Utilization rate of fish resources in Banggai Laut waters

Capture fisheries is one of the leading sectors that drive the economy of Banggai Laut Regency. Improved fishing technology is related to fishing efforts that will affect the sustainability of fish resource stocks in the waters of Banggai Laut Regency. This study aims to identify the rate of utilization of fish resources in an effort to develop a sustainable fisheries sector in Banggai Laut waters. The method approach used is "Surplus Production". This method serves as an estimator of the relative abundance of a fish resource in the waters of Banggai Laut Regency which is based on the catch per unit of fishing effort. The results showed that the capability of the fishing fleet in Banggai Laut Regency has not been able to reach potential fishing areas. The catch per unit effort (CPUE) of fish resources in Banggai Laut Regency still shows an increasing trend with the highest rate of increase by other fish group including crustaceans and mollusks, about 0.160 tons/unit in the 2014-2016 period. Meanwhile, the catch per unit effort of the large pelagic fish group showed an increasing trend with the lowest rate of increase, about 0.001 tons/unit in the 2014-2016 period. Therefore the utilization rate of fish resources in the waters of Banggai Laut Regency is still classified as under exploited.

Spatial and temporal distribution of phytoplankton with emphasis on the harmful and toxic algae in the Limboto Lake

This study aims to describe Limboto Lake's condition based on the spatial-temporal abundance of phytoplankton and the presence of harmful algae species. Sampling was conducted in February, March, and April 2018 at six stations. The phytoplankton found in Limboto Lake consisted of 7 divisions from 80 species, namely Chlorophyta (35 species), Euglenophyta (17 species), Bacillarophyta (13 species), Cyanophyta (7 species), Cryptophyta (4 species), Dinophyta (3 species) and Chyrosphyta (1 species). The results of the phytoplankton distribution analysis in Limboto Lake varied on average among stations as well as observation times. The results show that the average of phytoplankton abundance at stations 1, stations 2, stations 3, and stations 4 categorized as medium polluted waters with 4,903 ind/L, 5,000 ind/ L, 9,418 ind/L, and 10,049 ind/L, respectively. The abundance at station five is included in the lightly polluted category with an average phytoplankton abundance of 1,541 ind/L, while station 6 is in the heavily polluted category with the average value of 20,894 ind/L. Species that can be used as indicator species for pollution are those with the highest abundance value, namely Microcystis sp., which indicates that Limboto Lake contains high nitrate and phosphate.

The performance of Chlorella vulgaris growth on mass-scale cultivation

Phytoplankton have many benefits, including as a primary producer, natural food, bioindicator, and water pollution treatment. For this reason, their availability needs to be managed, one of which is through cultivation. The purpose of this study was to analyze the mass scale cultivation of Chlorella vulgaris. The research was conducted at the Technical Implementation Unit of Freshwater and Brackish Water Aquaculture, Situbondo, using a descriptive method. The data were analyzed statistically using MS. Excel 2016 software, and a multiple linear regression test was carried out to determine the effect of water quality parameters on the growth of C. vulgaris using the SPSS 16.0 application. The cultivation process started from strain preparation, water preparation, tank and culture media preparation, inoculation, fertilization, and then harvesting. The initial density of C. vulgaris used was 145x104 Cell. mL-1 in tank 1 and 188x104 Cell. mL-1 in tank 2. The results showed that the cell density value of C. vulgaris increased every day until it entered the exponential phase, namely on the 4th day of the culture activity, which was 507 x 104 in tank 1 and 536 x 104 Cell. mL-1 in tank 2. Furthermore, the value of water quality parameters that affected the growth of C. vulgaris in tank 1 and tank 2 was dissolved oxygen of 4.82-6.97 mg. L-1, pH 8.2-9.1, transparency of 20-45 cm, temperature was 26.8-28.2 oC, nitrate of 0.10-0.50 mg. L-1, phosphate of 0.75-2 mg. L-1, and salinity of 30-39 ppt.

Fish species composition in the Kaliotik River, Lamongan Regency, Indonesia

This research aimed to determine the species composition of fishes in the Kaliotik River, Lamongan Regency. The sampling was conducted from March to May 2020 at four stations. A total of 1031 samples caught by the fishing net during the study consists of Anabas testudineus, Trichogaster trichopterus, Hyposarcus pardalis, Mystus sp., Channa striata, Oreochromis mossambicus. The fish diversity index values indicated that the river is in low to moderate condition. The species was also slightly evenly distributed in the waters with no dominant species. Trichogaster sp. and Anabas testudineus are the two dominant species found in the waters with a relative abundance of 44 % and 41 %, respectively. The Kaliotik River ecosystem balance was affected by disposal from human activities along the riverbank.

Population structure of giant clams (tridacnidae) in Aceh Besar district waters

Giant clams have an essential ecological role in the coral reef ecosystem. Given the decreasing number of giant clams in nature, the status of giant clams as protected animals, and there is still little information about giant clams, data or information is needed to make policies regarding giant clam conservation management. This study aimed to determine the population structure of giant clams (Tridacnidae) in the coral reef area of Aceh Besar District. The research was conducted in May 2018, located in Aceh Besar Regency waters with six observation stations. Observation of giant clams is carried out using a visual census technique with the belt transect method. The observations showed that the giant clams found in Aceh Besar waters consisted of 2 species, namely Tridacna maxima and Tridacna crocea. Overall stations, the individual density of giant clams is 0.041 ind. m-2. The diversity index of giant clams shows a value ranging from 0–0.97, classified in the low diversity category. The similarity index value of giant clams is classified into the stressed to stable similarity category with values ranging from 0–0.97. The dominance index value of giant clams is classified in the medium to high dominance category with values ranging from 0.52 to 1. The distribution pattern of the two giant clam species found in the waters of Aceh Besar District has a uniform distribution pattern with values ranging from 0.20–0.29. The overall population structure of Tridacnidae is in unstable condition.

Density of the blue-black urchin Echinotrix diadema (Linnaeus, 1758) in Tomini Bay, Indonesia

The blue-black urchin has been widely known and utilized as food in the world, including Indonesia because sea urchin gonad can be consumed. However, the utilization of sea urchins in Gorontalo has not been performed. On the other hand, natural resources information is needed as the database for natural resources management in Tomini Bay. The aim of this study is to document the blue-black urchin Echinotrix diadema. This study conducted at Blue Marlin Beach, South Leato, Gorontalo, from November 2019 to December 2020. Sea urchin density was calculated with a 1 m × 1 m transect quadrate that positioned at interval 5 m in distance along 15 m of the transect line at the coral reef ecosystem. In parallel with the measurement of the density, sea urchin test diameter was measured with a Vernier caliper (0.01 mm accuracy), and the water temperature was measured with a thermometer. The results show that the average of sea urchin density is 3 ind. m–2 in November and December and 1 ind.m–2 in January. That density has no significant difference among the month. Moreover, the average size of the sea urchin test diameter is 60 mm in November, 63 mm in December, and 66 mm in January. The seawater temperature is 34 °C in November, 37 °C in December, and 33 °C in January. That results show that sea urchin density in the blue marlin beach is very low.

Estimation of gillnet selectivity for Tor tambra captured in Lirik River, Merangin Regency, Jambi Province

Fishing gear selectivity is the condition of a fishing gear that can catch fish the target of catching and escaped other fish so that selectivity has an essential role for fisheries managers who make regulations regarding the mesh size. The purpose of this study is to estimate the selectivity of gillnet fishing gear on Semah fish (Tor tambra). The method used in this research is the experimental fishing method. The results showed that the gillnet in the Lirik river has an estimated value of selectivity to Semah fish (Tor tambra) mesh size of 1.5 inches at a length of 48.59 cm and a mesh size of 2 inches at a length of 64.78 cm. Semah fish (Tor tambra) which have a length far below the estimated value of selectivity will be able to pass through the net without getting caught (escaped), and fish that have a length far above the estimated value of selectivity will be entangled.

Composition of coral species and benthic organism at Tiaka Oilfield, Tolo Bay, Central Sulawesi

This research aims to find out the composition of the coral and benthic organisms at Tiaka Oilfield. This study was conducted in July 2015. Monitoring of coral and benthic organisms used line intercept transect and visual census method. The research results indicated that 16 coral species were consisting of 6 genera. Coral species dominated by the genus Acropora. Benthic organisms that live in symbiosis with coral reef ecosystems in the Tiaka Oil Field were found 11 benthic species consisting of 54 species

Morphology and growth pattern of Nike fish (amphidromous goby larvae) in Gorontalo Waters, Indonesia

Nike is a terminology used by Gorontalo local community to name schooling of minuscule amphidromous goby fish that has a limited appearance in Gorontalo waters. Understanding the biological performance of Nike fish is vital for implementing management and conservation strategy. This study aims to analyze daily recruitment and to determine growth patterns of Nike fish population in nature. Sampling was conducted in the Gorontalo waters during March, April, and May 2018 using a fish net with a mesh size of 0.5 inches. The duration of the appearance of Nike schooling in waters varies every month. The number of fish samples collected each month in this study ranged from 150 to 300 individuals. This study reveals that body color diversity and morphology of Nike fish strongly alleged to depend on where and how long they appear in the waters. Based on the daily recruitment pattern, Nike fish population distributed in Gorontalo waters is predicted to consist of individuals from multi-generation with an average length range of 1.848–2.805 cm. During the sampling time, a positive allometric growth pattern indicated by the population.

The relationship between blue swimming crab (Portunus pelagicus) abundance and environmental parameters in Spermonde Archipelago

Management and conservation of the blue swimming crabs by the marine protected area method require the abundance and environmental parameter information of the blue swimming crab. The aim of this study is to analyze the changes in the relative abundance of the blue swimming crab and its environmental parameters. The study was conducted from March to July 2015, in the waters of Salemo Island, Spermonde Archipelago. The specimens were collected at the three fishing locations around the mangrove, seagrass, and coral reef ecosystems. The variable of relative abundance of the blue swimming crab is determined catch per effort. Samples of environmental parameters such as temperature and current speed are measured in situ. However, for the salinity, dissolved oxygen, ammonia, nitrate, plankton, and chlorophyll-a were analyzed in the laboratory. A comparison of the blue swimming crab abundance in each ecosystem was conducted by One Way ANOVA. Moreover, the relationship between blue swimming crab abundance with environmental parameters was analyzed by multiple regression. The results show that the blue swimming crab is abundant in the seagrass and coral reefs. The environmental parameter that significantly influences the abundance of the blue swimming crab is salinity. The suitable area for blue swimming carb protection based on abundances are seagrass and coral reef ecosystems.