scholarly journals Fish species composition and size structure exploited by gill net fishery in The New Calabar River, Nigeria

2019 ◽  
Vol 6 (1) ◽  
pp. 1
Author(s):  
Olaniyi Alaba Olopade ◽  
Henry Eyina Dienye ◽  
Ogheneforon Oderhohwo
Keyword(s):  
Species Composition ◽  
Fish Species ◽  
Size Structure ◽  
Mesh Size ◽  
Maximum Size ◽  
Abundant Species ◽  
Fish Stock ◽  
Size Selectivity ◽  
Gill Nets ◽  
Gill Net

The purpose of this study was to investigate the species composition and size selectivity of gillnets commonly used by the artisanal fishers in the New Calabar River, Rivers State, Nigeria. The data was collected during February-July 2018 from 3 sampling stations: SI Choba, S2 Ogbogoro, and S3 Iwofe all along the stretch of the river. Twenty-eight fish species were found belonging to 15 families. The prevalent families were Cichlidae, Mugilidae and Clupeidae representing 32.22%, 30.36% and 10.23% of the total catch, respectively. The most dominant species in terms of number were Liza falcipinnis (12.58%) and Mugil cephalous (12.26%) while in terms of biomass, the most abundance species were Xenomystus nigri (24.12%) and Lutjanus agennes (12.50 %). The girth and total lengths of the fishes ranged from 5.20±0.20 to 21.00±0.00 cm and 8.85±0.15 to 28.19±1.13 cm respectively. The length at first capture (L50%) for the most abundant species (Liza falcipinnis) was calculated to be 14.13 cm while that of L25% and L75% were 12.70cm and 15.25cm respectively. It was concluded that the gill nets used in the New Calabar River exploit fish species of small sizes and few medium sized specimens relative to species potential maximum size. It is therefore recommended that for an improved and sustainable exploitation fish stock of the New Calabar River, the use of gillnets of less than 25 mm-mesh sizes and “other gears” should be prohibited.Keywords: gill nets; species composition; mesh size; selectivity; New Calabar River

scholarly journals Estimation of size selectivity of fish species caught by different gears in the old Brahmaputra River

2014 ◽  
Vol 11 (2) ◽  
pp. 359-364 ◽  
Author(s):  
IS Saberin ◽  
MS Reza ◽  
NJ Ayon ◽  
M Kamal
Keyword(s):  
Fish Species ◽  
River System ◽  
Fish Stock ◽  
Market Size ◽  
Small Species ◽  
Size Selectivity ◽  
Brahmaputra River ◽  
Gill Net ◽  
Biodiversity Changes ◽  
Considerable Damage

Over the last couple of decades, the old Brahmaputra River, one of the ancient river systems of Bangladesh, has fallen in verge of biodiversity changes affecting its range of fauna and flora. Study was, therefore, conducted to investigate the selectivity of fish species caught by different fishing gears used in the old Brahmaputra River system over a period of 1 year. L50% of different gears was determined mainly for dominant species where 41 fish species were recorded. Highest L50% was recorded in gill net (fash jal) followed by basket trap (vair) whereas lowest value was recorded for seine net. Seine net, cast net, sidi bair and hand line (borshi) were considered non selective gears where fash jal and sidi bair were regarded as gear specific for large fish species and koi jal, ber jal, dharma jal, howra bair and koach were considered specific for small species. Among all the gears, seine net, cast net, koi jal and howra bair were found to be harmful for small species of fishes. Monofilamentous gill net (current jal) although marked as banned gear, was found to be operated in the river and causing considerable damage to the fish stock. Fash jal was considered as harmful gear for catfish as it was found to be used to catch fishes below legal size. It is suggested that fash jal should be restricted for several months, which may allow the newly stock fingerlings to grow to market size. DOI: http://dx.doi.org/10.3329/jbau.v11i2.19940 J. Bangladesh Agril. Univ. 11(2): 359-364, 2013

Estimating gill-net selectivity for five species caught in the South East Fishery, Australia

2001 ◽  
Vol 52 (4) ◽  
pp. 691
Author(s):  
Gurong Cui ◽  
Nicholas J. Bax ◽  
André E. Punt ◽  
Ian A. Knuckey
Keyword(s):  
Negative Binomial ◽  
Size Structure ◽  
Habitat Type ◽  
Mesh Size ◽  
Size Selectivity ◽  
Habitat Types ◽  
Formal Approach ◽  
Poisson Sampling ◽  
Gill Net ◽  
Stock Assessments

A formal approach to estimating selectivity patterns that allows for variability additional to Poisson sampling variability is outlined. This approach, which involves assuming that the catch of fish by a particular size of gill-net in a given size-class is distributed according to a negative binomial distribution, is applied to data for five of the species caught by experimental gill-nets in Australia’s South East Fishery. The data for two of these species (blue warehou and dogfish) are not compatible with the conventional assumption that the size of fish corresponding to maximum selectivity is linearly proportional to mesh size. Selectivity and population size-structure are found to depend on depth and habitat type for some of the species. It is necessary therefore to target future experiments to depth zones/habitat types in which the bulk of the catch is taken to estimate selectivity patterns for use in stock assessments.

The size selectivity of whiting (Merlangius merlangus euxinus) caught by gillnet in the eastern Black Sea of Turkey

2014 ◽  
Vol 94 (7) ◽  
pp. 1539-1544
Author(s):  
Ferhat Kalaycı ◽  
Tuncay Yeşılçıçek
Keyword(s):  
Black Sea ◽  
Fish Species ◽  
Sexual Maturity ◽  
Mesh Size ◽  
Size Selectivity ◽  
Selectivity Curve ◽  
Merlangius Merlangus

The size selectivity of traditional gillnets for whiting, (Merlangius merlangus euxinus) was investigated in the eastern Black Sea between June 2010 and June 2011. Experimental fishing operations were carried out by using gillnets of 16, 17, 18, 20 and 22 mm mesh size. A total of 2038 specimens belonging to 16 different fish species were caught during the experiment. The Share Each Length's Catch Total method was used to fit gillnet selectivity curves. Gillnet selectivity was best described by a bi-modal selectivity curve. The modal catch sizes were estimated as 14.81, 15.74, 16.66, 18.51 and 20.37 cm for 16, 17, 18, 20 and 22 mm mesh sizes, respectively. Modal lengths and spread values increased with increasing mesh size. The majority of fish (71.8%) caught by 16 mm mesh size were less than the length at first sexual maturity.

Status of fish biodiversity and fishing on Hau River, Mekong Delta, Vietnam

2020 ◽  
Vol 56 ◽  
pp. 14
Author(s):  
Vu Ngoc Ut ◽  
Au Van Hoa ◽  
Huynh Phuoc Vinh
Keyword(s):  
Species Composition ◽  
Fish Species ◽  
Mekong Delta ◽  
Middle Part ◽  
Fishing Ground ◽  
Sampling Gear ◽  
Fish Biodiversity ◽  
Gill Net ◽  
Fishing Gears ◽  
The Status

Fish biodiversity on Hau (Bassac) river was investigated to assess the status of species composition and fishing by fishing gears during a year. Sampling was implemented monthly at the upper part (An Giang province), middle part (Can Tho City) and lower part (Soc Trang province) of Hau River using trawl net as main sampling gear. Additionally, fish composition was also recorded from four other most popular fishing gears including cast net, gill net, fixed net and hook operated in the study sites. Fish species composition was determined by fishing gears and their abundance (CPUE) was calculated only from the main sampling gear (trawl net). The results showed that a total of 176 fish species belonging to 16 orders and 49 families was recorded. Perciformes was the most abundant group with 51 species followed by Cypriniformes with 46 species. The number of fish species was decreasing from upper part to lower part. Trawl net was considered the most destructive gear as up to 145 fish species caught by this device, followed by gill net with 98 species, fixed net 75, cast net 57, and hooks 16 species. CPUE was very low ranging from  0.53 kg.ha−1 h−1 to 26.30 kg.ha−1 h−1. Higher CPUE was recorded at lower part in compared to upper part and middle part, and at dry season in compared to rainy season. Regulation on fishing gears, fishing ground and season should be taken into consideration to protect and conserve the resources.

scholarly journals PERFORMANCE OF GILLNET-MESH SIZE SELECTIVITY FOR THREE FLYINGFISH SPECIES IN AMBON WATERS, MOLUCCAS PROVINCE

2010 ◽  
Vol 35 (2) ◽  
pp. 39-46 ◽  
Author(s):  
Barbara Grace Hutubessy ◽  
Augy Syahilatua
Keyword(s):  
Black Spot ◽  
Mesh Size ◽  
Maximum Size ◽  
Yellow Spot ◽  
Optimum Size ◽  
Size Selectivity ◽  
Flying Fish ◽  
Direct Applicability

The gillnets' performance for capturing flying fish was obtained from the selectivity parameters of each mesh size. Gillnet selectivity parameters for flying fish were estimated using multi-panel drift gillnets with four different mesh sizes in southern Ambon Island. The black-spot flying fish Cheilopogon suttoni reached peak selectivity at 20.34 cm for mesh size of 1.25", 24.37 cm (1.5") and 28.47 cm (1.75"). Peak selectivity occurred at 22.16 cm for the 1,25" mesh size in the yellow-spot flying fish Cheilopogon abei, with the maximum size selectivity at 31.61cm for the 1.75" mesh. The optimum size for the black-plain flying fish Hirundichthys oxycephalus was 18.67 cm for the 1.25" mesh size, and 22.37 cm for 1.50" mesh size. Selectivity was highest at 26.12 cm for the 1.75" mesh size. Gillnet used in this study was constructed specifically for targeting flying fish suggesting that information on mesh selectivity examined here should has direct applicability to local flying fish fishery.

scholarly journals Catching Technology of Fish Maw Snapper’s: Case Study of the KMN Nur Aqila07 Fishing Boat in Kumbe Village, Malind District, Merauke Regency, Papua

2021 ◽  
Vol 328 ◽  
pp. 08011
Author(s):  
Sajriawati Sajriawati
Keyword(s):  
Data Collection ◽  
Mesh Size ◽  
Fishing Gear ◽  
The Sun ◽  
Running Water ◽  
Gill Nets ◽  
Weight Range ◽  
Fishing Boat ◽  
Gill Net

The purpose of this study was to determine the fishing technology used by fishermen in Merauke to catch snapper and post-harvest handling of fish maw snapper. This research was conducted in January 2021 in Kumbe Village, Malind District. Data collection was carried out by interviewing fishermen on the fishing boat KMN Nur Aqila07. The results showed that the fishing boat KMN Nur Aqila07 has a weight specification of 30 GT. The main fishing gear is a drift gill net with a length of 50 meters with a width of 2 meters with a mesh size of 7.5 inches. The pulley machine is used to help pull the gill nets when they want to pull fishing gear (hauling). Fish maw of snapper is removed manually using a knife, then cleaned with running water and then dried in the sun to dry. Fish maw is sold dry. The highest price for fish maw is in the weight range of 150 grams which can reach Rp. 22,500,000 per kg, while the lowest price is in the weight range of less than 50 grams, which is Rp. 4,500,000 per kg.

scholarly journals High-Resolution Acoustic Cameras Provide Direct and Efficient Assessments of Large Demersal Fish Populations in Extremely Turbid Waters

2021 ◽  
Vol 11 (4) ◽  
pp. 1899
Author(s):  
Céline Artero ◽  
Simon Marchetti ◽  
Eric Bauer ◽  
Christophe Viala ◽  
Claire Noël ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Fish Species ◽  
Acoustic Signal ◽  
Size Structure ◽  
Demersal Fish ◽  
Fish Population ◽  
Spatial And Temporal Variation ◽  
Fish Stock ◽  
Actual Length ◽  
Marine Habitats

Monitoring fish species populations in very turbid environments is challenging. Acoustic cameras allow work in very poor visibility but are often deployed as a fixed observation point, limiting the scope of the survey. A BlueView P900-130 acoustic camera was deployed in rocky marine habitats off the coast of French Guiana in order to assess the total abundance, size structure and spatial distribution of a demersal fish population. The relevancy of using an acoustic camera to achieve these three objectives was evaluated by comparing acoustic data to those obtained from fishing surveys. The detection and identification of large demersal fish species were possible with the shape and size of the acoustic signal and acoustic shadow silhouette as well as swimming behavior. Mobile surveys combined with stationary surveys increased the probability of distinguishing individuals from inanimate objects. Estimated total length based on the acoustic signal underestimated the actual length of fish measured on deck, but the data showed the same trends in spatial and temporal variation. Acoustic cameras overcame the extreme lack of visibility by increasing knowledge of fish use of habitat, therefore providing much more efficiency in the effort, more accurate data on the abundance, size structure and spatial distribution than the fishing method. Thus, despite few limitations, acoustic camera surveys are far superior to fishing surveys in evaluating large demersal fish stock status.

scholarly journals Environmental factors predicting fish community structure in two neotropical rivers in Brazil

2007 ◽  
Vol 5 (1) ◽  
pp. 61-68 ◽  
Author(s):  
Yzel Rondon Súarez ◽  
Miguel Petrere Júnior
Keyword(s):  
Community Structure ◽  
Environmental Factors ◽  
Species Composition ◽  
Species Distribution ◽  
Fish Community ◽  
Abundant Species ◽  
Longitudinal Variation ◽  
Fish Community Structure ◽  
Gill Nets ◽  
The Difference

In order to assess the organization patterns of the fish communities in the Jogui and Iguatemi rivers, we collected fish with gill nets tri-monthly from November 1999 to August 2000. Hypostomus ancistroides and Parauchenipterus galeatus were the most abundant species in the Jogui and Iguatemi rivers, respectively. Longitudinal variation was more important than seasonal in determining the species composition in both rivers, and the difference between seasons was not statistically significant. Altitude was the most important factor determining species distribution.

scholarly journals UNA APROXIMACIÓN A LA ABUNDANCIA DE LOS BATOIDEOS CAPTURADOS ARTESANALMENTE EN SANTA MARTA (COLOMBIA)

2016 ◽  
Vol 36 ◽  
Author(s):  
Marcela Grijalba Bendeck ◽  
Carlos Polo Silva ◽  
Arturo Acero P.
Keyword(s):  
Relative Abundance ◽  
Abundant Species ◽  
Important Species ◽  
Gill Nets ◽  
Gill Net

Relative abundance of batoids fished in Playa Salguero and Don Jaca (Santa Marta) between March and October (2006) was estimated. Data taken at sampling periods varying between 12 and 26 days were used. 674 fishing operations with trawl net at Playa Salguero were analyzed. The general capture per effort unit (CPEU) mean in abundance was 0.46±0.07 individuals/hour and in biomass 0.09±0.02 kg/hour. The most abundant species was the endemic Urotrygon venezuelae, previously considered rare. At Don Jaca, 129 fishing operations with horizontal lines and 54 with gill nets were evaluated. CPEU at that locality was estimated in 8.53±2.04 kg/15hours for the horizontal lines and 11.00±5.90 kg/12hours for gill net; Dasyatis guttata was the most important species.

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