SPECIES AND SPATIAL DISTRIBUTION OF SEAGRASS IN TAM GIANG CAU HAI LAGOON, THUA THIEN HUE PROVINCE, VIETNAM

Hang T. T. Tran, Thang N. Ha, Tram D. Q. Nguyen

Faculty of Fisheries, University of Agriculture and Forestry, Hue University

ttthang87@hueuni.edu.vn 

Seagrasses are a group of marine angiosperms, which survive in a wide range of environmental conditions and are widely distributed in coastal zones. The global distribution of seagrass genera is remarkably consistent north and south of the equator; the northern and southern hemispheres share ten seagrass genera and only have one unique genus each. Several valuable ecosystems services are recognized for this resource, including wave attenuation, pollution attenuation, nursery and breeding habitat and, most recently, carbon sequestration. Seagrass is an identical blue carbon ecosystem, that is promoted as a natural based solution (NbS) to tackle the global warming. This habitat, however, has been degraded for different reasons worldwide. Therefore, understanding the current distribution and capability of seagrass carbon sequestration is highly required for further NbS implementation. In Vietnam, seagrasses are distributed across the coastal lines, which approximately 15 seagrass species are recognized. In Tam Giang Cau Hai lagoon, we designed 58 transects, approximately 174 sites in field surveys to collected seagrass samples, indicated a group of 6 species, including Halophila becarii, Halophila ovalis, Zostera japonica, Ruppia maritima, Halodule pinifolia and Halodule uninervis. But there were the differences between the north and the south of the lagoon. In the north of the lagoon, only 4 seagrass species were recorded including Halophila becarii, Zostera japonica, Halodule pinifolia and Halodule uninervis while in the south, Ruppia maritima and Halophila ovalis were added the number of seagrasses at here up to 6 species. In the north of the lagoon, Zostera japonica was the dominant species, while in the south, Halophila becarii was found almost the transects. Seagrass is distributed in a range of water depth 0.2 – 1.5 m, salinity 0 – 28 psu, substrata of mud, sandy mud, and muddy sand. Spatial distribution of seagrass is not ubiquitous but is closed to the shallow water and narrowed in the eastern, western, and nothern parts of the lagoon.

Keywords: seagrass, lagoon, Halophila becarii, Halophila ovalis, Zostera japonica, Ruppia maritima, Halodule pinifolia and Halodule uninervis.

GIANT CLAM: ENDANGERED SPECIES IN MALAYSIAN COASTAL WATERS

Mohd Hanafi Idris^1*, Abu Hena Mustafa Kamal¹, Mohd Sharol Ali¹, Shahrul Idham Ismail¹, Anuar Salam Sulaiman²

¹Faculty of Fisheries and Food Science, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia

²Resource Management and Marine Parks Division, Department of Fisheries Malaysia, Wisma Tani, Pusat Pentadbiran Kerajaan Persekutuan, 62628 Putrajaya, Malaysia

^*Corresponding author: hanafiidris@umt.edu.my

The giant clams are the members of the clam genus Tridacna that are the largest living bivalve was over four and a half feet (1.3 m) wide and weighed approximately 250 kg. The giant clam lives in flat coral sand or broken coral and can be found at depths of as much as 20 m in tropical latitudes of the east Indian and west Pacific oceans. A total of six species can be found in Malaysian waters: Tridacna crocea, Tridacna derasa, Tridacna maxima, Tridacna squamosa, Hippopus hippopus and Hippopus porcellanus. Tridacna crocea is the only species in Malaysia that has a stable population, while the others are considered to be endangered. Tridacna gigas is already extinct in Peninsular Malaysia and Hippopus porcellanus and Tridacna derasa are restricted to Sabah, Eastern Malaysia. Because of this, Malaysian Department of Fisheries has listed giant clams as a protected species. Monitoring, evaluation and conservation programs have been carried out by several private company, association and also the government such as the production of new seedlings, enforcement and control of tourism activities especially in marine parks. The main challenges for giant clam survival in Malaysia are climate variability, anthropogenic and awareness factors. Finally, this ecology conservation effort requires significant amount of fund and support from various stakeholders.

Keywords: Tridacna, endangered, ecology, conservation, Malaysia

STUDIES ON LENGTH-BASED STOCK ASSESSMENT OF SMALL PELAGIC FISH IN THE JAVA SEA, INDONESIA

 Wiwiet Teguh Taufani^1,3, Matsuishi Takashi Fritz^{1, 2}

¹ Graduate School of Global Food Resources, Hokkaido University, Japan

² Faculty of Fisheries Sciences, Hokkaido University, Japan

³ Department of Aquatic Resources, Faculty of Fisheries and Marine Science, Universitas Diponegoro, Indonesia

*Corresponding author: catm@fish.hokudai.ac.jp

Small pelagic fish have a significant role in the fishery by providing food and employment. The high pressure of fishing activity will impact the abundance of natural resources. Indonesia's Java Sea is mainly fished for small pelagic fish. If fishing mortality is significant and keeps increasing, it may damage the stock's sustainable utilisation. The yield per recruit (YPR) model is widely used for understanding the current status of the fish stock and shows the target of sustainable fishing activities by biological reference points. Moreover, YPR can be applicable in data-poor situations where only length frequency data of catch is available. The objective of this study is to apply the YPR for the length frequency data of small pelagic fish in the Java Sea, Indonesia. The small pelagic fishes used were Decapterus macrosoma, D. ruselli, Rastrelliger kanagurta, Amblygaster sirm and Selar crumenophthalmus. Data collection was carried out in August - November 2020 at fishing ports in the Java Sea. The variables used in YPR were asymptotic length, fishing mortality, length at the first capture and growth parameters, estimated by ELEFAN (Electronic Length Frequency Analysis). The size of the fish captured is dominated by small size (L_c < L_m). The F_current for each species is 0.09 for D. macrosoma, which is smaller than F_50%SPR, 1.81 for D. ruselli, larger than F_50%SPR, 0.48 for R. kanagurta, smaller than F_50%SPR, 1.13 for A.sirm, larger than F_50%SPR, and 0.75 for S. crumenophthalmus, larger than F_50%SPR. The status of small pelagic fish in the Java Sea differs according to comparative analyses of fishing mortality and length at first capture. In comparison, D. macrosoma is in excellent condition, R. kanagurta, A. sirm, and S. crumenophthalmus are all in good condition, while D. ruselli is in poor condition. This research is expected to offer suggestions for improving fisheries management.

Keywords: Small pelagic fish, Length-based stock assessment, TropFish R, Yield per Recruit, Java Sea

THE RELATIONSHIP OF OTOLITH SIZE TO THE LENGTH AND WEIGHT OF INDO-PACIFIC KING MACKEREL (Scomberomorus guttatus, BLOCH & SCHNEIDER, 1801) IN THE SOUTH OF YOGYAKARTA

Bayu Wicaksono Pitandoyo, Djumanto ^1,*

Department of fisheries, Faculty of Agriculture, Gadjah Mada University, Indonesia

^*Corresponding author: djumanto@ugm.ac.id

Indo-Pacific king mackerel (Scomberomorus guttatus) is one of the fish resources found in the southern waters of Yogyakarta. This study aims to determine the relationship between the length, width, and weight of otoliths to the length and weight of Indo-Pacific king mackerel. Indo-Pacific king mackerel, whose habitat is in the waters south of Yogyakarta, was caught using gill nets operated by local fishermen, from October 2021 to February 2022. The number of Indo-Pacific king mackerel samples collected was 96 individuals, consisting of 45 males and 51 females. Each fish sample was measured for total length and body weight, then otoliths were taken, and sex was determined through gonad ownership. Each otolith was measured in length, width, and weight, then the data were analyzed to determine the frequency distribution of length and weight, length-weight relationship, differences in left and right otolith sizes, differences in male and female otoliths, and the relationship between length and weight of fish and otolith size. The male Indo-Pacific king mackerel has a length and weight range of 33.1-47.3 cm, 255-805 g, respectively, while the female has a length and weight range of 29.2-55.1 cm and 170-1265 g. The male and females had a positive allometric growth pattern with a value of W=0.0032 L ^3.214 for males and W= 0.0043 L ^3.130 for females. Otoliths in male and female individuals and on the right and left were not significantly different. The length, width, and weight of the otolith have a linear and positive relationship to the length and weight of the fish. Otolith length to total length has a relationship pattern of OL=0.1932TL+0.7623 (R=0.883), and otolith length to weight has a relationship pattern of OL=0.0045 W+6.291 (R=0.859). The otolith width to total length has a relationship pattern of OWt=0.1932 TL+0.7623 (R=0.265), and the relationship pattern of otolith width to weight is OWt=0.0045 W+6.291 (R= 0.279). The otolith weight to fish length has a relationship pattern of OW=0.8305TL-17.388 (R=0.926), and the otolith weight to fish weight has a pattern of OWt=0.0045W+6.291 (R = 0.279).

Keywords: fish, growth, mackerel, southern Java.

PRELIMINARY REVISION OF LETHRINID SPECIES FROM THE EAST COAST OF PENINSULAR MALAYSIA WITH NOTES ON GEOGRAPHIC DISTRIBUTION EXTENSION

 Siti Asmal Mat Piah¹, Li Lian Wong², Ying Giat Seah^1,3,*

¹Faculty of Fisheries and Food Science, Universiti Malaysia Terengganu, Kuala Nerus, Terengganu, Malaysia

²Institute Marine Biotechnology, Universiti Malaysia Terengganu, Kuala Nerus, Terengganu, Malaysia

³South China Sea Repository and Reference Centre, Institute Oceanography and Environment, Universiti Malaysia Terengganu, Kuala Nerus, Terengganu, Malaysia

^*Corresponding author: ygseah@umt.edu.my

Malaysian marine fishes are still poorly explored or have yet to be thoroughly evaluated and validated, with approximately 34.8% classified as "data deficient". More taxonomic research is desperately needed in our country to update the fish diversity records. Lethrinids or “ikan landuk” are prioritised because the available literature is long overdue, there are no catalogued specimen practices, some known to be difficult to identify in preserved condition due to discoloration, and they are an important fisheries commodity in Malaysia. Taxonomic review was made through integrative method with comparative morphological characters and DNA barcoding techniques. Throughout the three (3) years of sampling from the fish landing ports of Lembaga Kemajuan Ikan Malaysia (LKIM) situated at the east coast of Peninsular Malaysia; the on-going research project has collected a total of 11 lethrinid species consisting three species from genus Gymnocranius and eight species from genus Lethrinus. Furthermore, two species namely Lethrinus olivaceus and Lethrinus semicinctus, previously known from East Malaysia with the former occur in Strait of Malacca, west coast of Peninsular Malaysia, are now documented as the first records with its new distribution ranges extending to the north of the east coast of Peninsular Malaysia. The research also provided a key to species of 11 species based on morphometric parameters and meristic counts. 

Keywords: Emperor fish, Taxonomy, New record, Biogeography, South China Sea

PHYLOGEOGRAPHY OF THE ASIAN AROWANA Scleropages formosus (OSTEOGLOSSIDAE) IN MALAYSIA: CONSERVATION IMPLICATIONS

Norli Fauzani Mohd Abu Hassan Alshari^1,2*, Sebastien Lavoue², Mohamad Asyraf Mohamad Sulaiman³, Md Zain Khaironizam², Siti Azizah Mohd Nor¹, Fazimah Aziz³

¹Institute of Marine Biotechnology, Universiti Malaysia Terengganu, Kuala Nerus 21030, Malaysia

²School of Biological Sciences, Universiti Sains Malaysia, Penang 11800, Malaysia

³Department of Aquatic Science, Faculty of Resource Science and Technology, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia

*Corresponding author: nfauzani0693@gmail.com

Habitat destruction and overexploitation of natural resources are causing threats to many wild species, with some of them have already gone extinct. Currently, one of the most endangered freshwater fishes in the world is the Asian arowana (Teleostei: Osteoglossidae: Scleropages formosus). Once common and widely distributed in Southeast Asia, only small remnant populations of Asian arowana are now scattered in Malaysia, Indonesia, south Myanmar, and south Cambodia. Whereas several aspects on the biology and ecology of the Asian arowana are known, there is limited information on the phylogeographic structure of its populations. The Asian arowana currently comprises about 10 allopatric populations in Malaysia (Peninsular Malaysia and Sarawak) exhibiting population-level body-colour variation. These populations can broadly be classified into three body-colour groups: green, gold and “green-nami.ˮ In this study, using individuals from nine Malaysian populations and a selection of three genetic markers, we tested two hypotheses to explain the phylogeography among the different populations of Asian arowana in Malaysia: 1) each color group form a monophyletic group, and 2) Pleistocene paleodrainages shaped the distribution and differentiation among populations. A time-calibrated phylogenetic reconstruction showed low genetic variability among all color varieties, and the gold and green-nami varieties are nested within the green variety making the latter paraphyletic. This rejected the first hypothesis. Instead, the Malaysian populations are structured into three allopatric lineages that better reflect the configuration of the Pleistocene paleodrainage system, suggesting the geographic distribution of populations is a better phylogenetic indicator than their body color. The results have important consequences on the conservation of the Asian arowana in Malaysia with each main genetic lineage requiring urgent and targeted attention.

Keywords: Asian arowana, phylogeography, paleodrainages, conservation