Environmental Engineering Reference
In-Depth Information
Indicator
Facet of
Other data
Strengths
Drawbacks
sustainability
required
Age/sex/size
Biological,
—
Relatively simple to measure.
Interpretation of results highly problematic,
structure in catch
financial
particularly in absence of comparable data on
sex/age/size structure in population.
Species
Biological,
Trend over time or
Trends in catch composition
Interpretation of point estimates requires data
composition in
financial
expected/actual
can indicate extirpation of
on expected or actual species composition in
catch
composition in
vulnerable species hence lack
catchment. Trends can be masked if catch
ecosystem
of sustainability at ecosystem
comes from areas with different underlying
level.
compositions. Power to detect change may be low.
Catch trend
Biological,
Population size at one
Relatively simple to measure—
Hard to disentangle causality—could
financial
point in time (or trend)
needs to be measured as close
be social-economic changes, effort
and productivity or
to source as possible. Declining
changes or changes in population size,
effort trend
catches may indicate lack of
hence the need for independent data
sustainability if all else is equal.
on these. May be trending towards
Can be normalised for effort if
new equilibrium rather than
data available. Catch as a function
unsustainable.
of population size gives harvest
mortality, which is a direct
measure of sustainability.
Effort trend
Biological,
Catch trend
Declining catch per unit
Without catch data, cannot be interpreted due to
social,
effort (CPUE) can indicate
range of potential causes. CPUE does not
financial
depletion. Relatively easy to
always have a linear relationship with population
obtain these data.
size. Effort is multi-faceted, and can be hard to
find a suitable metric for.
