Historical evidence of the influence of

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Historical evidence of the influence of climate
on some commercial fish populations of the
Barents and White seas Dmitry Lajus (State
University of St.Petersburg) Julia Lajus,
Alexey Kraikovsky, Zoya Dmitrieva, Daniil
Alexandrov (European University at
St.Petersburg RUSSIA Influence of Climate
Change on North Atlantic Fish Stocks, Bergen,
11-14 May 2004
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HISTORY OF MARINE ANIMAL POPULATIONS (HMAP) (part
of Census of Marine Life Project, Sloan
Foundation)
To use historical data for extracting
biologically significant information
Use of data for pre-statistical period (before
end of 19th century) for studying dynamics of
fish populations Problems - little
information on circumstances of fishing
(for instance, no data about
recruitment, little data
on fishing effort etc.)
- gaps in data series,
- often uncertain reliability
of data Advantages - potential for
obtaining long-term data series,
- in pre-statistical period fish
populations were not affected
by overfishinig, pollution, habitat
degradation etc.
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Data source recent findings from 17th and 18th
centuries in clostrial and state archives of
Moscow, St.Petersburg, Arkhangelsk.
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Poodsfoonts weight
Number
Date
Day of July 1770
Salmon caught
Salmon caught
Salmon caught
Salmon caught
Salmon caught
Salmon caught
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Data source recent findings from 17th and 18th
centuries in clostrial and state archives of
Moscow, St.Petersburg, Arkhangelsk.
Only data sets which allow us to account for
fishing effort, i.e. to analyse catch per unit
effor (CPUE) have been selected.
Two cases Fisheries of Solovetsky monastery for
cod and halibut at Kildin Island, 18th century.
Fisheries for Atlantic salmon in the White and
Barents sea basins, 17-18th century.
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Kildin Island and scheme of main currents and
fish migrations in the Barents Sea
Kildin Island
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Fishing for cod halibut at Murman coast by hook
and line
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?od and halibut ?atches (metric tonns/boat per
year) at fisheries of Solovetsky monastery,
Kildin Island
autocorrelations lag1, n22, r0,52
(p0,013) lag2, n21, r0,36 (p0,104)
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Atlantic salmon fisheries in the basins of
the White and Barents seas, 17-18th centuries
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Life cycle of Atlantic salmon in the Russian North
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Ancient stone drawing of salmon fishery White
Sea area, 6-7 thousand years ago
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Salmon fishing gear weir at Onega River, middle
of 19th c
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Salmon fishing gear
garva
ostroga
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Studied Atlantic salmon fisheries
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Catches of Atlantic salmon, number
Autocorrelations lag1, n29, r0,31,
(p0,101) lag2, n24, r0,51, (p0,010)
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Significant autocorrelations tell as about
non-random changes in catches. What are
potential reasons of such changes?
Variation in recruitment, and therefore, in
abundance of adult fish consequences - positive
correlation with temperature with some lag -
about ten years for cod and halibut and about
five for salmon - positive correation with
abundance of other populations from the north of
the distribution range - negative
correlation with populations from south of
species distribution range
Variation in migration patterns, and therefore,
in availability for coastal fisheries (cod and
halibut) consequence - negative correlation
with temperature without lag-period (?)
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Correlation of obtained data with available
relevant literature time-series for 17-18th
centuries
Sources Iceland temperatures (Bergtharssen,
1969), Greenland temperatures (Bolsheianov,
2000), Norwegian herring and cod landings
(Qiestad, 1994)
literature time-series
our data
Assessments of confidential levels accounted for
autocorrelations
Introduction of lags gives similar results
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Catches and weight of Atlantic salmon in the
Varzuga district
180000
160000
140000
120000
100000
80000
60000
40000
20000
0
1625
1660
1705
1730
1763
1872
1824
1902
1928
1958
2000
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Number and weight of salmon, caught by
Solovetsky Monastery at various fishing places in
Varzuga district in 1763 (Reference RGADA. F.
1201. Op. 5. D. 4538. L. 9 back -13 back)
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Conclusions
Historical data show - non-random year-to-year
variation in catch sizes of cod halibut and
Atlantic salmon - large variation in average
weight of Atlantic salmon in different
years. In absence of antropogenic influences
these changes must be explained by variation of
natural environmental conditions.
Likely, catches per unit effort of cod halibut
and Atlantic salmon in 17-18th centuries are
positively associated with temperature changes