Total marine fisheries extractions by country in the Baltic Sea

Catch (t x 10³)
Thousands
Thousands
236 Total marine fisheries extractions by country in the Baltic Sea: 1950-present, Rossing, Booth and Zeller
for each year was applied to the total population number to derive a complete time series of number of
recreational fishers. For example, the number of fishers in 1975 was 2 million, and given a total Swedish
population of 8.2 million, the percentage of recreational fishers was 24.4%.
The above recreational surveys were used to derive effort estimates (number of fishing days per fisher per
year), and a recreational catch rate per fisher per day. The number of recreational fishing days in 1975 was
25 million, which implies that the average number of fishing days per fisher in 1975 was 12.5. The
recreational catch in 1975 was 13,334 t, which gives a catch rate of 0.00053 t∙fisher -1 ∙day -1 . The 1975
number of fishing days and catch rate per fisher were carried back fixed to 1950. Thus, the recreational
catch per year from 1950-2007 was estimated as the product of estimated number of recreational fishers,
their average fishing time in days, and daily catch rate. The species specific catch for each study was used
to derive a fraction of total recreational catch per species where it was possible. These fractions were then
interpolated and applied to the calculated total recreational catch.
RESULTS
The present results represent a first attempt at assumption-based reconstruction of total catch time series
for Swedish fisheries in the Baltic Sea, from 1950-2007. Presented are data by species for the major
species, followed by examination of recreational catch estimates, and total estimates for Sweden. When
considering total reconstructed catch in comparison to official reported landings of species, the
reconstructed catch has been compared to the official landings data as defined for the present purposes,
namely ICES landings statistics. For time series data of each category by species, see Appendix Tables A1-
A9. For results presented by IUU components (rather than by species) see Appendix B.
Cod
ICES landings statistics for Swedish cod landings decreased from approx. 22,000 t∙year -1 during the 1950s
to around 17,000 t∙year -1 during the 1970s, and thereafter increased substantially to about 51,000 t∙year -1
during the 1980s with the all time high reported landings by ICES landings statistics in 1984 of almost
66,000 t (Figure 2a). ICES landings statistics for cod declined rapidly in the early 1990s, and in the last
five years averaged about 13,000 t∙year -1 (Figure 2a, Appendix Table A2).
ICES landings statistics were adjusted by around 3%,
mainly using adjustments from 1965-1975 from ICES
stock assessment working group report data (Figure 2a).
The adjustments resulted in raising reported landings to
around 23,000 t∙year -1 during the 1960s and around
18,000 t∙year -1 during the 1970s (Figure 2a, Appendix
Table A2).
Prior to the 1980s, unreported landings of cod were
estimated to be relatively small, averaging around 2,000
t∙year -1 (Figure 2b). From 1980 until the 2000s,
estimated unreported landings of between 3,000 and
17,400 t∙year -1 made up a large proportion of
unaccounted catches (Figure 2b). In more recent years,
unreported landings of cod for Sweden have declined to
around 1,900 t∙year -1 (Figure 2b; Appendix Table A2).
During the 1950s to 1970s, discards ranged between
1,900 and 3,400 t∙year -1 (Figure 2b). During the 1980s
discards increased to an average of around 7,100 t∙year -1 ,
however, discarding behavior remained stable in
relation to landings from 1950-1996 due to
conservatively assumed fixed discard rate and thereafter
varied year to year. In the last five years, the discards
were the largest component of the unaccounted catches,
with average discards of 2,500 t∙year -1 (Figure 2b).
70
60
50
40
30
20
10
0
a)
Adjustments
ICES landings statistics
100
1950 1960 1970 1980 1990 2000
b)
90
Recreational
80
70
Discards
60
50
Unreported
40
30
20
10
ICES landings statistics + adjustments
0
1950 1960 1970 1980 1990 2000
Year
Figure 2. Swedish cod landings in the Baltic Sea: a) ICES
landings statistics and adjustments; b) Sweden‘s
reconstructed cod catches in the Baltic Sea.