• Korean Journal of Ecology and Environment
• /
• v.53 no.2
• /
• pp.156-164
• /
• 2020

The accurate estimation of fish assemblages is highly dependent on the sampling gear used for sampling. We used data from 15 sampling sites along the Nakdong River, which is a large river in South Korea, to identify differences in assemblages and sizes of freshwater fishes collected with either cast nets or gill nets, the two most commonly used sampling gear in South Korea. The two gears differed in the fish assemblages they captured, with more species caught by gill nets. Further, due to its tighter mesh size, the cast net caught significantly smaller fishes than the gill nets(independent t-test, p<0.05). We found the cast net to be appropriate for species that inhabit shallow (less than 2 m) and open water, but inappropriate for deep water, habitats with plant beds, and nocturnal species. Thus, cast net sampling is not efficient in a large river environment, and a combination of sampling methods is more suitable for understanding fish assemblages in such habitats. In general, appropriate selection of fishing methods to specific habitats is necessary to improve data quality and minimize the misrepresentation of environmental conditions.

• Korean Journal of Ecology and Environment
• /
• v.43 no.1
• /
• pp.103-116
• /
• 2010

The key objective of this study was to analyze sampling efficiency of various fish sampling gears for a lentic ecosystem health assessment. This survey was conducted at twelve sampling locations of Jinyang Reservoir in November, 2008 and June, 2009. Sampling gears used in the field were fyke net (FN), gill net (GN), trammel net (TN), casting net (CN), minnow trap (MT), and kick net (KN). Fishes sampled in Jinyang Reservoir were 29 species, in which tolerant species, as a proportions of the total numbers, dominated the fish community compared to the sensitive species. Overall sampling indicated that 28 species (3,567 individuals) were sampled by the CN and 15 species (3,108 individuals) were sampled by the FN along with 14 species (577 individuals) by the TN, 7 species (107 individuals) by the GN, 6 species (59 individuals) by MT, and 5 species (95 individuals) by KN, respectively. Statistical analysis (MANOVA), based on CPUE of the fishing gears showed that fish species and numbers of the CN were significantly (p < 0.05) greater than those of any other sampling gears. In contrast, sampling gear of MT and KN showed the least efficiency in our survey. This survey is a preliminary results for the tests of sampling gear's efficiency in lentic ecosystems, thus further extensive studies are required for the verification.

• Korean Journal of Environmental Biology
• /
• v.31 no.2
• /
• pp.154-157
• /
• 2013

Length-weight relationships were estimated for 11 fish species caught in Baekya Island, Korea. Samples were caught in depths of <15 m by fish pots between November 2008 and July 2009. The sampling gear, fish pots, is a widely used as commercial fishing gear in shallow waters of the region. The most abundant families were Hexagrammidae (20.7%), Cottidae (18.5%), Tetraodontidae (14.8%) and Scorpaenidae (13.3%). Estimates for parameter b of the length-weight relationship ($W=aL^b$) ranged between 2.454 and 3.361.

• Journal of Ecology and Environment
• /
• v.38 no.3
• /
• pp.383-388
• /
• 2015

Reservoirs consist of two different environments, the littoral and the pelagic zone, and different fishing gear is commonly used in each zone-gill nets in the pelagic zone and electrofishing in the littoral zone. However, an active fishing gear, the cast net, is normally used instead of electrofishing for scientific studies in South Korea. In order to estimate cast net effectiveness for determining fish status in reservoirs, the study was conducted at 15 reservoirs with two different fishing gears: a cast net in the littoral zone and gill nets in the pelagic zone. When combining catches of both gears, species richness increased substantially compared to using one gear only. There was a size difference in fish caught by each net, and small fish were predominantly caught with the cast net due to its small mesh size (7 mm). The combined length of six species, used for length-weight relationship analysis, collected with the cast net was smaller than that collected with gill nets (independent t-test, P < 0.05). In this study, cast net sampling provided sufficient data for the littoral zone, but not enough to identify the overall fish assemblage in studied reservoirs. Utilization of only one gear can therefore lead to substantial underestimation of fish status, and a combination of both gears is recommended for determining more reliable estimates of fish status in reservoirs.

• Korean Journal of Ecology and Environment
• /
• v.55 no.4
• /
• pp.285-293
• /
• 2022

Sampling gears for collecting fish are diverse, and the community of fish varies according to the selection and characteristics of the sampling gears. The present study compared the characteristics of fish communities in Yedang reservoir using four sampling gears (kick net, cast net, gill net, and fyke net). The kick net and cast net were inefficient in collecting the number of individuals. However, they increased the species diversity of fish inhabiting the waterfront. Although not many individuals were collected, the gill net mainly collected large fish. The largest number of individuals was collected in the fyke net, and the dominance was high due to the high species selectivity. Through Self-Organizing Map (SOM) analysis, large fish were collected in the gill net, whereas small fish were collected in the fyke net. The characteristics and efficiency of the fish differed depending on the sampling gears. It is expected that researchers will need to use it appropriately according to the characteristics of the sampling gears when investigating the fish community.

• Korean Journal of Ecology and Environment
• /
• v.38 no.4 s.114
• /
• pp.482-493
• /
• 2005

The objective of this research was to evaluate an sampling effect of fish species and individual number on sampling techniques of electrofishing and conventional capture methods of cast net and kick net in 38 stream sites sampled during June - September, 2005. For the study, sampling gears were categorized as three types of electrofishing method (EM), conventional sampling technique (CM), and the combined technique (CT) of the electrofishing and the conventional method to compare statistical differences. Major differences of species composition between the CM and EM method were found in some benthic species of Misgurnus mizolepis and Iksookimia koreensis along with lithophilic species of Pungtungia herzi. These species were predominated in the EM rather than the CM, indicating that conventional sampling can underestimate the abundance of benthic or lithophilic species. In contrast ,individual number of typical water column species such as Zacco platypus and Zacco temmincki were more sampled by the CM, so that these fish populations were community overestimated. Also, t-tests on the types of sampling gear from various watersheds of Chogang Stream, Yugu Stream, Daejeon Stream, and Gap Stream showed that total individual numbers and species number in each stream were significantly (t values = 2.806-6.896, p values<0.05, n = 5-14) greater in the CT than the CM. Similar statistical significance (p<1.001, n = (10-24) on sampling seasons were observed during the monsoon and postmonsoon. These results indicate that if the electrofishing is not added to the conventional gears, the abundance of fish population and community can be underestimated and some benthic or lithophilic species may be excluded from the analysis, resulting in overall errors including sampling, fish fauna, and final judgement of community abundance. Overall our results strongly suggest that new application of electrofishing method along with the conventional sampling gears reduce sampling bias on underestimation of the real fish populations and communities.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.48 no.2
• /
• pp.128-136
• /
• 2012

Hybrid surveys using hydroacoustic and fish sampling gears such as trammel net, trap were conducted to investigate total biomass, distribution and dominant fish species of the demersal fishes in the marine ranching area (MRA) of Jeju. Four surveys were carried out in June, August, October and November using 38kHz quantitative echo sounder. Catch data using trammel net and trap were used to calculate biomass and to examine dominant fish species. Fish schools were mainly detected in the waters of 20 meters below and around Chagwido waters. By the result of fishing experiments, fish species living in MRA of Jeju were about 40 species, dominant fish species of a detectable fish such as Family Sparidae and Family Monacanthidae etc. were identified 59.4~68.8% of total biomass. Based on the hydroacoustic data, fish length-weight function and target strength information, mean density of the demersal fish estimated were as follows; 0.88g/$m^2$ on June, 1.12g/$m^2$ on August, 1.35g/$m^2$ on October and 1.18g/$m^2$ on November. An estimated average biomass in MRA of Jeju was founded 20.5 tons in 2007, 20.6 tons in 2008, 23.0 tons in 2009, 25.9 tons in 2010. The results showed that biomass of MRA is getting increased slowly. Therefore the hybrid survey method using hydroacoustic and fish sampling gears is assured an effective biomass survey in the waters of mixed species.

• Korean Journal of Ichthyology
• /
• v.20 no.4
• /
• pp.303-312
• /
• 2008

Seasonal variation in species composition and abundance of fishes was determined using monthly samples collected by a fyke net in coastal waters off Namhae Island in 2006. The sampling gear, both-side fyke net, is a widely used commercial fishing gear in shallow waters of the region. A total of 89 fish species was collected, the dominant species were Konosirus punctatus, Mugil cephalus, Lateolabrax japonicus, Acanthopagrus schlegeli, Sebastes inermis, Nibea mitsukurii, Clupeapallasii, Pampus echinogaster, Sebastes schlegeli and Limanda yokohamae. They accounted for 61.1% of the total number of individuals and 80.3% of the biomass. The dominant species were primarily composed of small individuals or juveniles of large-sized fishes. Abundance in the number of individuals and biomass showed peaks in April, May and September, and was lowest in January. Temporal change in fish abundance was related to the temperature and related factors.

• Korean Journal of Ecology and Environment
• /
• v.39 no.2 s.116
• /
• pp.245-256
• /
• 2006

Fish community in the Hoengseong Reservoir was investigated from April to October 2005. The total number of fish caught from the period was 8,626 fish representing 22 species and 8 families, using tyke net and trammel net. Besides biomass was 122.9 kg. In the fyke net, 8,168 individuals caught during the period represented 21 species belonged to 8 families, its biomass was 90.6 kg. On the other hand, 458 individuals caught in the trammel net during the period represented 16species belonged to 6 families, its biomass was 26.3 kg. The results showed that the trammel net had lower number of species, individuals, and less biomass compared to those of the tyke net. Number of species confirmed was increased according as mesh size of the net was smaller. Besides, the fyke net with small mesh size was able to collect not only small-sized fish but also large-sized fish so that it was suitable to study qualitative and quantitative analysis of fish fauna in detail. Whereas, the trammel net with proper mesh size was effective to determine composition of fish species in the studied area.