BI 3063 J. Mork H08
25
1 BI 3063 J. Mork H08 Genetic and biologic stock management N E A C N E A C The Northeast The Northeast Arctic Cod Arctic Cod biology biology stock structure stock structure exploitation exploitation management history management history
description
Genetic and biologic stock management. BI 3063 J. Mork H08. N E A C The Northeast Arctic Cod biology stock structure exploitation management history. Genetic and biologic stock management. BI 3063 J. Mork H08. - PowerPoint PPT Presentation
Transcript of BI 3063 J. Mork H08
1
BI 3063 J. Mork H08
Genetic and biologic stock management
N E A CN E A C
The Northeast Arctic CodThe Northeast Arctic Cod
biology biology stock structure stock structure
exploitation exploitation management historymanagement history
2
BI 3063 J. Mork H08
Genetic and biologic stock management
In their chapter on NEAC, Nakken et al. (2008) summarizes and evaluate the available information on trends and fluctuations throughout the 20th century in:
• fisheries• stock size • biological characteristics
They describe the development of our understanding of these fluctuations as well as the management measures which have been adviced and introduced in order to maintain the yield from the stock at a high and sustainable level.
3
BI 3063 J. Mork H08
Genetic and biologic stock management
The Migrations of the NEAC ("Skrei") according to Sars (1879)
4
BI 3063 J. Mork H08
Genetic and biologic stock management
5
BI 3063 J. Mork H08
Genetic and biologic stock management
The life cycles of cod stocks which show temporal stability (i.e. at least for hundreds of generations), typically show some relation to current systems.
In the northeast Atlantic, particularly along the Norwegian coast, the "Gulf stream", the Baltic rest-current, and the Norwegian coastal current all contribute in carrying pelagic organisms northwards. The eggs, larvae and small codlings are all pelagic. They are carried northwards from the spawning areas, which are typically to the south of the nursery areas. When the gonads mature prior to spawning, cod individuals are triggered to a contranatant swimming behaviour which brings them southwards along the Norwegian coast, and so compensates for the northwards transport of the pelagic stages. Hence the life cycle circle is closed.
When ocean currents are stable over long time periods (like the "Gulf stream"), cod stocks may adapt genetically to a life cycle that utilizes the benefits of free transport to nursery areas.
6
BI 3063 J. Mork H08
Genetic and biologic stock management
Transport by ocean currents:Transport by ocean currents:
a simulation modela simulation model(Stenevik & Sundby)(Stenevik & Sundby)
(link)(link)
7
BI 3063 J. Mork H08
Genetic and biologic stock management
8
0 5 10 15 20 25 30 35 40 4563
65
67
69
71
73
75
77
79
Longitude
Latit
ude
From Vikebø et al.
Results from computer simulationsof particle drift with currents alongthe coast of north Norway.
Blue trajectories represent verylight particles (high in the watercoulmn) and red trajectories markvery heavy particles.
Blue and red particles are proxiesfor "typical" eggs of NEAC andNCC, respectively.
NB! ntermediate weigth particletrajectories are not shown.
Genetic and biologic stock management
9
BI 3063 J. Mork H08
Genetic and biologic stock management
10
BI 3063 J. Mork H08
Genetic and biologic stock management
11
BI 3063 J. Mork H08
Genetic and biologic stock management
12
BI 3063 J. Mork H08
Genetic and biologic stock management
13
BI 3063 J. Mork H08
Genetic and biologic stock management
14
BI 3063 J. Mork H08
Genetic and biologic stock management
15
BI 3063 J. Mork H08
Genetic and biologic stock management
16
BI 3063 J. Mork H08
Genetic and biologic stock management
17
BI 3063 J. Mork H08
Genetic and biologic stock management
18
BI 3063 J. Mork H08
Genetic and biologic stock management
19
BI 3063 J. Mork H08
Genetic and biologic stock management
20
BI 3063 J. Mork H08
Genetic and biologic stock management
21
BI 3063 J. Mork H08
Genetic and biologic stock management
22
BI 3063 J. Mork H08
Genetic and biologic stock management
23
BI 3063 J. Mork H08
Genetic and biologic stock management
24
BI 3063 J. Mork H08
Genetic and biologic stock management
25
BI 3063 J. Mork H08
Genetic and biologic stock management
