Fishery Bulletin 108(3) 
312 
Table 2 
Susceptibility attributes and rankings used to determine the vulnerability of a stock becoming overfished 
Susceptibility attribute 
Definition 
Areal overlap 
The extent of geographic overlap between the known distribution of a stock and the distribution 
of the fishery. 
Geographic concentration 
The extent to which the stock is concentrated into small areas. 
Vertical overlap 
The position of the stock within the water column (i.e., whether is demersal or pelagic) in 
relation to the fishing gear. 
Seasonal migrations 
Seasonal migrations (i.e. spawning or feeding migrations) either to or from the fishery area 
could affect the overlap between the stock and the fishery. 
Schooling, aggregation, and other 
behavioral responses 
Behavioral responses of both individual fish and the stock in response to fishing. 
Morphological characteristics 
affecting capture 
The ability of the fishing gear to capture fish based on their morphological characteristics (e.g., 
body shape, spiny versus soft rayed fins, etc.). 
Desirability or value of the fishery 
The assumption that highly valued fish stocks are more susceptible to overfishing or to becoming 
overfished by recreational or commercial fishermen owing to increased effort. 
Management strategy 
The susceptibility of a stock to overfishing may largely depend on the effectiveness of fishery 
management procedures used to control catch. 
Fishing rate relative to M 
As a conservative rule of thumb, it is recommended that M should be the upper limit of F so as 
to conserve the reproductive potential of a stock. 
Biomass of spawners (SSB) 
or other proxies 
The extent to which fishing has depleted the biomass of a stock in relation to expected unfished 
levels offers information on realized susceptibility. 
Survival after capture and release 
Fish survival after capture and release varies by species, region, and gear type or even market 
conditions, and thus can affect the susceptibility of the stock. 
Impact of fisheries on essential fish 
habitat or habitat in general for 
nontargeted fish 
A fishery may have an indirect effect on a species by adverse impacts on habitat. 
a high-risk evaluation either from an abundance of (Table 3). The data-quality score is computed for the 
missing data or from the risk assessment of the avail- productivity and susceptibility scores as a weighted 
able data, with the result that the risk scores may be average and implies the overall quality of the data or 
inflated (Hobday et al. 1 ). In contrast, we considered belief in the score rather than the actual type of data 
missing data within the larger context of data quality, used in the analysis. Like Hobday et al. 2 , we divided 
and report the overall quality of data as a separate the data-quality scores into three groupings (poor >3.5; 
value. moderate 2. 0-3. 5; and good <2.0) for display purposes. 
A data-quality index was developed to represent the This information, along with more detailed descrip- 
information quality of individual vulnerability scores tions of data quality (e.g., mean score, range), is a 
based on five tiers, ranging from best data (or high be- quick and useful means of providing decision-makers 
lief in the score) to no data (or little belief in the score) with details on the uncertainty of the vulnerability 
