Research Article |
Corresponding author: Myung Sung Koo ( kms2736@koara.kr ) Academic editor: Sanja Matić-Skoko
© 2024 Seong Yong Moon, Mi Hee Lee, Kyung-Mi Jung, Myung Sung Koo.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Moon SY, Lee MH, Jung K-M, Koo MS (2024) Dynamics of fish community structure in the Yeosu Coast, Korea: A comprehensive analysis of daily set-net catch data during 2008–2022. Acta Ichthyologica et Piscatoria 54: 75-86. https://doi.org/10.3897/aiep.54.112388
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This study focuses on the Yeosu Coast, a critical ecological and economic zone on the Korean Peninsula. We conducted a comprehensive analysis of fish data obtained from daily set nets for the period of 2008–2022 (excluding 2017) to investigate variations in fish composition and community structure over a 15-year period. The catches were characterized by a prevalence of warm-water fish species, reflecting the temperate and subtropical character of the Yeosu Coast. The total catch during the study period was 3210.8 tonnes, with 2010 and 2016 registering the highest and lowest catches, respectively. Our analysis identified sea surface temperature as a primary factor correlated with these changes in species composition. The two dominant species, Scomberomorus niphonius (Cuvier, 1832) and Engraulis japonicus Temminck et Schlegel, 1846 together accounted for a remarkable 78.9% of the total catch. Notably, the Shannon–Weaver diversity index values were lower in 2015 than in 2008, indicating potential shifts in the community structure. Our analysis identified sea surface temperature as the most dominant factor that influenced these changes in species composition. Furthermore, we highlight the significant threats posed by climate change and the increasing number of jellyfish challenging fisheries on the Yeosu Coast. These threats have the potential to result in diminished set-net catches and declining biodiversity within this valuable ecosystem. Our findings underscore the importance of monitoring and addressing these ecological shifts to ensure the long-term sustainability of Yeosu Coast fisheries.
climate change, biodiversity, fish composition, sea surface temperature, Shannon–Weaver diversity index
The Yeosu Coast, located in the central-southern region of Korea, is a ria-type coast. It has a dynamically diverse marine environment owing to factors such as the Tsushima Warm Current (TWC), the Jeju Warm Current flowing from the West of Jeju Island, and the formation of southern coastal waters during winter, which spread beneath the weak water temperature layer in summer (
Hence, the Yeosu Coast boasts rich fish resources and supports fishing activities that employ various fishing gear. Among these, the most popular gear is the set net, which is a passive fishing method that intercepts fish schools using nets to guide them into a specific area for capture. While the pelagic and seasonally migratory fish species residing in offshore waters are the primary targets of set nets, catches are typically influenced by fluctuations in sea conditions, such as water temperature, in the deployment area. This attribute enables localized set nets to closely monitor the recruitment and catch trends of pelagic and migratory fish species (
Previous studies on set-net fisheries conducted along the Yeosu Coast have been primarily focused on the species composition and quantitative variations in set-net-caught fish (
Furthermore, the influence of climate change on the composition of marine ecosystems has been documented (
Data collection. The set-net fishing sites and real-time coastal information system for sea surface temperature (SST) by the Korea Oceanographic Data Center (KODC) in this study were located between Dolsan and Geumo Islands, Yeosu, Jeollanam-do (Fig.
Data analysis. To evaluate the species diversity of the captured fishery resources, the species diversity index (H׳) was calculated using the Shannon–Weaver diversity index (
where S is the total catch of species and Pi is the relative cover of ith species.
Changes in the fish community across ecological successions along the Yeosu Coast were analyzed over a 15-year study period using non-metric multidimensional scaling (nMDS). The nMDS ordinations were generated from Bray–Curtis similarity matrices calculated using log-transformed catch data for all species (
Sea surface temperature. Throughout the survey period, the mean monthly SST near Hwatae Island, near the Yeosu set nets, exhibited typical characteristics of temperate waters with well-defined seasonal shifts ranging from 6.78 to 26.76°C. The lowest SST was recorded in February 2018, whereas the highest was recorded in August 2018. Notably, elevated mean SST of 26.76 and 26.47°C were noted in the summers of 2018 and 2021, respectively, which were primarily attributed to the heightened coastal SST during the summer (Fig.
Species composition, diversity index, and catch characteristics. The set-net catch during the study period included 15 orders, 49 families, and 84 taxa of fish species. The highest number of species was observed in 2011, whereas the lowest was observed in 2021 (Fig.
Community structure and occurrence of major fish species. Using the fish catch data, cluster analysis was conducted using the Bray–Curtis similarity [%] and the nMDS array method based on a 70% similarity threshold. This analysis yielded Cluster A, comprising four clusters for the period 2008–2011, Cluster B for 2012–2015, and Cluster C for 2016–2022 (Fig.
Similarity percentage analysis (SIMPER) list of fish species captured in daily set nets in the Yeosu Coast, Korea during 2008–2022 contributing mostly to similarities within specified periods.
Cluster | Main species | Contribution [%] |
---|---|---|
Cluster A (2008–2011) | Scomberomorus niphonius | 5.91 |
Average similarity: 82.13 | Engraulis japonicus | 4.57 |
Pampus argenteus | 4.51 | |
Trichiurus japonicus | 4.25 | |
Lophius litulon | 4.15 | |
Cololabis saira | 3.80 | |
Cluster B (2012–2015) | Scomberomorus niphonius | 6.21 |
Average similarity: 83.28 | Engraulis japonicus | 5.42 |
Pampus argenteus | 4.80 | |
Trichiurus japonicus | 4.59 | |
Lophius litulon | 4.28 | |
Nibea albiflora | 3.89 | |
Cluster C (2016–2022) | Scomberomorus niphonius | 6.60 |
Average similarity: 76.65 | Pampus argenteus | 5.42 |
Trichiurus japonicus | 5.15 | |
Engraulis japonicus | 4.94 | |
Lophius litulon | 4.77 | |
Pampus punctatissimus | 4.57 |
Relations between major fish species and environmental factors. The analysis of annual patterns of catch fluctuations among the dominant species in the Yeosu set nets (Fig.
Analysis of species composition and community characteristics. We analyzed fish species composition and community characteristics using daily logbook data collected from March to December, which corresponds to the fishing season of the set nets located off the coast of Yeosu. Data from 2017 were excluded because of unavailability. Over the study period, water temperatures ranged from 6.78 to 26.76°C, with notable peaks in average annual water temperatures observed in 2018 and 2021, particularly during the summer months when they exceeded 25°C. The highest fish species richness was recorded in 2011, totaling 48 taxa, whereas the lowest was recorded in 2021. During this period, changes in the community composition of fish species were observed. Among these changes, the species that contributed to fish communities shifted. For example, Seriola spp. was the second most dominant fish taxon two decades ago; however, this position shifted to Engraulis japonicus after 2013. Based on daily catch data and considering the comparison of the sampling area, period, gear, and dominant species (Table
Comparison of the sampling area, period, gear, and dominant species of fish collected using set nets in the coastal waters of Yeosu, Korea during 2008–2022.
Parameter | Reference | ||
This study |
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Sampling area | Yeosu coast | Yeosu coast | Yeosu coast |
Sampling period | 2008–2022 | 2002–2003 | 2004–2011 |
Sampling gear | Large set net | Large set net | Large set net |
Dominant species | Scomberomorus niphonius | Scomberomorus niphonius | Scomberomorus niphonius |
Engraulis japonicus | Seriola spp. | Engraulis japonicus | |
Pampus argenteus | Sarda orientalis | Pampus argenteus | |
Trichiurus japonicus | Engraulis japonicus | Trichiurus japonicus | |
Pampus punctatissimus | Lophius litulon | Lophius litulon | |
Lophius litulon | Trichiurus japonicus | Sarda orientalis |
Community structure and subtropical fish species. Our study confirmed the statistical significance of the annual community structure of the Yeosu coastal set-net catch through cluster analysis. Among the fish species, fluctuations in the catch of Scomberomorus niphonius, Engraulis japonicus, Pampus argenteus, Trichiurus japonicus, and Lophius litulon, notably contributed to each cluster. Additionally, 11 subtropical fish species were identified. The catch frequencies of temperate and subtropical fish species showed an upward trend, with Sphyraena pinguis increasing since 2010, followed by Auxis rochei since 2018. Previous studies on the composition and occurrence of subtropical fish species in Korea were primarily conducted in Jeju Island, a region sensitive to subtropical climates. The increasing numbers of subtropical fish species observed over the years (
Fishing season and impacts of climate change. The fishing season of the Yeosu coastal set nets spans from spring (March and April) to early winter (December), with the peak catch concentrated in the fall months of October and November. Notably, Engraulis japonicus emerged as the primary target species at the beginning of the fishing season, extending from April to June. Subsequently, Scomberomorus niphonius became the main target species, mirroring the transition observed in the dominant species highlighted by
This study was supported by a grant from the National Institute of Fisheries Science (NIFS) of Korea (grant number R2024010). This research was supported by the Korea Institute of Marine Science and Technology Promotion (KIMST) and funded by the Ministry of Oceans and Fisheries (20210044).