The appearance of whale sharks (Rhincodon typus) is related to the availability of food in a water area, and it has become a tourist attraction which requires integrated management to prevent it from becoming threats to whale sharks. The appearance of whale sharks is regular throughout the year with the highest number of individuals occurring only in Kwatisore waters. This study aims to examine the bio-ecology of whale sharks related to their appearance based on individuals, quantity, time of appearance, and sex. Primary data collection carried out from January 16 to March 26, 2023, using a census method on 4 units of fishing lift-net deployed in Kwatisore waters. The results showed that 21 individual whale sharks appeared with a total of 225 occurrences in January, 245 occurrences in February, and 248 occurrences in March. There was also one new individual that migrated into Kwatisore waters with the ID number 184. Whale shark appearances mostly happened in the morning and the appearance percentage was 100% male with a total length ranging from 3 to 7.5 m. Environmental factors in Kwatisore waters were in normal conditions supporting the appearance of whale sharks. Keywords: Whale sharks, appearance, new individual, environmental factors

Sea turtle populations have declined due to habitat destruction and the widespread collection of eggs for commercial purposes. This study assessed the characteristics and suitability of semi-natural hatchery habitats for Olive Ridley Sea Turtles (Lepidochelys olivacea) at Batu Hiu Beach, Pangandaran, West Java, Indonesia, from June 1-July 31, 2023. The survey method and purposive sampling were employed to determine nesting sites based on turtle landing points.Biophysical habitat measurements were analyzed descriptively and statistically using one-way ANOVA and Tukey's post hoc test to compare sand temperature, sand humidity, and air humidity. An L. olivacea landed at site 4, laying 73 eggs in a natural nest with 34 cm nest depth and 24 cm nest diameter. Semi-natural nests measured 37 cm nest depth and 26 cm in nest diameter. The sand type at Batu Hiu Beach was characterized by black sand grains and fine sand substrate with a percentage of 51.02%. The temperature within the hatchery ranged from 25.3°C to 42.1°C. with average of 29.7 ± 1.88 °C.The sand humidity in the hatchery ranged from 2% to 14%, with an average daily humidity of 10 ± 0.22 %. The air humidity within the hatchery ranged from 56% to 94%, with a daily average of 85 ± 0.05 %. Based on all the analyzed parameters, the hatchery at Batu Hiu Sea Turtle Preservation were suitable with the nest criteria by Technical Guidelines for Sea Turtle Conservation Management by DKP for the hatching of L. olivacea eggs, with a hatching success rate of 85%.Keywords: Lepidochelys olivacea, temperature, humidity, sand type, hatching success

Water quality is the main factor that has a major influence on the growth and survival of Tilapia Larasati (Oreochromis niloticus). Nitrosomonas sp. and Bacillus sp. can optimize water quality through nitrification and denitrification processes and optimize feed utilization. This study aims to determine the effectiveness of using probiotic Nitrosomonas sp. and Bacillus sp. in O. niloticus maintenance media in improving water quality and growth. The method used was CRD with 4 treatments and 3 replications, namely treatment A (without probiotic), B (probiotic 1.0 µL/L), C (probiotic 1.5 µL/L), and D (probiotic 2.0 µL/L). This study used an aquarium measuring 40 x 30 x 40 cm filled with 20 liters of fresh water, and filled with 10 fish weighing 6.97 ± 0.20 g each (density of 1 fish/2 liters). Molasses as feed bacteria and probiotics were given according to the treatment dose. Siphon was accomplished twice a week according to the level of turbidity. Water changes once a week as much as 50 - 60%. The results from the study showed that the use of probiotics had a significant effect (P<0,05) in improving water quality and fish growth. The best result observed from treatment C, with the reduce ammonia and nitrite (0.002 and 1.291 mg/L), highest fish growth, specific growth rate, and survival rates (14.63±0.24 g; 2.48±0.01%/day; and 97±0,06%, respectively), and also lowest feed conversion ratio (1.07±0.02). Based on these results, the best dose for improving water quality and growth of O. niloticus is 1.5 µL/L.Key words: aquaculture, bioflock, organic matter, sludge, waste

Nitrate, phosphate, and silica are nutrients needed for the growth of phytoplankton populations. The primary objective of the present study was to establish the relationship between the nutrient composition (nitrate, phosphate, and silica) and phytoplankton abundance. Sampling was was conducted at three observation stations located in the tidal zone of Maitara Island coast, North Maluku. Collection of plankton samples in coastal waters using a 25 µm plankton net. Phytoplankton cells were identified and counted in the laboratory using an electric microscope with 100x magnification. Phytoplankton observations were carried out using the field of view method. Testing the concentration of nitrate, phosphate, and silica using spectrophotometer techniques. The research data were analyzed using a correlation test. The research findings indicated that the coastal waters surrounding Maitara Island were classified as oligotrophic waters, based on the nitrate and phosphate, and silica content. Oligotrophic waters have very low nutrient content such as nitrogen and phosphorus, causing low primary productivity. Simultaneously, nitrate, phosphate, and silica concentrations had a very strong correlation (R=0.823) with phytoplankton abundance. Partially, the correlation between nitrate concentration and phytoplankton abundance was classified as very strong (R=0.729). However, the correlation between phosphate concentration and phytoplankton abundance was moderately significant (R=0.577), and the correlation between silica concentration and phytoplankton abundance was weak (R=0.386). High concentrations of nitrate and phosphate in coastal waters lead to increased abundance of phytoplankton. However, high silica concentrations in waters can only increase the abundance of certain phytoplankton groups, for example diatoms and radiolarians. Keywords: Phytoplankton abundance, nitrate, phosphate, silica, Maitara Island

Indonesia covers over 15% of global tuna production. This has placed Indonesia as the top tuna-producing country in the world. Troll line is one of the fishing fleets that targets tuna as main catch, operates in many areas in Indonesia, including those bases at Palabuhanratu Nusantara Fishing Port in Sukabumi. Fishermen complained about uncertain changes of the fishing season in recent years. This causes fishermen unable to determine the right time for fishing. Some trolling fishermen suffer losses and even bankruptcy. This study tried to estimate fishing season for trolling fleets based on three main catch commodities: skipjack tuna, yellowfin tuna, and bigeye tuna. Data on catches and fishing trips are collected monthly from 2018 to 2022 from the Sukabumi Regency Central Capture Fisheries Statistics Agency. Data was processed using a catch-per-unit effort approach followed by a fishing season index analysis. Results show that the three main catch commodities have similar fishing season patterns. Peak fishing season is from the beginning of the east season in June to the middle of the second transition season in October. Productivity of the three commodities reached its lowest point in the lean season in January and February, in the middle and end of the west season.Keywords: catch composition, fishing season, productivity, tuna

The Serayu River is one of the longest rivers in Central Java. Dams built in the lower reaches of the Serayu River are thought to block the migration paths of fish and aquatic macrocrustaceans. This study aimed to determine the effect of dam on Varuna litterata migration and its molecular identification. This research was conducted using the observation method. Migration observations were made on vertical paths while molecular identification of V. litterata in the lower reaches of the Serayu River was compared with existing data in GenBank. The study covered the freshwater area above the Serayu Dam, the open area with freshwater below the Serayu Dam, and the open area with brackish water at the estuary of the Serayu River, with a study length of 33.37 km. The results showed that the presence of dams in the lower reaches of the Serayu River inhibited the migration pattern of V. litterata. The vertical shape of the dam causes only a few V. litterata to migrate to the top of the dam. The dam in the lower reaches of the Serayu River resulted in not many V. litterata being able to migrate to the top of the dam, so there were very few V. litterata found in the population upstream of the dam (115 ind). The results of molecular identification of V. litratata using the cytochrome C oxidase subunit I (COI) gene show that this crab is 100% the same as the data in GenBank and is closely related to Varuna yui and other Varunidae crab species.Keywords: Dams, Molecular, Migration, Serayu River, Varuna litterata

Tempe liquid waste (TLW) contains nutrients such as fat, protein, carbohydrates, nitrogen, phosphate, and potassium that could be used in fish rearing. Moreover, it has lactic acid bacteria (LAB) belonging to gram-positive microorganisms, which could decompose organic and inorganic matter in water. Therefore, this study aimed to determine whether TLW could have the potential to enhance Tilapia (Oreochromis niloticus) growth and improve feed efficiency. The study used 180 fish (6.04 ± 0.13 g) reared in twelve aquariums and TLW was obtained from boiling soybeans during the tempe production process in the village of Sanan, Malang. The research design was Completely Randomized Design (CRD), which involved four treatments, T0 (no TLW), T1 (3%), T2 (5%), and T3 (7%) with three replications. The result showed that T2 resulted in the highest growth rate (11.22 ± 0.29 g), specific growth rate (2.07 ± 0.32% / day), feed conversion rate (1.54 ± 0.16), feed efficiency (56.02 ± 1.24%) and survival rate (91.11 ± 0.58%) compared to others. Nonetheless, there was no difference in the absolute length (Lm) parameter at the end of the research. The research results also found that water quality remained favourable for supporting tilapia cultivation under all observed conditions, except for the oxygen levels in the control group, which fell below the standard (<3 mg L-1). Finally, the present study concluded that 5% of TLW could be the best; in contrast, the higher concentration of TLW decreased O. niloticus growth performance, feed efficiency, and survival rate.Keywords: fish development, tilapia, wastewater, water qualities

Dampelas Lake, also known as Talaga Lake, in Central Sulawesi Indonesia, lacks data on fish communities, especially biological aspects, including a wild population of bonylip barb Osteochilus vittatus (Valenciennes, 1842). Locally known as ikan nilem, this freshwater fish commodity is not native to Sulawesi. The purpose of this research was to analyze the length-weight relationship, condition factor and DNA barcode of the bonylip barb population in Dampelas Lake. Bonylip barb specimens (101 males and 78 females) were collected from Lake Dampelas during July 2023 using fish traps. The total length and weight ranges were 57-211 mm and 3-107 g. Length-weight relationships were W = 3×10-5 L2,8219 (males); W = 3×10-6 L3,2574 (females); and W = 1,1×10-5 L3,0176 (both sexes combined), indicating an isometric growth pattern. Condition factor ranged from 0.471-1.652 with similar mean values for males (1.01) and females (1.02). DNA barcodes for Lake Dampelas bonylip barbs nested in one of four O. vittatus clades, indicating a need for reviewing Osteochilus taxonomy. Most adult females had spent gonads, indicating seasonal spawning, with implications for developing an economically viable fishery which could also help control this non-native species in Dampelas Lake.Keywords: Cyprinidae, freshwater fisheries, growth pattern, introduced fish, mitochondrial DNA

The Java Sea is influenced by the west and east monsoons, which have an impact on hydrodynamic processes and chemical-biological water quality. Chemical-biological parameters play an important role in the food chain cycle that occurs in these waters. The quality of the eastern Java Sea waters is still limited by chemical-biological parameters, so the characteristics and distribution of these waters can be comprehensively known. chemical-biological. This study aimed to analyze the characteristics and distribution of nitrate, phosphate, oxygen, chlorophyll-A, and NPP parameters in the eastern Java Sea waters. This study used secondary data with daily temporal resolution from January to December 2020. Spatial analysis uses the climatological averaging method for 6 months as a statistical representative of the west monsoon and east monsoon. For each parameter, a vertical analysis was conducted to compare parameter values between the coastal waters of Tuban, Java Sea, and Banjarmasin Waters. Correlation analysis between parameters was conducted using the Pearson correlation method. Nitrate, phosphate, oxygen, chlorophyll-A, and NPP concentrations have temporal and spatial variability. Monsoon factors in Indonesia have a strong influence on the variability of nitrate, phosphate, oxygen, chlorophyll- A, and NPP concentrations. During the east monsoon, the concentration of chemical-biological parameters decreases, while in the west monsoon, the concentration increases and reaches its highest value. Generally, high concentrations occur in the northern and southern parts of the study site, around the coastal areas of Java and Kalimantan. Key Word: Chemical-Biological Parameters, Java Sea, Tuban Waters

Tropical Cyclone Seroja, which occurred in the Indian Ocean, was characterized by maximum wind speeds of 70 knots. As part of the impact assessment associated with the cyclone, wave height observations were conducted along its track and tidal examinations were carried out at Cape Cuvier and Kupang tidal stations. Therefore, this research aims to analyze the relationship between wind speed and wave height, as well as the impact of Cyclone Seroja on waves and tide. The results showed that Cyclone Seroja reached a very high intensity with maximum wind speeds of 70 knots and maximum wave height of 14.24 meters on April 11, 2021, at 06:00 UTC. Regression analysis showed an R-squared value of 0.716, indicating that 71.6% of the variation in wave height can be explained by wind speed. The correlation value of 0.846 indicated a strong relationship between wind speed and wave height. This research also analyzed the changes in residual tide height at Cape Cuvier tidal station on April 11, 2021, with a maximum residual height of 0.57 meters. Wave height propagation from wave station 1487 significantly influenced the residual tide value at Cape Cuvier, with wave height of 11.790 meters and a propagation speed of 40.42 km/h. At Kupang tidal station, there was a residual height change of up to 0.27 meters, caused by influence of low pressure around wave station 239, with an average pressure of 1001 pHa and an average wave height of 3.89 meters, propagating towards the Kupang tidal station during the formation phase of Tropical Cyclone Seroja. Keywords: Cyclone; Seroja; Wave; Tide; Indian Ocean.