Advances in Scale Assessment of Seabird Bycatch: A New Methodological Framework
This paper presents a methodology for indirectly estimating the scale of seabird bycatch using existing data. The study focuses on five key species of ducks that winter in the Polish waters of the Baltic Sea and are highly susceptible to bycatch: Long-tailed Duck, Velvet Scoter, Common Scoter, Great...
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ftdoajarticles:oai:doaj.org/article:e3174ec42db643bca328b03ceea74311 2023-08-20T04:06:45+02:00 Advances in Scale Assessment of Seabird Bycatch: A New Methodological Framework Dominik Marchowski 2023-06-01T00:00:00Z https://doi.org/10.3390/d15070808 https://doaj.org/article/e3174ec42db643bca328b03ceea74311 EN eng MDPI AG https://www.mdpi.com/1424-2818/15/7/808 https://doaj.org/toc/1424-2818 doi:10.3390/d15070808 1424-2818 https://doaj.org/article/e3174ec42db643bca328b03ceea74311 Diversity, Vol 15, Iss 808, p 808 (2023) waterbird bycatch conservation implications threshold values bycatch estimation Long-tailed Duck Velvet Scoter Biology (General) QH301-705.5 article 2023 ftdoajarticles https://doi.org/10.3390/d15070808 2023-07-30T00:35:57Z This paper presents a methodology for indirectly estimating the scale of seabird bycatch using existing data. The study focuses on five key species of ducks that winter in the Polish waters of the Baltic Sea and are highly susceptible to bycatch: Long-tailed Duck, Velvet Scoter, Common Scoter, Greater Scaup, and Tufted Duck. The evaluation units used are divided into the Bornholm (BS) and Gotland Subdivisions (GS) within the Polish Exclusive Economic Zone (PEEZ). The analysis acknowledges the lack of bycatch data for certain areas known to have high concentrations of diving birds and fishing activity. The population sizes of waterbirds were assessed using ship-based surveys and a distance sampling approach. Fishing effort data from the five winter seasons between 2015/2016 and 2019/2020 were analyzed. Bycatch rates were estimated based on surveys conducted in previous seasons, and threshold values for bycatch were established using the concept of “small numbers” defined in EU directives. The results show that within the GS of the PEEZ, the estimated average abundance of all diving waterbirds was 174,800 individuals, with an average annual bycatch of 7921 birds (4.5% of the total). The Velvet Scoter was the most abundant species, followed by the Long-tailed Duck. In the BS, the estimated average abundance of diving waterbirds was 624,600 individuals, with an average annual bycatch of 5056 birds (0.8% of the total). The Long-tailed Duck was the most numerous species, followed by the Velvet Scoter. Acceptable bycatch thresholds were exceeded for all species in both subdivisions despite a much smaller scale of bycatch in the BS. The findings highlight the need for effective management and conservation measures to address the high mortality of seabirds due to bycatch. The methodology presented in this study offers a valuable approach for estimating bycatch scale and can support efforts to minimize the impact on seabird populations. Article in Journal/Newspaper greater scaup velvet scoter Directory of Open Access Journals: DOAJ Articles Diversity 15 7 808 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
waterbird bycatch conservation implications threshold values bycatch estimation Long-tailed Duck Velvet Scoter Biology (General) QH301-705.5 |
spellingShingle |
waterbird bycatch conservation implications threshold values bycatch estimation Long-tailed Duck Velvet Scoter Biology (General) QH301-705.5 Dominik Marchowski Advances in Scale Assessment of Seabird Bycatch: A New Methodological Framework |
topic_facet |
waterbird bycatch conservation implications threshold values bycatch estimation Long-tailed Duck Velvet Scoter Biology (General) QH301-705.5 |
description |
This paper presents a methodology for indirectly estimating the scale of seabird bycatch using existing data. The study focuses on five key species of ducks that winter in the Polish waters of the Baltic Sea and are highly susceptible to bycatch: Long-tailed Duck, Velvet Scoter, Common Scoter, Greater Scaup, and Tufted Duck. The evaluation units used are divided into the Bornholm (BS) and Gotland Subdivisions (GS) within the Polish Exclusive Economic Zone (PEEZ). The analysis acknowledges the lack of bycatch data for certain areas known to have high concentrations of diving birds and fishing activity. The population sizes of waterbirds were assessed using ship-based surveys and a distance sampling approach. Fishing effort data from the five winter seasons between 2015/2016 and 2019/2020 were analyzed. Bycatch rates were estimated based on surveys conducted in previous seasons, and threshold values for bycatch were established using the concept of “small numbers” defined in EU directives. The results show that within the GS of the PEEZ, the estimated average abundance of all diving waterbirds was 174,800 individuals, with an average annual bycatch of 7921 birds (4.5% of the total). The Velvet Scoter was the most abundant species, followed by the Long-tailed Duck. In the BS, the estimated average abundance of diving waterbirds was 624,600 individuals, with an average annual bycatch of 5056 birds (0.8% of the total). The Long-tailed Duck was the most numerous species, followed by the Velvet Scoter. Acceptable bycatch thresholds were exceeded for all species in both subdivisions despite a much smaller scale of bycatch in the BS. The findings highlight the need for effective management and conservation measures to address the high mortality of seabirds due to bycatch. The methodology presented in this study offers a valuable approach for estimating bycatch scale and can support efforts to minimize the impact on seabird populations. |
format |
Article in Journal/Newspaper |
author |
Dominik Marchowski |
author_facet |
Dominik Marchowski |
author_sort |
Dominik Marchowski |
title |
Advances in Scale Assessment of Seabird Bycatch: A New Methodological Framework |
title_short |
Advances in Scale Assessment of Seabird Bycatch: A New Methodological Framework |
title_full |
Advances in Scale Assessment of Seabird Bycatch: A New Methodological Framework |
title_fullStr |
Advances in Scale Assessment of Seabird Bycatch: A New Methodological Framework |
title_full_unstemmed |
Advances in Scale Assessment of Seabird Bycatch: A New Methodological Framework |
title_sort |
advances in scale assessment of seabird bycatch: a new methodological framework |
publisher |
MDPI AG |
publishDate |
2023 |
url |
https://doi.org/10.3390/d15070808 https://doaj.org/article/e3174ec42db643bca328b03ceea74311 |
genre |
greater scaup velvet scoter |
genre_facet |
greater scaup velvet scoter |
op_source |
Diversity, Vol 15, Iss 808, p 808 (2023) |
op_relation |
https://www.mdpi.com/1424-2818/15/7/808 https://doaj.org/toc/1424-2818 doi:10.3390/d15070808 1424-2818 https://doaj.org/article/e3174ec42db643bca328b03ceea74311 |
op_doi |
https://doi.org/10.3390/d15070808 |
container_title |
Diversity |
container_volume |
15 |
container_issue |
7 |
container_start_page |
808 |
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1774718059801477120 |