American Fisheries Society 141st Annual Meeting
“New Frontier in Fisheries Management and Ecology: Leading the Way in a Changing World”
September 4-8, 2011
Ellen K. Pikitch: “Global Management of Forage Fish: Advice from the Lenfest Forage Fish Task Force” (Keynote) -
Panel Session “Global Conservation, Trophic Relationships and Ecology of Forage Fish in Marine Ecosystems”
Wednesday, September 7, 2011: 8:00 a.m. - 5:15 p.m.
618 (Washington State Convention Center)
Forage fish are, in many ecosystems, the foundation of the marine food web and a critical prey source for marine mammals, seabirds, and higher trophic level fish. They also account for nearly 40% of global wild marine fisheries catch, much of which is processed into fishmeal and fish oil for animal feeds. Most forage fisheries are managed with traditional single species approaches, designed to maximize fisheries yields. However, a growing body of scientific evidence indicates that forage fisheries, which commonly exhibit large population fluctuations in response to environmental variables, should be managed with an ecosystem-based approach, to sustain the other organisms that depend upon them while maintaining long-term economic benefits. A reduction in available prey-- due to fishing, environmental conditions, or a combination of both-- can have direct and lasting impacts on predator species. As fishing pressure on forage species is sustained or intensified, it will be critical to set fishing limits that account for the interconnected species and environmental variables affecting forage fish.
The Lenfest Forage Fish Task Force was established to address the need for practical guidance in implementing an ecosystem-based approach for forage fisheries. Presented here is an overview of the task force’s work, including new scientific revelations into the ecological consequences of forage fish removals. The task force developed several quantitative methods to gain a greater understanding of where forage fish are most important, and how various management strategies impact forage fish populations and predators. This presentation will review those methods and results, culminating in a set of practical, science-based recommendations that can be implemented in ecosystems with any level of scientific information or knowledge. Precautionary and ecosystem-based approaches to the management of forage fish are necessary to maintain their ecological role as prey under changing environmental and human conditions, and the Lenfest Forage Fish Task Force recommendations are an important first step in achieving this goal.
Konstantine J. Rountos: “Global Contributions of Forage Fish to World Fisheries and Ecosystems” (Panelist) - Panel Session “Global Conservation, Trophic Relationships and Ecology of Forage Fish in Marine Ecosystems”
Wednesday, September 7, 2011: 9:30 a.m.
618 (Washington State Convention Center)
Forage fish are pivotal to marine ecosystems and coastal economies around the world in a variety of ways. First, forage fish are valued as direct fisheries catch, representing some of the largest fisheries in the world. They also provide an important ecological support service as prey for higher trophic predators. This research is aimed at increasing our global understanding of how valuable forage fish are in marine ecosystems—both economically and ecologically. In order to quantify this, we conducted a meta-analysis of 72 Ecopath models from around the world, representing a wide variety of ecosystem types and latitudes. We examined three distinct roles of forage fish: 1) As an economic commodity (direct catch); 2) As prey for larger fish species that are commercially harvested; and 3) As prey for non-commercial predators. Here, we present the results in terms of both monetary value and catch volume, and identify patterns across latitudes and ecosystem types (e.g. upwelling ecosystems, tropical lagoons, Arctic ecosystems). These results show where forage fish are most important, and provide information that managers can use in addressing the tradeoffs between catching forage fish and leaving them to fulfill their ecological role.
Anna R. Webb: “Detecting Potential Population Trends in Non-Commercial Northeast Species
Full list of co-authors: Anna R. Webb, Ellen K. Pikitch, Adrian Jordan, Michael G. Frisk
Tuesday, September 6, 2011: 8:30 a.m.
614 (Washington State Convention Center)
Direct overfishing is not the only concern of global fisheries. Bycatch, habitat loss, food web alterations, and shifts in diversity and community composition are all potentially indirect effects on populations of both target and non-target species. The status of non-commercial species is largely unknown as management focus remains on linking changes in community and ecosystem disturbances to commercial populations for which sufficient data exists. The National Marine Fisheries Service Northeast groundfish bottom-trawl survey datasets were analyzed to address potential population fluctuations in commonly-encountered non-commercial species. A power analysis using data from the fall time-series (1963-2006) was conducted to determine the ability to identify significant declining trends within the next 10 or 15 years. Potential declining trends were chosen from IUCN A1 criteria stating that a 30%, 50%, or 70% decline over the longer of 10 years or 3 generations is sufficient to label a species as vulnerable, endangered, or critically endangered, respectively. Results indicated an overall low power for most species, and a strong divergence between unassessed and assessed species with much greater percentages of assessed species exhibiting a power greater than 0.6. The low power was caused by the high variance in the time-series trend for many species, and indicates that the survey trends cannot be confidently used alone as indicators of population status. However, some species were in a current period of significant decline as identified by a breakpoint and correlation analysis, and thus, still likely require management attention. Additionally, alternative methods to gather data on these species or surveying on a finer spatial and temporal scale may shed more light on population fluctuations within unassessed species and will contribute greatly to successful implementation of ecosystem-based fishery management.
Tuesday, September 6, 2011: 8:15 a.m.
4C-1 (Washington State Convention Center)
Adrian Jordaan: “Bycatch, Biodiversity and Understudied Species in the Northwest Atlantic”
Full list of co-authors: Adrian Jordaan, Anna R. Webb, Ellen K. Pikitch, Adrian Jordan, Michael G. Frisk
Recognition of bycatch impacts on sustainability of fisheries combined with an impetus for ecosystem approaches to management has created the need for improved understanding of traditionally understudied species. Bycatch events on unassessed species registered by the northeastern US observer program between 2003 and 2006 from bottom trawl, mid-water trawls, drift gillnet and sink gillnet fisheries were identified. National Marine Fisheries Service (NMFS) trawl data was analyzed to determine the geographic range of unassessed species in the last 10 years of the survey. Concentrations of capture events determined from observer data were compared to the NMFS survey generated distributions. We then focused on bottom trawls from both the observer and NMFS survey data for the Gulf of Maine, Georges Bank and the Mid-Atlantic regions, and species for which adequate data existed to determine a population trend. Trends in population decline from NMFS survey data were correlated to frequency of capture and total weight in the observer data. Spatial overlap in bycatch events and population abundance were determined, and locations of particularly high potential bycatch of unassessed species identified. Fish assemblage structure and migratory patterns were important in shaping results, as was observer coverage. The results will be placed into context by focusing on ecological approaches to fisheries, geographically-based management and protection of biodiversity.