Episodic human activities and seasonal impacts on the Tachypleus gigas (Müller, 1785) population at Tanjung Selangor in Peninsular Malaysia

Nelson, Bryan Raveen; Satyanarayana, Behara; Zhong, Julia Moh Hwei; Shaharom, Faizah; Sukumaran, Mithun; Chatterji, Anil

doi:10.1016/j.ecss.2015.08.003

Cited by 58 publications

(51 citation statements)

References 48 publications

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“…Asian horseshoe crabs, particularly tri‐spine horseshoe crab Tachypleus tridentatus and coastal horseshoe crab Tachypleus gigas , are regarded as a source of food and traditional medicine in China and Southeast Asia (Faridah et al, ; Liao et al, ; Shin, Li, & Cheung, ). In many parts of the world's oceans Asian horseshoe crab populations are in decline (Hsieh & Chen, ; Kwan, Hsieh, Cheung, & Shin, ; Nelson et al, ; Weng et al, ). Threats vary for individual species and among geographic populations, but all three Asian species are vulnerable to habitat degradation by coastal reclamation and development (Hsieh & Chen, ; Seino, Uda, Tsuchiya, & Tsuchiya, ).…”

Section: Introductionmentioning

confidence: 99%

Socio‐demographic drivers and public perceptions of consumption and conservation of Asian horseshoe crabs in northern Beibu Gulf, China

Huang

et al. 2019

Aquatic Conservation

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Overharvesting Asian horseshoe crabs for food is a primary threat to their populations. In the present study, 451 residents were interviewed from the northern Beibu Gulf, the coastal area that is believed to accommodate the highest density of the Chinese horseshoe crab Tachypleus tridentatus worldwide, to obtain baseline information on their consumption behaviour and underlying drivers. Based on the survey data, it is estimated that a mean individual consumption rate of ten meals per year. Nearly half of the respondents (49.7%) claimed that they had previously eaten at least two horseshoe crab meals. Among the six occupation categories (managers, professionals, workers, environmental‐related workers, fishers and farmers, and students), fishers and farmers were identified as the group that had eaten a significantly higher number of horseshoe crab meals, had consumed them more frequently, and had a greater intention of eating them than that of students. The age, education level, and salary of participants were the important socio‐demographic variables related to their consumption behaviour. More than one‐third of respondents decided to consume horseshoe crabs because they perceived them as tasty ‘seafood’ and valuable ingredients of traditional Chinese medicine. Eighty‐three per cent of participants reported an overall decrease in the number of horseshoe crabs in the region. Although the community was supportive towards horseshoe crab conservation, their ecological knowledge of horseshoe crabs was limited. The findings may be useful for providing insights to merge the gap between scientific data and management planning for the horseshoe crab population in the region. Conservation management initiatives, such as the involvement of fishers in monitoring and enforcement, developing a reporting system for landings and by‐catch, and implementing long‐term conservation education through the school curriculum could promote the protection and management of the population.

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Section: Introductionmentioning

confidence: 99%

Socio‐demographic drivers and public perceptions of consumption and conservation of Asian horseshoe crabs in northern Beibu Gulf, China

Huang

et al. 2019

Aquatic Conservation

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“…Presently, the emergence of T. gigas to Balok was lower than previous records [15,18,20]. Past surveys at Tanjung Selangor, the only T. gigas spawning site with long term investigations in Malaysia showed that beach conditions during SW monsoon was most favourable to the horseshoe crab for spawning [21]. Although field visits covered the most productive spawning season, as claimed by Zaleha et al [5] and John et al [6], spawning crabs were only spotted at Balok beach during June.…”

Section: Discussion Low Population Of Crabsmentioning

confidence: 67%

“…Following the usual method to obtain horseshoe crabs in Malaysia via net catching [18,19], the assessment of spawning crabs by hand collection is only limited to the studies of [15,20,21]. Although covering different sites, estimation of spawning crabs were based on arrivals and random finding of nests during low-tide periods.…”

Section: Introductionmentioning

confidence: 99%

Trailing the Spawning Horseshoe Crab Tachypleus Gigas (Müller, 1785) at Designated Natal Beaches on the East Coast of Peninsular Malaysia

Manca¹,

Mohamad²

2016

Cell Dev Biol

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Due to limited availability of literature on the spawning activity of Malaysian horseshoe crab, Tachypleus gigas (Müller, 1785), the reproduction behaviour and biology of this arthropod remains poorly understood. Hence, an investigation was carried out from April-July to trail spawning horseshoe crab amplexus at Balok and Cherating, the only known T. gigas spawning grounds on the east coast of Peninsular Malaysia. Through visual tracking during daytime full moon spring tides, the release of air bubbles indicate nest digging by female crabs. While air bubble formation aggravated, flagged aluminium poles were carefully driven into the sediment to mark the nest. Out of the 13 spawning T. gigas amplexus tracked, only one pair was able to dig up to 12 nests and release up to 2,575 eggs within the 2.5 hour spawning period. The female crabs dug nests at the intertidal regions, ranging 1.3-43.2 m from the highest tide marking on the beach. Interestingly after spawning, the horseshoe crabs returned to high seas during the residing tides as amplexus because the male crabs remained clinging onto the female crab's opisthosoma. The incidence of recapturing a tagged female crab with different attached male crab at Cherating indicates this spawning ground as natal beach. In addition, the presence of 8 horseshoe crab amplexus at Balok compared to only 5 amplexus at Cherating highlight preferable beach settings for spawning and/or the presence of larger spawning crab assemblages at the former beach. Since only 13 spawning horseshoe crab pairs were witnessed at Balok and Cherating, identification of factors that alter beach sediment composition and water chemistry as well as gender-specific poaching and excessive boating activities should be regulated to restore wild T. gigas populations.

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“…Similar to many living fossils, these species exhibit slow growth, low dispersal rates, long life span, small home range and delayed reproductive development (Hu, Kwan, Wang, Cheung, & Shin, ; Kwan, Shin, & Cheung, ; Sekiguchi, ). These life‐history characteristics render them vulnerable to habitat degradation (Nelson et al, ; Tripathy, Sivakumar, Sajan, Satyaranjan, & Choudhury, ), habitat loss (Hsieh & Chen, ; Lee & Morton, ), and over‐exploitation for human consumption and bleeding (Fu et al, ; Liao, Hsieh, et al, ; Shin, Li, & Cheung, ). Li, Xie, and Kwan () estimated that at least 100,000 pairs of tri‐spine horseshoe crabs, Tachypleus tridentatus , are bled annually to support endotoxin contamination tests of injectable drugs as specified in the Chinese Pharmacopeia.…”

Section: Introductionmentioning

confidence: 99%

Nursery habitat for Asian horseshoe crabs along the northern Beibu Gulf, China: Implications for conservation management under baseline gaps

Xie

Wang

et al. 2019

Aquatic Conservation

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Identification, protection and enhancement of essential habitats are priority issues for management and restoration of exploited species. The shores utilized by Asian horseshoe crabs as nurseries were surveyed and the coastal habitat characteristics were described in the northern Beibu Gulf of China. Regression models were applied to explore species‐habitat relationships. Fourteen and ten nursery sites were identified for Tachypleus tridentatus and Carcinoscorpius rotundicauda populations, respectively. Xiacun and Jinhaiwan in the eastern region of the northern Beibu Gulf were the essential nurseries for T. tridentatus, whereas Shanxin and Jiaodong in the western part were the primary nursery shores for C. rotundicauda. These shores supported high densities (4–6 individuals/100 m2) of juvenile horseshoe crab populations. Mangrove and seagrass coverage area, coupled with sediment physico‐chemical parameters, particularly grain size, and the environmental heterogeneity of nursery habitats explained the distribution pattern of juvenile populations. Most juvenile populations were found along the outer fringe of mangroves in the small shallow estuary, particularly near outflows of tidal creeks with generally higher chlorophyll a and organic carbon contents. The distribution of high‐density juvenile populations of both species also overlapped with areas of seagrass patches. These findings highlight the importance of mangroves and seagrasses in the nursery habitat use of Asian horseshoe crabs. Preserving the estuarine habitats with these vegetation types and identifying the high‐use nursery sites should be prioritised in China and other Asian places to conserve the declining Asian horseshoe crab populations.

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Episodic human activities and seasonal impacts on the Tachypleus gigas (Müller, 1785) population at Tanjung Selangor in Peninsular Malaysia

Cited by 58 publications

References 48 publications

Socio‐demographic drivers and public perceptions of consumption and conservation of Asian horseshoe crabs in northern Beibu Gulf, China

Socio‐demographic drivers and public perceptions of consumption and conservation of Asian horseshoe crabs in northern Beibu Gulf, China

Trailing the Spawning Horseshoe Crab Tachypleus Gigas (Müller, 1785) at Designated Natal Beaches on the East Coast of Peninsular Malaysia

Nursery habitat for Asian horseshoe crabs along the northern Beibu Gulf, China: Implications for conservation management under baseline gaps

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