LCA Food 2012 in Saint Malo, France! - Manifestations et colloques ...

PARALLEL SESSION 6B: FISHIERIES, SOIL, AND EMERGY METHODS 8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
2011). Meta data was selected for stock assessments between 1995-2010 regarding 42 out of 54 major European
stocks for which complementing BMSY values could be found (Froese and Proelß 2010). The FMSY and
BMSY reference values are consensus values, i.e. averages values based on three modelling approaches; 1) a
demographic yield per recruit analysis 2) a surplus production analysis and 3) a stock recruitment analysis
with corresponding confidence intervals (Froese and Proelß 2010). They are intended by the authors to be
updated every five years with the original assessment based on time series data up until 2008 (Froese et al.,
2011). Projection calculations were performed in the free statistical computing software R (www.rproject.org).
4. Results
All characterisation factors showed varied between stocks and years although 2010 are considered the main
dataset. For an overview the stocks during 2010 could be aggregated into species generalised factors, se fig.
1. However, the variation within species groups is considerable: with a coefficient of variation (CV) of 1.2
for WPY and 1.0 for both F-Overfishing and B-Overfishedness, regarding all species groups with 3 or more
stocks represented.
Figure 1. Characterisation of 2010 values of F-Overfishing (black), B-Overfishedness (grey) and Wasted
Potential Yield (dotted) ranked according to their common mass based indicator. Brackets indicate number
of stocks included. Y-axis measures lost catch in kg. Fish illustrations: FAO
Cod stocks were in worst shape in terms of wasted potential yield followed by plaice and whiting stocks,
which are all demersal (ground dwelling) species relatively far up in the trophic chain. The five best placed
species in relation to biotic resource use were all pelagic species of typically smaller body mass and mean
trophic level. Horse mackerel (one stock) placed midrange but negative F-Overfishing and B-Overfishedness
suggested that this score relates to under exploitation, all other species groups are subjects of missed yield
due to overexploitations in various extents.
5. Discussion
A Schaeffer projection of an aggregated stock biomass is not the state of the art projection of fish stock used
today to set exploitation quotas, even though it’s still frequently used to describe the main principals of exploitation
dynamics (Jennings et al., 2001). But it has been shown a useful tool for characterising the importance
of metadata retrieved from state of the art stock assessments, combining measurements of present exploitation
rate and the present state of biomass with MSY limits. We judge that it is sufficiently accurate for
general comparison between stocks and years in an LCA’s context for broad picture management. A central
limitation is that only the largest and most commercially important stocks will have sufficient data documentation,
rendering it practically useless for bycatches; however other completing methods for assessing bycatch
exist and could in future be completed with vulnerability indices.
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