Population dynamics of cod, Gadus morhua, in Porsangerfjord, Northern Norway - Analysis of back-calculated length at age from otoliths in 1992 and 2009
The thesis investigates growth of Atlantic cod (Gadus morhua) caught in 1992 and 2009, in Porsangerfjord North-Norway, with use of back-calculated length at age based on cod otoliths. The cod population in Porsangerfjord ecosystem have experienced major changes in abundance during the last decades:...
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Universitetet i Tromsø
2010
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ftunivtroemsoe:oai:munin.uit.no:10037/2668 2024-06-02T08:03:13+00:00 Population dynamics of cod, Gadus morhua, in Porsangerfjord, Northern Norway - Analysis of back-calculated length at age from otoliths in 1992 and 2009 Larsen, Trine Holm 2010-09 12091619 bytes application/pdf https://hdl.handle.net/10037/2668 eng eng Universitetet i Tromsø University of Tromsø https://hdl.handle.net/10037/2668 URN:NBN:no-uit_munin_2413 Attribution-NonCommercial-ShareAlike 3.0 Unported (CC BY-NC-SA 3.0) openAccess Copyright 2010 The Author(s) https://creativecommons.org/licenses/by-nc-sa/3.0 VDP::Matematikk og naturvitenskap: 400::Zoologiske og botaniske fag: 480::Marinbiologi: 497 VDP::Matematikk og naturvitenskap: 400::Zoologiske og botaniske fag: 480::Økologi: 488 fiskeribiologi FSK-3960 Master thesis Mastergradsoppgave 2010 ftunivtroemsoe 2024-05-07T08:42:34Z The thesis investigates growth of Atlantic cod (Gadus morhua) caught in 1992 and 2009, in Porsangerfjord North-Norway, with use of back-calculated length at age based on cod otoliths. The cod population in Porsangerfjord ecosystem have experienced major changes in abundance during the last decades: a dramatic decline in the costal cod population, and environmental influences. A back-calculation method estimating length at previous age was done on cod otoliths. The otoliths were embedded in black resin and transversely cut before photographed in a stereomicroscope. Growth zones in otoliths were measured and growth was back-calculated for previous length at age. In the outer areas (A - B) adult cod, above 5 years of age, were longer at age in the second time period (1998 - 2009) than cod from the first time period (1980 - 1992). Adult cod grew faster in outer areas than in inner areas (C - D) in 1992. In outer area cod had better growth for 1 year old, and 5 - 7 year old, than in inner area (C) in 2009. In conclusion, increasing sea temperature seem to play maybe the most important role in increased mean length at age for adult cod, above 5 years of age, caught in 2009, compared to cod caught in 1992. In addition, a shift from abundance of cod in inner areas with cold sea temperature in 1992, towards outer warmer areas in 2009 has probably also contributed to increased length at age for older cod. Master Thesis atlantic cod Gadus morhua North Norway Northern Norway University of Tromsø: Munin Open Research Archive Norway |
institution |
Open Polar |
collection |
University of Tromsø: Munin Open Research Archive |
op_collection_id |
ftunivtroemsoe |
language |
English |
topic |
VDP::Matematikk og naturvitenskap: 400::Zoologiske og botaniske fag: 480::Marinbiologi: 497 VDP::Matematikk og naturvitenskap: 400::Zoologiske og botaniske fag: 480::Økologi: 488 fiskeribiologi FSK-3960 |
spellingShingle |
VDP::Matematikk og naturvitenskap: 400::Zoologiske og botaniske fag: 480::Marinbiologi: 497 VDP::Matematikk og naturvitenskap: 400::Zoologiske og botaniske fag: 480::Økologi: 488 fiskeribiologi FSK-3960 Larsen, Trine Holm Population dynamics of cod, Gadus morhua, in Porsangerfjord, Northern Norway - Analysis of back-calculated length at age from otoliths in 1992 and 2009 |
topic_facet |
VDP::Matematikk og naturvitenskap: 400::Zoologiske og botaniske fag: 480::Marinbiologi: 497 VDP::Matematikk og naturvitenskap: 400::Zoologiske og botaniske fag: 480::Økologi: 488 fiskeribiologi FSK-3960 |
description |
The thesis investigates growth of Atlantic cod (Gadus morhua) caught in 1992 and 2009, in Porsangerfjord North-Norway, with use of back-calculated length at age based on cod otoliths. The cod population in Porsangerfjord ecosystem have experienced major changes in abundance during the last decades: a dramatic decline in the costal cod population, and environmental influences. A back-calculation method estimating length at previous age was done on cod otoliths. The otoliths were embedded in black resin and transversely cut before photographed in a stereomicroscope. Growth zones in otoliths were measured and growth was back-calculated for previous length at age. In the outer areas (A - B) adult cod, above 5 years of age, were longer at age in the second time period (1998 - 2009) than cod from the first time period (1980 - 1992). Adult cod grew faster in outer areas than in inner areas (C - D) in 1992. In outer area cod had better growth for 1 year old, and 5 - 7 year old, than in inner area (C) in 2009. In conclusion, increasing sea temperature seem to play maybe the most important role in increased mean length at age for adult cod, above 5 years of age, caught in 2009, compared to cod caught in 1992. In addition, a shift from abundance of cod in inner areas with cold sea temperature in 1992, towards outer warmer areas in 2009 has probably also contributed to increased length at age for older cod. |
format |
Master Thesis |
author |
Larsen, Trine Holm |
author_facet |
Larsen, Trine Holm |
author_sort |
Larsen, Trine Holm |
title |
Population dynamics of cod, Gadus morhua, in Porsangerfjord, Northern Norway - Analysis of back-calculated length at age from otoliths in 1992 and 2009 |
title_short |
Population dynamics of cod, Gadus morhua, in Porsangerfjord, Northern Norway - Analysis of back-calculated length at age from otoliths in 1992 and 2009 |
title_full |
Population dynamics of cod, Gadus morhua, in Porsangerfjord, Northern Norway - Analysis of back-calculated length at age from otoliths in 1992 and 2009 |
title_fullStr |
Population dynamics of cod, Gadus morhua, in Porsangerfjord, Northern Norway - Analysis of back-calculated length at age from otoliths in 1992 and 2009 |
title_full_unstemmed |
Population dynamics of cod, Gadus morhua, in Porsangerfjord, Northern Norway - Analysis of back-calculated length at age from otoliths in 1992 and 2009 |
title_sort |
population dynamics of cod, gadus morhua, in porsangerfjord, northern norway - analysis of back-calculated length at age from otoliths in 1992 and 2009 |
publisher |
Universitetet i Tromsø |
publishDate |
2010 |
url |
https://hdl.handle.net/10037/2668 |
geographic |
Norway |
geographic_facet |
Norway |
genre |
atlantic cod Gadus morhua North Norway Northern Norway |
genre_facet |
atlantic cod Gadus morhua North Norway Northern Norway |
op_relation |
https://hdl.handle.net/10037/2668 URN:NBN:no-uit_munin_2413 |
op_rights |
Attribution-NonCommercial-ShareAlike 3.0 Unported (CC BY-NC-SA 3.0) openAccess Copyright 2010 The Author(s) https://creativecommons.org/licenses/by-nc-sa/3.0 |
_version_ |
1800747694247903232 |