Analysis of relationship between sea surface temperature (SST) and Chlorophyll-a (chl-a) improves our understanding on the variability and productivity of the marine environment, which is important for exploring fishery resources. Monthly level 3 and daily level 1 images of Moderate Resolution Imaging Spectroradiometer Satellite (MODIS) derived SST and chl-a from July 2002 to June 2011 around the archipelagic waters of Spermonde Indonesia were used to investigate the relationship between SST and chl-a and to forecast the potential fishing ground of Rastrelliger kanagurta. The results indicated that there was positive correlation between SST and chl-a (R=0.3, p<0.05). Positive correlation was also found between SST and chl-a with the catch of R. kanagurta (R=0.7, p<0.05). The potential fishing grounds of R. kanagurta were found located along the coast (at accuracy of 76.9%). This study indicated that, with the integration of remote sensing technology, statistical modeling and geographic information systems (GIS) technique were able to determine the relationship between SST and chl-a and also able to forecast aggregation of R. kanagurta. This may contribute in decision making and reducing search hunting time and cost in fishing activities.
The effects of salinity on the gastric emptying time (GET) and absorption of nutrient along the alimentary tract of tiger
grouper (TG) × giant grouper (GG) (Epinephelus fuscoguttatus × E. lanceolatus) hybrid were studied. Juveniles TG×GG
hybrid grouper (10.0 ± 0.5 cm total length; 50.5 ± 2.0 g) were reared in different salinities (10, 15, 20, 25 and 30 parts per
thousand (ppt)) and fed with commercial pellet diet during the 60-day experimental period. The fish were then slaughtered
sequentially at different time intervals after initial feeding to obtain GET. Our results showed that low salinity (10-20 ppt)
lead to a shorter GET in the hybrid grouper. The shortest and longest GETs were observed in 15 ppt (12 h) and 30 ppt (18
h) treatments, respectively. Apparent digestibility coefficient (ADC) using ash contents was measured to determine the
absorption of nutrient in each treatment. The absorption of macronutrient in TG×GG hybrid grouper was increased as
the salinity decreased. The highest absorption occurred in 15 ppt (72% protein, 75% lipid, 68% carbohydrate and 74%
energy) while the lowest absorption occurred in 30 ppt (59% protein, 64% lipid, 34% carbohydrate and 55% energy).
The findings of this study suggested that 15 ppt salinity facilitates faster digestion and maximize the nutrient absorption
of TG×GG hybrid and may enhance the growth rate of this newly developed grouper species.
The growth form and condition of the tiger grouper × giant grouper (TGGG) hybrid were evaluated under four temperatures (22°C, 26°C, 30°C, and 34°C) and two diets (pellet and shrimp). The growth form of fish was determined over a 30 day experimental period using the length–weight relationship (LWR) method. The TGGG hybrid grouper exhibited a negative allometric growth (b < 3) at all temperatures and diets at the beginning of the experiment (0 day), which indicated that fish would become lighter as they increased in size. Conversely, toward the end of the experiment (30 d), the TGGG hybrid grouper showed a negative allometric growth (b < 3) at 22°C and 34°C on both pellet and shrimp diet as well as demonstrated an isometric growth (b = 3) at 26°C fed on both diet and 30°C on pellet diet only, which indicated that the shape of the fish would not change with increasing weight and length. However, a positive allometric growth (b > 3) was observed at 30°C when the fish were fed on shrimp diet, which indicated that fish weight would increase with increasing length and size. The condition factors (K and Kn) in the initial (0 d) and final (30 d) measurements were greater than 1, thereby indicating the wellbeing of the TGGG hybrid grouper, except for those fish fed on both pellet and shrimp diet under 22°C and 34°C. Therefore, diet did not have a significant effect (p > 0.05) on the growth and condition of TGGG hybrid grouper, whereas temperature significantly influenced the growth and condition of the fish. All in all, grouper farmers can culture TGGG hybrid grouper between 26°C and 30°C, whereas the best growth and condition could be observed by culturing the fish at 30°C fed on shrimp.
The study was conducted at Merambong Shoal (01°19.979’N, 103°35.965’E) in the Sungai Pulai estuary, Johor Straits, Malaysia from January to December 2005. Standing biomass of male and female Strombus canarium sub populations was calculated monthly based on the abundance value of each cohort and on the length-weight relationship. Secondary production was estimated using increment summation method, upon recognition of cohorts following the size-frequency distribution analysis using Bhattacharya and Hasselblad’s NORMSEP methods. Monthly variations in standing biomass
(B) and production (P) showed higher values during the wet season compared to dry season, which indicate seasonal variations. Total production (P) was estimated at 0.14 gAFDWm-2yr-1 and 0.45 gAFDWm-2yr-1, while the annual mean population biomass was estimated at 0.13 gAFDWm-2 and 0.26 gAFDWm-2, for males and females, respectively. The P/ ratio was therefore calculated at 1.08 yr-1 for male and 1.73 yr-1 for female, which was within the values reported for other gastropod species. Estimates using empirical methods commonly used in secondary production studies found
that none could be applied to the species. Considering the large amount of time, effort and resources involved in the conventional production estimation method, more studies are needed to establish a reliable production estimates for S. canarium, and possibly other gastropod species within the tropical region.
Samples of Pinna bicolor Gmelin and Pinna deltodes Menke were collected from the seagrass bed of Sungai Pulai, covering Merambong shoal, Tanjung Adang shoal and Merambong Island off south western coast of Johor, Malaysia for morphological study from August 2005 to June 2006. It was observed that P. deltodes is associated with hard substratum and P. bicolor is associated with soft substratum in the study area. Physically there was no difference between P. bicolor and P. deltodes. The species were identified on the basis of nine internal and external characteristics of the valves. The two species were found to be morphologically different on the basis of width of sulcus, distance between posterior adductor muscle to posterior dorsal nacreous layer, dorsal posterior margin length and shell width.
Kandungan hidrokarbon polisiklik aromatik (PAH) dalam tiga spesies ikan yang berbeza tabiat pemakanan dan habitat, iaitu Lolong (Selar boops), Kerisi (Nemipterus peronii) dan Mengkarong (Trachinocephalus myops) dari luar pantai Pulau Perhentian, Malaysia ditentukan. Tiga individu daripada setiap spesies dipilih secara rawak dan kandungan 10 sebatian PAH diukur, iaitu fenantrena, antrasena, fluorantena, pirena, benzo(a)anthracene benzo(a)antrasena, krisena, benzo(a)fluorantena, benzo(k)fluorantena, benzo(e)pirena dan dibenzo(a,h)antrasena dalam otot ikan ditentukan. Pengekstrakan PAH menggunakan kaedah Soxhlet dan kandungannya diukur dengan kromatografi gas - spektrometri jisim (GC-MS). Jumlah PAH dalam tisu ikan yang dikaji adalah pada julat 17.89 – 42.18 ng/g berat basah dan 393.98 – 511.07 ng/g mengikut berat lipid. Kandungan PAH dalam tisu jenis ikan menurut berat basah adalah Mengkarong (42.18 ng/g)> Lolong (25.61 ng/g)> Kerisi (17.89 ng/g), sementara menurut berat lipid ialah Kerisi (511.07 ng/g)> Mengkarong (409.50 ng/g)> Lolong (393.98 ng/g). Otot Kerisi mengandungi kandungan lipid paling sedikit, iaitu 3.5 % berbanding dengan Lolong (6.5 %) dan Mengkarong (10.3 %). Tidak ada penumpukan PAH yang jelas dalam lipid tisu ikan (kolerasi Pearson, p>0.05) dan ketiga-tiga spesies ikan tidak menunjukkan kandungan PAH yang berbeza (ANOVA, p>0.05). Berdasarkan kadar pengambilan ikan pada 142.2 g/hari, pengiraan kepekatan potensi setara (PEC), iaitu nilai potensi karsinogenisiti sebatian PAH, ketiga-tiga spesies ikan adalah pada julat 0.41 – 0.63 ng/g berat basah. Nilai ini lebih rendah daripada nilai garis panduan yang ditetapkan oleh USEPA, iaitu 0.67 ng/g berat basah.
The abundance of marine benthic organisms often exhibits distinct distributional patterns, which is generally governed by many physical and biological factors specific to the habitat. In this study, the spatial and temporal variations in abundance of the dog conch, Strombus canarium Linnaeus 1758, a commercially important marine gastropod, was investigated. Assessment of conch abundance at Merambong seagrass bed, Malaysia, was conducted using a transect belt method. Sampling stations were randomly selected and environmental parameters associated with the habitat were recorded. The species showed distinct spatial distributional pattern. Conch densities were significantly higher in sheltered areas, mainly in mixed seagrass bed dominated by Halophila spp. and with high sediment organic content. The densities were relatively very low in areas dominated by the tape seagrass, Enhalus acoroides. The species studied also showed distinct temporal variation in abundance. The abundance value was seasonally varied with highest density recorded during the wet monsoon season (p<0.05). The densities were otherwise very low during the dry season, except for a slight peak in July. Since the conch is a very important fishery species within the Johor Straits and regulations on their harvesting is still lacking, this information would be very important for their sustainable management.
DNA Barcoding, primarily focusing on cytochrome coxidase subunit I (COI) gene has been appraised as an effective tool for species identification. Nonetheless, species identification based on molecular approach is essential for discrimination of look-alike species. In this study, we focused on the marine fishes Family Nemipteridae, one of the commercially important group distributed within the surrounding seas of Malaysia. Some of the samples were collected during the National Demersal Trawl Survey in the Exclusive Economic Zone of East Coast Peninsular Malaysia by the Department of Fishery Malaysia. A 652bp region of COI was sequenced for 74 individuals from nine putative species. Additional 34 COIsequences from GenBank were also included in this study making the total number of samples analysed to 108 individuals. The averageKimura 2-parameter (K2P) nucleotide divergence was 0.34% among individuals within species and 6.97% within genera. All putative species formed monophyletic clades in both Neighbour-joining (NJ) and Maximum-likelihood (ML) trees. However, there was a potential misidentification in specimen identified as Nemipterus tambuloides,as the specimen did not group with their own taxa. It was genetically grouped in Nemipterus thosaporni clade. This study supports the effectiveness of COIgene in species discrimination of Family Nemipteridae.
A new species of Larimichthys from Terengganu, east coast of Peninsular Malaysia is described from specimens collected from the fish landing port at Pulau Kambing, Kuala Terengganu. Larimichthys terengganui can be readily distinguished from other species of the genus by having an equally short pair of ventral limbs at the end of the gas bladder appendages, which do not extend lateral-ventrally to the lower half of the body wall, and fewer dorsal soft rays (29-32 vs. 31-36) and vertebrae (24 vs. 25-28). Larimichthys terengganui can be distinguished from L. polyactis and L. crocea by having a gill raker at the angle of first gill arch shorter than the gill filament. Furthermore, the second anal spine in L. terengganui is equal or slightly shorter than eye diameter (vs. shorter in L. polyactis); L. terengganui has 8-9 anal soft rays (vs. only 7 in L. pamoides). Snout length of L. terengganui is greater than eye diameter, whereas in L. crocea the snout is shorter than eye diameter. A key to species of Larimichthys is provided. All obtained specimens of the species were recorded from Terengganu waters, east coast of Peninsular Malaysia.
Benthic species, though ecologically important, are vulnerable to genetic loss and population size reduction due to impacts from fishing trawls. An assessment of genetic diversity and population structure is therefore needed to assist in a resource management program. To address this issue, the two-spined yellowtail stargazer (Uranoscopus cognatus) was collected within selected locations in the Indo-West Pacific (IWP). The partial mitochondrial DNA cytochrome c oxidase subunit 1 and the nuclear DNA recombination activating gene 1 were sequenced. Genetic diversity analyses revealed that the populations were moderately to highly diversified (haplotype diversity, H = 0.490-0.900, nucleotide diversity, π = 0.0010-0.0034) except sampling station (ST) 1 and 14. The low diversity level, however was apparent only in the matrilineal marker (H = 0.118-0.216; π = 0.0004-0.0008), possibly due to stochastic factors or anthropogenic stressors. Population structure analyses revealed a retention of ancestral polymorphism that was likely due to incomplete lineage sorting in U. cognatus, and prolonged vicariance by the Indo-Pacific Barrier has partitioned them into separate stock units. Population segregation was also shown by the phenotypic divergence in allopatric populations, regarding the premaxillary protrusion, which is possibly associated with the mechanism for upper jaw movement in biomechanical feeding approaches. The moderate genetic diversity estimated for each region, in addition to past population expansion events, indicated that U. cognatus within the IWP was still healthy and abundant (except in ST1 and 14), and two stock units were identified to be subjected to a specific resource management program.