Bottom Gill Research Articles

Vertical distribution of Lake Superior cisco (Coregonus artedi) spawning aggregations and implications for population monitoring

Cisco (Coregonus artedi) support an evolving commercial roe fishery in Wisconsin waters of Lake Superior. To monitor trends in spawning cisco abundance, fishery managers recently began estimating adult biomass and exploitation using fall hydroacoustic surveys, which were combined with gill net surveys to inform apportionments of acoustic data. The gill net survey design consisted of paired top-suspended and bottom-set gill nets, but only the sex ratios from top nets are currently used with the hydroacoustic surveys due to an assumption that cisco in Lake Superior are pelagic spawners. However, the vertical sex distribution of cisco during spawning aggregations has been described as dynamic, with males becoming more bottom-oriented throughout the spawning season. We used multilevel aggregated binomial regressions to: 1) determine if there is bias between top and bottom gill net catches of cisco for either sex and if it changes throughout the spawning season, 2) evaluate how the vertical distribution of males and females may create bias in sex ratios used to estimate exploitation, and 3) explore the effect that maturity (i.e., gonadal development) has on vertical distribution during spawning aggregations. We identified sex-specific bias in vertical catch location that has the potential to bias estimates of sex ratio, and the source of this bias may be attributable to maturity driven changes in behavior. These findings highlight a need for caution when relying on gill nets to apportion cisco sex ratios during spawning aggregations and provide support for a non-pelagic alternative hypothesis of spawning behavior.

The Influence of Traditional Bottom Set Gill Net Dimension with the Daily Catches of Rastrelliger Faughni at the Karangantu Archipelago Fisheries Port, Banten Province, Indonesia

The Karangantu Archipelago Fisheries Port has a central role in provincial fisheries in Banten Province, Indonesia. This role shows that fisher catches are necessary to support regional needs, so that the fishing process up to the dimensions of fishing also helps the catch potential. The measurements of the fishing gear refer to the type of fishing gear, the type of vessel (GT), the number of boxes, and the number of fishers who act as crew members (ABK) during the fishing process. This study aims to measure the influence of the dimensions of fishing gear on the catches obtained by fishers at the Karangantu Archipelago Fisheries Port. The research method uses quantitative methods, based on the results of linear regression of the dependent and independent variables, and interviews in data collection. The results show that the variables of ship weight, number of boxes, and number of crew members had a common effect, 0.35 or 35 %, on fish catches. The low coefficient indicates the influence of the dimensions of the fishing gear is not always the primary determinant. There are 65 % physical and production variables to maximize the dimensions of the fishing gear to support increased catches. Based on this influence analysis, it can be used as a reference for maximizing the dimensions of fisher fishing gear to support increased catches, given the role of Karangantu Archipelago Fisheries Port as a supplier of fish at the provincial level. Highlights The field survey time is essential to decide due to habitual results because of weather differences All fishers observed are using rampus nets (bottom gill net) as their fishing gear Correlation between fishing gear dimensions and daily fish catches analyzed with statistical quantitative methods by linear regression The fish gear dimension does not significantly affect daily fish catches, proven by the low coefficient of determination (R-squared) of 0.35 Other factors that affect daily fish catches of fishers are location, environmental conditions, and physical water

Impact of Marine Debris to Fishing Operation at Ambon Bay

Marine debris is a serious problem around the world. The entry of garbage into the sea not only threatens the survival of various marine organisms but also disturbs fishing activities, thereby reducing fishermen’s production and income. This study aimed to identify the fishing gear damaged by marine debris during fishing operations and analyze how much the marine debris impacted the production of various fishing units. Data were obtained from 101 fishermen operating at Ambon Bay by observation, interview, and descriptive analysis. Obstacles by the trash during fishing operations are among the trash twisted or attached to fishing gear; trash are twisted at the propeller of the boat and damage the fishing gear. On the fishing line group, the main hurdle is on the vertical hand line, where the trash are entangled at the hook; on the gill net group, the main hurdle is on the bottom gill net, where the trash are twisted to body net; and on the seine group, the main constraint is on the beach seine, where the trash are trapped in the cod end. This condition causes a decline in production, with the biggest impact on the bottom gill net, with a decrease in production of 4.38% from the average production per trip.

Growth Patterns and Mortality of Lobster Panulirus ornatus from the Catch of Bottom Gill Net Fishers in the Western Waters of Tarakan Island

Large-bodied Panulirus ornatus lobsters are economically important because they are an aquatic biota. It is one of the most important commodities in the city of Tarakan. The aim is to analyze the growth patterns and mortality of P. ornatus from the West Waters of Tarakan City. Method using a quantitative descriptive. The purposive sampling method was used by dragging the gill net fishing gear to the P. ornatus lobster ground area, and the collection was carried out 16 times in 7 months (December 2021-July 2022). The results of P. ornatus showed that the male sex ratio was higher than the female. The growth model was allometrically negative, and the criteria for the condition index were fat and thin. The growth pattern of Model Von Bertalanffy males is slower than females. However, the growth rate to achieve asymptotic growth for males is faster than for females. The total mortality, catch mortality, and exploitation rate of males was higher than females. However, the mortality of the female nature was higher than that of males. P. ornatus should be managed in the waters of West Tarakan using the domestication and restocking technique to increase sustainability.

Fisherman productivity of bottom gill net and drift gill net during covid-19 in Napabalano Sub- District Napabalano District Muna Regency

This study aims to determine the productivity of fisherman who use bottom gill nets and drift gill nets during the Covid-19 period. This research was conducted in Napabalano Village, Napabalano District, Muna Regency from April to May 2022. The sampling method used was the census method with the number of respondents being 8 bottom gill net fisherman and 8 drift gill net fisherman. Data was collected trough interviews, observation and documentation. Analysis of the data used is the productivity Analysis. The results of the study showed that the productivity obtained by bottom gill net fisherman averaged 2.42, meanwhile, the productivity obtained by drift gill net fisherman is 3.01 on average. Thus, the two fishing gears are declared productive because the average productivity value is >1.

Fishing characteristics and spatial distribution of blue swimming crab size (Portunus pelagicus) in the waters of Pati District, Central Java Province

The increasing Blue swimming crab/BSC fishing activity is a response to the high demand of the international market. One of the potential coastal waters for BSC capture fisheries is Pati Regency. However, biological information related to BSC resources is still limited in this area. Therefore, the purpose of this study is to analyze the characteristics of BSC fishing and the size structure of the caught BSC. The study was conducted from December 2020 to March 2021. The method of data collection is observation and interview with fishermen, while the analysis is carried out descriptively. The location of BSC fishing is divided into 3 zones. The characteristics of BSC fishing locations include those related to the distance from the coastline, technical aspects and types of fishing gear, as well as the operational system of capture. The distance from the coastline in zone 1 is about 1-2 miles, zone 2 is about 2-3 miles, and zone 3 is more than 3 miles. The types of fishing gear used in zone 1 are bottom gill net, zone 2 and zone 3 are trapnet. The operational system of capture in zone 1 and zone 2 is carried out with daily trips, while in zone 3 it is carried out with weekly trips (babang). The distribution of carapace width sizes in zone 1 ranges from 44.00-139.00 mm (average 104.80±11.00 mm), in zone 2 it ranges from 72.10-138.00 mm (average 107.90±12.30 mm), and in zone 3 it ranges from 101.40-177.60 mm (average 126.50±11.50 mm).

Dampak Pandemi Covid-19 pada Kelayakan Usaha Perikanan Rajungan di Teluk Banten

The Archipelagic Fishing Port of Karangantu located in Banten Bay is one of the blue swimming crab fishing centers in the Java Sea. Covid-19 pandemic had significant effect on blue swimming crab fisheries in Karangantu, especially on the increasing of fishing operational cost, decreasing of price, and limited acces for market distribution. This study aims to analyse the feasibility of blue swimming crab fisheries activity using bottom gillnet in Banten Bay after Covid-19 pandemic. The research was conducted in May-June 2021 in Karangmulya Village, Kasemen District, Serang City with a total of 22 respondents. The data were collected using deep interview with each respondent who was selected purposively. The analysis of business feasibility was conducted based on the parameters of the ratio between income and costs (R/C), payback period (PP), and net present value (NPV). The results show the Covid-19 induced the decreasing of R/C ratio value from 2.08 before to 1.81 after Covid-19 pandemic, respectively. The value of PP also increased from 0.65 years to 0.68 years. Moreover, the potential profit of blue swimming crab fishing also decreased from IDR 55 million before Covid-19 to IDR 52 million after Covid-19 pandemic. However, due to the positive NPN value, the blue swimming crabs fishing actvity using bottom gill nets in Banten Bay is still feasible to be developed. Keywords: blue swimming crab, Covid-19, impact, fisheries

Length‐weight relationships and condition factors of 28 fish species belonging to Leuciscidae (Cypriniformes) from Turkey

Length-weight relationships (LWRs) were estimated for 28 freshwater fish species belonging to the family Leuciscidae. Length-weight relationships (LWRs) were estimated for 28 freshwater fish species belonging to the family Leuciscidae. Surveys were undertaken during the spring, summer, and autumn of 2014 and 2015, as well as from 2017 to 2019. Fish were sampled in 13 different water basins using a backpack electroshoker as a standard sampling method. The water depth varied between 2 and 40 cm depending on the habitat. Sampling was done by using bottom gill nets, which were designed to be 30 m in length and reach 1.5 m in depth, consisting of 12 different mesh panels (each panel is 2.5 m in length with 5, 6.25, 8, 10, 12.5, 15.5, 19.5, 24, 29, 35, 43, and 55 mm). The nets were settled-up at the end of the day and collected in the morning after being left in the water overnight for at least 12 h. The estimated values of parameter b ranged from 2.683 (Squalius berak) to 3.349 (Alburnus carianorum). R2 values varied from 0.888 to 0.998, indicating a high degree of the positive relationship between length and weight. The maximum total lengths of seven of the studied species are new records and have not yet been reported in any database.

Aqui vem o grande “jaú” Zungaro jahu (Ihering 1898) (Teleostei, Pimelodidae): um novo caso alarmante de introdução de peixes em uma ecorregião neotropical com alto endemismo

Abstract: Aim Non-native fish species have been closely related to serious damage to aquatic biodiversity due to their negative effects on native fauna. We aim to report the first and alarming occurrence of the non-native catfish “jaú” Zungaro jahu in the Iguaçu River basin above the Iguaçu Falls, a high-endemism Neotropical ecoregion for fish. Methods Fish samplings were taken with a bottom gill net in the Segredo Reservoir, where they were anesthetized in benzocaine hydrochloride and fixed in formaldehyde in the field, later identified in the laboratory and housed at the Museu de História Natural do Capão da Imbuia (MHNCI). Results Our recent samplings in the Iguaçu River basin recorded one non-native individual of the catfish “jaú” Zungaro jahu in the Segredo Reservoir. Conclusions We mainly intend to alarm about the risk of expansion of the occurrence of this non-native species throughout the cascading reservoirs in the Iguaçu River where it could potentially develop serious damage to the trophic chain, predation of small-sized endemic species, and competition, especially in the sites where the endemic and endangered pimelodid “surubim-do-iguaçu” (Steindachneridion melanodermatum) maintains viable populations, currently restricted to the Lower Iguaçu River basin exhibiting recent signs of a population bottleneck.

Faktor-Faktor yang Mempengaruhi Tingkat Kesejahteraan Nelayan Jaring Rampus (Bottom Gill Net) di Pelabuhan Perikanan Pantai (PPP) Bondet Kabupaten Cirebon, Jawa Barat

Bondet Coastal Fishery Port (PPP) is located in Cirebon Regency, which is adjacent to Grogol Village, Gunung Jati District, Cirebon Regency, where Grogol Village is one of the villages as a center for fishing fishermen with fishing gear mostly rampus nets. The rampus net (bottom gill net) is one of the fishing gear that can generate a source of income for fishermen in Grogol Village, Gunungjati District, Cirebon Regency which can be operated and produce fish almost every month. The purpose of this study is to explain the welfare of fishermen which can be analyzed in terms of income and expenditure. Bottom gill net fishermen. The method used in this research is descriptive method. This study uses a survey technique, which is a way of collecting data from a number of units or individuals at the same time. The data obtained were analyzed through financial analysis of the fishing business using rampus nets at the Coastal Fishery Port (PPP) Bondet, Cirebon Regency. The results showed that there was income inequality among Bottom Gill Net fishermen in Grogol village with a Gini coefficient value (inequality) of 0.24. Based on welfare indicators, according to BPS and the results of the summation of scores, it is known that bottom gill net fishermen in Grogol village have a high level of welfare (scores 20-24) with a total score of 23, and based on statistical analysis using NTN, the NTN value for bottom gill net fishermen in Grogol village is equal to 9,6 %, where NTN > 1, it can be stated that all Bottom Gill Net fishermen respondents are prosperous. There is no difference in the final result of the level of welfare according to BPS and NTN.

Composition of types fishing gear in Barru regency waters in the pandemic time of Covid-19

The potential of marine fish resources in Districts Barru is multi-species, especially pelagic fish. Therefore, in the management and utilization of fishery resources it is very possible for the community to be able to operate various fishing gear. This study aims to determine the composition of the types of fishing gear operated by fishermen in Barru Districts waters of during the pandemic Covid 19. Data collection was carried out from September to October 2020 in around the waters and coastal areas in Barru Districts. This study used a descriptive survey method, by collecting available data (secondary data) in the form of: categories of types and numbers of fishing gears. besides that, field observations will also be carried out. During the pandemic Covid-19, the operation of fishing gear in Barru Districts waters was 13 types of fishing gear, with a composition consisting of four types of fishing gears that were predominantly used, namely 622 drifting gill nets (28.4%), hand lines (21, 7%), Bottom gill nets (19.9%), trolling line (9.6%). Meanwhile, the least used fishing gear was 8 Bagan Tancap (lift net) (0.4%).

Analisis Kelayakan Usaha Penangkapan Ikan dengan Jaring Rampus (Bottom Gill Net) di Desa Bandengan Kecamatan Mundu Kabupaten Cirebon, Jawa Barat

Research was conducted from March to May 2020 at Bandengan Village, Mundu District, Cirebon Regency, West Java. Bandengan Village is a village located on the outskirts of the panatai with the majority of the population being fishermen. The fishing gear used by the fishermen of Bandengan Village includes rampus nets (Bottom Gill Net). Based on the results of the financial analysis including business income analysis, revenue and cost balance analysis, business feasibility analysis, net present value, internal rate of return (IRR) and payback period, the analysis of business income was obtained Rp. 22,346,000, - income and cost balance analysis 1.79, business feasibility analysis with Net Benefit 2.92, with a discount rate of 13%, the value of the catch in years 1 to 10 is Rp. 50,736. 000, -, at the end of the fifth year the remaining machine value is Rp. 1,000,000, -, and at the end of the project value of Rp. 9.500.000, -, consisting of boats Rp. Rp. 2,500,000, -, rampus fishing gear of Rp. 500,000, -, and a machine of Rp. 1,000,000, -, in order to obtain a Net Present Value of Rp. 125,798,041, -, Internal Rate Of Return (IRR) 47.46% and pay back period of 2.86 years. Thus, the use of rampus net fishing gear in Bandengan Village, Mundu District, Cirebon Regency is feasible to be developed, in addition to the higher quality catch, it is also included in environmentally friendly fishing gear.

First reference on reproductive biology of Butis koilomatodon in Mekong Delta, Vietnam

BackgroundThe key to fishery management is knowing the appropriate reproductive strategies of the targeted fish. For most gobiid species, the iteroparous pattern is dominant compared to semelparity. Albeit Butis koilomatodon plays an important role in the Mekong Delta’s food supply, its reproductive biological data have not been known. Hence, this study was conducted to provide new fundamental knowledge of reproductive traits of Butis koilomatodon in the Mekong Delta.ResultsA total of 1314 individuals (903 males and 411 females) were monthly collected by bottom gill nets from July 2019 to June 2020 at six sampling sites along estuarial and coastal regions, from Tra Vinh to Ca Mau provinces, southern of Vietnam. pH and salinity of these six sampling sites are 7.72–7.93 pH and 11.17–26.17‰, respectively. The pH varies with sites, but not seasons; whereas a reverse case is found in salinity. Different types of oocytes are found in histological specimens of ovaries prove that B. koilomatodon is a multi-spawner. The gonadosomatic index value, together with the monthly presence of mature ovaries reveal that this species spawns throughout the year. The length at first mature male Butis koilomatodon (5.1–8.6 cm) is higher than that of females (4.8–6.7 cm), except in Hoa Binh and Dong Hai. Batch fecundity (3085 to 32,087 eggs/female) increases with fish weight (1.48–12.30 g) and length (4.8–9.0 cm) due to high determination values (r2 > 0.6).ConclusionKnowledge of reproductive traits gained from this study was a reference source for future studies and helped manage this species’ resources.

C Catch Per Unit Effort (CPUE) Rhynchobatus sp Menggunakan Gill Net Dasar Di Wilayah Pengelolaan Perikanan 711 (WPP NRI 711) Pada Fishing Base PPI Sungai Kakap Kalimantan Barat

Rhynchobatus springeri (R. springeri) and Rhynchobatus australiae (R. australiae), which belong to wedgefish species, are the main target of captures of the bottom gill net fishery at PPI Sungai Kakap, West Kalimantan, a fishing ground in the Indonesian Fisheries Management Area 711 (WPP NRI 711). The fin is the main part in business activity in fisheries and has been exported due to high demand with promising price. But, there is a scarcity of research on this species (Jabado, 2019) especially the information about the level of vulnerability of the wedgefish species. The status of R. springeri and R. australiae are critically endangered on the International Union for Conservation of Nature (IUCN) Red List (Jabado, 2019; Kyne, 2019; Kyne et al, 2019a; IUCN, 2012). CPUE is the amount of fish catch per unit of effort. The term ‘effort’ in this research is the length of days at sea per trip of fishing operation. Data collection includes the number of landings of Rhynchobatus species and length of days at sea from each fishing vessel during the years of 2016 and 2019. Microsoft Excel was used for data analysis. The results showed that the average CPUE was 54.34 piece/trip, or 1,512.19 kg/trip and 1.75 piece/day, or 48.78 kg/day per ship. The correlation between CPUE and effort is positively significant. At the CPUE piece/trip, the linear equation shown as follow y = 0.3583x-38.531 with R2 = 0.8724 or R = 0.9340. Whereas, at the CPUE kg/trip, the linear equation was y = 9,0823x-842,11 with R2 = 0,791 or R = 0,889 (Y is CPUE and X is effort).

Condition of shrimp commodity capture fisheries in pangandaran regency, West Java

The high potential of capture fisheries makes Pangandaran have abundant fishery resources. One of the excellent commodities in Pangandaran is shrimp and is an economic source for fishermen. This research was conducted to see the condition of shrimp commodity capture fisheries in Pangandaran Regency. The research was carried out in August-October 2019 at Pangandaran Regency Waters with the main focus on shrimp. The method used in this research is the case study method. Data used consists of primary data and secondary data obtained from the local department. The research results shows that the fishing gear used by Pangandaran fishermen to catch shrimp is 459 units of bottom gill nets, 315 units of trammel nets, 25 units of danish seine, and 27 units of beach seine. The fishing vessels which are mostly operated by fishermen in Pangandaran Regency is 1919 types of fishing vessels with a size of

Reproduction of White-Spotted Rabbitfish (<i>Siganus canaliculatus</i> Park, 1797) in the Waters of the Buntal Island, Kotania Bay, West Seram-Mollucas

White-Spotted Rabbitfish (Siganus canaliculatus Park, 1797) are herbivorous fish that are associated with seagrass habitat and are widely distributed in mangrove and coral reef habitats. The waters of the Buntal Island – Kotania Bau have an ecosystem of seagrass medows, mangroves and coral reefs, with the association of S. canaliculatus as one of the target catch of fishermen. The purpose was study to analyze the biological aspects of S. canaliculatus, including: sex ratio, size of first maturity, and fecundity. The research was conducted from October 2015 until January 2016 in the waters of Buntal Island, Kotania Bay. Fish samples were collected from fishermen's catch using bottom gill nets and Set net. Each fish sample was dissected for sex determination and gonad maturity level. The analysis is used to see the relationship between body length and weight and fecundity. The results showed that 167 fish and 149 female fish. The ratio of male and female was balanced, namely 52.85%: 47.15% or 1.1: 1 (X2count 4.13 <X2table 11.34). The size of first maturity of female is 14.98 cm (14.5 - 15.5 cm) smaller than the male 18.9 cm (18.8 - 19.1 cm). The high potential of S. canaliclulatus based on the Fecundity obtained was in the range of 524,000 - 1,286,359 eggs. There is a positive relationship between body length and fecundity, indicating that the value of Fecundity increases with body size. To support its sustainable use in the wild, it is necessary to regulate the size of S. canaliculatus that can be harvest at a body length of > 15 cm TL, to provide opportunities for spawning and support population growth before exploitation, thus supporting responsible and sustainable fisheries.

Size Structure and Sex Ratio of Black Tip Reef Shark (<i>Carcharhinus melanopterus</i>) Landed in the TPI Paotere of Makassar City and TPI Beba of Takalar Regency, Province South Sulawesi

Carcharhinus melanopterus in the southern waters of the Makassar Strait is caught with bottom longlines and bottom gill nets as bycatch, caught throughout the year without any management arrangements. The research objective was to obtain information about the size structure and sex ratio of C. melanopterus in the southern waters of the Makassar Strait. The method used is a survey method. Sample measurements were carried out at TPI Paotere Makassar City and TPI Beba Takalar Regency, South Sulawesi Province from July to September 2020. Measurement of total body length (TL:cm) and determining the sex ratio were carried out directly in the field. The results of the study on 144 sample fish showed that the total length range for C. melanopterus landed at the Paotere TPI was the same as those landed at the Beba TPI at sizes between 58 - 135 cm TL with an average length of 91.18 ± 3.32 cm TL and sizes between 51 - 139 cm TL with an average length of 91.1±2.21 cm TL for both male and female sex, respectively.The comparison of C. melanopterus landed in the two fish landing sites was in a balanced state but the male sex was smaller than the female sex.The sex ratio of male and female C. melanopterus is balanced. Most (69.44%) female C. melanopterus caught were relatively young.

Length‐weight relationship of 74 fish species caught in the continental coast of Ecuador

This work analysis the length-weight relationships for fish species captured by artisanal fishery along the continental coast of Ecuador. Fishermen used the following fishing gear: beach seine nets (5.1–31.8 mm), shrimp trawl nets (21.8–31.8 mm) and bottom gill nets (54.1–203.2 mm). Sampling took place during the years 2012 and 2014. Frequency of sampling was monthly, and it was completed systematically from Southern toward Northern Provinces. Length-weight relationship (LWR) was realized by the power model (y = a × xb), for species with a bivariate dataset >70. A total of 59 commercial and 15 non-commercial species were registered. For 74 species, our analysis including a higher total length not reported in LWR estimates previously. The determination coefficient (r2) value was always above 0.95.

Length‐weight relationship of fish species captured around an artificial offshore reef (northern Rio de Janeiro, Brazil)

The present work provides length-weight relationships (LWRs) for fish species captured around artificial offshore reef deployed 5 km from Guaxindiba Port, northern Rio de Janeiro, Brazil. The fish were captured during two sampling periods each year between 1996 and 2017 using bottom gill nets (25 mlength × 3 mdepth; 30 mm mesh). The fish were kept on ice and the biometric data, including total length (cm) and total wet weight (g) were determined in the laboratory. A total of 16 species belonging to 10 families were analyzed with Sciaenidae being the species richest family (5 spp) in the samples. The new value of LWRs for Sphyraena guachancho and new maximum sizes recorded for seven species highlight the scarcity of information on biological aspects of South America coastal fishes. These LWRs should assist fisheries scientist and managers to complement their further studies of population parameters to improve management decisions.

A Study of mono multifilament bottom gill net in Rembang waters

The mono multifilament bottom gill net was an alternative design to the monofilament bottom gill net for Rembang waters. Monofilament bottom gill net was legal fishing equipment but its use by traditional fishermen in Rembang waters was minimal and this number is now decreasing. This research aimed to analyze effective fish catch of monofilament and mono multifilament bottom gill nets with the addition of swivel and baits. This research employs experimental fishing by comparing fish catch effectiveness between the two types of bottom gill nets. It was conducted in Rembang waters in Central Java from May to June 2018. Treatment variables involved consist of bottom gill net design and fishing time. The ANOVA two-way data analysis was then used to compare results. Results show that fish catch effectiveness of mono multifilament bottom gill net is 66.01%, higher than monofilament bottom gill net, which has 33.99%. It was also found that the highest fish catch effectiveness was attained when the mono multifilament bottom gill net was operated at night (60.08%). Furthermore, the ANOVA analysis (sign 0.05) shows that the design of fishing equipment and fishing time also influence fish catch effectiveness. Hence, it can be concluded that the mono multifilament bottom gill net with swivel and bait operated at night does better at catching demersal fish, compared to its monofilament gill net without swivel and bait counterpart operated during the day.