Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 8819
Title: Evaluation of robust single-species harvest control rules for managing reef fish in the Gulf of Mexico
Author: Michelle Masi, C. H. Ainsworth, I. C. Kaplan, M. J. Schirripa
Publication Year: In press
Journal: Marine and Coastal Fisheries
Keywords: Gulf of Mexico,harvest control rule,Ecosystem base management,multi-species,Atlantis ecosystem model,

This study highlights the importance of inter-specific interactions among marine organisms and the effect that these trophic interactions have on the development of effective, adaptive management strategies for reef fishes in the Gulf of Mexico. To represent the spatially and temporally constrained, inter-specific interactions among reef fishes we employ Atlantis (a spatially explicit, biogeochemical ecosystem model) as our simulation tool. Within Atlantis, we evaluate the performance of a 2-point harvest control rule that adaptively increases fishing mortality linearly between upper and lower biomass thresholds based on the available biomass of the stock(s). This example demonstrated the use of a ¿blanket¿, 2-point HCR that assesses the available biomass of several reef fish species (often co-caught in fishing gear) both simultaneously and objectively. To estimate the impact of reef fish fishing on species abundance and biodiversity in the ecosystem, we examine four ¿low¿ and four ¿high¿ fishing mortality scaler scenarios. All model projections are forward-looking, representing a fifty-year time horizon (2010 to 2060). We evaluate the performance of the 2-point harvest control rules under the eight fishing mortality scenarios using ecosystem metrics that were previously found to robustly track changes in ecosystem function caused by fishing. We found that the lower F scenarios produced an ecologically distinct ecosystem state compared to the higher F scenarios, where relatively higher levels of fishing mortality (particularly on predators such as the Deep Serranidae group) resulted in an increase in prey availability in later years of the simulation. This led to an increase in the overall productivity of the ecosystem over time, and higher catch and biomass of most other reef fish groups at equilibrium (year 50). Our results suggest that a better understanding of inter-specific interactions among targeted reef fishes and their prey is critical to developing ecosystem-based management strategies for the Gulf of Mexico. 

Theme: Ecosystem approach to improve management of marine resources
Foci: Provide scientific support for the implementation of ecosystem-based management
Characterize ecological interactions (e.g. predation, competition, parasitism, disease, etc.) within and among species.