Horseshoe crab (HSC) populations around the world are declining in recent decades mainly due to destruction of breeding grounds and habitats. A short-term solution for this problem is captive breeding and artificial rearing. This experiment aimed at looking for a source of good sperm donors for in-vitro fertilization and captive breeding. Tachypleus gigas were collected from Balok Beach, Kuantan, Pahang, Malaysia. Crabs were divided to wild and captive groups. Wild T. gigas sperm was collected on the same day, while sperm of captive T. gigas was collected after 5 months of captivity to assess captivity effect on sperm traits. Sperm density and sperm viability were studied and correlated to morphometric measurements. The results indicated that T. gigas from Balok is a good sperm donor. Captivity was found to affect sperm traits where sperm density dropped significantly and sperm viability increased slightly. Intraocular width to carapace width ratio (IO-Car) of the HSC body correlated to sperm density, hence can be used as an indicator for donor selection during sampling. In conclusion, T. gigas from Balok can be used as a sperm donor for in-vitro fertilization for T. gigas propagation.
Horseshoe crab is a unique Arthropoda which is also known as a living fossil because of its ancient morphological appearance. The animal established its existence since 300 million years ago and maintained its morphology to present day. The greatest proportion of adult horseshoe crab mortality is probably due to human activity. Horseshoe crabs in Malaysia are harvested for local consumption or marketed to the neighbor country. Series of survey were carried out to understand the exploitation status and collection technique of horseshoe crab in selected coast, Pahang and Malacca coastal area. Interviews were carried out with fisherman that involved in horseshoe crab exploitation activities. Data collected from 100 respondents were analyzed to compare the exploitation activity in both coastal areas. Respondents were mostly fisherman which used both techniques; collecting on shoreline and net fishing to catch horseshoe crab. More people significantly (p<0.05) used traditional collection method (hand harvest at shoreline) in Pahang (56.1%) compared to those in Malacca (34.15%). 65.85% collectors in Malacca adopted the netting method while, only 43.9% collectors in Pahang preferred the same method to collect adult horseshoe crabs coming to the shore during spawning season. The frequency of netting method monthly was significantly higher (p<0.05) in Malacca than Pahang. This resulted to the higher horseshoe crab quantities caught by 50 respondents in Malacca (16860 per month) than Pahang (4180 per month). The initial results from this survey indicate an alarming condition faced by the horseshoe crab coming to the beach for nesting. Monitoring program should be planned to sustain the fishery activity on horseshoe crab in Malaysia.
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