• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.6
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• pp.997-1005
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• 2014

We analyzed annual and seasonal variations in fish species composition and distribution patterns using both daily catch and quantitative analysis data collected from a set-net fishery over a period of two years (2011-2012) on the coast of Dapo, Geoje Island. Set-net fishing season in this area is from May to November, and the annual yield based on the daily catch data was 171,412 kg in 2011, and 102,611 kg in 2012. In total, there were 46 species (belonging to 36 families and 12 orders) in 2011, and 41 species (belonging to 25 families and 9 orders) in 2012. The dominant species in terms of numbers were Trachurus japonicus, Engraulis japonicus, Clupea pallasii, Scomber japonicus, and Sphyraena pinguis. The range in fork length for T. japonicus and E. japonicus was from 3.2 to 23.9 cm, and from 2.6 to 13.3 cm, respectively. The fork length of recruiting juveniles to the Dapo set-net fishing ground ranged from 4.6 to 7.8 cm (median) for T. japonicus, and from 4.1 to 5.0 cm (median) for E. japonicus. The fact that most of the fish caught from the two species were at immature growth stages implies that the coast of Dapo can act as a nursery area for these migratory species.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.6
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• pp.934-941
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• 2020

The spatial and temporal catch variations of Argentine shortfin squid Illex argentinus in the Southwest Atlantic Ocean (SWA) were analyzed using Korean squid-jigging fishery data collected through electronic reporting system (ERS) from 2016 to 2020. The ERS linked with GPS has been implemented for collecting fishing data from all Korean fishing vessels operating in international waters since November 2015. The fishing period of the Korean squid-jigging fishery in the SWA runs from early summer to autumn (December to June) in the Southern Hemisphere. The fishing ground was extended from 42°S to 48°S along the Patagonian continental shelf and slope, and the main fishing ground was formed around the Falkland Islands. The yearly catch per unit effort (CPUE) of I. argentinus fluctuated between 1.69 and 7.53 tons/day. In this study, during the fishing season, a south and westward shift on the fishing ground was observed indicating the feeding migration of the south Patagonian stock. The shift in monthly fishing centroids differed according to fishing season. The gradual southward shifts of fishing centroids were observed in the catch years (2017 and 2018), whereas unapparent shifts in fishing centroids were observed in the low catch years (2016 and 2019).

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.60 no.1
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• pp.27-36
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• 2024

The towing distance, which is speed over the ground, and the water flow quantity, which is speed through the water, were used when estimating the amount of Metapenaeus joyneri resources that rose to the surface at night using the swept area method in order to compare and analyze the difference. It was conducted using a shrimp dredge, trial fishing gear for catching Metapenaeus joyneri. Catch during the entire survey period was 188.9 kg. Monthly catch ranged from 3.1 to 109.2 kg, highest in June and lowest in September. The swept volume calculated using the speed over the ground was about 13% higher than using the speed through the water. Metapenaeus joyneri resources estimated using the towing distance ranged from 320.1 to 14,649.8 kg. Resources estimated using the water flow quantity ranged from 278.5 to 12,886.3 kg. Therefore, the amount of Metapenaeus joyneri resources estimated using the speed over the ground was about 14% higher than the method using the speed through the water, indicating that the amount of resources was overestimated.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.49 no.4
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• pp.440-448
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• 2013

Estimations on population ecological parameters of the small yellow croaker, Larimichthy polyactis in Korean waters, were calculated using catch data based on coastal and offshore drift gillnet fishery and biological data from 2010 to 2012. The population ecological parameters included survival rate, instantaneous coefficient of natural and fishing mortality and age/length at first capture. The survival rate (S) of the small yellow croaker was estimated to be 0.20 from catch curve method. The instantaneous coefficient of natural mortality (M) was estimated to be 0.46/year with Alverson and Carney method. The instantaneous coefficient of total mortality (Z) was 1.611/year, used to be transformed the survival rate and the instantaneous coefficient of fishing mortality (F) were 1.153/year. The length at first capture ($L_c$) was 19.1cm by Pauly method, and the age at first capture ($t_c$) was 1.303 years of the small yellow croaker by the coastal and offshore drift gillnet fishery.

• The Journal of Fisheries Business Administration
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• v.30 no.2
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• pp.55-77
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• 1999

As the population grows, the importance of the fishery industry continues to rise. It is therefore vital to support and promote sustainable fishery industry. However, the fishery production has been declining, mainly due to overdevelopment and depletion in fishery resources and stricter limits on development limits caused by growing concerns over the marine environment and ecology. Recently, international activities related to marine environmental and its ecosystems conservation, have been vigorously pursued. The United Nations Convention on The Law of The Sea has stipulated the protection and conservation of the marine environment, and the implementation of fishery resources development, made in harmony with the environment and fishery resources and based upon scientific findings and principles has become important. Accordingly, fishery industry must pay thorough attention to marine ecological and environmental problems and its international fisheries regime. Fisheries development can affect fishery resources, their environment and ecosystems. Adverse ecological effects resulting from fishery resources development practices in general include overdevelopment and incidental development of non target species, physical degradation of seabed habitants and degraduation of water quality. It has now become more important than ever to build up fishery resources development while achieving the conservation of biodiversity and the marine environment, as well as the restoration of destroyed ecosystems. To maintain fishery industry, it is necessary to develop bioeconomic fishery production system and industry policies for the ESSD(environmentally sound and sustainable development) given that maintenance of a favourable marine environment will ensure the fishery resources productivity. These bioeconomic system and policies are necessary to ensure the sustainability and viability of the fishery industry under ESSD fisheries concepts.

• The Journal of Fisheries Business Administration
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• v.51 no.1
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• pp.19-36
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• 2020

The purpose of this paper is to analyze the productivity of the costal fisheries in Jeonnam Province. In this study, the operational characteristics and Cobb-Douglas production function of coastal fisheries were examined based on a research on the actual condition of costal fisheries (RACF). The statistical analysis of RACF data reveals that Cobb-Douglas production function consists of the three variables: fishing quantity per ton-age, the number of fisherman per ton-age and fishing equipment cost per ton-age. The results of this study show us that the relation and productivity between labor and capital of the operational equipment in the coastal fisheries. If extensive comparable biological and market data become available, analysis model can be widely applied to yield more accurate results.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.6
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• pp.907-916
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• 2013

The aim of this study was to compare community structure of larval fish species in the northern East China Sea during normal meteorological conditions in autumn 2009, during the El Ni$\tilde{n}$o period in 2009-2010, and during the La Nina period in 2010. Fifty taxa were recorded during the study period; the most dominant species were Benthosema pterotum and Gobiidae spp. In October 2008 during the normal period, warm water from the Tsushima Warm Current (TWC) intruded more into the surface and middle layers, and cold water affected by the Yellow Sea Cold Water (YSCW) intruded into the bottom layer. In October 2009 during the El Ni$\tilde{n}$o period, intrusion of the China Coastal Water (CCW), which has low salinity (<32.2 psu), was more apparent than intrusion of the TWC or YSCW. In October 2010 during the La Nina period, intrusion of the TWC and CCW was relatively weak, resulting in the lowest temperature and highest salinity observed during the study period in the eastern part of the study area. Hierarchical cluster, one-way ANOSIM (analysis of similarities), and SIMPER (similarity-percentages procedure) analyses provided two main results. First, the abundance of the most dominant larval fish species in autumn of the normal period was greater than that in autumn of the El Ni$\tilde{n}$o/La Nina periods, resulting in a significant difference in ichthyoplankton community structure between the periods. The abundance of Benthosema pterotum increased in the normal period, possibly influenced by the intrusion of cold water from the YSCW; the abundance of species residing in Korean waters (e.g., Gobiidae spp.) probably decreased during the El Ni$\tilde{n}$o/La Nina periods. The second finding was that the abundance of subtropical larval fish in autumn of the normal period was generally larger than that during autumn of the El Ni$\tilde{n}$o/La Nina periods. This could have been induced by the stronger intrusion of warm water from the TWC during the normal period. Although differences in oceanographic conditions between El Ni$\tilde{n}$o and La Nina periods were observed, the differences in ichthyoplankton community structure between the two periods were not significant.

• Korean Journal of Ichthyology
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• v.33 no.1
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• pp.37-42
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• 2021

This study sought to reveal spawning period and sex inversion of black seabream, Acanthopagrus schlegelii collected off the coast of Tongyeong, Korea. The monthly gonodosomatic index (GSI) showed the same pattern of between both sexes, and it was estimated that black seabream spawned once a year (between April and May). Histological examination revealed the transition from male to female sex, size of fork length bisexual gonad with ovarian (primary hermaphrodite; progress from male to female, MF) was seen at 20.5 to 39.6 cm and bisexual gonad with testicular (post hermaphrodite; female development and Male degeneration, FM) was seen at 26.4 to 50.2 cm. The egg diameters was in the range of 0.02 to 0.60 mm, with the smallest average egg diameter of 0.09 mm in February, the highest average egg diameters of 0.43 mm in August, and the range of fecundity was number of eggs 277,148 (33.9 cm) to 2,772,421 (34.1 cm).

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.50 no.4
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• pp.455-466
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• 2014

Seasonal variations in species composition of catches were explored using seasonal samples caught by shrimp beam trawl in the Geum river estuary in 2011. During the study period, total catches were collected 91 species as fish 47 species, crustacean 28 species, mollusca 4 species, gastropoda 5 species, shellfish 3 species and others 4 species. The dominant species were Exopalaemon carinicauda, Eriocheir leptognathus, Palaemon gravieri, Mugil cephalus, Acanthogobius hasta, Cynoglossus joyneri, Pennahia argentata and Coilia nasus. The amount of species in spring and summer was higher than in autumn. The diversity index (H') was 0.43~0.96, evenness index (EI) was 0.14~0.25, and richness index (RI) was 1.54~4.25. Using cluster analysis 91 species were divided into 4 groups. Group I appeared mainly in spring and summer. Group II appeared only in summer. Group III appeared in winter and spring, and Group IV in spring and autumn.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.5
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• pp.760-767
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• 2015

First annulus formation and age determination of otoliths were examined for chub mackerel Scomber japonicus collected in Korean waters over the one year from January to December in 2009. Translucent zone was regarded as an annual mark. Age interpretation criteria was based on the data of the number of translucent zone, capture date, and edge type of the otolith, assuming the nominal birthday to be 1 January. Monthly changes in mean marginal index indicated that translucent zone was formed once a year, mainly in June. The otolith of 0-ring group was detected comparing the progression by month of the smaller fish length, appearing to be a single first opaque zone. The average distance from the core to the first translucent zone was ~1.77 mm, provided as supplementary information to increase ageing accuracy. The ageing criteria for chub mackerel was made to determine correct year-class with the purpose of effective stock assessment. This method using nominal birthdate and edge type analysis could estimate age of fish closer to the true age than purely counting the number of translucent zone on a whole otolith.