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Fishery Bulletin 109(2) 
Residual 
Figure 5 
Composite distributions of log-deviations from the mean, pooled for four meta- 
analytic groupings (rockfish, roundfish, flatfish, and coastal pelagic species). 
remains an active field of research. This fact is reflected 
by the range and changes over time in the ways that 
risk and uncertainty have been represented in fisheries 
assessments (see reviews by Francis and Shotton, 1997, 
and Patterson et ah, 2001). 
Our characterization of uncertainty does not include 
variability attributable to sources other than terminal- 
year biomass, which would tend to lead to negatively 
biased estimates of scientific uncertainty. Procedures 
for incorporating forecast uncertainty have been de- 
veloped (Shertzer et al., 2008) and could be blended 
with our approach. Likewise, there is fertile ground to 
be explored with respect to uncertainty in F MSY . Dorn 
(2002), for example, has developed a Bayesian prior for 
rockfish spawner-recruit steepness (h) that expresses 
uncertainty in estimates of stock productivity (see also 
Brooks et ah, 2010). Because steepness maps almost 
directly onto F MSY over a diverse range of groundfish 
life history patterns (Punt et al., 2008), a distribution 
of fishing mortality rates could be developed by math- 
ematical composition of these functions, conditioned 
on the form of the stock-recruitment relationship. We 
assumed that estimates of F MSY have negligible error 
and, as a consequence, uncertainty in OFL arises only 
from uncertainty in biomass estimates — an obvious 
simplification. 
Although we elected to characterize uncertain- 
ty by analyzing variability in biomass estimates 
from historical stock assessments, an alternative 
approach might be to use decision table results, 
which are a required element in groundfish stock 
assessments. Specifically, the PFMC terms of ref- 
erence for groundfish assessments 2 require the 
development of a decision table for use in charac- 
terizing uncertainly in stock assessments. The 
guidance states the following: 
Once a base model has been bracketed on either 
side by alternative model scenarios, which cap- 
ture the overall degree of uncertainty within 
the assessment, a 2-way decision table analysis 
(states-of-nature versus management action) is 
the preferred way to present the repercussions of 
uncertainty to management. An attempt should 
be made to develop alternative model scenarios 
such that the base model is considered twice as 
likely as the alternative models, i.e., the ratio of 
probabilities should be 25:50:25 for the low stock 
size alternative, the base model, and the high 
stock size alternative. 
