications of increased fishing pressure (Ha et al. 2016). In 2015, catches were just slightly lower (6,100 tonnes), while an apparent decrease in fishing effort was indicated compared to 2013 and 2014. Because there have been no recent fleet surveys, it is assumed for stock assessment purposes that the number of boats estimated in 2013 has remained constant (Ha et al. 2016) . The 2015 stock assessment highlighted this as a potential source of error.

Viet Nam
Pots
Trends

Relative to gillnets, traps ("normal" and Chinese) disproportionally exploit smaller size, immature crab. The majority of trap caught crab, and the smallest average size crab are taken by Chinese trap. In 2015, 57.5% of the individual crab were caught by Chinese trap, and of these 87% were immature. The overall portion of the catch in the Chinese trap increased by both number and volume from 2014 to 2015 (Ha et al. 2016) . 

2.MANAGEMENT QUALITY

MANAGEMENT

Vietnam’s central government’s Ministry of Agriculture and Rural Development (MARD) (formerly the Ministry of Fisheries) has broad management authority over fishery resources.  Local Division of Agriculture and Rural Development (DARD) branches of the MARD implement management measures and activities at the provincial scale (Banks and Holt 2009) . DARD’s jurisdiction extends out to 24 nautical miles from shore. 

Until 2013, there were no stock assessments to inform management strategies, and management measures have largely been limited to seasonal closures, vessel and gear restrictions, and a minimum landing size (MLS) (10 cm with a 15 cm margin of tolerance) (Banks and Holt 2009)(Ha et al. 2014)(Ha et al. 2016) .  Historically, the priority of the managing entity has been to expand effort and provide greater fishing opportunity for small boats, and there are apparently no licensing limits restricting access to this fishery sector (i.e. no limits on fleet size).

Reportedly, a crab management plan was completed in 2011, and updated in 2016 (Poseidon ARM Ltd. 2017) , but it is unclear whether this is a formally adopted plan, and there do not appear to be publicly available documents associated with it.   Stock assessment investigations over the past several years (Ha et al. 2016)(Ha et al. 2014)(Ha et al. 2016) have allowed an emerging picture as to the stock’s exploitation status; however the tools that would allow for a more robust strategy and harvest control rule are not fully developed. Meanwhile, options available for further limiting exploitation of the stock remain within categories of the already existing suite of management measures (time, area and gear restrictions, and size limits).  There are opportunities to better enforce measures, and to adapt methods of implementation, based on stock assessment information, such that measures can more effectively protect the stock. Performance in this regard appears to be mixed but evolving (Poseidon ARM Ltd. 2013)(Poseidon ARM Ltd. 2014)(Poseidon ARM Ltd. 2017) . Compliance with the MLS has been poorly enforced, in part because it has been undermined by the margin of tolerance (Banks and Holt 2009) . As of 2016, DARD had reportedly started to enforce the MLS, and had submitted a request to MARD to eliminate the tolerance margin; but the request had yet to be approved (Poseidon ARM Ltd. 2017) . Following recommendation by the Crab Advisory Council (CAC) in 2014, DARD set new and larger mesh size limits for nets, normal traps and Chinese traps (Poseidon ARM Ltd. 2015) .  More recent scientific recommendations pertaining to protections for immature and spawning crab, including still larger standard trap mesh size, seasonal and area closures, and banned use of the Chinese trap, have yet to be executed (Ha et al. 2016)(Poseidon ARM Ltd. 2017) . A focus of the Kien Giang FIP has been to promote development of a co-management system, as a means of building community awareness and participation, strengthening support for management practices, and ensuring their successful application. The intended approach under this system is for the management entity, DARD, to undertake their responsibilities within a coordinated effort supported by community co-management groups, and a Crab Advisory Council (CAC), which has already been created under the FIP initiative.

Recovery Plans

CPUE is evidently reducing, but there are no rebuilding strategies in place.

COMPLIANCE

There are compliance systems in place, but historically monitoring, surveillance and enforcement of regulatory measures have not been strong (Banks and Holt 2009) .  Landing size restrictions have not been respected or enforced. There have been past reports of systematic non-compliance pertaining to landing size limits, seasonal closures, failure to complete logbooks, processors receiving undersized crab, and sales of juvenile crab for aquaculture feed (Poseidon ARM Ltd. 2015) . A number of planned strategies aimed at fostering compliance and effective enforcement of regulations are in various stages of implementation as part of the Kien Giang BSC FIP (Poseidon ARM Ltd. 2017) . In 2016 it was reported that DARD was implementing enforcement checks on vessels. Inspection efforts were credited as being responsible for some level of improvement in compliance levels. A logbook system and observer program have been initiated since the onset of the FIP, and are undergoing continued development and strengthening.

There is some concern regarding unregulated fishing in neighboring Cambodia, and its potential impacts on the Kien Giang BSC population, which may be an overlapping stock.

3.ENVIRONMENT AND BIODIVERSITY

BYCATCH
ETP Species

Last updated on 31 January 2018

There is no stock assessment of retained species. Sharks and rays, due to their low fecundity, can be vulnerable to repetitive fishing pressure. Some species of shark and ray species are caught, but most are considered to be at low risk from this fishery, based on Productivity-Susceptibility Analysis (PSA) (Ha et al. 2015 ; Ha et al. 2016) . The brownbanded bamboo shark, rated as "Near Threatened" according to the IUCN (Dudgeon et al. 2016) is more of a concern and considered a "medium risk". 

The fishery does take place close to nesting sites of Green turtle (Chelonia mydas) and hawksbill turtle (Eretmochelys imbricate), both critically endangered according to the IUCN (Mortimer and Donnelly 2008)(Seminoff 2004) . There has been concern regarding risk of entanglement due to increased displacement of gear, and the fact that hawksbill turtles are known to feed on crab (Banks 2010) , especially immediately after moulting (Kailola et al. 1993) . However, risk of interaction is reported to be low based on RIMF observor reporting (Ha et al. 2015)(Ha et al. 2016)(Ha et al. 2014)  (Poseidon ARM Ltd. 2015)(Poseidon ARM Ltd. 2017) .

Other Species

Last updated on 31 January 2018

A large variety of non-target, non-ETP species are captured in both the trap and gillnet gears in this fishery (Ha et al. 2014).  However, with the exception of the spotted moray (Gymnothorax moringa), which was evaluated as a "medium" risk species based on PSA,  the risk of harm is considered low (Ha et al. 2015 ; Ha et al. 2016) . All bycatch is reportedly retained and sold locally (Banks and Holt 2009).

HABITAT

Last updated on 31 January 2018

There has been no monitoring of trends in habitat structure in the regions used for blue swimming crab fishing. The coral reefs and sea grass beds appear to have been maintained although actual impacts of fishing activities have not been measured. Both trap and gillnet fisheries were considered a low risk to habitat in Kien Giang waters based on a consequence analysis (Ha et al. 2015). Fishermen frequently return to the same grounds, and benthic assemblages are unlikely to be disrupted; there also does not appear to be significant turbidity resulting from the fishing activity. While interactions may take place, for example through continued anchoring, risk of habitat structure and function is considered low based on habitat consequence analysis (Ha et al. 2015 ; Ha et al. 2016) .  The wide geographic dispersion of fishing activity may limit the impact of interactions. 

Marine Reserves

Last updated on 31 Jan 2018

The Phu Quoc marine protected area (MPA) was established in 2007 for the protection of coral reef ecosystems, sea-grass beds, mangrove forests, and endangered and rare species such as green turtle, leather back turtles, dolphin and dugong (Walton et al. 2015) . There are two BSC spawning grounds within the MPA (Banks and Holt 2009) .  Fishermen appear compliant with the MPA restrictions. The effectiveness of the MPA has not been assessed (Walton et al. 2015) .

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.

No data available
No data available
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DATA NOTES

Notes:

  1. There is insufficient data to calculate quanititative scores. Qualitative scores have been determined, based on the limited information available (please mouse-over for details).

Socio-economic scores evaluation (draft) for Vietnam blue swimming crab

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Fishery Improvement Projects (FIPs)

SELECT FIP

Access FIP Public Report

Progress Rating: A
Evaluation Start Date: 1 Nov 2013
Type: Comprehensive

Comments:

Progress rating remains at A. Stage 4 progress reported within last 12 months

1.
FIP Development
Sep 09
2.
FIP Launch
Feb 16
Oct 15
3.
FIP Implementation
Dec 15
4.
Improvements in Fishing Practices and Fishery Management
Apr 18
5.
Improvements on the Water
Dec 15
6.
MSC certification (optional)
MSC certificate made public

Certifications

Marine Stewardship Council (MSC)

No related MSC certifications

Sources

Credits

Poseidon. 2010. Blue swimming crab scoping for Fishery Improvement Project, Kien Giang Province, Vietnam. Final Report. Richard Banks, Poseidon Aquatic Resource Management Ltd. 22 April 2010.

WWF Vietnam. 2010. Blue Swimming Crab Fisheries in Vietnam – Power Point Presentation (Bali, 29 March 2010).

References

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