By Anthony R. Marshak and Stephen K. Brown, National Oceanic and Atmospheric Administration National Marine Fisheries Service, Office of Science and Technology, 1315 East-West Highway, Silver Spring, MD 20910. E-mail: [email protected]; [email protected]
The 2016 releases of the National Marine Fisheries Service (NMFS) Ecosystem-Based Fisheries Management (EBFM) Policy (NMFS 2016a) and Road Map (NMFS 2016b) are shifting fisheries science and management from a traditional single-stock focus toward a more comprehensive approach, requiring a greater understanding of ecological factors that affect fisheries species. Of key importance to these efforts is identifying habitats that are most essential for sustaining living marine resources (LMRs) and understanding the relationships between habitat dynamics and LMR productivity. Since LMRs rely on a mosaic of environments that influence their ecologies throughout their life cycles, habitats are a relevant unit of analysis to help operationalize EBFM. However, relatively few habitats have been characterized in detail and studied in a systematic manner, leaving knowledge gaps that can limit scientific advice and management options.
The Marine Fisheries Habitat Assessment Improvement Plan (HAIP) was created to improve the availability of ecological information for federally managed species and habitats, and is now used to set NMFS’ strategy for pursuing habitat science, developing more robust assessments for scientifically sound management of marine fisheries and their associated habitats, and guiding program priorities (NMFS 2010). In this document, habitat assessment is defined as, “the process and the products associated with consolidating, analyzing, and reporting the best available information on habitat characteristics relative to the population dynamics of fishery species and other living marine resources” (NMFS 2010). The HAIP set out two major goals: 1) improve the identification of essential fish habitat (EFH), and 2) reduce habitat-related uncertainty in stock assessments. Due to a lack of comprehensive data on distribution and abundance of habitat types; limited data on habitat-specific vital rates (e.g., natural mortality), catchability, and movement among habitats; and the complexities of assimilating habitat data into population models, many stock assessments do not explicitly consider habitat information, despite its potential to reduce uncertainty in abundance estimates and in modelling population dynamics.
Presently, much foundational habitat information on species-habitat relationships is still needed to enhance the efficacy of NMFS science in meeting its conservation and management mandates. Because NMFS is responsible for managing nearly 500 stocks, it is necessary to prioritize this work to ensure resources are devoted to the species and habitats for which habitat assessments can provide the greatest potential benefit in terms of improved fisheries management. HAIP-recommended regional habitat assessment prioritizations (NMFS 2011) are helping to focus scientific investigations to address this need. The EBFM Road Map includes the HAIP-based habitat assessment prioritization as a component of a broader ecosystem-level risk assessment to identify taxa and habitats that are most vulnerable to human and natural pressures, with the intent of systematically investigating relationships among priority stocks and habitats.
NMFS has supported habitat assessments (NMFS OST 2017) that led to improved stock assessments and supported the goals of EBFM for several managed species since the 2010 release of HAIP. A well-publicized example is work led by John Manderson and colleagues at the Northeast Fisheries Science Center that examined temperature-dependent fluctuations in Butterfish Peprilus triacanthus habitat to account for shifts in their catch in fishery-independent surveys. Catch data were recalibrated to account for this habitat-related influence on distribution, with the results applied to refining the stock assessment that had previously underestimated their numbers. As a direct result of this study, the Butterfish quota was increased seven-fold, from 3.2 million lb in 2014 to 22.5 million lb in 2015, and the stock was no longer declared as overfished (Adams et al. 2015). Another example is work conducted by Shelton et al. (2014) that integrated spatial habitat and fisheries effort data to improve estimates for West Coast groundfish species. The results of this study have the potential to enhance groundfish stock assessments as well as to provide information relevant to the California Current Integrated Ecosystem Assessment (IEA) combine and separate; (NOAA 2017b). Other examples include studies that improved catchability estimates of Alaska snow crab populations (resulting in an increase in their overfishing limits by 64%), provided habitat-specific growth and productivity rates of juvenile penaeid shrimps in the Gulf of Mexico, as well as habitat assessments for a suite of species including Summer Paralichthys dentatus and Winter Pseudopleuronectes americanus flounder, sardine species, West Coast groundfishes, and Southeast reef fishes—all of which can advance ecosystem modeling and inform EBFM.
Applied understanding of the ecological role of habitat in marine ecosystems through habitat research and assessments can strengthen EBFM implementation. Studies should integrate physical habitat characterizations (including substrate and water column) with the quantification of ecological relationships between habitats and LMRs at the species and multi-species levels. They should also account for physical and biological connections among habitats, since the connections between habitats may be indirect (e.g., through food chains), and the habitat dependencies of fishes change over their life cycles. An important connection for NMFS is between inshore and offshore habitats, because many anthropogenic impacts (including hydropower effects, river diversions, and water quality impairments) extend inland within freshwaters where diadromous species and their prey occur. Additionally, these and many other human factors continue to impact downstream estuarine and coastal areas throughout watersheds, where many nursery habitats are located, while the harvests managed by NMFS primarily take place offshore in federal waters. Multi-scale approaches that address the integral role of habitat from the population to ecosystem level can lead to more holistic assessments of LMRs and facilitate improved design and analysis of fishery-independent surveys, reduced uncertainty in stock assessments, and enhanced EFH designations and ecosystem models. Under an EBFM context, a systematic approach to habitat research is warranted that considers multiple habitats in a given area to better delineate EFH across multiple life stages, species and trophic levels. Improved information on shared habitats among stocks also can be used to reduce bycatch, and a better understanding of habitat disturbance by fishing and other anthropogenic activities can be used to reduce or mitigate effects on local, stock, and ecosystem-level productivity.
Since the publication of the HAIP, NMFS has supported research to improve habitat science and habitat assessments by funding short-term, small-scale projects. Building on these efforts, NMFS is working to enhance support for habitat science through habitat-centric efforts, including NOAA’s Habitat Blueprint (NOAA 2017a), and by increasing habitat information that is available to ecosystem science efforts such as NOAA’s IEA program. Despite limited resources and budgetary challenges, advances in habitat science and in the promotion of habitat conservation continue to be made since the release of the HAIP, and are now being applied in a broader EBFM context. Continued focus on the habitat aspects of ecosystem processes and their associated species will lead to a more complete implementation of an ecosystem approach to management, and provide for the most scientifically sound conservation of our managed species, the ecosystems that support them, and the sustainability of our fisheries.
We thank the Habitat Assessment Improvement Plan coauthors and working group members for their continued efforts to advance habitat science priorities for NOAA and for their input to this article. We additionally thank Jason Link, Rebecca Shuford, and Rebecca Peters for their reviews of earlier drafts.
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NMFS (National Marine Fisheries Service). 2010. Marine fisheries habitat assessment improvement plan. Report of the National Marine Fisheries Service Habitat Assessment Improvement Plan Team. U.S. Department of Commerce, NOAA Technical Memorandum. NMFS-F/ SPO-108. Available: https://www.st.nmfs.noaa.gov/st4/documents/ habitatAssessmentImprovementPlan_052110.PDF. (March 2017).
NMFS (National Marine Fisheries Service). 2011. Habitat Assessment Prioritization. A report by the Habitat Assessment Prioritization Working Group. NMFS, White Paper. Silver Spring, Maryland. Available: https://www.st.nmfs.noaa.gov/ecosystems/habitat/prioritization/ index. (March 2017). NMFS (National Marine Fisheries Service). 2016a. Ecosystem-Based Fisheries Management Policy of the National Marine Fisheries Service, National Oceanic and Atmospheric Administration. Available: http:// www.nmfs.noaa.gov/op/pds/documents/01/01-120.pdf..(March 2017).
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NMFS OST (National Marine Fisheries Service Office of Science and Technology). 2017. Ecosystem Science—Improving the Use of Habitat Information in Stock Assessments. Available: http://www.st.nmfs. noaa.gov/ecosystems/habitat. (March 2017).
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