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Desrita, Hasugian FK, Yusni E, Manurung VR, Rambey R. 2021. Feeding habits of Tinfoil barb Barbonymus schwenenfeldii in the Tasik River, South Labuhanbatu, North Sumatra, Indonesia. Biodiversitas 22: 2131-2135. Research on feeding habits of Tinfoil barb, Barbonymus schwanenfeldii was carried out in the Tasik River from July to August 2020. This study aims to determine the composition of foods consumed by Tinfoil barb fish, and the availability of natural food in the Tasik River from 3 sampling stations. Fishes were caught using a gillnet with a mesh size of 3.18 cm, then the fish samples were dissected, and the digestive tract was taken and preserved with 10% formalin. A total of 138 Tinfoil bars were caught for this study. Analysis of stomach contents found that Tinfoil barb ate phytoplankton (41-48%) as the primary food, moss (25-38%), plant pieces (13-17%), worms (2-11%) as a complementary food and few of insects (0-4%), zooplankton (0-1%) as other foods. Based on analysis of food item values, all types of food and ratio within the intestine length and the total length showed that Tinfoil Barb was classified as omnivorous. The availability of natural foods for Tinfoil Barb in the Tasik River consists of the genera Asteroinella, Bacillaria, Bidulphia, Cestom, Gyrosigma, Gonatozygon, Oscillatoria, and Thalassiora.

Desrita, Muhtadi A, Leidonald R, Sibagaring RD, Nurfadillah 2020. Biodiversity of nekton in Batangtoru River and its tributaries in North Sumatra, Indonesia. Biodiversitas 21: 2344-2352. Batangtoru River which flows from the Tapanuli highlands (i.e., Sipirok, Tarutung, Siborong-borong, and Silangit) to the southwestern Indian Ocean is an important habitat for aquatic organisms in the western region of North Sumatra. This research was done to provide basic data on biodiversity of aquatic organisms in Indonesia, especially North Sumatra. The study was conducted in July-August 2019. Nekton was captured using backpack electrofishing units (12 volts and 9 Amperes), traps, nets, and bamboo trap. This study found 68 nekton species, consisting of fish (57 species), crab (3), shrimp (6), lobster (1), and 1 freshwater turtle (1). In general, nekton found in the Batangtoru River and its tributaries are native and economically valuable fish (Tor and eel), including the newly discovered species, which was, Hemibagrus caveatus. Invasive fish found consisted of 6 species, i.e., Cyprinus carpio, Oreochromis mossambicus, Oreochromis niloticus, Xiphophorus helleri, Hypostomus plecostomus, and Trichogaster pectoralis. The only invasive crustacean found was freshwater crayfish (Cherax quadricarinatus).

Coral reefs are one of the typical ecosystems in coastal areas that have ecological and economicvalue. There are many cases of coral reef damage in Salah Nama Island caused by natural andhuman factors. Coral reefs damage is mostly caused by human activities such as water pollution,destructive fishing and using of ship anchors. Activity of devotion society aims to provideinformation and skills to fishermen groups in Salah Nama Island about coral transplantationtechniques, as well as conducting coral transplantation activities as one of the efforts to preservethe ecosystem of coral reefs. Based on the description of the problems and objectives of devotionsociety, the activities that have been done are counseling to the partner fishermen abouttransplantation and coral benefits in ecosystem, transplantation practice and coral transplantationmonitoring.

Desrita, Muhtadi A, Tamba IS, Ariyanti J, Sibagariang RD. 2018. Community structure of nekton in the upstream of Wampu Watershed, North Sumatra, Indonesia. Biodiversitas 19: 1366-1374. River is a habitat for many aquatic organisms. Water quality is the main river characteristic that strongly influences distribution pattern, biodiversity, and abundance of aquatic organisms. Nekton is aquatic organism that swims and moves actively on their desire, for example, fish, shrimp, amphibian and also big aquatic insects. The purpose of this research was to know the habitat condition and biodiversity of nekton in the upstream of Wampu watershed. The habitat condition was measured by examining the temperature, visibility, flow velocity, depth of waters, dissolved oxygen, pH, kind of substrate, the width of the river, body width of river and rate of flow of the river. The type of nekton was determined by catching the nekton using a backpack of electrofishing unit with an electric flow of 12 Volt and 9 Ampere. The upstream habitat condition of Wampu watershed was characterized by big stone, pebble, sandy type of substrate with moderate to strong current flow, and the clear aquatic. Physical and chemical parameters in upstream of Wampu watershed were still sustainable and appropriate as habitat for fish and shrimp. The result of this research showed a variety of nekton collected, comprised of 27 species of fish, five species of shrimp of inland water. Two species of fish from Tor genera, i.e., T. soro and T. tambroides were also found in this study. The highest diversity (H´) in this research site was the Bahorok River (2.12), followed by Landak River (1.93) at the second, and the lowest was Berkail River with only about 1.50 diversity index.

Susetya IE, Desrita, Ginting EDD, Fauzan M, Yusni E, Saridu SA. 2018. Diversity of bivalves in Tanjung Balai Asahan Waters, North Sumatra, Indonesia. Biodiversitas 19: 1147-1153. Local and regional market demands for bivalves increase outside Tanjung Balai City and Asahan District Waters, North Sumatra, Indonesia. As a result, high exploitation of bivalves occurred. In the other hand, there were less comprehensive information and studies on the diversity of bivalves in this area. This study aimed to determine the diversity of bivalves and water quality of Tanjung Balai Asahan Waters; was conducted between July 2016 and November 2017. Sampling of bivalves was conducted monthly. Several physical and chemical parameters were quantified. Data analysis included community structure analysis and Principal Component Analysis (PCA). The result showed that there were 16 species of bivalves from 7 families in Tanjung Balai Asahan Waters. Station 2 had the highest composition of bivalves, while the lowest was noted at Station 1. The mean abundance of bivalves at stations 1, 2 and 3 were 352±22 ind/m2, 222±14 ind/m2 and 388±30,2 ind/m2, respectively. In general, the index of diversity was categorized as low to moderate. The evenness index was categorized as low to high, while the dominance index indicated the absence of dominant species at almost all stations except station 1. Water quality of the waters was still in capacity to support the life of bivalves. Based on PCA analysis, it was obtained that the abundance of bivalves was positively correlated with nitrite, nitrate, phosphate, salinity, and pH.

In fishing activity, the success is indicated by the number of catches that extremely influenced by the conditions of fishing ground. Information of the potential fishing ground is needed for fishermen to increase the effectiveness and efficiency in fishing activity. Sea Surface Temperature (SST) and chlorophyll-a in waters are two things that can affect the potential of fishing ground. The research aims to create distribution map of SST and chlorophyll-a and to presume the potentials of fishing ground in Malacca Strait based on distribution of SST and chlorophyll-a in Malacca Strait (2015-2019). The data of SST and chlorophyll-a distribution in Malacca Strait were using Aqua MODIS satellite imagery. Based on the result of SST and chlorophyll-a analysis, potential fishing ground in Malacca Strait is expected located around East Aceh in Western season, Malaysian waters in the Transition I season, between Asahan and Malaysian waters in Eastern season and between Deli Serdang and East Aceh in the Transition II season.

The purpose of this study was to determine the morphometric and meristic characteristics, growth of Signal barb fish in the Tasik river. The method used in this research is a survey method. Morphometric characteristics of Signal barb fish Bodyweight (BW) ranges from 4-73 gr, Total Length (TL), Standard Length 6.3-15.5 mm (SL), Head Length (HL) 1.8-2.5, Snout Length (SL) 0.5, Dorsal Fin Height (DFH) 2.3, Dorsal Fin Length (DFL) 3-7, Eye Diameter (EM) 0.8, Tail Trunk Height (TTH) 0.8-1.8, Body Height (BH) 2-4.5, Pectoral Fin Length (PFL) 2 cm and Belly Fin Length (BFL) 2 cm. The meristic characteristics of Signal barb fish are the number of Linnea Literalis (LL) as many as 35-38 scale, 13 Circular Body Scales (CBS), 11-13 Front Fin Dorsal Scales (FFDS), the Scales Around the Tail (SAT) a total of 5, Dorsal Fin (DF) of DI. 23-26 fin radii, Ventral Fin (VF) of 9 fin radii, Pectoral Fin (PF) of 11-14, Anal Fin (AF) a total of 7 fin radii and a Caudal Fin (CF) a total of 20-22 fin radii. The growth pattern of signal barb fish in the Tasik River is negative allometric with the condition factor value an average value of 0.42

This research was conducted from October to November 2016 The samples was taken from 3 stations with repeating 3 times in Tanjungbalai Aquatic of North Sumatra Province. Regression equation for relationship length, height, and thickness of Anadara granosa, Anadara gubernaculum dan Anadara inaquivalvis shell to wet weight of flesh i.e Y = 2.950x – 1.3328, Y = 3.246x – 0.8254, Y = 3.01x – 0.5625, Y = 2.143x – 1.0492, Y = 2.2876x – 0.5419, Y = 1.7524 – 0.1926, Y = 2.6734x – 0.9413, Y = 2.6422x – 0.6525, Y = 2.315x – 0.2351. While for correlation coefficient relationship length with wet weight of A. granosa, A. gubernaculum, A. inaquivalvis of 0.796; 0.747; 0.899. Correlation coefficient height with wet weight were found of 0.821; 0.729; 0.909. Correlation coefficient thickness with wet weight of flesh were found of 0.798; 0.754; 0.910.

The purpose of this study was to examine the food habits and length-weight relationship of java barb (BarbonymusgonionotusBleeker) in Reubeeriver, Pidie. This study was conducted in August – September 2017. Ten samples fish were collected using purposive sampling method from the fishermen's landing sites along Reubeeriver. The digestive tract investigation showed that as many as 8 from 10 total fish sample were filled by food. Then, the food wasexamined and resulted in 6 types: moss liver (Antheceroptopsida sp.), bamboo roots pentung (Dendrocalamusasper), bilis fish (Mystacoleucus sp.), fig leaf (Ficusracemosa), jerbung shrimp (Penaeusmerguiensis), and worms (Lumbricusrubellus). The highest percentage of occurrence frequency and index of propenderence found on Moss respectively 100% and 57%, while the highest percentage of volumetric value obtained on shrimp (35%). The analysis of food habits indicated that Java barb (Barbonymusgonionotus) in Reubee River is a group of omnivores that tend to be herbivorous fish with a ratio of 3:1 gut length. The result of calculation of lenght-weight relationship on 50 fish samples depicted an average of 127.42 mm with an average weight of 56.46 grams. While the result of growth pattern calculation was allometrik negative with b value equal to 0.938 which means long growth was faster than weight fish body. The condition factor gave a normal pattern with a value of 107.16.

Asiatic hard clam (Meretrix meretrix) was one of molluscs (bivalve) with economical value. However, fishing activities were presumed to cause a decline in population. This condition was strengthened by the size of the clam which became smaller nowadays. The purpose of this study was to determine spatial distribution of M. meretrix, length distribution, and length-weight relationship. The study was conducted at 3 stations, consisted of Station I at Asahan River estuary which was located by mangrove forest, Station II at the sea and Station III at the waters near mainland of Batu Bara Regency. Estimation growth of M. meretrix was examined following FISAT II method. The density of M. meretrix was dominant at Station I which was low in salinity and high in organic matter. The class interval of 23-34 mm at station I dominated length distribution. Length-weight relationship was found to be very strong with determinant value approaching

The upstream of Wampu Waters is a habitat for various fish species including Tor spp fish. Fluctuating conditions of habitat will greatly affect the existence of fish as diversity, uniformity, dominance, and abundance of fish. This research was conducted to determine of the condition of habitat and diversity of Tor spp fish in the upstream of Wampu waters. Measurement of habitat conditions by measuring current velocity, depth, temperature, visibility, DO and pH. The method was used n this research is descriptive post facto with fishing using backpack electrofishing units, 12 volts and 9 amperes of battery with the multiple-pass depletion operation technique. Habitat conditions in both research locations are good and appropriate to support the life of fish of Tor spp. Tor fish species was found are Tor soro and Tor tambroides with low fish diversity index of Tor spp of 0.5 for the Bahorok River and 0.61 for the Berkail River, lowest evenness index of 0.09 was found in the Bahorok River and 0.11 in the Berkail River and lowest dominance index of 0.17 were found in the Bahorok River and 0.2 in the Berkail River.

Yellowstripe scad included the one of commodity that has an important economic value in the Malacca Strait. Fish were found mostly in Indonesian of waters made this fish as one of the main target catch. But, it can had negative impact on the population of the fish. The study is done at Belawan Waters on March until May 2017 that which is purposed to study about the frequency distribution of length, determine the parameters of growth and, determine mortality rate and the rate of exploitation in order to provide appropriate management model for the fish resource. Yellowstripe scad was observed around 360 samples with the length range between 110 - 175 mm. The fish separated by bhattacarya method used the aid software FISAT II. A pattern of growth Yellowstripe scad alometrik negative with growth coefisien (K) 1.1 with length asimtotic (L∞) 181.65. The rate of mortality total ( Z) yellowstripe scad 4.34 per year at the rate of mortality natural ( M ) 1.204 per year and rate mortality by fishing (F) 3.136 per year in order to obtain the rate of exploitation 0.722. The value of this exploitation rate has exceeded the value of the optimum exploitation of 0.5.