Michael J. Fogarty

Integrated ecosystem assessments: developing the scientific basis for ecosystem-based management of the ocean.

Integrated ecosystem assessments challenge the broader scientific community to move beyond the important task of tallying insults to marine ecosystems to developing quantitative tools that can support the decisions national and regional resource managers must make.

Managing for ocean biodiversity to sustain marine ecosystem services

Managing a complex ecosystem to balance delivery of all of its services is at the heart of ecosystem-based management. But how can this balance be accomplished amidst the conflicting demands of stakeholders, managers, and policy makers? In marine ecosystems, several common ecological mechanisms link biodiversity to ecosystem functioning and to a complex of essential services. As a result, the effects of preserving diversity can be broadly beneficial to a wide spectrum of important ecosystem processes and services, including fisheries, water quality, recreation, and shoreline protection. A management system that conserves diversity will help to accrue more “ecoservice capital” for human use and will maintain a hedge against unanticipated ecosystem changes from natural or anthropogenic causes. Although maintenance of biodiversity cannot be the only goal for ecosystem-based management, it could provide a common currency for evaluating the impacts of different human activities on ecosystem functioning and can...

Pathways between Primary Production and Fisheries Yields of Large Marine Ecosystems

The shift in marine resource management from a compartmentalized approach of dealing with resources on a species basis to an approach based on management of spatially defined ecosystems requires an accurate accounting of energy flow. The flow of energy from primary production through the food web will ultimately limit upper trophic-level fishery yields. In this work, we examine the relationship between yield and several metrics including net primary production, chlorophyll concentration, particle-export ratio, and the ratio of secondary to primary production. We also evaluate the relationship between yield and two additional rate measures that describe the export of energy from the pelagic food web, particle export flux and mesozooplankton productivity. We found primary production is a poor predictor of global fishery yields for a sample of 52 large marine ecosystems. However, chlorophyll concentration, particle-export ratio, and the ratio of secondary to primary production were positively associated with yields. The latter two measures provide greater mechanistic insight into factors controlling fishery production than chlorophyll concentration alone. Particle export flux and mesozooplankton productivity were also significantly related to yield on a global basis. Collectively, our analyses suggest that factors related to the export of energy from pelagic food webs are critical to defining patterns of fishery yields. Such trophic patterns are associated with temperature and latitude and hence greater yields are associated with colder, high latitude ecosystems.

Predicting climate effects on Pacific sardine.

For many marine species and habitats, climate change and overfishing present a double threat. To manage marine resources effectively, it is necessary to adapt management to changes in the physical environment. Simple relationships between environmental conditions and fish abundance have long been used in both fisheries and fishery management. In many cases, however, physical, biological, and human variables feed back on each other. For these systems, associations between variables can change as the system evolves in time. This can obscure relationships between population dynamics and environmental variability, undermining our ability to forecast changes in populations tied to physical processes. Here we present a methodology for identifying physical forcing variables based on nonlinear forecasting and show how the method provides a predictive understanding of the influence of physical forcing on Pacific sardine.

Application of a Yield and Egg Production Model Based on Size to an Offshore American Lobster Population

Abstract We estimated size-specific growth, maturation, yield, and egg production per recruit for an offshore population of American lobster Homarus americanus. The yield and egg production model explicitly considered individual variability in growth. The model also incorporated the interaction between the growth and reproductive cycles of mature females and accommodated molt-related mortality for males and females. Growth rates of offshore American lobsters considerably exceeded estimates for inshore populations; yield and egg production per recruit were correspondingly higher. Simulations indicated that yield per recruit was maximized at low levels of fishing mortality for both males and females. Inclusion of molt-dependent mortality in these simulations resulted in lower levels of yield per recruit and less convex yield curves for both sexes. At high levels of fishing mortality, changes in the predicted mean size of the catch became small, indicating that detecting increases in mortality rates from siz...

Role of egg predation by haddock in the decline of an Atlantic herring population

Theoretical studies suggest that the abrupt and substantial changes in the productivity of some fisheries species may be explained by predation-driven alternate stable states in their population levels. With this hypothesis, an increase in fishing or a natural perturbation can drive a population from an upper to a lower stable-equilibrium population level. After fishing is reduced or the perturbation ended, this low population level can persist due to the regulatory effect of the predator. Although established in theoretical studies, there is limited empirical support for predation-driven alternate stable states in exploited marine fish populations. We present evidence that egg predation by haddock (Melanogrammus aeglefinus) can cause alternate stable population levels in Georges Bank Atlantic herring (Clupea harengus). Egg predation by haddock explains a substantial decoupling of herring spawning stock biomass (an index of egg production) from observed larval herring abundance (an index of egg hatching). Estimated egg survival rates ranged from <2–70% from 1971 to 2005. A population model incorporating egg predation and herring fishing explains the major population trends of Georges Bank herring over four decades and predicts that, when the haddock population is high, seemingly conservative levels of fishing can still precipitate a severe decline in the herring population. These findings illustrate how efforts to rebuild fisheries can be undermined by not incorporating ecological interactions into fisheries models and management plans.

Are exploited fish populations stable

Shelton and Mangel (1) examined patterns of variability in fish populations and concluded that the higher stock variability observed in exploited species results from heightened effects of stochastic forcing in the supposed absence of nonlinear dynamics. In contrast, Anderson et al. (2) found that higher variability in these stocks is attributable to amplified nonlinear behavior in noisy ecological systems under exploitation. Here, we reconcile these apparently conflicting views and demonstrate that stochasticity of demographic parameters directly enhances nonlinearity (2–4), thus challenging assessments of stability based on statistical fits to noise-free models.

Metapopulation dynamics of coastal decapods

Publisher Summary This chapter adopts a more general definition of metapopulation as a number of populations distributed over space, linked through dispersal processes. Marine decapod crustaceans, such as lobsters, crabs, and shrimp, support important fisheries from tropical to polar seas. The high unit value of decapods and their longstanding importance in coastal fisheries have provided powerful incentives for scientific study of their ecology and population dynamics. Observed spatial patterns of benthic life stages, larval dispersal mechanisms, genetic structure, and the level of synchrony in fluctuations in abundance are consistent with underlying metapopulation structures for the decapods considered in the chapter. Although there is sufficient evidence to conclude that metapopulation structure and dynamics are important in decapod populations and that marine reserves may be particularly appropriate for species with their life history, a complete understanding of decapod metapopulation dynamics is still faraway. The dynamic behavior of metapopulations depends on tendencies in local single population behavior and the connectivity among these populations.

Combining stock, multispecies, and ecosystem level fishery objectives within an operational management procedure: simulations to start the conversation

Original Article Combining stock, multispecies, and ecosystem level fishery objectives within an operational management procedure: simulations to start the conversation Sarah K. Gaichas*, Michael Fogarty, Gavin Fay, Robert Gamble, Sean Lucey, and Laurel Smith NOAA NMFS Northeast Fisheries Science Center, 166 Water Street, Woods Hole, MA 02543, USA School for Marine Science and Technology, University of Massachusetts Dartmouth, 200 Mill Road, Fairhaven, MA 02719, USA *Corresponding author: tel: þ1 508 495 2016; fax þ1 508 495 2258; e-mail: sarah.gaichas@noaa.gov

Drivers of euphausiid distribution and abundance in the Northeast U.S. Shelf Large Marine Ecosystem

Drivers of euphausiid distribution and abundance in the Northeast U.S. Shelf Large Marine Ecosystem Michael R. Lowe*, Gareth L. Lawson, and Michael J. Fogarty Biology Department, Woods Hole Oceanographic Institution, 266 Woods Hole Rd, Mail Stop #34, Woods Hole, MA 02543, USA School of Renewable Natural Resources, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, USA Ecosystem Assessment Program, Northeast Fisheries Science Center, NOAA Fisheries Center, 166 Water Street, Woods Hole, MA 02543, USA