Evaluating the utility of a Novel Harvest Control Rule in the management of long-lived sporadically recruiting species through Management Strategy Evaluation

• Main Author: Kelly, Cian
• Format: Master Thesis
• Language: English
• Published: The University of Bergen 2019
• Subjects: HCR; simulation modelling; Blim; Btrigger; SSB; FLBEIA; MSE; Ftarget; 751999; Barents Sea; Greenland; Atlantic salmon; Salmo salar
• Online Access: http://hdl.handle.net/1956/20734

Fish species that exhibit sporadic recruitment, late maturity and that are long-lived, can be difficult to manage. The issue arises from the high variability in stock dynamics. Where there are significant interannual fluctuations in biomass, it is difficult to harvest the population in a sustainable manner, avoiding stock collapse while maintaining high yields and catch stability. The aim of this project was to inform the management of species with the above stock characteristics through computer simulation of two Harvest Control Rules (HCRs) using Management Strategy Evaluation (MSE). MSE is a method used to simulate the performance of different management strategies under different criteria. HCRs are the flexible management rules which convert biological information into catch advice. Both management tools have become increasingly common in fisheries management. Escapement HCRs are most commonly used for the conservation of the spawning population in short-lived species such as Atlantic salmon (Salmo salar). In this study, the utility of a Novel HCR, which reflected an Escapement HCR, was tested on a stock whose dynamics was informed by Greenland halibut (Reinhardtius hippoglossoides). The Novel HCR was formulated to conserve the biomass from spikes in recruitment of a long-lived species, by exclusively targeting the fraction of biomass above a threshold biomass level. The performance of this Novel HCR was compared to a traditional ‘hockey-stick’ ICES HCR through MSE using the FLBEIA model in R software. The model results indicated that there were trade-offs between the two HCRs. The Novel HCR provided relatively high yields with low risk of stock collapse, but came at the cost of a high fraction of moratoria and high interannual variability in catches. Depending on the management objectives, the Novel HCR can be successfully used in the sustainable exploitation of long-lived species with sporadic recruitment. The results of this paper will help to inform the management of Greenland halibut in the Barents Sea. ...