REPORT OF THE WORKING GROUP ON FISH ECOLOGY (WGFE)

The proportion of large fish (community abundance ratio of large fish to all fish) is apromising yet still untested (via simulation) ecosystem quality indicator (EcoQO).Management advice based on this EcoQO may preserve many desirable qualities offish communities (e.g. trophic balance) but not necessarily all of them; therefore, thedesired community qualities (management objectives) should be clearly stated insimulation testing to determine the utility of the proportion of large fish forpreserving them.• A clear community response to community exploitation rate is not obvious fromempirical analyses. It may be also that exploitation rates vary with a community’spotential to support fisheries.• Simulation is perhaps the only tool currently available to adequately test thesensitivity, responsiveness and specificity of most community indicators.• Geostatistical methods were explored for their ability to complement mappingmethods in the examination of abundance-occupancy relationships (Section 3.4)• Although WGFE feels that essential fish habitat issue are very important and a keywork area for the group, it is still not clear how to define essential fish habitat in acontext useful for management. General functional habitat categories have beendescribed but it is not clear what kind of specific advice science should currentlyoffer on protecting habitats fitting in one or more of these categories.• WGFE recognises a need to liaise with other working groups to build upon activitiesin the areas of habitat mapping, with respect to both maps of abiotic habitatparameters and biotic components (e.g. WGMHM). These broadscale maps arefundamental to relating the distribution of fish to the distribution, structure andfunction of sea floor habitats, and for identifying important fish habitats.• Because most WGFE work considers fish communities at the scale of entire seas andnot coastal fish communities, it is not well equipped to deal issues related specificallyto nearshore fish communities namely issues of the Water Framework Directive.Though WGFE has sometimes been successful at including relevant specialists fromthis domain into its meetings, it has proven difficult to maintain the expertise as mostof the other work of WGFE is of limited interest to estuarine ecologists and theirrespective institutions. Therefore WGFE recommends that the Diadromous FishCommittee and/or Living Resources Committee give consideration to forming agroup specifically to examine estuarine ecosystems and transitional waters. WGFEcould then liaise with this group on questions related to EcoQOs.