Comparative in effective of mesh size of collapsible crab trap to blue swimming crab fishery using four sizes of trap was conducted in Kung Kraben Bay, Chanthaburi Province. The size of trap in the bottom was varied three size; 2.00 inch, 2.50 inch and 3.00 inch. And the last size was 2.50 inch in every side. This study aimed to use for fishery improvement project in collapsible crab trap adaptive measurement. Sampling was conducted four times in February, May, August and November 2017. The result found that mesh size 2.00 inch can harvested crab highest quantity. The average weigh was 639.16 g whereas Catch per Unit and Effort (CPUE) 21.31 g/trap. Moreover, this size of trap an also harvested highest many species of by catch (20 species). The highest proportion was found in Charybdis affinis (28.82%). The sex ratio between male and female was 1:1.15. The result also showed that size distribution of crab in each size (2.00 inch, 2.50 inch, 3.00 inch and 2.50” inch) was found in highest range 81.00-90.00 mm, 81.00-90.00 mm, 91.00-100.00 mm and 101.00-110.00 mm, respectively. Size distribution of blue swimming crab (carapace with) fishery in Kung Kraben Bay was conducted and found highest in range 101.00-110.00 mm. The result also showed that crabs, which were low size than 60.00 mm, they were still continuously harvesting (8.50%).
Reproductive biology of female blue swimming crab was conducted from January to December 2017. These data aimed to use for making regulation in forbidden harvested female blue swimming crab in spawning season. The result found that ovary development in stage 3 and 4 was highest from June to December. The values were 53.57, 36.11, 62.07, 55.56, 45.16, 44.45 and 53.33, respectively. Gonad somatic index was 1.74% - 4.31%. The result also showed 3 high peaks on August (4.31%), December (4.05%) and January (3.49%). First size at maturity was 9.80 centimeter. Abundance of female crab in each station was no significantly different (P>0.05) whereas abundance of crab in each season was significantly different (P<0.05). Crabs were found in dry season (83.00%) higher than wet season (17.00%). Moreover, the relationship between abundance of female crab with physical factors was no correlated (P>0.05).
Population structure study of blue swimming crab Portunus pelagicus (Linnaeus, 1758) under the Fishery Improvement Project at Kung Krabaen Bay, Chanthaburi Province was conducted from January to December 2017. The result of population dynamic by using monthly sampling of size distribution of crab analysed by FiSAT program software found that growth parameter of male crab was L∞ = 13.13 cm ; K = 0.26 per year while the growth parameter of female crab was L∞ = 13.13 cm, K = 0.61 per year. Total mortality of male and female crab were indicated by 0.00 and 2.2 per year, respectively. The recruitment period occurred all year round with two peaks. The first peak was during March to May and the second peak was during July to October. The exploitation rate was 0.26. Sex ratio of male to female was 1:0.96. Size distribution of carapace width was ranged 9-10 cm. Average size of crab was 11.15± 1.90 cm. The relationship between carapace width and weight were W = 0.0107CW 1.8716and 0.021CW1.7167 in male and female crab, respectively. Moreover, This research found that station, time and season were influenced to abundance of crab. Highest abundance was found in pelagic area (station J) and lowest abundance was found in reforested mangrove (station C) at night time during dry season (P<0.05). The proportion of juvenile and adult male crab by using collapsible crab trap were 19% and 81% while the proportion of juvenile and adult female crab were 14% and 86%. For the proportion of juvenile and adult male crab by using crab gill net were 26% and 74%.For the proportion of juvenile and adult female crab were 11% and 89%. The relationship between abundance of crab and physical factor was no correlate. Moreover, diversity of bycatch was found 29 genera and 33 species. In summary, the result from this research found that. The exploitation rate was decreased when compare with previous study. It showed that the population structure of blue swimming crab had increased a good trend. These were from the affection of fishery improvement project; increasing the mesh size of collapsible crab trap to 2.5 inch and also found that size range distribution of blue swimming crab was increased to 9.0 –10 cm. moreover, there has been reducing use bycatch in 20 species. Therefore, we should be continuously conduct the fishery improvement project particularly increasing the mesh size of trap in every side because 1) the first size of capture will be increased2) there has been decreasing the exploitation rate 3) the average range will be increased and 4) there has been decreasing utilization of small bycatch. These have been helping blue swimming crab and bycatch in Kung Krabaen Bay be sustainability.
The result of seagrass indicator in both of Chaolao beach and Kung Krabaen Bay was found that the percent of coverage was ranged 30%-100% and 47.78%-100%, respectively. These results were compared with the standard value of seagrass in previously research. Moreover, both of the seagrass was sparse in the wet season (30-40%) and return to very dense in dry season (80-100%). The water quality and physical factor in both areas were standard condition.
The genetic study of bycatch including some marine crab and fish was also determined by analyzing the nucleotide sequences of Cytochrome oxidase I (COI) gene and comparing all sequences with GenBank and BOLD genetic databases. From a total of 33 crab specimens and 14 fish specimens,11 species and 14 species of marine crab and fish were identified with high genetic similarity (97.84-100%).
This research aimed to isolate actinomycetes from the gill and innards of some species of sea crab such as Portunus pelagicus, Thalamita crenata and Scylla serrata using spread plates and culture on humic acid vitamin agar. All 12 isolated actinomycete were tested for their inhibition activity to Pseudomonas aeruginosa ATCC 28753, Escherichia coli ATCC 25922, Bacillus cereus, Staphylococcus aureus ATCC 25923, Candida albicans ATCC 90028, Fusarium oxysporum and Phytophthora sp. C2.IP-M01 and GC-D01 were display the good inhibit of Candida albicans ATCC 90028, Fusarium oxysporum and Phytophthora sp. C2. The crude extract of actinomycetes, IP-M01 and GC-D01, were extracted using ethyl acetate as solvent. It showed texture sticky substance. The minimum microbicidal concentration (MMC) value of Candida albican ATCC 90028 was tested by broth microdilution technique. The result showed that MMC against both Candida albican ATCC 90028 were 64 and 128 µg/ml (100%), respectively. Characteristic ofIP-M01 and GC-D01, were studied by slide culture technique. It was found that isolate IP-M01 produced dark gray spores. The spore line was a chain, Rectiflexibiles, it has a straight, slightly curved end. GC-D01 isolates had white to gray colonies and white to gray spores. Spore characteristics were spiral, open spiral. The sequence of the 16S rRNA gene and phylogenetic tree were analyzed and constructed.The isolates GC-A02, GC-A03, GC-M01, IP-M01, IP-M02 and IT-M01 were similar to Streptomyces diastaticus subsp. ardesiacus NRRL B-1773T in the range 97-100%. And, the isolates GB-A01, GC-A03, GC-D01, IP-A01, IT-A01 and IT-A02 were similar to Kitasatospora phosalacinea DSM 43860T is in the range of 96-99 percent.
