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  • Water lettuce and water spinach as potential feed ingredients for Nile tilapia Oreochromis niloticus

    Manuel, Eljhon; Gutierreez, Regie; Naorbe, Marissa (2020-07-01)
    Nile tilapia (Oreochromis niloticus) is an omnivore and is considered as one of the important aquaculture commodities. Different plant-based ingredients like corn, “ipil-ipil” leaves and even micro and macroalgae were already tested to reduce the cost on the use of animalbased protein source. This preliminary study therefore, is an attempt to assess the potential of water lettuce and water spinach as feed ingredients through average body weight (ABW), specific growth rate (SGR), survival rate and feed conversion ratio (FCR) of juvenile O. niloticus. Three treatments [water lettuce (WL), water spinach (WS), water lettuce and water spinach (WL+WS)] were prepared in the form of three different diets [Diet 1 (1:1 water lettuce: fish meal), Diet 2 (1:1 water spinach: fish meal) and Diet 3 (1:0.5:0.5) (fish meal: water lettuce: water spinach)] each replicated thrice and fed to tilapia for 60 days. Tilapia growth showed no significant differences in all diets. The diet with water spinach (Ipomoea aquatica) significantly improved the SGR. Based on the result, the I. aquatica could be included both in a simple or complex diet together with water lettuce (Pistia stratiotes). It took 30 days for O. niloticus to adjust to the introduced diets as reflected to their survival rate but the FCR was higher when fed with the test diets compared to the recorded commercially-fed tilapia. Overall, I. aquatica has an excellent performance for O. niloticus culture.
  • Note on the availability of Philippine Forest Turtle Siebenrockiella leytensis in online reptile markets

    Janssen, Jordi; Sy, Emerson (2020-07-01)
    The Philippine Forest Turtle Siebenrockiella leytensis is a critically endangered species endemic to the Palawan group of islands, where it is better known under the English name of Palawan Forest Turtle. No permits have been issued by the Philippine authorities to collect and/or trade in native live wild-caught reptiles since 2001, yet, the trade of captive-bred individuals is allowed. Regardless, evidence of this species breeding in captivity is very scarce and limited to two documented events. Although strictly protected, illegal trade seems to continue with sightings of this species in China, USA, and Europe. Here we report the results of a six-month survey in nine countries/regions carried out to estimate the availability of this species in the online pet trade. We monitored over 60 social media platforms (e.g. Facebook groups, MeWe) and reptile classified websites in Europe, United States of America, Malaysia, Japan, China, Taiwan, South Korea, Hong Kong SAR and the Philippines between 1 February 2019 and 31 July 2019. Only one advertisement offering two Philippine Forest Turtles was observed during the study period. On 30 June 2019, two adult Philippine Forest Turtles were offered for sale in a Japanese pet store. In addition, an advertisement was found outside the study period in Hong Kong, suggesting that there is still international demand for this critically endangered species.
  • First record of Thalassina kelanang (Crustacea: Decapoda: Thalassinidae) from the Philippines

    Albarico, Frank Paolo Jay; Gacutan, Rogelio; Bedi, Agatha Maxine (2020-07-01)
    The first record of mud lobster Thalassina kelanang (Moh and Chong, 2009) from the Philippines was documented in the mangrove forest of Suyac Island, Sagay City, Province of Negros Occidental. The male specimen with a total length of 16.5 cm and 4.5 cm carapace width was found surfacing the mangrove substrate in January 2019. Further survey yielded two more specimens. The specimens had an obtuse rostrum, and a deep median sulcus, which extends posteriorly, nearly the same length but behind the adrostral carinae. The slenderly elongate petasma bears conspicuous spines in the proximal lateral margin. The mounds of T. kelanang with heights ranging from 5 to 15 cm were smaller compared to those of Thalassina anomala. This is the fourth Thalassina species reported from the Philippines.
  • Antimicrobial property of the epidermal mucus of Tilapia Oreochromis spp.

    Sajorne, Recca; Mabuhay-Omar, Jhonamie (2020-07-01)
    This study was conducted to determine and compare the antimicrobial property of the epidermal mucus of Tilapia (Oreochromis spp.) from two environmental conditions, the fish tank and fishpond. The antimicrobial property was determined using Filter Paper Disc Diffusion Method with Amoxicillin and Nystatin as the positive controls and distilled water as the negative control. Results showed significant differences in the effects of the treatments when tested against Escherichia coli, Staphylococcus aureus, Bacillus cereus, Bacillus subtilis, Bacillus megaterium, Pseudomonas aeruginosa, Candida albicans, Aspergillus niger and Aspergillus flavus (p<0.05). The Duncan’s Multiple Range Test further proved that the mucus of Tilapia from fishpond was significantly higher in terms of antibacterial property compared to mucus of Tilapia from fish tank. On the other hand, both of the epidermal mucus of Tilapia from fishpond and fish tank did not show any inhibitory effect against P. aeruginosa and A. niger. The epidermal mucus of Tilapia showed bacteriostatic, fungistatic and bactericidal effects against test microorganisms. Based on the results, the mucus of Oreochromis spp. from fishpond and fish tank are potential sources of antimicrobial compounds.
  • High density of Tridacna crocea in Rita Island, Puerto Princesa City, Palawan, Philippines

    Daño, Jemima; Villanueva, Elmer; Dolorosa, Roger (2020-07-01)
    In spite of being a protected species in the Philippines, the Tridacna crocea or crocus clam, the smallest among eight known giant clam species in the country, is getting rare in most reef areas of Palawan. However, a high density of this species has recently been noted in Rita Island, Ulugan Bay. A total of 44 photos with known dimensions having a total area of 13.26 m2 suitable habitats with clams were analyzed for size structure and density of T. crocea. In total, 215 T. crocea were noted with 84.91 (±25.6) mm average shell length (±sd). The average density (±sd) was 16.22 (±15.75) individual (ind)∙m-2 but the clams had occurred up to 17 individuals in 0.28 m2 or 59.91 ind∙m-2. This high density of T. crocea could be due to suitable environment and the absence of exploitation within the vicinity of the island resort. The importance of other resorts in biodiversity conservation may be investigated.
  • Commonly gleaned macro-benthic invertebrates in a small offshore island of Cawili, Cagayancillo, Palawan, Philippines

    Ardines, Randy; Mecha, Niño Jess Mar; Dolorosa, Roger (2020-07-01)
    The inhabitants of small offshore islands are highly dependent on the health and availability of their resources. However, pieces of information about the commonly gleaned species in some remote areas are sparsely documented. In this study, we inventoried the species composition of the widely gleaned macro-benthic invertebrates such as gastropods, bivalves, and sea cucumbers in Cawili Island, a small inhabited island in the middle of the Sulu Sea in Palawan, Philippines. The samples obtained from fishers and snorkeling activities in shallow areas revealed a total of 85 species belonging to 27 families. Most of these were gastropods, composed of 68 species under 20 families. The list includes nine protected species (four gastropods, two bivalves, and three sea cucumbers). Gastropods and bivalves were mostly used for food and display in the house of the fishermen (souvenir), while the sea cucumbers were exclusively harvested for trade. Sustainable fishery activities are needed in this small offshore island where people heavily rely on their marine resources.
  • Chart Adequacy evaluation method in ”The IHO-IOC GEBCO Cook Book” : Improvements in towards the use of this method and its application example in the coastal waters of Japan

    Ogawa, Haruka; Hashimoto, Takafumi; Sumiyoshi, Masanao; Mori, Hirokazu (2020)
    Evaluation of survey priorities is crucial for hydrographic surveys, which is required to ensure the safety of navigation under limited survey resources. In this study, we introduce the “Nautical Chart Adequacy Evaluation Procedure” proposed by Klemm et al. (2016), which that considers multiple factors such as the sounding depth, vessel traffic, hydrographic characteristics, and bathymetric difference. We apply this method to the waters around Japan as a trial and discuss the possibility of its effective utilization.
  • Installation of a kilohertz laser on the satellite laser ranging system at the Shimosato Hydrographic Observatory

    Fukura, Hiroko; Seo, Noritsune; Inoshiro, Hidekazu; Kinugasa, Tomohiro; Nakanishi, Masahito; Yamaguchi, Tetsuro (2020)
    The satellite laser ranging system for the satellite laser ranging (SLR) observations in the Shimosato Hydrographic Observatory (SHO) has been in operation for almost 10 years since its last update in 2009. In order to enhance the safety and usability of the observation system, the SHO updated the laser ranging equipment in 2018. The new system uses a laser oscillator with a changeable pulse repetition rate up to 1 kHz (i.e., kilohertz laser), by which we can collect the ranging data at a higher rate than by the former one with a pulse repetition rate of 5 Hz. The relevant updates on the control devices and software contribute to the simplification of the SLR operation. These updates will enable the SHO to continue to provide highquality laser ranging data to the International Laser Ranging Service(ILRS) as a Global Geodetic Observing System (GGOS) site.
  • Adoption of CUBE depths in multibeam hydrographic survey results: introduction of optimization cases in foreign hydrographic organizations

    Sumiyoshi, Masanao; Kurita, Hirokazu; Yasuhara, Toru; Hashimoto, Takafumi; Ogawa, Haruka; Nagasawa, Ryosuke; Nagano, Katsuyuki; Yoshizawa, Makoto; Shinbo, Tomohiko; Akiyama, Yuhei (2020)
    Advanced hydrographic organizations have recently adopted CUBE depths in multibeam hydrographic survey results. In this report, we analyze some expected effects of the CUBE algorithm and a multibeam survey based on CUBE depths in hydrographic survey results, which have been developed outside Japan. In addition we discuss some changes in the fundamental ideas that are at the background of multibeam hydrographic surveys.
  • Etching printmakers of the nautical charts in the early days of the Japanese Hydrographic Office.

    Sato, Satoshi (2020)
    The names of the etching printmakers are found in the early Japanese nautical charts published from 1872 to 1878. Recent investigations on old Japanese charts revealed that 14 etching printmakers created the copper plates of the nautical charts, including MATSUDA Ryuzan, who was the etching printmaker of the first modern Japanese chart. To print large volumes is one of the requirements of modern nautical charts. This paper described the careers and achievements of these important etching printmakers, in order to promote a deeper understanding of the situation surrounding chart printings in the early days of the Japanese Hydrographic Office.
  • Efforts to forecast the current condition of Sagami Bay.

    Muneda, Koji (2020)
    Sea current information is used in a variety of fields, including navigation safety, marine economic activities, marine environment conservation, and marine leisure. The Japan Coast Guard’s Hydrographic and Oceanographic Department conducts observations in Sagami Bay using ocean shortwave radar, and discloses and provides flow information on its website. The current information of Sagami Bay is for the past current based on the actual situation, and there is no information on the current conditions in the future. Future current information is helpful for marine activities. For example, ship operators can use it to plan safe and economical operations, while marine leisure people can use it to know the current time suitable for fishing. In addition, it is indispensable for the Japan Coast Guard to predict drifting in order to rescue drifters due to maritime accidents. This report describes a study for creating future flow information in Sagami Bay using data observed by ocean shortwave radar. It shows that the current condition in Sagami Bay also has tidal components, but components other than tidal currents are dominant. A method of estimating components other than the tidal current using moving averages and predicting them from past ocean shortwave radar data was studied. As a result, it was possible to forecast that components other than tidal current could be used practically.
  • Survey on the method of creating a tidal current harmonic constants data set.

    Muneda, Koji (2020)
    Sea current information is used in a variety of fields, including navigation safety, marine economic activities, marine environment conservation, and marine leisure. The Japan Coast Guard’s Hydrographic and Oceanographic Department has been conducting ocean current observations, tidal current observations, coastal current surveys, and so on to collect information on ocean currents, and has been publicizing the results in order to contribute to the public. In this paper, a technique for simulating tidal current, one type of the ocean current information, is reported. In order to make it a data for preparation in the research of 2018, we investigated the method of creating a tidal harmonic constants data set, and report the results.
  • Harmonic analysis of tidal data with missing values based on the least squares method.

    Tsuchiya, Chikara (2020)
    Principally, if the observed period is one year, a set of 60 harmonic constants can be analyzed using hourly tidal data with a large amount of missing values by the least squares method of tidal harmonic analysis. In this paper, the response of the harmonic constants to the amount of missing values using tidal observation data at a tide gauge is investigated. It is shown that harmonic constants are robust in the case of sporadic missing values, of which the proportion is less than 80% of the observations. It is also shown that harmonic constants are robust in the case of continuous missing values, of which the proportion is less than 30% of the observations.
  • Issues related to the computation of the mean sea level for hydrographic surveys.

    Sato, Satoshi (2020)
    The chart datum is defined as the value Zo under the mean sea level. The mean sea level is determined by the average of longterm sea level data. In the hydrographic survey in Japan, the mean sea level is usually deduced from the short term mean sea level during the survey, by comparing it with the mean sea level at the neighboring tide station of the same duration. It used to be thought that the seasonal variation of the sea level is removed by this computation, but little analysis has been done on the degree of error generated by this computational method. In this paper, it is shown that the errors for the estimation of the mean sea level based on this computational method, which compare the short-term mean sea level with the monthly mean sea levels of neighboring tide stations, are almost all within 0.10 m. This means that the errors are within an acceptable range. However, some problems exist in operation regarding to this estimation of the mean sea level. The biggest problem is that the mean sea level is sometimes computed by this method, even though there is a tide station at the sur vey site, which has been monitoring the sea level for a long time. Because this computational method has some error, the mean sea level should be determined only by the data of the tide station at that site.
  • Astronomical observation of the Japan Hydrographic Department

    Okumura, Masayuki (2020)
    The astronomical observation work at the Hydrographic and Oceanographic Department of the Japan Coast Guard( JHOD) was completed in 2008. The astronomical observation work was emphasized as the basis for determining the longitude and latitude necessary for the compiling of nautical charts and hydrographic surveying since its establishment in 1871, and has since been improved and expanded. The astronomical observation work at the JHOD has long contributed to hydrography for a long time, changing its aim from determining longitude and latitude to maintaining the accuracy of the nautical almanacs and using it for geodesy. Ten years have passed since the completion of the astronomical observation work at the JHOD, and the past memorandums of the astronomical observation work at the JHOD, including the history of the each hydrographic observatory and the changes in equipment, are compiled in this paper as a reference for future generations.
  • Study on local user's terminal of DCS (NOAA satellite).

    Kuramoto, Shigeki; Ueno, Yoshizo; Fujiwara, Nobuo (1984)
  • A method of sounding selection using an electronic computer.

    Ueda, Hidetoshi; Nishizawa, Kunikazu (1984)

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