Evolution of effort and the efficacy of input controls in controlling fishing mortality in the Icelandic female lumpsucker (Cyclopterus lumpus) gillnet fishery

The female lumpsucker (Cyclopterus lumpus) gillnet fishery in Iceland has been managed exclusively through input controls for several decades. The present study assessed how different components of total effort have changed from 1985 to 2024 and how different components of effort influenced an estimate of relative fishing mortality (F_proxy). F_proxy could be predicted from a combination of the number of boats participating in fishery, the average number of gillnets hauled per day, the average number of fishing days utilised in the season and an index of under/over estimation of the biomass index. Time period was also included in the model as there was a change in the catch per unit effort (CPUE) at a given level of biomass index from 2004 to 2005 when limits on the number of fishing days pre boat was introduced. The number of boats with a licence to participate in the fishery currently exceeds the capacity of the fishery, thus if the number of boats were to rise to historical highs, then F_proxy would rise above the management target. Total catch is primarily managed through the number of consecutive days a boat can fish for, however, the number of boats has a greater impact on fishing mortality than the number of fishing days. We present a model which can predict F_proxy for a given level of effort, but this requires the number of boats which will participate in the fishery to be known. In terms of maintaining fishing mortality within sustainable limits, the effort system could be considered to be successful. However, the management of this fishery is now changing to an output-controlled fishery, but the experience from this fishery serves as a good model for other fisheries where management systems have a limited capacity to control catch.