The Spatial Distribution Dynamics of Shark Bycatch by the Longline Fishery in the Western and Central Pacific Ocean
Shark bycatch represents a substantial issue in the management of oceanic fisheries. Utilizing data on shark bycatch from the longline fishery, as released by the Western and Central Pacific Fisheries Commission, this study applied the boosted regression tree model to examine the impact of environme...
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MDPI AG
2025-02-01
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| Series: | Journal of Marine Science and Engineering |
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| author | Shengyao Xia Jiaqi Wang Xiaodi Gao Yiwei Yang Heyang Huang |
| author_facet | Shengyao Xia Jiaqi Wang Xiaodi Gao Yiwei Yang Heyang Huang |
| author_sort | Shengyao Xia |
| collection | DOAJ |
| description | Shark bycatch represents a substantial issue in the management of oceanic fisheries. Utilizing data on shark bycatch from the longline fishery, as released by the Western and Central Pacific Fisheries Commission, this study applied the boosted regression tree model to examine the impact of environmental factors on the bycatch per unit effort (BPUE) of key bycatch species, as well as to predict the spatial distribution dynamics of both BPUE and bycatch risk (BR). The findings emphasize that the oxygen concentration, sea surface temperature, and chlorophyll-a concentration are paramount to sharks’ BPUE. Furthermore, the study compared the variations in environmental preferences across diverse shark species, pinpointing key environmental attributes defining the ecological niches of distinct shark populations. The spatial predictions identified the hotspots of BPUE and BR for the bigeye thresher shark (<i>Alopias superciliosus</i>), longfin mako (<i>Isurus paucus</i>), silky shark (<i>Carcharhinus falciformis</i>), and oceanic whitetip shark (<i>Carcharhinus longimanus</i>) in tropical latitudes (10° S to 15° N), and for the blue shark (<i>Prionace glauca</i>) and shortfin mako (<i>Isurus oxyrinchus</i>) in temperate zones (south of 30° S or north of 30° N). The geometric center analysis indicated that all shark species exhibited large annual fluctuations in BPUE and BR, and most populations displayed significant shifting trends. Several grids (5° × 5°) were identified as high-risk areas due to their considerable contribution to bycatch. Furthermore, the geometric centers of BR were observed to shift eastward towards equatorial waters, compared to the geometric centers of BPUE. This underscores the necessity of considering factors beyond BPUE when identifying critical areas for the implementation of area-specific bycatch mitigation measures. The insights derived from this study can enhance and support the development and enforcement of targeted area-based fishery management initiatives. |
| format | Article |
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| institution | DOAJ |
| issn | 2077-1312 |
| language | English |
| publishDate | 2025-02-01 |
| publisher | MDPI AG |
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| series | Journal of Marine Science and Engineering |
| spelling | doaj-art-b3fe427ba4a14b3c9f950b0d8a032c222025-08-20T02:44:32ZengMDPI AGJournal of Marine Science and Engineering2077-13122025-02-0113231510.3390/jmse13020315The Spatial Distribution Dynamics of Shark Bycatch by the Longline Fishery in the Western and Central Pacific OceanShengyao Xia0Jiaqi Wang1Xiaodi Gao2Yiwei Yang3Heyang Huang4Shanghai Ocean University, Shanghai 201306, ChinaShanghai Ocean University, Shanghai 201306, ChinaEast China Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Shanghai 200090, ChinaShanghai Ocean University, Shanghai 201306, ChinaShanghai Ocean University, Shanghai 201306, ChinaShark bycatch represents a substantial issue in the management of oceanic fisheries. Utilizing data on shark bycatch from the longline fishery, as released by the Western and Central Pacific Fisheries Commission, this study applied the boosted regression tree model to examine the impact of environmental factors on the bycatch per unit effort (BPUE) of key bycatch species, as well as to predict the spatial distribution dynamics of both BPUE and bycatch risk (BR). The findings emphasize that the oxygen concentration, sea surface temperature, and chlorophyll-a concentration are paramount to sharks’ BPUE. Furthermore, the study compared the variations in environmental preferences across diverse shark species, pinpointing key environmental attributes defining the ecological niches of distinct shark populations. The spatial predictions identified the hotspots of BPUE and BR for the bigeye thresher shark (<i>Alopias superciliosus</i>), longfin mako (<i>Isurus paucus</i>), silky shark (<i>Carcharhinus falciformis</i>), and oceanic whitetip shark (<i>Carcharhinus longimanus</i>) in tropical latitudes (10° S to 15° N), and for the blue shark (<i>Prionace glauca</i>) and shortfin mako (<i>Isurus oxyrinchus</i>) in temperate zones (south of 30° S or north of 30° N). The geometric center analysis indicated that all shark species exhibited large annual fluctuations in BPUE and BR, and most populations displayed significant shifting trends. Several grids (5° × 5°) were identified as high-risk areas due to their considerable contribution to bycatch. Furthermore, the geometric centers of BR were observed to shift eastward towards equatorial waters, compared to the geometric centers of BPUE. This underscores the necessity of considering factors beyond BPUE when identifying critical areas for the implementation of area-specific bycatch mitigation measures. The insights derived from this study can enhance and support the development and enforcement of targeted area-based fishery management initiatives.https://www.mdpi.com/2077-1312/13/2/315oceanic sharksenvironmental preferencebycatch hotspotslongline fisheryWestern and Central Pacific |
| spellingShingle | Shengyao Xia Jiaqi Wang Xiaodi Gao Yiwei Yang Heyang Huang The Spatial Distribution Dynamics of Shark Bycatch by the Longline Fishery in the Western and Central Pacific Ocean Journal of Marine Science and Engineering oceanic sharks environmental preference bycatch hotspots longline fishery Western and Central Pacific |
| title | The Spatial Distribution Dynamics of Shark Bycatch by the Longline Fishery in the Western and Central Pacific Ocean |
| title_full | The Spatial Distribution Dynamics of Shark Bycatch by the Longline Fishery in the Western and Central Pacific Ocean |
| title_fullStr | The Spatial Distribution Dynamics of Shark Bycatch by the Longline Fishery in the Western and Central Pacific Ocean |
| title_full_unstemmed | The Spatial Distribution Dynamics of Shark Bycatch by the Longline Fishery in the Western and Central Pacific Ocean |
| title_short | The Spatial Distribution Dynamics of Shark Bycatch by the Longline Fishery in the Western and Central Pacific Ocean |
| title_sort | spatial distribution dynamics of shark bycatch by the longline fishery in the western and central pacific ocean |
| topic | oceanic sharks environmental preference bycatch hotspots longline fishery Western and Central Pacific |
| url | https://www.mdpi.com/2077-1312/13/2/315 |
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