Fish Population Dynamic and Stock Assessment

1.7.5. Inclusion criteria

It is also critical that data include species that:

· are directly impacted

· have high turnover rates, which may provide a noisy but early warning;

· define the habitat, as these often have a disproportionate or keystone role in the system; and

· are from the upper trophic level, which are typically both vulnerable in their own right due to their life history characteristics, but also integrative of pressures and patterns at large scales.

· There is likely to be differential signal strength in pelagic and demersal system as pelagic systems are easier to characterize (require fewer parameters), but are more variable leading to longer periods before trends are detected. Concerns regarding the availability of extended time series at a single location may be addressed by considering snapshots at multiple different locations under differential perturbation (e.g., fishing) pressure, so that it will still be possible to get a gradient and contextualiation for any individual location. Caution may be necessary in such a situation though, as there may be problems if a changing environmental (or other) effect is masking the fishing effect.