Environmentally Driven Ecological Fluctuations on the Faroe Shelf Revealed by Fish Juvenile Surveys
Comprehensive late June surveys have for decades been carried out on the Faroe shelf in order to estimate the abundance of juvenile fish – the 0-group. The abundance of cod juveniles has previously been used in recruitment studies, while the ecological implication of the 0-groups has hitherto receiv...
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Format: | Article |
Language: | English |
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Frontiers Media S.A.
2019-09-01
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Series: | Frontiers in Marine Science |
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Online Access: | https://www.frontiersin.org/article/10.3389/fmars.2019.00559/full |
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author | Sólvá Jacobsen Eilif Gaard Hjálmar Hátún Petur Steingrund Karin Margretha Húsgarð Larsen Jákup Reinert Sólveig Rósa Ólafsdóttir Meinhard Poulsen Helga Bára Mohr Vang |
author_facet | Sólvá Jacobsen Eilif Gaard Hjálmar Hátún Petur Steingrund Karin Margretha Húsgarð Larsen Jákup Reinert Sólveig Rósa Ólafsdóttir Meinhard Poulsen Helga Bára Mohr Vang |
author_sort | Sólvá Jacobsen |
collection | DOAJ |
description | Comprehensive late June surveys have for decades been carried out on the Faroe shelf in order to estimate the abundance of juvenile fish – the 0-group. The abundance of cod juveniles has previously been used in recruitment studies, while the ecological implication of the 0-groups has hitherto received less attention. Here we examined the pelagic 0-group stage in four of the main fish species on the Faroe shelf: cod, haddock, Norway pout and sandeel, representing more than 90% of all juvenile fish on the shelf. A positive relationship between length and abundance at the 0-group stage is observed for all juveniles, and the inter-annual variability was highly similar among the four fish species. Based on this knowledge, we produced a new ecological indicator for the central Faroe shelf ecosystem – the 0-group length index. The 0-group length index is characterized by marked peaks in 1984, 1987, 1994, 2000, 2009, and 2017, which appear to be related to the shelf primary production from spring to mid-summer, and possibly to the marine climate surrounding the Faroe shelf. There is a better temporal overlap between the fish larvae and their prey (i.e., small- to medium sized zooplankton) in years with an early and intensive bloom, while late and/or weak blooms lead to unfavorable feeding conditions. We furthermore show that a large abundance of 0-group fish has the potential to graze down and thus regulate the biomass of large-sized zooplankton during late June. In addition to this top-down influence the 0-group fish clearly impact commercial fish stocks and seabird colonies, and our 0-group length index is therefore a key ecological indicator for the state of the entire central Faroe shelf ecosystem. |
first_indexed | 2024-04-14T05:20:47Z |
format | Article |
id | doaj.art-bbecd9acc43940b5ad64cd28845228a1 |
institution | Directory Open Access Journal |
issn | 2296-7745 |
language | English |
last_indexed | 2024-04-14T05:20:47Z |
publishDate | 2019-09-01 |
publisher | Frontiers Media S.A. |
record_format | Article |
series | Frontiers in Marine Science |
spelling | doaj.art-bbecd9acc43940b5ad64cd28845228a12022-12-22T02:10:11ZengFrontiers Media S.A.Frontiers in Marine Science2296-77452019-09-01610.3389/fmars.2019.00559441343Environmentally Driven Ecological Fluctuations on the Faroe Shelf Revealed by Fish Juvenile SurveysSólvá Jacobsen0Eilif Gaard1Hjálmar Hátún2Petur Steingrund3Karin Margretha Húsgarð Larsen4Jákup Reinert5Sólveig Rósa Ólafsdóttir6Meinhard Poulsen7Helga Bára Mohr Vang8Faroe Marine Research Institute, Tórshavn, Faroe IslandsFaroe Marine Research Institute, Tórshavn, Faroe IslandsFaroe Marine Research Institute, Tórshavn, Faroe IslandsFaroe Marine Research Institute, Tórshavn, Faroe IslandsFaroe Marine Research Institute, Tórshavn, Faroe IslandsFaroe Marine Research Institute, Tórshavn, Faroe IslandsMarine and Freshwater Research Institute, Reykjavík, IcelandNakskov Gymnasium og HF, Nakskov, DenmarkFaroe Marine Research Institute, Tórshavn, Faroe IslandsComprehensive late June surveys have for decades been carried out on the Faroe shelf in order to estimate the abundance of juvenile fish – the 0-group. The abundance of cod juveniles has previously been used in recruitment studies, while the ecological implication of the 0-groups has hitherto received less attention. Here we examined the pelagic 0-group stage in four of the main fish species on the Faroe shelf: cod, haddock, Norway pout and sandeel, representing more than 90% of all juvenile fish on the shelf. A positive relationship between length and abundance at the 0-group stage is observed for all juveniles, and the inter-annual variability was highly similar among the four fish species. Based on this knowledge, we produced a new ecological indicator for the central Faroe shelf ecosystem – the 0-group length index. The 0-group length index is characterized by marked peaks in 1984, 1987, 1994, 2000, 2009, and 2017, which appear to be related to the shelf primary production from spring to mid-summer, and possibly to the marine climate surrounding the Faroe shelf. There is a better temporal overlap between the fish larvae and their prey (i.e., small- to medium sized zooplankton) in years with an early and intensive bloom, while late and/or weak blooms lead to unfavorable feeding conditions. We furthermore show that a large abundance of 0-group fish has the potential to graze down and thus regulate the biomass of large-sized zooplankton during late June. In addition to this top-down influence the 0-group fish clearly impact commercial fish stocks and seabird colonies, and our 0-group length index is therefore a key ecological indicator for the state of the entire central Faroe shelf ecosystem.https://www.frontiersin.org/article/10.3389/fmars.2019.00559/full0-group fishFaroe shelfprimary productionzooplanktonsilicatesurvival |
spellingShingle | Sólvá Jacobsen Eilif Gaard Hjálmar Hátún Petur Steingrund Karin Margretha Húsgarð Larsen Jákup Reinert Sólveig Rósa Ólafsdóttir Meinhard Poulsen Helga Bára Mohr Vang Environmentally Driven Ecological Fluctuations on the Faroe Shelf Revealed by Fish Juvenile Surveys Frontiers in Marine Science 0-group fish Faroe shelf primary production zooplankton silicate survival |
title | Environmentally Driven Ecological Fluctuations on the Faroe Shelf Revealed by Fish Juvenile Surveys |
title_full | Environmentally Driven Ecological Fluctuations on the Faroe Shelf Revealed by Fish Juvenile Surveys |
title_fullStr | Environmentally Driven Ecological Fluctuations on the Faroe Shelf Revealed by Fish Juvenile Surveys |
title_full_unstemmed | Environmentally Driven Ecological Fluctuations on the Faroe Shelf Revealed by Fish Juvenile Surveys |
title_short | Environmentally Driven Ecological Fluctuations on the Faroe Shelf Revealed by Fish Juvenile Surveys |
title_sort | environmentally driven ecological fluctuations on the faroe shelf revealed by fish juvenile surveys |
topic | 0-group fish Faroe shelf primary production zooplankton silicate survival |
url | https://www.frontiersin.org/article/10.3389/fmars.2019.00559/full |
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