Growth Parameters of Sentani Gudgeon Fish (Oxyeleotris heterodon) in Sentani Lake, Papua

ABSTRACTThe Sentani Gudgeon Fish (Oxyeleotris heterodon, Weber 1907) from the family Butidae with the general name Sentani Gudgeon is known locally as Gabus Malas and Himen. Sentani Snakehead Fish is one source of animal protein that is very important for the community around Lake Sentani. The population of the Sentani Gudgeon Fish species is at a crucial level. The issue could be affected by environmental pressures, continuous catches, competition with introduced species from outside Papua, intensive predation systems, and imbalances in ecological systems. The condition made a decline in population size until it became extinct. Gudgeon Sentani fish is the main target of catching in the lake. This condition significantly affects stock, size when first captured, population decline, reproductive cycle, and average catch. Until now, data and information on the growth of snakehead fish as the basis for fisheries management in the waters of Lake Sentani are not widely known. Considering the importance of preserving the native species of Lake Sentani, especially the Snakehead Fish, efforts to manage the fisheries in Lake Sentani's waters are urgent. This research was conducted in March - October 2020, located at Lake Sentani. The specimens were obtained from the catch of fishers with various gill nets and chopsticks. Enumerators or field assistants assisted the recording of the number and measurement of the total length of fish caught by fishermen daily. The results of the analysis showed: asymptotic size (L?) 46.20 cm, growth coefficient (K) 0.29, the total mortality rate (Z) 0.80 per year, natural mortality (M) 0.74 per year, the mortality rate due to fishing (F) 0.06 per year and exploitation rate (E) 0.075 per year.

Formation and optimization of costs of production fishing activity of vessels

В работе рассмотрен процесс формирования производственных издержек в трех различных сценариях промысловой обстановки, описаны издержки, возникающие в каждом из сценариев. Выполнена оценка вероятности наступления того или иного сценария промысловой обстановки. Сформулирован подход к определению средневзвешенных издержек судна. Сформулирован подход для определения средневзвешенного улова судна на основании многолетних данных о добыче промыслового объекта. Данная оценка может быть использована при планировании работы добывающего судна. Полученные значения средневзвешенных затрат подсистем «добыча» и «обработка» производственного процесса на добывающем судне, а также средневзвешенное значение суточного вылова использованы в задаче оптимизации режима обработки суточного вылова с условием минимизации затрат. Приведен пример расчет среднесуточного вылова и решение оптимизационной задачи для промыслового объекта сардина иваси. The paper considers the process of forming production costs in three different scenarios of the fishing situation, describes the costs arising in each of the scenarios. The probability of occurrence of a particular scenario of the fishing situation is estimated. An approach to determining the weighted average costs of a vessel is formulated. An approach is formulated to determine the weighted average catch of a vessel based on long-term data on the production of a fishing object. This assessment can be used when planning the operation of a mining vessel. The obtained values of the weighted average costs of the subsystems "production" and "processing" of the production process on the producing vessel, as well as the weighted average value of the daily catch, are used in the task of optimizing the processing mode of the daily catch with the condition of minimizing costs. An example is given of calculating the average daily catch and solving the optimization problem for the sardine ivasi fishing object.

PERBANDINGAN HASIL TANGKAPAN JALA LEMPAR PADA UKURAN MATA JARING YANG BERBEDA DI DANAU KERINCI

Nets are a simple fishing tool which principally confines fish so they cannot escape. The mesh sizes that are often used by the people of Kerinci Lake are the mesh sizes of 2.5 inches and 4.5 inches. The research objective was to compare the catch of jala lempar with mesh sizes of 2.5 inches and 4.5 inches in Kerinci Lake. The method used is the experimental fishing method by catching 16 trips. The results showed that the catch of jala lempar with a mesh size of 2.5 inches got a catch with a weight of 53.930 kg and a total of 266 fish, while a 4.5 inch mesh size obtained a catch with a weight of 33.844 kg and a total of 51 fish. the type of fish that you get is tilapia and barau. The use of different mesh sizes on the Net fishing gear shows a significant difference (P <0.05) to the weight of the catch, at mesh size 2.5 inch, with an average catch weight of 3.371 kg while the mesh size is 4.5 inches. obtained an average catch weight of 2.111 kg. Based on this research, it can be concluded that using a 2.5 inch mesh size results in more catch than 4.5 inches in size

Importance of recreational shore angling in the archipelago of Madeira, Portugal (northeast Atlantic)

In 2017, a total of 4825 licences were issued for shore angling in Madeira. Surveys were conducted on 734 anglers, some in the government fisheries office during the licence request and others during the fishing activity. Shore angling is practised throughout the year, mostly at weekends and during day time, and with an increase in summer. More than 60% of the anglers are unemployed, have low incomes, and spend on average €254 per person per year on this activity, adding up to a total of €1.16 million per year. Shore angling average number of fishing days per year per fisher was 65.1±62.0 and the average catch per unit of effort was 0.35±0.26 kg/angler/hour. The estimated total annual catch was 520.7 t. Forty-three teleost species, 2 elasmobranchs and 6 invertebrates were identified in the catches. Despite the limitations and inaccuracies inherent to the surveys, they still provided valuable information and gave a general perception of the recreational shore fisheries in Madeira. The possible impact on the most captured species, such as the white seabream, Diplodus sargus (Linnaeus, 1758), and the parrotfish Sparisoma cretense (Linnaeus, 1758), should be analysed because high fishing pressure could affect populations and ecosystems.

Optimal shape of the harvest control rule for different fishery management objectives

To determine the optimal shape of the harvest control rule (HCR) achieving common fisheries management objectives (maximizing the average catch, reducing the deviation of yields, and avoiding stock collapse) and ensure robustness to observation errors, we estimate the optimal values of biological reference points (BRPs) composing the HCR. While traditional HCRs usually consist of three BRPs based on the fishing mortality coefficient (F3-HCR), we introduce an alternative HCR defined by 21 BRPs based on the catch levels (C21-HCR) to cover various possible shapes of HCR including smooth ones. We compare the shape and the performance between the optimal C21-HCR and the optimal F3-HCR and conclude that the optimal HCR can be composed of the gradual combination of the basic strategies: the constant escapement strategy, the constant harvest rate (CHR) strategy, and the constant catch strategy. However, the current F3-HCR does not necessarily allow this combination and generally returns lower performance levels than the optimal C21-HCR (since the basic strategy is confined to CHR) excluding the range of low biomass. This result will provide a clear perspective to improve HCR according to the magnitude of assessment errors and to compromise multiple fisheries management objectives when various stakeholders are involved.

WATER BIOLOGICAL RESOURCES OF THE REPUBLIC OF MORDOVIA: THE MOKSHA RIVER

The article is focused on the problem of biological resources of the Republic of Mordovia. The Moksha River is traditionally the main fishery water body in the Republic of Mordovia. There have been presented the results of comprehensive fisheries research for 2009-2015 carried out on the segment of the Moksha within the Republic of Mordovia. Analysis of the food supply has shown a significant underutilization of zoobenthos, phytoplankton and macrophytes. Using the data, which are the average indicators of the food reserve over the years, the river’s production capabilities were calculated and made 418.6 tons or 186.9 kg/ha. According to the results of research catches with fixed nets and minnow seines, the composition of the fishing ichthyofauna was determined, where roach, perch, goldfish dominated in number, roach, crucian carp, bream, perch dominated in biomass. There were recorded in total 29 fish species, mainly carp species. There has been defined the ichthyomass of fish aged two years and older, which varies from year to year within 141.3-180.2 tons or 63-81 kg/ha, and taking into account juvenile species it will make 108 kg/ha. As for the most significant species in the fish ichthyofauna (roach and silver carp) the increase in fish production was calculated (8.6 and 14.9, correspondingly) and the total catch quotas were determined. Under the constant value of the average catch per year effort, they amount to 50-60 tons. Taking into account the free food reserve due to the reproduction and protective measures carried out at the expense of compensation funds for the damage caused to aquatic biological resources, the catch of marketable fish species in the Moksha River can be in-creased in 2.0-2.5 times.

Diversification insulates fisher catch and revenue in heavily exploited tropical fisheries

Declines in commercial landings and increases in fishing fleet power have raised concerns over the continued provisioning of nutritional and economic services by tropical wild fisheries. Yet, because tropical fisheries are often data-poor, mechanisms that might buffer fishers to declines are not understood. This data scarcity undermines fisheries management, making tropical fishing livelihoods particularly vulnerable to changes in marine resources. We use high-resolution fisheries data from Seychelles to understand how fishing strategy (catch diversification) influences catch rates and revenues of individual fishing vessels. We show that average catch weight decreased by 65% over 27 years, with declines in all nine species groups coinciding with increases in fishing effort. However, for individual vessels, catch diversity was associated with larger catches and higher fishing revenues and with slower catch declines from 1990 to 2016. Management strategies should maximize catch diversity in data-poor tropical fisheries to help secure nutritional security while protecting fishing livelihoods.

Characterization of Beach Seine Operations in Pangandaran Beach, Indonesia

The coastal area in Pangandaran Regency, in general, has been developed as an area for tourism conservation and fisheries activities. Pangandaran beach which facing the oceans has potential in the fisheries sector which is quite potential so that Pangandaran regency is one of the regions in Indonesia that has potential in capture fisheries. There are various types of fishing gear used in fishing activities in Pangandaran, one of them is beach seine. Beach seine is local wisdom that is still maintained in Pangandaran so that this fishing gear is still operated. The purpose of this research is to investigate the operation of beach seine in Pangandaran water. The research was carried out in August 2018 on the East Coast of Pangandaran. The method used in this research is a survey method and analyzed descriptively. The beach seine operation phase is divided into three stages, preparation, stocking nets, and catching catches. The main catches of beach seine in Pangandaran consist of hairtail fish (Trichiurus spp) with an average of 172 fish and white pomfret (Pampus argentus) with an average of 99 fish. The bycatch is 7 species of fish with a total average of 1990 fish. The beach seine in Pangandaran has an average catch rate of 31.05 km/hour.

Composition and catch rate of folded cube fish pots in the sea of Tuban Regency

This study aimed to determine the composition and catch rate of folded cube fish pots in the seawater of the Tuban Regency. The research was conducted in December 2018 located in the Sokorejo, Tuban Regency, using 30 units of folded cube fish pots with a size of 50x50x50 cm2. The cube folded trap installation was done in 10 times of catch trip and installed in the morning. The catches were collected, identified, and measured for their individual length and weight. The crabs were measured for the length and width of their carapace. The catching result of folded cube fish pots was classified into five types which are fish group (48.97%), crabs group (29.59 %), swimmer crabs (7.1%), Land hermit crab (6.12%), and mud snails (8.16%). The result showed that Two-spined Arm Swimming Crab (Charybdis anisodon) was the most dominant type of catch equal to 29.59% of the total catch, while other types of catch that were quite common are Pig Faced Leather Jacket (Paramonacanthus choirocephalus) (9.18%), and Crescent Pearch (Terapon jarbua) (8.16%). The average catch rate for folding cube was 32%/trip with a weighted average catch of 436.58 gr/trip.

FISHERY IN THE TRIBUTARIES OF YAMUNA RIVER (KEN RIVER, PAISUNIRIVER) AND GANGA RIVER (TONS RIVER)

A study on the landings of various species recorded randomly from December 2003 to June 2004 from fish landing and marketing centers on the Ken at Banda, on the Paisuni at Karwi and Tons at Chakghat and Sadiapur (Prayagraj), revealed that the average catch day-1 of the Ken river was dominated by Cyprinus carpio followed by Aorichthys spp. and miscellaneous fish. In contrast the Paisuni R. was dominated by Labeo calbasu followed by Hypophthalmichthys molitrix and miscellaneous while the latter group dominated over Aorichthys spp and L. calbasu in the Tons R. Among selected species Labeo rohita commands higher price (Rs 61.7), Tor tor moderate (Rs 52.5) and L. calbasu lower price (Rs 37.5).