Occurrence of basking shark Cetorhinus maximus in southern Portuguese waters: a two-decade survey
There is a general consensus that many shark species are declining in numbers. However, effective management measures often depend on knowing how trends in abundance and distribution are influenced by environmental conditions. Several efforts to describe the occurrence and distribution of basking sh...
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Online Access: | http://hdl.handle.net/10400.1/13225 https://doi.org/10.3354/meps12007 |
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ftunivalgarve:oai:sapientia.ualg.pt:10400.1/13225 2023-05-15T15:53:50+02:00 Occurrence of basking shark Cetorhinus maximus in southern Portuguese waters: a two-decade survey Couto, Ana Queiroz, Nuno Relvas, Paulo Baptista, Miguel Furtado, Miguel Castro, Joana Nunes, Maria Morikawa, Hirofumi Rosa, Rui 2017-02 http://hdl.handle.net/10400.1/13225 https://doi.org/10.3354/meps12007 eng eng Inter-Research 0171-8630 1616-1599 http://hdl.handle.net/10400.1/13225 doi:10.3354/meps12007 restrictedAccess Sea-surface temperature Northern California current Multidecadal oscillation Atlantic oscillation Recruitment success Western-Australia Regime shifts Eastern North Ningaloo reef Whale sharks article 2017 ftunivalgarve https://doi.org/10.3354/meps12007 2022-05-30T08:48:52Z There is a general consensus that many shark species are declining in numbers. However, effective management measures often depend on knowing how trends in abundance and distribution are influenced by environmental conditions. Several efforts to describe the occurrence and distribution of basking sharks Cetorhinus maximus have been made in northern Europe, particularly around the UK, but nothing is known regarding their occurrence in southern areas, such as the south of Portugal. Using 2 decades of observational data collected in the south of Portugal, we show that the occurrence of basking sharks in the area was highly seasonal, with individuals being observed mainly during spring. Based on in situ and satellite-derived environmental variables and climate indices, we also demonstrate that temporal trends were associated with the beginning of the upwelling season and that the inter-annual changes were related to lower values of sea surface temperature, North Atlantic Oscillation index, upwelling index, 2-mo lagged chlorophyll a and 3-mo lagged Atlantic Multidecadal Oscillation index, and higher values of 2-mo lagged upwelling index. These findings suggest that basking sharks are associated with the expansion of cold waters following upwelling events in the region, probably due to the aggregation and increase of zooplankton. Although the temperature recorded during our study years ranged from 14 to 24 degrees C, sharks were mainly observed when temperatures were lower than 20 degrees C, corroborating their preference for colder water. This study provides the first knowledge on the habitat use of basking sharks in southern European Atlantic areas. PROMAR Project [31-03-05-FEP-0037] Portuguese Foundation for Science and Technology (FCT) Article in Journal/Newspaper Cetorhinus maximus North Atlantic North Atlantic oscillation Universidade do Algarve: Sapienta Marine Ecology Progress Series 564 77 86 |
institution |
Open Polar |
collection |
Universidade do Algarve: Sapienta |
op_collection_id |
ftunivalgarve |
language |
English |
topic |
Sea-surface temperature Northern California current Multidecadal oscillation Atlantic oscillation Recruitment success Western-Australia Regime shifts Eastern North Ningaloo reef Whale sharks |
spellingShingle |
Sea-surface temperature Northern California current Multidecadal oscillation Atlantic oscillation Recruitment success Western-Australia Regime shifts Eastern North Ningaloo reef Whale sharks Couto, Ana Queiroz, Nuno Relvas, Paulo Baptista, Miguel Furtado, Miguel Castro, Joana Nunes, Maria Morikawa, Hirofumi Rosa, Rui Occurrence of basking shark Cetorhinus maximus in southern Portuguese waters: a two-decade survey |
topic_facet |
Sea-surface temperature Northern California current Multidecadal oscillation Atlantic oscillation Recruitment success Western-Australia Regime shifts Eastern North Ningaloo reef Whale sharks |
description |
There is a general consensus that many shark species are declining in numbers. However, effective management measures often depend on knowing how trends in abundance and distribution are influenced by environmental conditions. Several efforts to describe the occurrence and distribution of basking sharks Cetorhinus maximus have been made in northern Europe, particularly around the UK, but nothing is known regarding their occurrence in southern areas, such as the south of Portugal. Using 2 decades of observational data collected in the south of Portugal, we show that the occurrence of basking sharks in the area was highly seasonal, with individuals being observed mainly during spring. Based on in situ and satellite-derived environmental variables and climate indices, we also demonstrate that temporal trends were associated with the beginning of the upwelling season and that the inter-annual changes were related to lower values of sea surface temperature, North Atlantic Oscillation index, upwelling index, 2-mo lagged chlorophyll a and 3-mo lagged Atlantic Multidecadal Oscillation index, and higher values of 2-mo lagged upwelling index. These findings suggest that basking sharks are associated with the expansion of cold waters following upwelling events in the region, probably due to the aggregation and increase of zooplankton. Although the temperature recorded during our study years ranged from 14 to 24 degrees C, sharks were mainly observed when temperatures were lower than 20 degrees C, corroborating their preference for colder water. This study provides the first knowledge on the habitat use of basking sharks in southern European Atlantic areas. PROMAR Project [31-03-05-FEP-0037] Portuguese Foundation for Science and Technology (FCT) |
format |
Article in Journal/Newspaper |
author |
Couto, Ana Queiroz, Nuno Relvas, Paulo Baptista, Miguel Furtado, Miguel Castro, Joana Nunes, Maria Morikawa, Hirofumi Rosa, Rui |
author_facet |
Couto, Ana Queiroz, Nuno Relvas, Paulo Baptista, Miguel Furtado, Miguel Castro, Joana Nunes, Maria Morikawa, Hirofumi Rosa, Rui |
author_sort |
Couto, Ana |
title |
Occurrence of basking shark Cetorhinus maximus in southern Portuguese waters: a two-decade survey |
title_short |
Occurrence of basking shark Cetorhinus maximus in southern Portuguese waters: a two-decade survey |
title_full |
Occurrence of basking shark Cetorhinus maximus in southern Portuguese waters: a two-decade survey |
title_fullStr |
Occurrence of basking shark Cetorhinus maximus in southern Portuguese waters: a two-decade survey |
title_full_unstemmed |
Occurrence of basking shark Cetorhinus maximus in southern Portuguese waters: a two-decade survey |
title_sort |
occurrence of basking shark cetorhinus maximus in southern portuguese waters: a two-decade survey |
publisher |
Inter-Research |
publishDate |
2017 |
url |
http://hdl.handle.net/10400.1/13225 https://doi.org/10.3354/meps12007 |
genre |
Cetorhinus maximus North Atlantic North Atlantic oscillation |
genre_facet |
Cetorhinus maximus North Atlantic North Atlantic oscillation |
op_relation |
0171-8630 1616-1599 http://hdl.handle.net/10400.1/13225 doi:10.3354/meps12007 |
op_rights |
restrictedAccess |
op_doi |
https://doi.org/10.3354/meps12007 |
container_title |
Marine Ecology Progress Series |
container_volume |
564 |
container_start_page |
77 |
op_container_end_page |
86 |
_version_ |
1766389014609264640 |