Stocks status of kilka in Iranian waters of the Caspian Sea

Abstract

The present study considered the situation of kilka stocks in last decades by using overfished biomass threshold, fishing effort ratio and fishing mortality proxy during 1991-2010. The CPUE index of anchovy and mixed-species of kilka indicated an undepleted from 1991 to 2000. In 2000, the CPUE ratio declined to close to the “in danger" region, and subsequently collapsed to “overfished" region from 2001 to 2007 for both of anchovy and mixed-species of kilka. The CPUE ratios of common kilka have been in an overfished state during 1991-2003. During 2008-2010 the biomass increased and the CPUE ratio of common kilka and mixed-species moved to not overfished region. The control rule of anchovy kilka showed that overfishing was occurring from 1998 to 2010, ovefishing-effort was exceeded the overfihing threshold (MFMT) by 12-66%. The trajectory of the phase-plot of biomass proxy (CPUE ratio) and fishing mortality proxy (Effort ratio) of anchovy kilka showed that the status of the fishery of anchovy kilka has generally declined since 1998 collapsed to lowest level in 2010. The trajectory for common kilka has generally increased since 1991 which it was closed to the fisheries management target in 2007. In conclusion, in the new condition, common kilka is the main species in the Caspian Sea. For stock recovery of anchovy kilka, the catch of kilas must be restricted during reproduction periods, and also, a coordinated international effort is needed.