Fisheries Theme Team

Fisheries Oceanography

Background

The overall goal of fisheries oceanography is to understand and predict the effects of ocean and atmospheric processes at varying temporal and spatial scales on marine ecosystems and resources. Operational fisheries oceanography is largely interested in how ocean processes influence fish distribution, availability, and abundance and how they impact fisheries and their management. One specific goal is to understand the natural causes of variability in year-class strength of harvested fish species and apply that knowledge to management. Temperature, enrichment, concentration, and transport are some of the physical mechanisms affecting fluctuations of marine resources. Research to investigate the various intervening processes must be interdisciplinary and requires expertise in physical and biological oceanography, meteorology, climatology, fisheries science, and ecology.

Research in fisheries oceanography can be conducted at different temporal/spatial scales. Small- and meso-scale (process-oriented) work pertains to physical and food-chain processes over relatively short time scales. Regional-scale work examines processes which impact the interannual variability in populations, while large-scale work is basin-wide to global. Since global climate variability impacts regional ecosystem dynamics, the spatial domain often must be expanded. Observational data and modeling are key elements in all of these scales.

Much of the work done to date in fisheries oceanography has been process-oriented, such as the Georges Bank GLOBEC program, NOAA/COP South Atlantic Bight Recruitment Experiment (SABRE), portions of Fisheries Oceanography Coordinated Investigations (FOCI), and Fisheries and the Environment (FATE), all of which are multi-agency efforts.

Georges Bank GLOBEC is a research project whose goal is to understand the population dynamics of two key fish and two zooplankton species in terms of their coupling to the physical environment and in terms of their predators and prey, and to be able to predict changes in the distribution and abundance of these species as a result of changes in their physical and biotic environment as well as to anticipate how their populations might respond to climate change. SABRE hopes to understand the relationship between variation in environmental factors and the variable recruitment of estuarine-dependent species, mainly menhaden, in the South Atlantic Bight. The goal of FOCI is to understand the recruitment of walleye pollock in the Gulf of Alaska and Bering Sea. The goal of FATE, a FY 2000 NOAA budget initiative,is to determine the physical mechanisms responsible for decadal and basin-scale variation in the production of key marine fish stocks and to ultimately develop coupled biophysical models for ecological indicators for use in stock assessments and risk-averse management decisions.

Research Needs

Climate and ecosystem shifts (regime shifts) on decadal and basin temporal/spatial scales occur rapidly as climate system components realign themselves. Such shifts are significant for fisheries management. The traditional thinking in fisheries management is that recruitment varies randomly about some long-term mean level. However, this paradigm is inconsistent with some current thinking which suggests that a given stock can experience several quite different mean abundance and recruitment levels each persisting for one or two decades before transitioning rapidly to another level in response to changes in the ocean environment. The ability to detect such shifts and forecast their impacts on ecosystems and resources is critical to the management of those resources.

Climate-ecosystem linkages can be established through ecological observations leading to time series of biological and physical indicators. Comprehensive sets of such indicators, except for fishery-independent surveys, fishery catch statistics, and biological sampling of catches, do not exist for any marine ecosystems, and available time series of biological data are, for the most part, incomplete in time and space.

Numerical modeling to simulate physical and biological processes (i.e., recruitment variability, compensatory mechanisms, and species interactions) that control the abundance of living marine resource populations occurring at larger temporal/spatial scales is progressing more rapidly than the data needed for input and to evaluate output. Increased cost-effective monitoring of physical and biological systems on appropriate scales coupled with the development of proxy indicator time series is needed.

Diagnostic physical/biological ecosystem models will have to identify principal modes of ecosystem variation and leading indicators of future regime shifts. Complex models of ocean circulation in the North Pacific have been developed, many of which simulate three-dimensional circulation features and are driven by realistic wind field and buoyancy forcing. There is progress in linking these models to lower trophic level production. In addition, upper trophic level predator-prey models have been developed to evaluate species interactions. The combined development of coupled biophysical models of lower trophic level responses and spatially explicit models of upper trophic level feeding dynamics has led to a new threshold of understanding. These models will help quantify ecosystem responses to climate change, climate variability, and harvest levels from fisheries. Further studies in various regions are needed for understanding and discriminating between cause and effect represented by ecological indicators.

The scientific bases for defining policy issues relative to climate-driven environmental change and fisheries resource use in the long-term and at global scales require investigation.

Sea Grant Involvement

Interdisciplinary, interagency, and international collaboration will be required to satisfactorily address the broad-scale research needs identified both to date and in the future relative to the impact of environmental processes on living marine resources. Participation by Sea Grant researchers in all such endeavors will be required.

A Climate and Fisheries program, co-sponsored by the National Sea Grant Office, a number of government agencies, American Fisheries Society, and several other professional scientific societies, has been launched and will extend from mid-2000 to the end of 2001 to summarize and evaluate current scientific knowledge on this topic, identify key information and research needs, stimulate further interdisciplinary research collaboration, promote and help collaborate future budget initiatives, generate public and political interest in and support of needed research, and provide a springboard for continued efforts beyond the 18-month life of the program. An international symposium addressing climatological impacts on living aquatic resources will be held in August 2001, with the proceedings published thereafter.