Borneo Journal of Marine Science and Aquaculture (BJoMSA)

Identifying Populations of the Marble Goby, Oxyeleotris marmorata (Bleeker, 1852) by Otolith Shape Analysis and Their Spawning Seasons in Likas Bay, Sabah, Malaysia

Gunzo Kawamura — 2024-12-31

The marble goby, Oxyeleotris marmorata is native to fresh and brackish waters of Southeast Asia. The yield of wild O. marmorata has been decreased drastically and urgent conservation actions are required to prevent extinction. In the Likas Bay, Oyeleotris marmorata is caught throughout the year by local fishermen using various fishing gears. In fisheries management, population is a fundamental biological unit and population identification of a species is important. The population structure of this marine stock was determined by otolith shape analysis and their spawning season in the Likas Bay was determined by ovarian observations. A total of 147 specimens were procured between 2018 and 2019; size ranged from 443 g to 3,264 g BW. The curvature index of the otoliths was analyzed by Bhattacharya’s method and found that the frequency distribution of curvature indices is a mixture of two normal components, indicating two different populations. The specimens with mature or spent ovaries were found in samples collected in January – February and September, showing two spawning seasons. The age of each specimen was estimated by counting the vertebral annuli. The estimated age ranged from 5 to 14 years. The minimum size and age of spawners was 338 mm TL, 499 g BW and 5 years old. The findings obtained in this study provide basic biological parameters of O. marmorata populations in Likas Bay.

Refining of Water Masses at Sarawak Waters, Malaysia

Ann Aletheia Manson — 2024-12-31

Water mass identification is essential to understand the dynamics of water circulation. The waters off Sarawak are influenced by the northeast and the southwest monsoons. We studied the physical oceanography of the South China Sea along these waters, from data collected during the Prime Marine Scientific Expedition 2009. The expedition was organized by the Malaysian Ministry of Science, Technology, and Innovation through the National Oceanography Directorate. The physical properties of seawater were obtained using the 'Conductivity-Temperature-Depth' (CTD) profiler from the ocean surface to a water depth of 523 meters. Measurements were recorded from 62 stations, with the furthest offshore distance being approximately 471 kilometers from the nearest point of Sarawak's mainland. The aim of this study is to identify the mass features of Sarawak waters. We employed the T-S diagram and refined the water masses based on previous studies conducted in the South China Sea. The constructed vertical salinity and temperature profiles showed that salinity increases towards the sea bottom, whereas temperature decreases as water depth increases. Five water masses were identified off Sarawak waters, namely Continental Shelf Water (CSW), Open Sea Water (OSW), Maximum Salinity Water (MSW), Permanent Thermocline Water (PTW), and Water Mass 1 (WM1). WM1 is derived from the mix of OSW and MSW masses. Results of this study are useful for studies in primary productivity and the distribution of marine resources in these waters.

The First Record of Sona Sea Catfish Pseudosciades sona (Hamilton 1822) in Sabah, Malaysian Borneo, on the Basis of Morphological and Molecular Data

B. Mabel Manjaji-Matsumoto — 2024-12-31

The Sona Sea Catfish Pseudosciades sona is widely distributed across the Indo-West Pacific, including Malaysia. In this paper, we report the first record of the species from Sabah, based on morphological and molecular data. The single specimen of Pseudosciades sona was obtained during a field survey, from the fish market in Beluran, Sabah. The DNA of the specimen has been sequenced and data was published in elsewhere. The species is diagnosed by a combination of morphometric characteristics, including 10–12 pectoral-fin rays, long head (27.59%–31.85% of SL), long snout (28.89%–35.86% of HL), wide mouth (58.04%–65.72% of HL), eye diameter (12.90%–15.75% of HL), distance between below the eye to the bottom of the head (18.95%–24.57% of HL), distance between behind the eye and the margin of operculum (55.75%–60.32% of HL), bony interorbital width (53.67%–60.03% of HL), long bases of dorsal-fin (5.21%–6.18% of SL), anal-fin (13.12%–16.64% of SL), pectoral-fin (5.21%–6.18% of SL), and pelvic-fin (4.14%–5.34% of SL). This paper describes the morphological features of this species, with a brief discussion on catfish conservation and its significance as a fishery resource in Malaysia.

Cinnamon Essential Oil (EOCIN) Functional Diet: Effect on Growth Performance and Health Status of Penaeus vannamei in Super-Intensive Tank Culture

Padilah Bakar* — 2024-12-31

A field trial was conducted to assess the application of cinnamon essential oil (EOCIN) in the super-intensive culture of white shrimp (Penaeus vannamei). The objective of this study is to determine the efficacy of EOCIN on growth performance and prophylaxis in prevention against two common diseases in farmed shrimps, specifically acute hepatopancreatic necrosis disease (AHPND) and Enterocytozoon hepatopenaei (EHP). The EOCIN dose regime, set at 1.5% (v/w kg feed), was administered for 14 days in two series of application. The experiment was carried out in two replicates for the EOCIN and control involving four (4) tank cultures, 34 m in diameter with estimation of 300,000 pieces of shrimps per tank at stocking density of 300 pieces/m² in a single cycle of culture production. An increased in weight gain of shrimp from EOCIN group was recorded compared to control, particularly in grow-out shrimps at DOC40-56 after completion of 28-days of EOCIN application. Shrimp Specific Growth Rate (SGR) showed a compensatory growth of 4.5856% day^-1 from the EOCIN group compared with control, 4.0586% day^-1. Average daily weight gain for EOCIN (0.2328 g/day) was higher than control (0.1733 g/day), with survival rates of 80% and 75%, respectively. The FCR for EOCIN was lower (1.503) compared to control (2.014). The EOCIN additive regime used in this study improved the growth performance of white shrimps in particular, prevention against AHPND and control low prevalence of EHP infection detected in the early culture.

The Potential of Ocean Thermal Energy Conversion (OTEC) in Sabah, Malaysia: A Systematic Review

Muhammad Fikri Zhafran Mohd Rawi* — 2024-12-31

Ocean Thermal Energy Conversion (OTEC) is a relatively new technology that leverages on the temperature difference between warm surface seawater and cold deep seawater to generate electricity with no harmful emissions. This type of energy has become an important research topic for sustainable development due to the large energy resources contained in the ocean. Malaysia has a great potential to harness this type of energy due to its long coastline. We studied Sabah's coastal waters for its potential in OTEC. Sabah’s coast is blessed with a range of productive coastal marine ecosystems coupled with several deep-sea islands. These diverse marine features translate into the type of OTEC plant suitable for implementation in Sabah. A systematic literature review (SLR) approach was utilized to compile, review, and assess literature advocating for OTEC, the different types of OTEC plants and analytical methods used in OTEC plant site-selection. We identified five potential sites for OTEC plants in Sabah. These include three sites in the northeast, namely Layang-Layang Island, Mengalum Island, and Mantanani Island, and two sites in the southeast, namely Tawau and Kalumpang. The availability of potential sites in Sabah indicates that the OTEC system – not only as a source of unlimited and environmentally friendly renewable energy, but also as a means of freshwater production – is a viable option for implementation in the State. OTEC systems can be diverted to allocate a portion of the electricity generated for operating adjacent water desalination plants, for generating sample volumes of water suitable for human consumption, and aquaculture and agricultural purposes.

*Editors’ Note: As of December 2024, Layang-Layang Island remains closed to public and there are currently no socio-economic activities on the Island.