Aquatic Environment and Biodiversity Annual Review 2012

AEBAR 2012: Non-protected bycatch
Figure 5.15 (reproduced from Richard et al. 2011): Risk ratio (total annual potential fatalities / PBR) for
each of the studied taxa except black-browed albatross. The risk ratio is displayed on a logarithmic scale.
The threshold where the number of potential bird fatalities equals the PBR is presented by the vertical
black line. The bars indicate the 95% confidence intervals of the distributions. Taxa are sorted in
decreasing order of the lower confidence level of the risk ratio.
Many limitations were identified in the risk assessment. These may result in biased estimates (either
too high or too low) of the risk of fishing to some seabirds. Moreover, some fisheries were not
included in our analysis, and other sources of human-induced mortality were ignored. The conclusions
of our results should therefore be interpreted with caution, as some taxa might be at risk, even if their
risk ratio was estimated to be lower than one. Conversely, the fisheries-related fatalities may be
overestimated in poorly observed fisheries because the method is designed to answer the question
“how bad could it be?” (e.g., Figure 5.16 which shows the results of different estimation approaches
and questions). The method assumed a high number of captures in the absence of data to the contrary,
so the estimated potential fatalities in poorly-observed fisheries may be higher than the actual
fatalities.
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