Gillnets Of Mesh Sizes Research Articles

Fish diversity in the Nong Leng Sai Wetland, Phayao Province, Northern Thailand, after deep-water dredging

Abstract. Tuncharoen S, Manetam K, Pornpuang S, Chaisan W, Panprommin D, Soonthornprasit K, Pitakpol S. 2024. Fish diversity in the Nong Leng Sai Wetland, Phayao Province, Northern Thailand, after deep-water dredging. Biodiversitas 25: 2738-2746. This study aimed to explore changes in the diversity of fish species in the Nong Leng Sai Wetland, Mae Chai District, Phayao Province, Northern Thailand, after just completed deep-water dredging while shallow-water dredging is in progress. Therefore, three different gill net mesh sizes collected fish specimens from January to July 2022. The results showed that 25 species belong to 23 genera, 13 families from 7 orders, and 21 native and 4 introduced fish species. The fish comprised of the miscellaneous group was the most composed by weight and number, accounting for 45.5% and 52%, respectively, followed by the carp, 38.6% by weight and 45.6% by number. The fish diversity after dredging has decreased, including species and quantity, compared to the diversity reported before. Physical changes in the Nong Leng Sai Wetland resulted from deep water dredging, including increasing water depth, more water storage volume, increased turbidity, and lack of fish shelter and natural food, affecting the diversity of fish species. Furthermore, dredging has stimulated the recovery of aquatic ecosystems regarding water quality, habitat of aquatic animals, and appropriate natural food, which is important for increasing the diversity of fish species and quantities.

Length-Weight Relationship and Condition Factor of Synodontis schall (Bloch & Schneider, 1801), from Roseires Reservoir, Sudan

This study was carried out to investigate the length-weight relationship and condition factor of the Mochokid catfish S. schall, a commercially important fish species in the Roseires reservoir on the Blue Nile, Sudan. A total of 643 specimens were collected using the multi-filament gillnets of mesh sizes (4.0, 8.0, 10.0, and 12.0 cm) and twine (No. 2 and 12) during the period from November 2015 to October 2016; Samples were collected from four sites namely: Awal Bab, Elregiba, Kirma, and Wad El Mahi.; The length and weight of sampled fish were measured and recorded on the sampling sites and used to determine a length-weight relationship. The growth coefficient (b) ranged from 1.196 to 2.649, with moderate to high correlations (r) between 0.437 and 0.798. Values of (b) were less than 3 indicating a negative allometric growth pattern, whereas weight increased at a lower rate than length. The condition factor (K) ranged from 1.966 ± 0.696 to 3.856 ± 3.856, suggesting the fish were in good health condition throughout the sampling sites. The findings of this study provide valuable insights into the biological aspects of S. schall, which can form the basis of sustainable management and conservation policy for the fishery resource of this economically important fish species in the Roseires reservoir.

The catch amount of Mediterranean horse mackerel Trachurus mediterraneus (Steindachner, 1868) gillnets in the Sea of Marmara

The small-scale fishermen in the coastal area of the Marmara Sea between April and June caught the Mediterranean horse mackerel Trachurus mediterraneus (Steindachner, 1868) with gillnets. This target species, T.mediterraneus and significant amounts of non-target species are caught in these nets. So, the technical and structural characteristics of the gillnets for a commercial fishermen were determined and the target and non-target species were evaluated in catching operations. The multifilament gillnet mesh size of 18 milimeters polyamid, twine thickness of 210d/2, hanging ratio of 0.33 and the total length of approximately 200 meters. Also, guarding nets were added to gillnets. The total amount was determined as 397.8 kilograms (kg) and 9204 individuals (ind). The weight of T.mediterraneus was constituted 39.3% of the total weight. The in of T.mediterraneus was constituted 43.4% of the total ind. While the catch per unit effort (CPUE) for T.mediterraneus was calculated at 0.026 kg/m.operation-1 and 0.7 ind/m.operation-1, the CPUE for the total amount was calculated at 0.066 kg/m.operation-1 and 1.5 ind/m.operation-1. The total economic value was calculated at 15814.4 Turkish Liras (TL), which 9390 TL from T.mediterraneus and 6424.4 TL from non-target species. This study is important in terms of revealing for the first time the catch efficiency of gillnets used by commercial fishermen to catch T.mediterraneus in the coastal area of the Marmara Sea, which is an important fishing area. These results will contribute to the creation of management plans and fisheries management for species-specific fishing gear used in a region.

Effect of mesh size in monofilament and multifilament gillnets on catch efficiency in the Black Sea whiting (Merlangius merlangus) fishery

Gillnets are widely used fishing gear for targeting various fish species. Gillnet fisheries use different gear configurations such as different mesh sizes and number of netting twines (mono- or multifilament) depending on the species targeted. Gillnet fishery targeting whiting (Merlangius merlangus) is one of the economically important year-round fisheries in the Black Sea. However, large bycatch of whiting below minimum landing size (MLS) has led to a stock decrease, questioning sustainability of this fishery. This study evaluated how netting twine construction and mesh size can affect the capture probability of whiting. The results showed that changes in gillnet mesh size significantly affect the capture probability with increased mesh size reducing the average capture probability of undersized whiting from around 60%–5%. The results showed no significant differences in the average catch efficiency between monofilament and multifilament gillnets of the same mesh sizes; however, monofilament gillnets showed an increased catch efficiency for some length classes of whiting > MLS. Based on these results, use of 32 or 34 mm mesh size monofilament gillnets is advisable for sustainable whiting fisheries management in the Black Sea.

Effect of gillnet mesh size on the capture probability and capture patterns in the Asian paddle crab (Charybdis japonica) fishery

In the Asian paddle crab (Charybdis japonica) gillnet fishery in the Yellow Sea, China, the minimum mesh size (MMS) regulation has been of a major importance due to high bycatch rates of undersized crabs. In this study, we evaluated how gillnet mesh size can affect the capture probability of C. japonica and capture patterns in this fishery by comparing the performance of gillnets with four different mesh sizes (60, 70, 80, and 90 mm). Our results showed that changes in gillnet mesh size significantly affect the capture probability of different sizes of crabs. Specifically, increased mesh size decreased the capture probability of undersized crabs and their fraction in the catches decreased from 64 % to 24 % when mesh size was increased from 60 mm to 90 mm. In contrast, gillnets with larger mesh sizes significantly improved the capture probability of legal-sized crabs. Moreover, no significant differences were observed for the species catch composition between gillnets of different mesh sizes. Based on these results, we recommend 90 mm as the MMS in gillnets to improve sustainability in C. japonica fishery.

Assessment of motorized commercial gillnet fishery of the three commercially important fishes in Lake Tana, Ethiopia

This study was conducted from July 2010 to June 2011 to assess the status of motorized commercial gillnet fishery of the three commercially most important fishes in Lake TanaLabeobarbusspp., Oreochromisniloticus(Nile tilapia) and Clariasgariepinus (African catfish). Catches were monitored daily and additional information on number of gillnets used, mesh size of gill nets and location of fishing grounds were collected. Data on the Labeobarbus species composition were collected 3 days per month. The total fish yield from the main fishing grounds of the commercial fishery was 238 metric tons/year. The catch of tilapia was 71%, that of catfish 18% and that of Labeobarbus 11% of the total catch. Peak production was from March - May 2011. Most effort (80%) was allocated to the North Eastern Floodplain (NEFP). The total number of gillnets set and boat trips made were 85,943 and 3104, respectively, which is much higher than reported previously. Consequently, the Catch per Unit effort (CpUE; kg/trip) of the 2010/2011 production year was with 64.7 ± 3 (95% CL) kg much lower than reported previously. The CpUE of all three fish taxa was lower than previously reported, but especially the LabeobarbusCpUE was much lower than before (6.1 kg). An integrated management plan and research program for the Lake Tana basin is urgently required to prevent the collapse of an important fishery and the extinction of the only known cyprinid species flock in the world.

Survey on fish diversity, resource potential and current production level ofmajor rivers in the Benishangul Gumuz Region; Ethiopia

With an estimated total population of 667,049 people, the region is situated at the lower fresh water reaches of the Abay basin. The rivers mainly grouped as Flood Rivers, where there are extremes of annual fluctuation in water level from severe flood to sometimes complete desiccation in dry season. There exists also considerable difference in numbers of species inhabiting various river systems attributed to the size of the river as represented by its basin area or correlated with the length of main channel or stream order. Five major rivers of the basin were chosen purposely. Sampling was made during 2011 and gillnets of different mesh sizes were used. For the estimation of the potential fish yield of each river, the simplest model relating catch and river length was used. Compared to the other rivers, the diversity of fish in Dabus River was lower. Totally 29 commercially important fish species,grouped in to 11 families, has been known to present. The dominant family in these river systems is Cyprinidae with a diversity of 9 species. Current fish production in the region is estimated only as 183 tons/yr. The estimated total fish production potentials of sampled rivers is found to be 2,400 tons/yr indicating that there is the possibility to increase the current level of production more than 13 times. Inaddition, the exploitation is limited to subsistence level. The most potential river in the region is Abay with an estimated potential of 1680 tons/year and Anger contributes the least potential.

A biological perspective for the fishery management of a small urban lake in Indonesia: a case study on the reproductive stage of the red devil (Amphilopus citrinellus) in Situ Cilodong, West Java, Indonesia

The presence and establishment of invasive alien fish species is one of the biggest threats to aquatic biodiversity. The red devil, Amphilopus citrinellus, is one of the emerging invasive species and its occurrence is massively detected in common water bodies in tropical areas such as Indonesia. However, the topic remains under-reported from the small urban lakes. This study aims to present the reproductive characteristics of the fish in Situ Cilodong, a small urban lake in the country, that can be used as a principal reference for population control. The sampling was conducted in June 2021 and May 2022 using a mix of seven mesh-sized gillnets. The results of the length-weight relationship reveal that both the female and male fish perform isometric growth type. The calculated Gonad Somatic Index (GSI) and the histological analysis confirmed that the fish is a multi-spawner species. The results imply that sustainable population control efforts must include intensive catch and engage a participatory approach between the legal authority and the local fishers.

Impacts of tilapia aquaculture on native fish diversity at an ecologically important reservoir.

The Temengor Reservoir is the second largest reservoir in Peninsular Malaysia. Located in the northwestern state of Perak, it was selected to develop a large-scale tilapia (Oreochromis niloticus) aquaculture facility within the Aquaculture Industrial Zone (AIZ) in 2008 due to its favourable environmental conditions. No record of tilapia has ever been reported in the natural waters prior to this. However, a post-establishment study recorded tilapia sightings in the natural waters of this lake. The cultured tilapia was easily recognizable with the elongated mouth and body, and long caudal fin. It is postulated that these were escapees from the floating cages that had invaded the natural waters and would negatively impact the native fish species. To test our hypothesis, we investigated the impact of the aquaculture facility on native fish diversity through a spatial design. The study was focused on assessing the impact of tilapia culture at sites nearer to the AIZ vs more distant sites, the former with a greater likelihood of receiving escapees. Two major sites were chosen; within 5 km (near-cage) and within 5-15 km (far-cage) radii from the AIZ. Fish sampling was conducted using multiple mesh sizes of gill nets (3.7, 5.1, 6.5, 7.6, and 10.2 cm) deployed at the littoral zone of the sampling points. Species diversity, abundance, dietary habits, and habitat preference were investigated. The CPUE (individual/hour) of native fish species at the far-cage site of the AIZ Reservoir was found to be significantly higher (p < 0.05) than that at the near-cage site. Principal component analysis (PCA) based on diet and habitat preferences showed that the tilapia, O. niloticus had almost overlapping diet resources and habitat with native fish species. We conclude that there is a correlation between the reduced catches of native species (based on CPUE) and the high presence of tilapia. Thus, appropriate actions must be implemented for strategic and effective planning in terms of native fish conservation.

Growth patterns and reproductive aspect of Naleh (Barbonymus sp.) in Krueng Lanca, Nagan Raya Regency, Aceh Province

Naleh (Barbonymus sp.) is one species of native fish found in Aceh Waters. This study examines the growth patterns and reproductive aspects of the fish in Krueng Lanca of Nagan Raya, Aceh Province. The study lasted five months (January - May 2022). Sampling was carried out purposively, once a month, on five different stations using gill nets (mesh size: 0.5 inches, 1.0 inches, and 1.5 inches and cast nets (D: 6 meters, mesh size: 0.5 inches). A total of 171 Naleh was caught in these waters. The calculation results obtained a length-weight relationship W = 0,0003*L2.2234 (r2 = 0.8823) for males, which shows the nature of allometric and W = 6E-06*L3.0684 (r2 = 0.8566) for females which shows the isometric. The sex ratio of Naleh in these waters was 1.1: 1. The size of the first mature gonads was 60-69 mm (males) and 90-99 mm (females) with a Gonadosomatic Index of 1.92-3.04 % (Males) and 8.73-11.61 % (females). The peak of the Naleh spawning season in Krueng Lanca waters was thought to occur from March to April, with the number of eggs ranging from 1,853-3,813 and a diameter of 1.18-1.43 mm. Based on the oocyte distribution, the peak of spawning of the fish was categorized as multiple spawners.

Food and feeding habits of the Nile tilapia Oreochromis niloticus (Linnaeus, 1758) from Ribb reservoir, Lake Tana sub-basin, Ethiopia

This study aimed to examine the food and feeding habits of Oreochromis niloticus at the Ribb reservoir for sustainable management. A total of 512 specimens were collected using gillnets of different mesh sizes. Of these, 348 (67.9 %) fish had different foods, while 164 (32.1%) fish had empty stomachs. Mud was the main food item that accounted for 89.1% of estimated stomachs and 55.1% of the total volume in the diet. Detritus and phytoplankton were the second most important food items contributing 25.1% and 14.1% of the total volume respectively. Prey items differed depending on the fish size (ANOVA, p < 0.05). The smallest-sized fish preferred detritus, zooplankton, and mud while the food items such as mud and phytoplankton were preferred by the larger-sized fish species from the Ribb Reservoir. The seasonal variations in food composition were observed (ANOVA, p < 0.05). The volumetric contribution of foods such as mud and detritus were higher in the dry season and contributed in 61.2% and 19.2% respectively. During the wet season, phytoplankton and detritus were the most important food items and their corresponding volumetric contributions were 52.3% and 42.1% of the total volume in the stomach O. niloticus Generally, O. niloticus exhibited omnivorous feeding habits in their diet from the newly established Ribb Reservoir. It is possible to conclude that food and feeding habits of O. niloticus influenced by seasons, and fish sizes from Ribb Reservoir. Therefore, water buffer zone management is needed to improve the food and feeding habits of this fish for the better sustainable utilization.

Assessment of Length-Weight Relationship of Nile Tilapia Oreochromis niloticus (Linnaeus 1758) from Qua Iboe River Estuary, Southeastern, Nigeria

The Length-Weight Relationship (LWR) of Oreochromis niloticus from the Qua Iboe River Estuary was studied for 12 months; from April 2021-March 2022. Fish samples were collected from the catches of artisanal fisheries using various mesh sizes of gill and cast nets. The b values in males ranged from 2.25-3.08 with a mean of 2.7333 0.2743 while that of the females varied between 2.41 and 2.930 with a mean value of 2.7075 0.1804). The overall growth coefficient in the LWR (W=aLb) ranged from 2.25-3.08 with a mean value of 2.72±0.04. Both males and females recorded negative allometric growth, and the exponents were significantly less than isometric (p&lt;0.05). Higher b values were recorded in males. There was no significant difference between the b-values of males and females (p&gt; 0.05) during this study with the respective exponential relationships. These data indicated that the length-weight relationships were similar in both sexes during the study period. A higher b-value was recorded in the wet season but there was no significant difference (p&gt; 0.05) between the dry (November-March) and wet season (April-October).This study provides the basic information which could enhance production potential of O. niloticus and its sustainable development, culture and management in Qua Iboe River Estuary,Nigeria.

Ichthyofauna Diversity and Its Distribution in a Low-Saline Lake of Indonesia

Lake Siombak is a tidal lake that is an estuary around the lake covered with various mangrove trees. It is interesting to study the fish's spatial and temporal distribution as a unique and distinctive tidal lake ecosystem. This research was conducted for a year (from September 2018 to August 2019). Fish sampling was performed by installing gill nets (mesh size 1 inch) and cast nets (mesh size 0.5 inch). Gill nets and cast nets were installed at high and low tides during the full moon. This research showed that there were 27 species of 20 families. Tilapia, Mudskipper, Indo-pacific tarpon, and mainly Rice Fish are always found in Lake Siombak. The fish group at Lake Siombak consists of freshwater fish (mainly: Tilapia, Catfish, and Snakehead), brackish fish (mainly: Mudskipper, Rice fish, and Indo-pacific tarpon), and marine fish (mainly: Milkfish, Kanda mullet, and John's snapper). The actual resident in Lake Siombak consists of Oryziidae, Tilapia, and mudskipper. Other fish are temporary resident fish except for Lutjanidae and Scatophagidae as visitor fish during high tide and high salinity periods (dry season) and Synbranchidae during low salinity (rainy season).

Reproductive biology of Indian mackerel, Rastrelliger kanagurta (Cuvier, 1816) in the southern waters of West Java (FMA 573)

Indian mackerel is a small pelagic fish with important economic value in Java Island. This study aims to analyze the reproductive characteristics and determine management recommendations for the Indian mackerel in the southern waters of West Java. Fish monthly sampling collection was conducted at three fish landing ports: PPI Ciwaru, PPN Palabuhanratu, and PPI Binuangeun from July to December 2022. A total of 1,038 fish samples, comprised of 582 males and 456 females, were examined. The sex ratio was unbalanced, with a value of 1:0.79. Gonadosomatic indexes ranged from 0.19-0.95 and 0.45-3.41 for males and females, respectively. The fish fecundity ranged from 27,027 to 87,837 eggs. The Indian mackerel is predicted to spawn every month, with a peak season in August, and performs a total spawner pattern. The Indian mackerel reached the size of the first maturity gonad at 198.5 mm and 197 mm for males and females, respectively. Management strategies for Indian mackerel in the southern waters of West Java include setting the catch size above the first mature gonad size (197 mm), the mesh size of gillnets above 1.5 inches, and limiting fishing activities during the spawning season (July, August, and September).

Seasonal variation in the expression pattern of heat shock protein 70 and 90 in Common carp (Cyprinus carpio) from Karataş Lake, Burdur, Türkiye.

Organisms have evolved defense mechanisms to protect themselves from stressful conditions. The expression of heat shock proteins is considered a valid indication of protection from the adverse effects of hostile conditions. In this study, we used immunohistochemistry to investigate the seasonal effects of some abiotic factors on heat shock protein 70 and 90 (HSP70 and HSP90) expression in the liver, gills, and muscle tissues of 24 Common carp (Cyprinus carpio) caught in Karataş Lake (Burdur, Türkiye) using gillnets of various mesh sizes. We also measured some physicochemical parameters on-site at sampling time and took water samples for further analyses of other physicochemical parameters and heavy metals. Immunostaining for HSP90 was stronger than for HSP70 in both liver and gill samples. Liver and gill structures exhibited significant seasonal differences in HSP70 and HSP90 immunoreactivity, and the same was true for immunostaining for HSP70 and HSP90 in muscle samples. Some physicochemical properties seemed to vary considerably between seasons, with Fe, Mn, and Zn levels tending to exhibit changes throughout the seasons. However, these levels were considered acceptable for human health. In conclusion, this study suggests that substantial changes in HSP70 and HSP90 expression may be essential for seasonal adaptation and tolerance. Further research on fish HSPs would greatly contribute to aquaculture, which is essential for meeting food requirements.

The Productivity of Gillnet Mesh Size as A Substitute for Cantrang in Tamasaju Village, North Galesong District, Takalar Regency

The Productivity of Gillnet Mesh Size as A Substitute for Cantrang in Tamasaju Village, North Galesong District, Takalar Regency

Gillnet Selectivity Estimating for Sustainable Stock Management of Endemik Tarek (Alburnus tarichi Güldenstädt, 1814) Population in Lake Van (Eastern, Turkey)

This study was carried out to estimate the selectivity properties of gillnets for Tarek (Alburnus tarichi Güldenstädt, 1814) in Lake Van, Turkey. The Tarek is the most fished freshwater fish species in Turkey. The study was carried in 2021 fishing season at seven different sampling locations in the lake. Gillnet selectivity estimated was based on eight different gillnet mesh sizes (i.e. 1.25, 1.6, 2.0, 2.5, 3.1, 3.9, 4.4, 4.8 cm). The SELECT method was used to determine the selectivity parameters. According to the gamma model, optimum modal lengths for 1.25, 1.6, 2.0, 2.5, 3.1, 3.9, 4.4 and 4.8 cm mesh sizes were estimated as 6.61, 8.46, 10.58, 13.22, 16.39, 20.62, 23.27 and 25.38 cm respectively. When considering the minimum landing size, the findings of the study showed that use of gillnets which have less than 3.9 cm mesh size should be prohibited for the fishing of A. tarichi in Lake Van.

Length‐weight relationships of 12 dominant fish species from a Ramsar Wetland in India: Vembanad Lake

AbstractThe present study describes the length‐weight relationships (LWRs) of 12 dominant finfish species from Vembanad Lake, India, from June 2015 to May 2016. Samples were carried out using a wide range of fishing gears such as gill nets (mesh sizes 20–60 mm), seine nets (mesh sizes 8–16 mm), cast nets (mesh sizes 6–8 mm) and hook and lines. The values of the exponent b ranged from 2.506 (Glossogobius giuris) to 3.305 (Heteropneustes fossilis) and regression parameters R2 from .960 (Carinotetraodon travancoricus) to .995 (G. giuris). The study reports the new maximum total length (TLmax) for Hyporhamphus xanthopterus and first reference regarding length‐weight relationships for Mystus oculatus, Ompok malabaricus and C. travancoricus. The results provide useful information for preparing sustainable resource management plans and conservation strategies for these species in the lake and similar ecosystems.

First biometrics record of bartail flathead, Platycephalus indicus ( ) from the Bay of Bengal, Bangladesh

For the very first time the sex ratio, length-weight relationships (LWRs), length-length relationships (LLRs), form factor, as well as condition factor were calculated for bartail flathead, Platycephalus indicus, captured with gill nets (mesh size: 2.0–6.0 cm) from the Bay of Bengal, Bangladesh, from August 2021 to January 2022. A digital caliper was used to measure the length to 0.1 cm accuracy, and an electronic balance was used to quantify weight to the accuracy of 0.01 g. The sex ratio for the sample was 1: 0.76 (Male: Female). The estimates of slope in the fitted linear regressions relating logarithms of weights to logarithms of the total, standard, and fork lengths varied from 2.978 to 3.297, and the coefficient of determination from 0.89 to 0.97. Moreover, the three-length measures were also strongly associated (r2 > 0.996; P < 0.05). For the males, females, and combined sexes, the computed form factors were 0.0111, 0.0112, and 0.0107, correspondingly. For both males and females, individuals in the 33–36 cm and 27–30 cm length classes exhibited the highest and lowest in all the four condition factors, respectively. The size at first sexual maturity for combined sex of P. indicus was 30.2 cm in total length in the Bay of Bengal, Bangladesh. These results of the study will help with the conservation and long-term management of this species in the Bay of Bengal, Bangladesh, and other nearby nations.

Length–weight relationships for nine fish species from the Ulungur River basin, Northwest China

The present study provides length–weight relationships (LWRs) for nine fish species from the Ulungur River basin, Northwest China (46°08′-47°30′ N, 87°00′-90°30′ E). The fishes were collected quarterly (Spring, Summer and Autumn) from 2019 to 2021 with multi mesh composite gill nets (mesh size: 8.6 × 8.6 cm, 3.9 × 3.9 cm, 1.3 × 1.3 cm, 2.0 × 2.0 cm, 11.0 × 11.0 cm, 1.6 × 1.6 cm, 2.5 × 2.5 cm, 4.8 × 4.8 cm, 3.1 × 3.1 cm, 1.0 × 1.0 cm, 7.0 × 7.0 cm, 5.8 × 5.8 cm; with 2.5 m long for each mesh, and a total length of 30 m.). The estimate of coefficient b for species ranged positively from 2.536 to 3.259, respectively. The coefficient of determination (r2) for each species with range of 0.911–0.986.