GLERL Publications
Fisheries Resources

Brochures and Information Sheets

(GLERL Brochures and Information Sheets are available Print-on-Demand from the Internet at http://www.glerl.noaa.gov/pubs/brochures/)

GREAT LAKES ENVIRONMENTAL RESEARCH LABORATORY. Lake Huron Foodweb. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 2 pp. (February 2007)

GREAT LAKES ENVIRONMENTAL RESEARCH LABORATORY. The Impact of Diporeia spp. Decline on the Great Lakes Fish Community. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 2 pp. (June 2006) PDF

GREAT LAKES ENVIRONMENTAL RESEARCH LABORATORY. Lake Michigan Foodweb. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 2 pp. (May 2002) PDF

GREAT LAKES ENVIRONMENTAL RESEARCH LABORATORY. Fish acoustics at the Great Lakes Environmental Research Laboratory. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 2 pp. April 2000. PDF

Recent Scientific Publications

(GLERL Publications are available free of charge. Ordering information. Complete lists of GLERL publications.)

2008

POTHOVEN, S. A., and C. P. Madenjian. Changes in consumption by alewives and lake whitefish after Dreissenid mussel invasions in Lakes Michigan and Huron. North American Journal of Fisheries Management 28:308-320 (2008). http://www.glerl.noaa.gov/pubs/fulltext/2008/20080005.pdf

2007

BELETSKY, D., D. M. MASON, D. J. SCHWAB, E. S. Rutherford, J. J. Janssen, D. F. Clapp, and J. M. Dettmers. Biophysical model of larval yellow perch advection and settlement in Lake Michigan. Journal of Great Lakes Research 33:842-866 (2007). http://www.glerl.noaa.gov/pubs/fulltext/2007/20070041.pdf

Godby, N.A. Jr., E.S. Rutherford, and D.M. MASON. Diet, feeding rate, growth, mortality, and production of juvenile steelhead in a Lake Michigan tributary. North American Journal of Fisheries Management 27:578-592 (2007). http://www.glerl.noaa.gov/pubs/fulltext/2007/20070009.pdf

Holker, F., H. Dorner, T. Schulze, S.S. Haertel-Borer, S.D. PEACOR, and T. Mehner. Species-specific responses of planktivorous fish to the introduction of a new piscivore: implications for prey fitness. Freshwater Biology 52(doi:10.1111/j.1365-2427.2007.01810.x):1793-1806 (2007).

HÖÖK, T.O., E.S. Rutherford, D.M. MASON, and G.S. Carter. Hatch dates, growth rates, and over-winter mortality of age-0 alewives in Lake Michigan: Implications for habitat-specific recruitment success. Transactions of the American Fisheries Society 136:1298-1312 (2007). http://www.glerl.noaa.gov/pubs/fulltext/2007/20070028.pdf

HÖÖK, T. O., E. Gorokhova, and S. Hansson. RNA:DNA ratios of Baltic Sea herring larvae and copepods in embayment and open sea habitats. Estuarine, Coastal, and Shelf Science 76:29-35 (2008).

2006

DeMaster, D., M. Fogarty, D.M. MASON, G. Matlock, and A. Hollowed. Management of living marine resources in an ecosystem context. White paper #2. In Ecosystem Science Capabilities Required to Support NOAA’s Mission in the Year 2020. NOAA Technical Memorandum NMFS-F/SPO-74. S.A. Murawski and G.C. Matlock (Eds.). NOAA, National Marine Fisheries Service, Silver Spring, MD, pp. 15-28 (2006). http://www.glerl.noaa.gov/pubs/fulltext/2006/2006tm74.pdf

Godby, N.A. Jr., E.S. Rutherford, and D. M. MASON. Diet, feeding rate, growth, mortality, and production of juvenile steelhead in a Lake Michigan tributary. North American Journal of Fisheries Management 27:578-592 (2007).

Holker, F., H. Dorner, T. Schulze, S.S. Haertel-Borer, S.D. PEACOR, and T. Mehner. Species-specific responses of planktivorous fish to the introduction of a new piscivore: implications for prey fitness. Freshwater Biology 52(doi:10.1111/j.1365-2427.2007.01810.x):1793-1806 (2007).

Höök, T.O., M.J. McCORMICK, E.S. Rutherford, D.M. MASON, and G. S. Carter. Short-term water mass movements in Lake Michigan: Implications for larval fish transport. Journal of Great Lakes Research 32:728-737 (2006). http://www.glerl.noaa.gov/pubs/fulltext/2006/20060044.pdf

Lindberg, W. J., T. K. Frazer, K. P. Portier, F. Vose, J. Loftin, D. J. Murie, D. M. MASON, B. Nagy, and M. K. Hart. Density-dependent habitat selection and performance by a large mobile reef fish. Ecological Applications 16(2):731-746 (2006). http://www.glerl.noaa.gov/pubs/fulltext/2006/20060009.pdf

LUDSIN, S.A., C.H. HAND, J.E. Marsden, B.J. Fryer, and E. A. Howe. Micro-elemental analysis of statoliths as a tool for tracking tributary origins of sea lamprey. 2006 Project Completion Report, Great Lakes Fishery Commission, Ann Arbor, MI, 106 pp. (2006). http://www.glerl.noaa.gov/pubs/fulltext/2006/20060046.pdf

MASON, D.M., B. Nagy, M. Butler, S. Larsen, D.J. Murie, and W.J. Lindberg. Integration of technologies for understanding the functional relationship between reef habitat and fish growth and production. In Emerging Technologies for Reef Fisheries Research and Management. J.C. Taylor (Ed.). NOAA Professional Paper NMFS No. 5. NOAA National Marine Fisheries Service, Seattle, WA, pp. 105-116 (2006). http://www.glerl.noaa.gov/pubs/fulltext/2006/20060047.pdf

POTHOVEN, S. A., and T. F. NALEPA. Feeding ecology of lake whitefish in Lake Huron. Journal of Great Lakes Research 32:489-501 (2006). http://www.glerl.noaa.gov/pubs/fulltext/2006/20060030.pdf

POTHOVEN, S.A., H.A. VANDERPLEOG, J.F. CAVALETTO, D.M. KRUEGER, D.M. MASON, and S.B. BRANDT. Alewife planktivory controls the abundance of two invasive predatory cladocerans in Lake Michigan. Freshwater Biology 52 (doi:10.1111/j.1365-2427.2007.01728.x):561-573 (2007).

POTHOVEN, S. A., T. F. NALEPA, C. P. Madenjian, R. R. Rediske, P. J. Schneeberger, and J. X. He. Energy density of lake whitefish Coregonus clupeaformis in Lakes Huron and Michigan. Environmental Biology of Fishes 76:151-158 (2006). http://www.glerl.noaa.gov/pubs/fulltext/2006/20060031.pdf

2005

Bunnell, D. B., C. P. Madenjian, and T. E. CROLEY II. Long-term trends of bloater (Coregonus hoyi) recruitment in Lake Michigan: evidence for the effect of sex ratio. Canadian Journal of Fisheries and Aquatic Sciences 63:832-844 (2006). http://www.glerl.noaa.gov/pubs/fulltext/2006/20060005.pdf

Dobiesz, N. E., D. A. McLeish, R. L. Eschenroder, J. R. Bence, L. C. Mohr, M. P. Ebener, T. F. NALEPA, A. P. Woldt, J. E. Johnson, R. L. Argyle, and J. C. Makarewicz. Ecology of the Lake Huron fish community, 1970-1999. Canadian Journal of Fisheries and Aquatic Sciences 62:1432-1451 (2005). http://www.glerl.noaa.gov/pubs/fulltext/2005/20050012.pdf

HONDORP, D. W., S. A. POTHOVEN, and S. B. BRANDT. Influence of Diporeia density on diet composition, relative abundance, and energy density of planktivorous fishes in southeast Lake Michigan. Transactions of the American Fisheries Society 134:588-601 (2005). http://www.glerl.noaa.gov/pubs/fulltext/2005/20050011.pdf

KRUEGER, D. M., and T. R. Hrabik. Food web alterations that promote native species: The recovery of cisco (Coregonus artedi) populations through management of native piscivores. Canadian Journal of Fisheries and Aquatic Sciences 62:2177-2188 (2005). http://www.glerl.noaa.gov/pubs/fulltext/2005/20050022.pdf

LUDSIN, S. A., B. J. Fryer, and J. E. Gagnon. Comparison of solution-based versus laser ablation inductively coupled plasma mass spectrometry for analysis of larval fish otolith microelemental composition. Transactions of the American Fisheries Society 135:218-231 (2006). http://www.glerl.noaa.gov/pubs/fulltext/2006/20060002.pdf

Madenjian, C. P., D. V. O’Connor, S. A. POTHOVEN, P. J. Schneeberger, R. R. Rediske, J. P. O’Keefe, R. A. Bergstedt, R. L. Argyle, and S. B. BRANDT. Evaluation of a Lake Whitefish bioenergetics model. Transactions of the American Fisheries Society 135:61-75 (2006). http://www.glerl.noaa.gov/pubs/fulltext/2006/20060001.pdf

Madenjian, C. P., S. A. POTHOVEN, J. M. Dettmers, and J. D. Holuszko. Changes in seasonal energy dynamics of alewife (Alosa pseudoharengus) in Lake Michigan after invasion of dreissenid mussels. Canadian Journal of Fisheries and Aquatic Sciences 63:891-902 (2006). http://www.glerl.noaa.gov/pubs/fulltext/2006/20060004.pdf

Madenjian, C. P., S. A. POTHOVEN, P. J. Schneeberger, D. V. O'Connor, and S. B. BRANDT. Preliminary evaluation of a Lake Whitefish (Coregonus clupeaformis) bioenergetics model. In Proceedings of a Workshop on the Dynamics of Lake Whitefish (Coregonus clupeaformis) and the amphipod Diporeia spp. in the Great Lakes. L. C. Mohr and T.F. Nalepa (eds.). Great Lakes Fishery Commission, Technical Report 66, Ann Arbor, MI, 189-202 (2005). http://www.glerl.noaa.gov/pubs/fulltext/2005/20050010.pdf

Madenjian, C. P., D. W. HONDORP, T. J. Desorcie, and J. D. Holuszko. Sculpin community dynamics in Lake Michigan. Journal of Great Lakes Research 31:267-276 (2005).

Madenjian, C. P., T. O. Hook, E. S. Rutherford, D. M. MASON, T. E. CROLEY II, E. B. Szalai, and J. R. Bence. Recruitment variability of alewives in Lake Michigan. Transactions of the American Fisheries Society 134:218-230 (2005). http://www.glerl.noaa.gov/pubs/fulltext/2005/20050002.pdf

MASON, D. M., T. B. Johnson, C. J. Harvey, J. F. Kitchell, S. T. Schram, C. R. Bronte, M. H. Hoff, S. J. LOZANO, A. S. Trebitz, D. R. Schreiner, E. C. Lamon, and T. Hrabik. Hydroacoustic estimates of abundance and spatial distribution of pelagic fishes in western Lake Superior. Journal of Great Lakes Research 31:426-438 (2005). http://www.glerl.noaa.gov/pubs/fulltext/2005/20050026.pdf

NALEPA, T. F., L. C. Mohr, B. A. Henderson, C. P. Madenjian, and P. J. Schneeberger. Lake Whitefish and Diporeia spp. in the Great Lakes: An overview. In Proceedings of a Workshop on the Dynamics of Lake Whitefish (Coregonus clupeaformis) and the amphipod Diporeia spp. in the Great Lakes. L. C. Mohr and T.F. Nalepa (eds.). Great Lakes Fishery Commission, Technical Report 66, Ann Arbor, MI, 3-20 (2005). http://www.glerl.noaa.gov/pubs/fulltext/2005/20050005.pdf

POTHOVEN, S. A. Changes in Lake Whitefish diet: Lake Michigan. In Proceedings of a Workshop on the Dynamics of Lake Whitefish (Coregonus clupeaformis) and the amphipod Diporeia spp. in the Great Lakes. L. C. Mohr and T.F. Nalepa (eds.). Great Lakes Fishery Commission, Technical Report 66, Ann Arbor, MI, 127-140 (2005). http://www.glerl.noaa.gov/pubs/fulltext/2005/20050006.pdf

Tirelli, V., D. Borme, F. Tulli, M. Cigar, S. Fonda Umani, and S. B. BRANDT. Energy density of anchovy, Engraulis encrasicolus L. in the Adriatic Sea. Journal of Fish Biology 68:982-989 (2006). http://www.glerl.noaa.gov/pubs/fulltext/2006/20060036.pdf

2004

BELETSKY, D., D. J. SCHWAB, D. M. MASON, E. S. Rutherford, M. J. McCORMICK, H. A. VANDERPLOEG, and J. J. Janssen. Modeling the transport of larval yellow perch in Lake Michigan. Proceedings of the Estuarine and Coastal Modeling 8th International Conference, Monterey, CA, November 3-5, 2003. American Society of Civil Engineers, 439-454 pp. (2004).

Hedges, K. J., S. A. LUDSIN, and B. J. Fryer. Effects of ethanol preservation on otolith microchemistry. Journal of Fish Biology 64:923-937 (2004). http://www.glerl.noaa.gov/pubs/fulltext/2004/20040004.pdf

Hook, T. O., E. S. Rutherford, S. J. Brines, D. J. SCHWAB, and M. J. McCORMICK. Relationship between surface water temperature and Steelhead distributions in Lake Michigan. North American Journal of Fisheries Management 24:211-221 (2004).

Johnson, T. B., M. H. Hoff, A. S. Trebitz, C. R. Bronte, W. P. Brown, T. D. Corry, J. F. Kitchell, S. J. LOZANO, D. M. MASON, J. V. Scharold, S. T. Schram, and D. R. Schreiner. Spatial patterns in assemblage structures of pelagic forage fish and zooplankton in western Lake Superior. Journal of Great Lakes Research 30(Supplement 1):395-406 (2004). http://www.glerl.noaa.gov/pubs/fulltext/2004/20040033.pdf

Kracker, L. M., L. Zhou, J. M. Jech, J. K. Horne, J. A. Tyler, and S. B. BRANDT. Spatial and temporal variance in fish distributions: A Lake Ontario case study. In State of Lake Ontario (SOLO) - Past, Present, and Future. M. M. (Ed.). Aquatic Ecosystem Health and Management Society, 385-406 (2003).

LUDSIN, S. A., B. J. Fryer, Z. Yang, S. Melancon, and J. L. Markham. Exploration of the existence of natural reproduction in Lake Erie lake trout using otolith microchemistry. 2004 Project Completion Report. Great Lakes Fishery Commission, Ann Arbor, MI, 45 pp. (2004). http://www.glerl.noaa.gov/pubs/fulltext/2004/20040036.pdf

POTHOVEN, S. A., and H. A. VANDERPLOEG. Diet and prey selection of alewives in Lake Michigan: seasonal, depth, and interannual patterns. Transactions of the American Fisheries Society 13077 (2004).

BRANDT, S. B. and D. M. MASON. Effect of nutrient loading on Atlantic Menhaden (Brevoortia tyrannus) growth rate potential in the Patuxent River. Estuaries 26(2A):298-309 (2003).

RAIKOW, D. F. Food web interactions between larval bluegill (Lepomis macrochirus) and exotic zebra mussels (Dreissena polymorpha). Canadian Journal of Fisheries and Aquatic Sciences 61(3):497-504 (2004). http://www.glerl.noaa.gov/pubs/fulltext/2004/20040009.pdf

Roy, D., G. D. Haffner, and S. B. BRANDT. Estimating fish production potentials using a temporally explicit model. Ecological Modeling 173:241-257 (2004). http://www.glerl.noaa.gov/pubs/fulltext/2004/20040011.pdf

2003

Bronte, C. R., M. P. Ebener, D. R. Schreiner, D. S. DeVault, M. M. Petzold, D. A. Jensen, C. Richards, and S. J. LOZANO. Fish community change in Lake Superior, 1970-2000. Canadian Journal of Fisheries and Aquatic Sciences 60:1552-1574 (2003). http://www.glerl.noaa.gov/pubs/fulltext/2003/20030016.pdf

Cook, P. M., J. A. ROBBINS, D. D. Endicott, K. Lodge, P. D. Guiney, M. K. Walker, E. W. Zabel and R. E. Peterson. Effects of Aryl Hydrocarbon receptor-mediated early life stage toxicity on Lake Trout populations in Lake Ontario during the 20th Century. Environmental Science and Technology 37(17):3864-3877 (2003).

Hook, T. O., E. S. Rutherford, S. J. Brines, D. M. MASON, D. J. SCHWAB, M. J. McCORMICK, G. W. Fleischer and T. J. DeSorcie. Spatially explicit measures of production of young alewives in Lake Michigan: linkage between essential fish habitat and recruitment. Estuaries 26(1):21-29 (2003).

Krause, A. E., K. A. FRANK, D. M. MASON, R. E. Ulanowicz, and W. W. Taylor. Compartments revealed in food-web structure. Nature 426:282-285 (2003). http://www.glerl.noaa.gov/pubs/fulltext/2003/20030014.pdf

Mora, C., P. M. Chittaro, P. F. Sale, J. P. Kritzer, and S. A. LUDSIN. Patterns and processes in reef fish diversity. Nature 421:933-936 (2003).

PRICE, H., S. A. POTHOVEN, M. J. McCORMICK, P. C. Jensen and G. L. FAHNENSTIEL. Temperature influence on commercial Lake Whitefish harvest in eastern Lake Michigan. Journal of Great Lakes Research 29(2):296-300 (2003).

2002

BRANDT, S. B., D. M. MASON, M. J. McCORMICK, B. M. LOFGREN, T. S. HUNTER, and J. A. TYLER. Climate change: implications for fish growth performance in the Great Lakes. American Fisheries Society Symposium 32:61-76 (2002).

2001

JECH, J. M., and J. K. HORNE. Effects of in situ target spatial distributions on acoustic density estimates. ICES Journal of Marine Science 58:123-136 (2001). One goal of acoustic-based abundance estimates is to accurately preserve spatial distributions of organism density and size within survey data. We simulated spatially random and spatially auto-correlated fish density and sbs distributions to quantify variance in density, abundance, and backscattering cross-sectional area estimates, and to examine the sensitivity of abundance estimates to organism spatial distributions and methods of estimating acoustic size. Our results show that it is difficult to simultaneously estimate fish density and maintain accurate sb-frequency distributions. Among our acoustic backscatter estimation methods, a weighted-mean from a local search window provided optimal estimates of density, abundance and crbs. Other methods tended to bias either crbs or density estimates. This analysis identifies the relative importance of variance sources when estimating organism density using spatially-indexed acoustic data.

Luo, J., K. J. Hartman, S. B. BRANDT, C. F. Cerco, and T. H. Rippetoe. A spatially-explicit approach for estimating carrying capacity: An application for the Atlantic menhaden (Brevoortia tyrannus) in Chesapeake Bay. Estuaries 24(4):545-556 (2001). A spatially-explicit methodology was developed for estimating system carrying capacities of fish stocks, and used to estimate the seasonal and spatial patterns of carrying capacity of Chesapeake Bay for Atlantic menhaden (Brevoortia tyrannus). We used a spatially-explicit three-dimensional (3-D) model that divided the heterogeneous habitat of Chesapeake Bay into over 4,000 cubes. Each cube represented a volume of water that was characterized by a specific set of environmental variables (phytoplankton biomass, temperature, and dissolved oxygen) driven by the 3-D water quality model. Foraging and bioenergetics models transformed the environmental variables into measures of potential growth rates of menhaden. Potential carrying capacity of menhaden was estimated as a function of phytoplankton production, menhaden consumption rate, and potential growth rate, combining phytoplankton production, thermal habitat, and menhaden physiology into one ecological value that is a measure of habitat quality from the perspective of the fish. Seasonal analysis of the Chesapeake Bay carrying capacity for Atlantic menhaden suggested two bottleneck periods: one in early June and a second during the fall. The fall bottleneck in carrying capacity was at about 10 billion age-0 fish. Annual recruitment of age-0 menhaden for the entire Atlantic coast of the U.S. ranged from 1.2-18.6 billion fish between 1955 and 1986. It appears that carrying capacity of Chesapeake Bay does not limit the coastwide production of young menhaden. Any conditions such as nutrient reduction strategies, further eutrophication, or global climatic warming, that may influence the carrying capacity during the fall or early June periods, may ultimately alter coastwide abundance of menhaden through changes in Chesapeake Bay carrying capacity.

MASON, D. M., A. Goyke, S. B. BRANDT, and J. M. Jech. Acoustic fish stock assessment in the Laurentian Great Lakes. In The Great Lakes of the World (GLOW): Food-web, health and integrity, M. Munawar and R.E. Hecky (Eds.), Backhuys Publishers, Leiden, The Netherlands, pp. 317-339 (2001). Applications of underwater acoustics in the Great Lakes can be traced back to the1960s. These early studies focused on fish distributions at power plant thermal plumes (Spigarelli et al., 1973; Stuntz, 1973), and on estimating zooplankton distribution and biomass (McNaught, 1968). During these early years, data assimilation consisted of a paper chart recorder and an analog recording of output voltages on magnetic tape. Even with limited technology, McNaught (1969) was one of the first researchers, in marine or freshwater environments, to propose and develop a multi-frequency sonar system for size-class discrimination of zooplankton. Due to data storage and analysis limitations, these early studies were completed on a localized scale. With technological improvements in electronic and computer technology, larger scale surveys were conducted on Lakes Michigan (Brandt, 1975, 1978, 1980; Brandt et al., 1980; Janssen and Brandt, 1980), Huron (Argyle, 1982), and Superior (Heist and Swenson, 1983) and provided the first quantitative estimates of fish abundance, density, and spatial distribution. Using a 50 kHz single beam scientific echo sounder and deconvolution techniques (Peterson et al., 1976), Brandt (1980) studied the diel vertical migration, thermal ecology, and spatial segregation of various life stages of alewives in Lake Michigan. He found that alewife migrate to the thermocline at night and disperse, and that adult and young-of-the year (YOY) alewives thermally segregate. This information was the foundation for nighttime assessment of alewives in the Great Lakes. Heist and Swenson (1983) estimated rainbow smelt abundance in the western basin of Lake Superior during 1978-1980 to provide prey fish numbers used in reestablishing the native piscivore community and for assessing the impact of an expanding commercial fisheries. Their acoustics application was one of the first in the Great Lakes that focused on direct management applications.

Pothoven, SA; Nalepa, TF; Schneeberger, PJ; Brandt, SB. 2001. Changes in diet and body condition of lake whitefish in southern Lake Michigan associated with changes in benthos. North American Journal of Fisheries Management, 21 (4): 876-883 NOV 2001. We evaluated the long-term trends of the benthic macroinvertebrate community (1980-1999) and biological attributes of lake whitefish Coregonus clupraformis (1985-1999) in southeastern Lake Michigan. We also determined what food types were important to lake whitefish in an area where the amphipod Diporeia had not yet declined in 1998 and how the diet of lake whitefish changed as Diporeia declined during 1999-2000. Zebra mussels Dreissena polymorpha invaded the study area in 1992; Diporeia began to decline in 1993 and was nearly absent by 1999. The body condition of lake whitefish decreased after 1993 and remained low thereafter. The length at age and weight at age of lake whitefish was lower in 1992-1999 than in 1985-1991. After declines of Diporeia off the city of Muskegon, Michigan, between 1998 and 1999-2000, the proportion of Diporeia in the diet by weight fell from 70% to 25% and the percent occurrence decreased from 81% to 45%. In contrast, the proportion of take whitefish that ate other prey, such as Mysis relicta (an opossum shrimp), ostracods, oligochaetes, and zooplankton, increased in the same period. At sites south of Muskegon, where the density of Diporeia has been low since 1998, chironomids, zebra mussels, and fingernail clams (Shacriidae family) were the most important diet items of lake whitefish. Decreases in body condition and growth are associated with the loss of the high-energy prey resource Diporeia, the consumption of prey with lower energy content, such as zebra mussels, and possible density-dependence. Commercial harvests of lake whitefish will probably decrease because of low body condition and growth. Future management may require changes in harvest quotas, size restrictions, and depth restrictions as zebra mussel-related impacts spread northward in Lake Michigan.

Norcross, BL; Brown, ED; Foy, RJ; Frandsen, M; Gay, SM; Kline, TC; MASON, DM; Patrick, EV; Paul, AJ; Stokesbury, KDE. 2001. A synthesis of the life history and ecology of juvenile Pacific herring in Prince William Sound, Alaska. Fisheries Oceanography, 10: 42-57 Suppl. 1 2001. ABSTRACT: Physical and biological variables affecting juvenile Pacific herring (Clupea pallasi) in Prince William Sound (PWS) from 1995 to 1998 were investigated as part of a multifaceted study of recruitment, the Sound Ecosystem Assessment (SEA) program. Though more herring larvae were retained in eastern PWS bays, ages-0 and -1 herring used bays throughout PWS as nursery areas. Water transported into PWS from the Gulf of Alaska (GOA) contributed oceanic prey species to neritic habitats. Consequently, variations in local food availability resulted in different diets and growth rates of herring among bays. Summer food availability and possible interspecific competition for food in nursery areas affected the autumn nutritional status and juvenile whole body energy content (WBEC), which differed among bays. The WBEC of age-0 herring in autumn was related to over-winter survival. The limited amount of food consumption in winter was not sufficient to meet metabolic needs. The smallest age-0 fish were most at risk of starvation in winter. Autumn WBEC of herring and winter water temperature were used to model over-winter mortality of age-0 herring. Differences in feeding and energetics among nursery areas indicated that habitat quality and age-0 survival were varied among areas and years. These conditions were measured by temperature, zooplankton abundance, size of juvenile herring, diet energy, energy source (GOA vs. neritic zooplankton), WBEC, and within-bay competition.

TYLER, J. A., and S. B. BRANDT. Do spatial models of growth rate potential reflect fish growth in a heterogeneous environment? A comparison of model results. Ecology of Freshwater Fish 10:43-56 (2001). Spatial models of fish growth rate potential have been used to characterize a variety of environments including estuaries, the North American Great Lakes, small lakes and rivers. Growth rate potential models capture a snapshot of the environment but do not include the effects of habitat selection or competition for food in their measures of environment quality. Here, we test the ability of spatial models of fish growth rate potential to describe the quality of an environment for a fish population in which individual fish may select habitats and local competition may affect per capita intake. We compare growth rate potential measurements to simulated fish growth and distributions of model fish from a spatially explicit individual-based model offish foraging in the same model environment. We base the model environment on data from Lake Ontario and base the model fish population on alewife in the lake. The results from a simulation experiment show that changes in the model environment that caused changes in the average growth rate potential correlated extremely highly (r2>=0.97) with changes in simulated fish growth. Unfortunately, growth rate potential was not a reliable quantitative predictor of simulated fish growth nor of the fish spatial distribution. The inability of the growth rate potential model to quantitatively predict simulated fish growth and fish distributions results from the fact that growth rate potential does not consider the effects of habitat selection or of competition on fish growth or distribution, processes that operate in our individual-based model and presumably also operate in nature. The results, however, do support the use of growth rate potential models to describe the relative quality of habitats and environments for fish populations.

Willette, TM; Cooney, RT; Patric, V; MASON, DM; Thomas, GL; Scheel, D. 2001. Ecological processes influencing mortality of juvenile pink salmon (Oncorhynchus gorbuscha) in Prince William Sound, Alaska. Fisheries Oceanography, 10: 14-41 Suppl. 1 2001. Our collaborative work focused on understanding the system of mechanisms influencing the mortality of juvenile pink salmon (Oncorhynchus gorbuscha) in Prince William Sound, Alaska. Coordinated field studies, data analysis and numerical modelling projects were used to identify and explain the mechanisms and their roles in juvenile mortality. In particular, project studies addressed the identification of major fish and bird predators consuming juvenile salmon and the evaluation of three hypotheses linking these losses to (i) alternative prey for predators (prey-switching hypothesis); (ii) salmon foraging behaviour (refuge-dispersion hypothesis); and (iii) salmon size and growth (size-refuge hypothesis). Two facultative planktivorous fishes, Pacific herring (Clupea pallasi) and walleye pollock (Theragra chalcogramma), probably consumed the most juvenile pink salmon each year, although other gadids were also important. Our prey-switching hypothesis was supported by data indicating that herring and pollock switched to alternative nekton prey, including juvenile salmon, when the biomass of large copepods declined below about 0.2 g m(-3). Model simulations were consistent with these findings, but simulations suggested that a June pteropod bloom also sheltered juvenile salmon from predation. Our refuge-dispersion hypothesis was supported by data indicating a five-fold increase in predation losses of juvenile salmon when salmon dispersed from near-shore habitats as the biomass of large copepods declined. Our size-refuge hypothesis was supported by data indicating that size- and growth-dependent vulnerabilities of salmon to predators were a function of predator and prey sizes and the timing of predation events. Our model simulations offered support for the efficacy of representing ecological processes affecting juvenile fishes as systems of coupled evolution equations representing both spatial distribution and physiological status. Simulations wherein model dimensionality was limited through construction of composite trophic groups reproduced the dominant patterns in salmon survival data. In our study, these composite trophic groups were six key zooplankton taxonomic groups, two categories of adult pelagic fishes, and from six to 12 groups for tagged hatchery-reared juvenile salmon. Model simulations also suggested the importance of salmon density and predator size as important factors modifying the predation process.

2000

DEMERS, E., S. B. BRANDT, K. L. BARRY, and J. M. JECH. Spatially-explicit models of growth rate potential: linking estuarine fish production to the biological and physical environment. In Estuarine Synthesis: A Synthetic Approach to Research and Practice, J.E. Hobbie (Ed.), Island Press, Washington, DC, pp. 405-425 (2000). Estuaries are high-yield fishing areas that are characterized by spatial heterogeneity in physical and biological conditions. Models of fish production have traditionally been based on systemwide averages of environmental conditions, but habitat heterogeneity can substantially infiuence fish growth. Growth rate potential (GRP) provides a spatially explicit approach that integrates the heterogeneous nature of estuaries into a simple modeling framework. In this chapter, we describe and illustrate the application of GRP to compare potential growth of two piscivQres and to determine the potential growth of a non-native species introduced into an estuary. Acoustically derived prey distributions and temperature profiles were merged in a spatially explicit analysis to estimate and compare GRP of striped bass and bluefish in Chesapeake and Delaware Bays. In this analysis, bluefish grew better in the thermal regimes and prey biomass available during midsummer while striped bass had higher potential growth during fall. This suggests that, although striped bass and bluefish use similar prey resources, they may be thermally and temporally segregated, thereby reducing competitive overlap. In our second example, GRP results indicate that the suitability of Chesapeake Bay for the growth of chinook salmon (a non-native, hypothetical invader) was very low during summer, whereas in October, water temperature and prey availability could possibly support chinook salmon growth. This spatially explicit approach proved to be a valuable tool to study fish production in estuarine systems where heterogeneous conditions can affect populations at systems levels.

HORNE, J. K. Acoustic approaches to remote species identification. Fisheries Oceanography 9(4):356-371 (2000). Noninvasive species identification remains a longterm goal of fishers, researchers; and resource managers who use sound to locate, map, and count aquatic organisms. Since the first biological applications of underwater acoustics, four approaches have been used singly or in combination to survey marine and freshwater environments: passive sonar; prior knowledge and direct sampling; echo statistics from high-frequency measures; and matching models to low-frequency measures. Echo amplitudes or targets measured using any sonar equipment are variable signals. Variability in reflected sound is influenced by physical factors associated with the transmission of sound through a compressible fluid, and by biological factors associated with the location, reflective properties, and behavior of a target. The current trend in acoustic target identification is to increase the amount of information collected through increases in frequency bandwidth or in the number of acoustic beams. Exclusive use of acoustics to identify aquatic organisms reliably will require a set of statistical metrics that discriminate among a wide range of similar body types at any packing density, and incorporation of these algorithms in routine data processing.

HORNE, J. K., P. D. Walline, and J. M. JECH. Comparing acoustic model predictions to in situ backscatter measurements of fish with dual-chambered swim bladders. Journal of Fish Biology 57:1105-1121 (2000). Lavnun Mirogrex terraesanctae have a dual-chambered swim bladder and are the dominant fish species in Lake Kinneret, Israel. Bi-monthly acoustic assessments are used to monitor lavnun abundance but the relation between the amount of reflected sound and organism morphology is not well described. Predictions from Kirchhoff-ray mode (KRM) backscatter models show a sensitivity of echo amplitude to fish length and fish aspect. Predicted mean KRM target strengths matched maximum in situ target strength measurements of eight tethered fish within 2.5 dB at 120 kHz and within 7 dB at 420 kHz. Tilt and roll of lavnun during tethered measurements increased variance of backscatter measurements. Accurate abundance and length frequency distribution estimates cannot be obtained from in situ acoustic measurements without supplementary net samples.

JECH, J. M., and J. Luo. Digital Echo Visualization and Information System (DEVIS) for processing spatially-explicit fisheries acoustic data. Journal of Fisheries Research 27:115-124 (2000). Spatially explicit analysis of fisheries acoustic data preserves heterogeneity observed in spatial distributions of fish. A software system - Digital Echo Visualization and Information System (DEVIS) - has been developed to process digital underwater acoustic data for spatially-explicit fisheries acoustic research. This system can be used to obtain spatial and temporal distributions of fish density, fish abundance, and fish lengths for management applications and for ecological modeling. DEVIS first reads digital data, corrects the data according to the sonar equation, discriminates individual targets, and vertically and horizontally integrates the data into a two-dimensional array of mean volume backscattering strength. Individual target information (TS, spatial location) is meshed with the volume backscattering array, and representative acoustic sizes are estimated in array cells with missing target information. Estimation methods for acoustic sizes and potential biases in abundance estimates are introduced and discussed. The final output is the spatial distribution of numeric density and fish length by length classes and for all fish. Data obtained on Lake Erie in September 1994 and on Chesapeake Bay in July 1995 were processed using DEVIS and are shown graphically. Steps required to process digital data are described and how these data can be applied to fish ecology is shown.

Kitchell, J. F., S. P. Cox, C. J. Harvey, T. B. Johnson, D. M. MASON, K. K. Schoen, K. Aydin, C. Bronte, M. Ebener, M. Hansen, M. Hoff, S. Schram, D. Schreiner, and C. J. Walters. Sustainability of the Lake Superior fish community: Interactions in a food web context. Ecosystems 3:545-560 (2000). The restoration and rehabilitation of the native fish communities is a long-term goal for the Laurentian Great Lakes. In Lake Superior, the ongoing restoration of the native lake trout populations is now regarded as one of the major success stories in fisheries management. However, populations of the deepwater morphotype (siscowet lake trout) have increased much more substantially than those of the nearshore morphotype (lean lake trout), and the ecosystem now contains an assemblage of exotic species such as sea lamprey, rainbow smelt, and Pacific salmon (chinook, coho, and steelhead). Those species play an important role in defining the constraints and opportunities for ecosystem management. We combined an equilibrium mass balance model (Ecopath) with a dynamic food web model (Ecosim) to evaluate the ecological consequences of future alternative management strategies and the interaction of two different sets of life history characteristics for fishes at the top of the food web. Relatively rapid turnover rates occur among the exotic forage fish, rainbow smelt, and its primary predators, exotic Pacific salmonids. Slower turnover rates occur among the native lake trout and burbot and their primary prey-lake herring, smelt, deepwater cisco, and sculpins. The abundance of forage fish is a key constraint for all salmonids in Lake Superior. Smelt and Mysis play a prominent role in sustaining the current trophic structure. Competition between the native lake trout and the exotic salmonids is asymmetric. Reductions in the salmon population yield only a modest benefit for the stocks of lake trout, whereas increased fishing of lake trout produces substantial potential increases in the yields of Pacific salmon to recreational fisheries. The deepwater or siscowet morphotype of lake trout has become very abundant. Although it plays a major role in the structure of the food web it offers little potential for the restoration of a valuable commercial or recreational fishery. Even if a combination of strong management actions is implemented, the populations of lean (nearshore) lake trout cannot be restored to pre-fishery and pre-lamprey levels. Thus, management strategy must accept the ecological constraints due in part to the presence of exotics and choose alternatives that sustain public interest in the resources while continuing the gradual progress toward restoration.

POTHOVEN, S. A., T. F. NALEPA, and S. B. BRANDT. Age-0 and age-1 yellow perch diet in southeastern Lake Michigan. Journal of Great Lakes Research 26(2):235-239 (2000). Age-0 yellow perch (Perca flavescens) were collected during October 1998 and age-1 yellow perch were collected during June 1999 from southeastern Lake Michigan off St. Joseph and Muskegon, Michigan, to evaluate diets relative to recent ecosystem changes. Size range of yellow perch examined was 72 to 118 mm. In October at a 15-m site off Muskegon, both Gammarus spp. and Isopoda were found in nearly 71% of age-0 yellow perch stomachs, and accounted for 71 and 26% of the diet by weight respectively. The following spring at the 15-m site (June 1999), Gammarus spp. and Isopoda were only a small part of age-l yellow perch diet, and Chironomidae and Mysis relicta dominated the diet. In October at depths of 25 to 35 m, M. relicta, was found in 100 and 80% of the age-0 yellow perch containing food off Muskegon and St. Joseph, respectively, and comprised over 96% of the diet by weight. Gammarus spp., Isopoda, and M. relicta were eaten in higher numbers than would be expected based on their low abundance in the environment. The high occurrence of Gammarus spp. and Isopoda in yellow perch diet may indicate ongoing changes in the nearshore benthic community.

Richardson-Heft, C. A., A. A. Heft, L. Fewlass, and S. B. BRANDT. Movement of Largemouth Bass in Northern Chesapeake Bay: Relevance to sportfishing tournaments. North American Journal of Fisheries Management 20:493-501 (2000). Largemouth bass Micropterus salmoides have been displaced as far as 50 km from where they were caught in Chesapeake Bay tidewater angling tournaments. Two concerns are whether largemouth bass return to capture areas or whether they stockpile at tournament release sites. To answer these questions, movements of 82 largemouth bass tagged with radio transmitters and 146 largemouth bass tagged with streamer tags were observed during 1991-1995. Fish were collected by boat electrofishing near two disparate tournament weigh-in stations on the eastern and western shores of northern Chesapeake Bay. Some largemouth bass (43 radio-tagged, 58 streamer-tagged) were displaced 15-21 km to the other station; controls (39 radio-tagged, 88 streamer-tagged) were released where they were caught. Movement patterns were similar for displaced largemouth bass: 43% from the Susquehanna River (western shore) and 33% from the Northeast River (eastern shore) exhibited directed movement towards initial capture areas by returning to their original capture areas. Among the controls, only 4% of Susquehanna River and 6% of Northeast River fish traveled to the opposite shore, demonstrating that return movement was not random. For displaced bass that returned to original capture areas, those released in the spring tended to return within 3 months, whereas bass released in the fall returned within 7-12 months. For both groups, this typically occurred when water temperatures were between 12.0°C and 22.5°C. Most radio-tagged largemouth bass (64%) were located more than 0.5 km from their release sites (i.e., the designated stockpiling zone) 7 d after release. The final located positions for radio-tagged largemouth bass averaged 9.6 km from the release sites, and 95% were at least 0.5 km from the release sites. Results from our study demonstrate that displaced largemouth bass tend to return to their capture areas and that short-term stockpiling of largemouth bass at tournament release areas was possible, but that long term stockpiling did not occur.

Walline, P. D., J. A. TYLER, S. B. BRANDT, I. Ostrovsky, and J. M. JECH. Lavnun abundance: how changes may affect consumption of Lake Kinneret zooplankton. Arch. Hydrobiol. Spec. Issues Advances in Limnology 55:493-511 (2000). The Israeli Water Commissioner has subsidized the removal from Lake Kinneret of lavnun, the endemic cyprinid Acanthobrama terraesanctoe, since the 1994-1995 fishing season. One of the rationales for the removal program is that reduced consumption of zooplankton by lavnun will increase production of zooplankton and their subsequent consumption of phytoplankton. Here, we use acoustic measures of fish population distribution and abundance, and bioenergetic and spatial modeling to assess the effect of lavnun removal on potential consumption of zooplankton in Lake Kinneret. Two lakewide acoustic surveys were made (in April and June 1998) with a dual-beam acoustic system to measure the fish population. On each survey a salinity and temperature profiler was used to measure the water temperature field in the lake. We used these data and spatially explicit bioenergetic models to determine potential consumption by fish. The size distribution and abundance of the measured fish population were manipulated to calculate potential consumption under various scenarios. Geostatistical interpolation of spatial models provided lakewide measures of fish abundance and potential consumption. Our analysis suggests that the lavnun dilution program has the desired effect of substantially reducing potential zooplankton consumption by lavnun. Further, model scenarios indicated that targeting smaller fish in the removal program could produce an even greater decrease in potential zooplankton consumption than that so far achieved by either the dilution program or by commercial fishing.

1999

HORNE, J. K., P. E. Smith, and D. C. Schneider. Comparative examination of scale-explicit biological and physical processes: recruitment of Pacific hake (Merluccius productus). Canadian Journal of Fisheries and Aquatic Sciences 56(1):170-179 (1999). The creation, maintenance, and destruction of aquatic organism distributions result from biological and physical processes that operate at different spatial and temporal scales. Rate diagrams plot and contour ratios of process rates as a function of spatial and temporal scale to summarize the relative importance of demographics, growth, and kinematics. We demonstrate the utility of this approach by examining physical and biological processes that influence the distribution and survival of larval and juvenile Pacific hake (Merluccius productus) in the California Current region. Processes that influence changes in hake biomass switch from mortality and drift among larvae to somatic growth and active locomotion among juveniles: Comparison of hake rate diagrams with those of capelin (Mallotus villosus) and Atlantic cod (Gadus morhua) show that dominant processes differ across scales, across life history stages, and across species.

HORNE, J. K., and J. M. JECH. Multi-frequency estimates of fish abundance: constraints of rather high frequencies. ICES Journal of Marine Science 56:184-199 (1999). Traditional scientific echosounders operate at discrete frequencies ranging from 38 to 420 kHz. We investigated the applicability and accuracy of length-based population estimates using commercially available acoustic frequencies and the inverse approach under ideal conditions. The inverse approach combines modelled and measured backscatter values to estimate the abundance of organisms in specified length classes. Reference backscatter values of individual fish were calculated using a Kirchhoff-ray mode backscatter model. Single and multi-cohort fish populations were simulated based on length-frequency samples from purse seine catches of threadfin shad (Dorosoma petenense) and used to calculate the total frequency-dependent volume backscatter of each population. A non-negative least squares (NNLS) algorithm was used to estimate total abundance and numbers of fish in each length class. Total abundance estimates were within < I-38% of population numbers. Within length-class estimates were inconsistent among frequency combinations and across length-class criteria. Increasing the number of frequencies does not guarantee improved accuracy of within length-class abundance estimates. Predictability of inverse simulations is non-linear when rather high frequencies are combined with non-monotonic scattering models. Accuracy of length-based abundance estimates is optimized by maximizing the amplitude range of reference backscatter measures and the number of features identified by reference scattering points.

Houde, E. D., S. Jukic-Peladic, and S. B. BRANDT. Fisheries: Trends in Catches, Abundance and Management. In Ecosystems at the Land-Sea Margin, T. Malone et al. (eds.), 341-366 (1999). Fisheries of the Chesapeake Bay (CB) and Northern Adnatic Sea (NA) are reviewed and compared with respect to constituents ofthe catch, trends, and management issues. Recent nnnual landings have been approximately 100,000 and 275,000 tons in the NA and CB, respectively. Clupeoid fishes (anchovies, sardines or menhaden) dominate the fish biomasses and catches in both ecosystems. Fishenes on anadromous and estuarine dependent species are more important in CB, and diverse, demersal fisheries are relatively more important in NA. Although total catches have remained high, anchovy stocks in the NA collapsed in the 1980s, and oysters and shad/ever herring stocks in CB declined to collapses dunug the past three decades. Eutrophication, overfishing, and problems of interjurisdictional management are common to the two ecosystems. The co-management of commercial and recreational fisheries is an issue in CB. Fish productivity and catches are higher in CB than in the NA on a per unit volume, area, and nutrient input basis. Yield per unit of prunary production is slightly higher in the NA. A part of the difference between the two systems is accounted for by the dominance of landings and production of menhaden, a phytoplanktivore, from Chesapeake Bay. Recent progress in development of national and international management accords (Slovenia, Croatia, Italy) is evident in the NA, and interstate plans are now required in the CB. In both systems, prospects for continued high fisheries productivity depend upon effective ecosystem and fisheries management.

POTHOVEN, S. A., B. Vondracek, and D. L. Pereira. Effects of vegetation removal on Bluegill and Largemough Bass in two Minnesota lakes. North American Journal of Fisheries Management 19:748-757 (1999). Abundance and growth of bluegill, Lepomis macrochirus, diet and growth of largemouth bass, Micropterus salmoides, and abundance of age-0 largemouth bass were evaluated in two treatment and three reference lakes in Minnesota to assess the effects of whole-lake herbicide treatments. Lakes were evaluated 1 year prior (1993), during (1994), and after (1995) treatment. In reference lakes, vegetation, fish growth, abundance, and diet remained relatively unchanged throughout the study. Herbicide applications in May 1994 decreased the percentage of sampling stations with vascular vegetation from 100% to 33% in Parkers Lake and 63% in Zumbra Lake betvveen August 1993 and 1994. Vegetation returned to some areas of Parkers Lake in 1995 (77%) but continued to decline in Zumbra Lake (43%). Purse-seine catch per effort (CPE) of small bluegill (60-100 mm) decreased following treatment but returned to pretreatment levels the following year, whereas CPE of large bluegill (> 100 mm) increased in 1994 in trap nets and remained constant in gill nets and large bag seines. Age-0 largemouth bass abundance was not affected by vegetation removal. Growth of bluegills and largemouth bass was greater in 1994 than in the previous 4-5 years. Largemouth bass stomachs contained more fish prey and were empty in fewer instances only during 1994 in Zumbra Lake. Because few treatment effects were sustained during the posttreatment year, whole-lake treatments with herbicide may not be a useful tool for longterm management of bluegills or largemouth bass unless annual or semiannual treatments are an acceptable social, biological, and economic strategy.

Rudstam, L., J. K. HORNE, and G. Gleischer. Translation of acoustic data to fish abundance (and standardization of acoustic methods for the Great Lakes region). Report from the Great Lakes Acoustic Workshop III, Cornell Biological Field Station, February 11-12, 1999. 12 pp. (1999).

1998

HORNE, J.K., and C.S. Clay. Sonar systems and aquatic organisms: matching equipment and model parameters. Canadian Journal of Fisheries and Aquatic Sciences 55:1296-1306 (1998). Acoustic technology is an accepted and important component of aquatic research and resource management. Despite the widespread use of echosounders, few guidlines aid in the choice of appropriate sonar system parameters for acoustic surveys. Choice of acoustic carrier frequency is analogous to the choice of spotlight color used to illuminate a painting. Three primary biological factors influence the scattering of sound by aquatic organisms: swimbladder presence, organism length, and organisms behavior. We illustrate the influence of these factors on the amplitude of backscattered echoes using a Kirchhoff-ray mode scattering model to quantify fish and zooplankton backscatter as a function of carrier frequency, fish length, and swimbladder aspect. Model results illustrate that echo amplitudes from aquatic organisms are largely dependent on the presence or absence of a swimbladder. Target strengths generally increase with increasing carrier frequency and organism length. Swimbladder angle relative to the incident sound wave affects scattering amplitudes at all frequencies. Measurements of backscatter from swimbladdered fish are relatively robust when the ratio of fish length to acoustic frequency wavelenth ranges between 2 and 10. As fish length to frequency wavelength ratios increase, echo amplitudes become more dependent on aspect and peak when the swimbladder is perpendicular to the acoustic wavefront.

HORNE, J.K., and J.M. JECH. Quantifying intra-species variation in acoustic backscatter models. Proceedings, 135th Meeting of the Accoustical Society of America, Seattle, WA, August 20-26, 1998. 1821-1822 (1998). Fisheries researchers are increasing the use of acoustic backscatter models in estimates of fish and zooplankton abundance. Target strength models based on measurements from a few fish may be applied to all individuals of the same species at frequency. The choice of carrier frequency combined with morphological and behavioral differences among organisms will influence amplitudes and variability of backscattered echoes. We quantified variability in backscatter of Atlantic cod (Gadus morhua) and brook trout (Salvelinus fontinalis) using data from digitized x-rays and Kirchhoff-ray mode models. Backscatter means and variances were combined to map the probability of discriminating cod from trout backscatter over a range of aspect angles, fish lengths, and acoustic frequencies.

JECH, J.M., and J.K. HORNE. Sensitivity of acoustic scattering models to fish morphometry. Proceedings, 135th Meeting of the Acoustical Society of America, Seattle, WA, August 20-26, 1998. 1819-1820 (1998). Current efforts to model fish backscatter use digitized images of fish anatomy to realistically represent swimbladder shape, volume, and aspect. X-rays images of Atlantic cod (Gadus morhua) were digitzed at high resolution to examine the effects of varying image resolution on predicted backscatter as a function of carrier frequency and swimbladder shape. Backscatter amplitude scattering curves diverge with decreasing image resolution and increasing carrier frequency in the geometric scattering region. Image resolution has less effect on backscatter amplitude variability at/near resonance than in the geometric

TYLER, J. A. GRP Map Maker: A User's Guide to Spatial Models of Fish Habitat Combining Acoustic Data and Bioenergetics Models. NOAA Technical Memorandum ERL GLERL-110, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, (NTIS# PB99-114837/XAB) 51 pp. (1998). ftp://ftp.glerl.noaa.gov/publications/tech_reports/glerl-110

Current Research Projects (Some projects pending external funding)

(Task Reports for all continuing projects are available at http://www.glerl.noaa.gov/res/)

• Study Group on Fisheries Acoustics in the Great Lakes
• Development of Bioelectrical Impedance Analysis (BIA) for a rapid assessment of fish condition
• Modeling historic and spatial variation of Great Lakes fish maturation schedules
• Recruitment of Great Lakes Fishes: A Meta-analysis
• Evaluation of the Hazard of Microcystis Blooms for Human Health through Fish Consumption
• Causes, Consequences and Correctives of Fish Contamination in Detroit River AOC
• Effects of Diporeia Declines on Fish Diet, Growth and Food Web Dynamics in Southeast Lake Michigan
• Temperature & salinity effects on growth & survival of juvenile penaeid shrimps
• Diets and condition of forage fish in southern Lake Huron
• Implications of Cercopagis and Bythotrephes to Alewife Recruitment and Stability of the Lake Michigan Pelagic Food Web
• Ontogenetic and Seasonal Variation of young Non-Native Fish energy densities in L. Michigan
• An Evaluation of Bioenergetics Modeling for Lake Whitefish in Lake Michigan
• Ecology of Lake Whitefish and Response to Changes in Benthic Communities in Lake Huron
• Ecosystem Variability and Estuarine Fisheries
• River discharge as a predictor of yellow perch recruitment in Lake Erie
• Salmonid Spawning Stock Abundance, Recruitment and Exploitation in the Muskegon River, Michigan
• Watershed - Great Lakes Interactions: Defining the Ecological Footprint of the Muskegon River Watershed on Fisheries in Nearshore Lake Michigan
• Habitat-Mediated Predator-Prey Interactions in the Eastern Gulf of Mexico
• Regional Collaboration in Environmental Monitoring and Forecasting in the Northern Adriatic Sea