Multispecies Size Composition: A Conservative Property of Exploited Fishery Systems?

摘要: During the past three decades species composition and abundance of finfishes on Georges Bank has changed dramatically, as measured by standardized trawl surveys fishery performance data. Notwithstanding dramatic shifts in composition, aggregate size (normalized numbers-at-length) remained relatively stable. The descending limb numbers-at-length curve estimates weighted average rates survival growth (cumulative energy transfer) from one length category to next. Observed changes slope can be correlated with various stanzas exploitation regime. Similar studies other temperate ecosystems indicate much different characteristic slopes catch-at-length curves. conservation within may indicative size-based trophic interrelationships that tend buffer fish production at against perturbations particular and/or components highly-networked food webs. If such feedback mechanisms exist, they have important implications for development long-term multispecies management policy. A modelling approach is outlined, along data requirements analyses.