INCOFISH WP5 MPAs on Continental Shelves Fisheries and Ecosystem Management.
It moves as you go... baselines in Limfjorden environmental history DK INCOFISH unit: Poul Holm Bo...
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Transcript of It moves as you go... baselines in Limfjorden environmental history DK INCOFISH unit: Poul Holm Bo...
“It moves as you go...” baselines in Limfjorden environmental history
DK INCOFISH unit:
Poul Holm
Bo Poulsen
Anne H. Marboe
Department of History and Social Theory
University of Roskilde
INCOFISH, WP2 Workshop Tallin, 3 March 2006
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Limfjorden
Salinity 5000BP - 1990s.
Limfjord baselines c. 1980-2006
• Mussel scraping• Suffering from depletion of grounds• Mussel & oyster farming• No other commercial fishery• Some angling
Data: gov. Statistics, ongoing sci. surveys
Baselinesc. 1860-1980
• Commercial fishing for– Eel– Plaice– Herring
• Cradle of modern Danish fishing– Most important fishing area in DK until c. 1900
• Regime shift c. 1980
• Data: gov. Stats., pioneering mar. Bio. In 19th c.
Lif JacobsenThe Limfjord fishery: Economic and
ecological explanations for the collapse of the 1920´s
Key events in the Limfjord fishery (1890-1925): 1888 First national Fishery Law Introduction of motor driven boats in the
fisheries around 1905. Increasing number of fishermen. Increasing amount of fishing gear. 1923/25 Legislation of motor driven winches for
pulling seines onboard. Focus on the main species:Eel, plaice, cod and herring
Based on: The Danish Annual Fishing Report 1888-1921Copy of The Fishing Controls correspondence, etcReports from The Danish Biological Station etch
Growing fishing effort, 1890-
1925 • Due to the increasing
number of:
• Fulltime fishermen.• Motor driven boats
(from 1905)• Amount of fishing
gear. (“standing gear”)
Value of fishing gear primarily used for catching herring, eel, plaice and cod.
0
200.000
400.000
600.000
800.000
1.000.000
1.200.000
1891 1895 1900 1905 1911 1916 1921
Kr.
i 19
14-p
rice
Relationship between effort, cost and yield.
The interrelationship between the various objectives.Source: Cunningham m.f.: Fisheries Economics an introduction.p.118.
Outcome of investment, 1891-1930.
0
0,5
1
1,5
2
2,5
3
1891 1895 1900 1905 1911 1916 1921 1925 1930
TC, (total cost) and Effort continually increasing.
SMEY, (static maximum economic yield) reached by 1895.
TR, (total revenue) become smaller due to a negative development in prices (from 1917)
foa, (bio economical equilibrium) reached by 1921.
MSY, (maximum sustainable yield): ?
Baselinesc. 1825-1850s
• Period of transition• Commercial fishery
– Herring collapse– Eel crisis– Whitefish disappears– Emergence of plaice– Emergence of Aurelia
• Invention of Danish seine
Limfjorden
North Sea breach in 1825
Baselinesc. 1600-1825
• Phases of very large herring fisheries
• Also commercial fisheries for:– Eel (Anguilla anguilla)– Whitefish, (Coregonus lavaretus)
Data: pre-stat. era; but proxy data from historical archives
400 years of catching herring
catches of herring, 1600-1999
0
2.000
4.000
6.000
8.000
10.000
12.000
14.000
16.000
18.000
1600 1625 1673 1698 1721 1746 1794 1819 1842 1867 1890 1915 1940 1963 1988
ton
nes
Time series of fishing effort
Pound nets
Pound nets 1752-1862
Number of pound nets for spring fishery at Nørlå and Fruens Grund, both at Nibe
0
100
200
300
400
500
600
700
800
900
1755 1760 1765 1770 1775 1780 1785 1790 1795 1800 1805 1809 1814 1819 1824 1829 1834 1839 1844 1849 1854 1859
Beach seines
Seines in different areasSeines in Kær County, 1779-1852
12
14
13 13 13
0 0
4 4
0
2
4
6
8
10
12
14
16
1770 1775 1780 1785 1790 1795 1800 1805 1810 1815 1820 1825 1830 1835 1840 1845 1850
Seines at Løgstør, 1801-1851.
0
2
4
6
8
10
12
14
16
18
20
år 1805 1810 1815 1820 1825 1830 1835 1840 1845 1850
Gill nets
Number of gillnet boats from Gjøl to Hals, 1741-1841.
275
147137
99
187
220
355
46
00
50
100
150
200
250
300
350
400
1740 1750 1760 1770 1780 1790 1800 1810 1820 1830 1840 1850 1860 1870
Eksport af ål
Ål udført fra Aalborg, 1801-1845.
87,7
45,4
36,7
13,316,0
3,88,3
2,61,2 2,1 0 0,6 0 0 1,7
8,4
0
10
20
30
40
50
60
70
80
90
100
1800 1805 1810 1815 1820 1825 1830 1835 1840 1845
ton
s
Bundgarn til helt
Cpue whitefish
Fangst pr. indsats i Østerild-, Tømmerby- og Mellem Fjorde samt Hovsør Havn, 1812-29.
0
200
400
600
800
1000
1200
1400
1812 1814 1816 1818 1820 1822 1824 1826 1828 1830 1832
An
tal h
elt
pr.
bu
nd
gar
n
Social consequences
antal beskæftigede ved de vigtigste limfjordsfiskerier, 1820-1860
0
1000
2000
3000
4000
5000
1820 1840 1860cirka tidspunkt
anta
l bes
kæft
iged
e
sild ål helt rødspætter
Baseline(s) report
• ‘Same’ water - very different ecosystems over 4 centuries
• Causes of change? Depending on baseline• Regime shifts• Fishing mortality• Climate change• Hydrographic change• Episodic events• Societal changes