# NOAA Tech Memo NWFSC-7: Part 3: Ecosystem Assessments

#### West Coast Estuarine Inventory

In 1988, the CZES Division entered into a cooperative study with NOAA's National Ocean Service to compile a summary data base on living marine resources in selected estuaries of Washington, Oregon, and California. This data base is the West Coast component of NOAA's National Estuarine Inventory. The final West Coast inventory, in atlas form, presents a review of available data on the distribution, abundance, and life-history of 47 economically and ecologically important species from 32 West Coast estuaries. The completed and computerized data base enables comparisons between species, groups of species, specific life-stages, estuaries, and geographic regions.

This inventory is the necessary first step in providing documentation which will allow coordinated regional management strategies. When complete, the study will provide a ready reference to key organisms and their distributions and will direct researchers and resource managers toward estuaries and species about which more data are required. 

All of 1989 (and part of 1990) was spent collecting data on various species and estuaries. Much of this information was gathered from important unpublished and "gray literature" sources authored by a variety of groups and individuals. Of special value was the input from meetings with regional estuarine experts who provided firsthand knowledge of specific species and estuaries. 

In March 1990, a report presenting a summary of distribution and abundance data was completed and distributed. In 1991, a report was produced that presents species life-history summary data and some analysis of distribution and abundance data. These reports were followed by a publication in 1992 that evaluates the relationship between estuarine physical factors and estuarine fish biogeography. Currently, a publication that discusses spawning escapement and hatchery production of salmonids in West Coast estuarine basins is in review.

#### Bibliography

Emmett, R. L., S. A. Hinton, and M. E. Monaco.In prep. Spawning escapement and hatchery production of salmonids in 21 West Coast estuarine basins. (Will be available from National Marine Fisheries Service, Point Adams Biological Station, P.O. Box 155, Hammond, OR 97121.)

Emmett, R. L., S. L. Stone, S. A. Hinton, and M. E. Monaco.1991. Distribution and abundance of fishes and invertebrates in West Coast estuaries, Vol. II: Species life history summaries. NOAA's Estuarine Living Marine Resources Project, Rep. No. 8, 329 p. (Available from National Marine Fisheries Service, Point Adams Biological Station, P.O. Box 155, Hammond, OR 97121.)

Monaco, M. E., and R. L. Emmett.1988. National estuarine inventory: Estuarine Living Marine Resources Project; Washington State component, 82 p. (Available from National Marine Fisheries Service, Point Adams Biological Station, P.O. Box 155, Hammond, OR 97121.)

Monaco, M. E., T. A. Lowry, and R. L. Emmett.1992. Assemblages of U.S. West Coast estuaries based on the distribution of fishes. J. Biogeogr. 19:251-267.

Monaco, M. E., D. M. Nelson, R. L. Emmett, and S. A. Hinton.1990. Distribution and abundance of fishes and invertebrates in West Coast estuaries, Vol. I: Data summaries. NOAA's Estuarine Living Marine Resources Project, Rep. No. 4, 240 p. (Available from National Marine Fisheries Service, Point Adams Biological Station, P.O. Box 155, Hammond, OR 97121.)

#### Columbia River Estuary Long-Term Management Strategy

Each year, the COE dredges and disposes of more than 1.5 million m3 of sediment from the navigation channel between River Kilometers 7 and 46 in the Columbia River estuary. Existing upland dredged-material disposal sites are almost filled to capacity, and options for the disposal of this volume of sediment are presently extremely limited. Accordingly, in 1988 the COE initiated a study to develop a Long Term Management Strategy (LTMS) for dredging and disposal operations in the Columbia River estuary. The goal of the LTMS is to ensure that future dredging and disposal activities will be economical, minimize adverse environmental impacts, and take advantage of opportunities for beneficial uses of dredged material.

One of the major concerns associated with new in-water disposal sites, especially when creating islands, is the effect on aquatic biological communities. To address this concern, the CZES Division initiated a study to assess aquatic resources in intertidal and subtidal habitats at or adjacent to five present or potential disposal areas in the Columbia River estuary: Desdemona Sands, Taylor Sands, Rice Island, Miller Sands, and Jim Crow Sands. Specific objectives of the study were 1) to describe bottom sediment characteristics and the benthic invertebrate and fish communities at each area and 2) to compare bottom sediment characteristics, benthic invertebrate, and fish communities at Millers Sands at present with those that existed from 1975-77. The comparison will weigh the effects of the marsh and lagoon at Miller Sands, which was created with dredged material from 1975 to 1976.

Benthic samples and fishes were collected at the five study areas in the Columbia River estuary during four surveys in 1988 and 1989. All five areas are productive estuarine habitats. Miller Sands and Jim Crow Sands in particular appear to be important feeding and rearing areas for several species of fishes, including juvenile chinook salmon, starry flounder (Platichthys stellatus), and peamouth (Mylocheilus caurinus).

Fish and benthic invertebrate densities were higher in 1989 than in 1975 to 1977 at the Miller Sands lagoon, suggesting that the creation of the marsh and lagoon was a beneficial use of dredged material. However, multiple years of sample collection and analysis will be required to determine if measured increases in abundances of fishes and invertebrates were strictly the result of habitat changes or were due to natural, interannual cycles in abundances of species.

#### Bibliography

Hinton, S. A., G. T. McCabe, Jr., and R. L. Emmett.1990. Fishes, benthic invertebrates, and sediment characteristics in intertidal and subtidal habitats at five areas in the Columbia River estuary. Report to U.S. Army Corps of Engineers, Contracts E86880158, E86890107, E86900048, 92 p. + Appendixes. (Available from Northwest Fisheries Science Center, 2725 Montlake Blvd. E., Seattle, WA 98112-2097.)

McConnell, R. J., S. J. Lipovsky, D. A. Misitano, D. R. Craddock, and J. R. Hughes.1978. Habitat development field investigations at Miller Sands marsh, an upland habitat development site, Columbia River, Oregon. Appendix B: Inventory and assessment of pre-disposal and post-disposal aquatic habitats. Final Report to U.S. Army Corps Engineers, 328 p. (Available from U.S. Army Corps of Engineers, Waterways Experimental Station, Vicksburg, MS 39180.)

#### Impacts of Coastal Dredging and Dredge Disposal

During the 1980s, the CZES Division conducted a number of field surveys to assess the abundance and habitat of benthic invertebrates, demersal fishes, and large epibenthic organisms at key locations along the Washington and Oregon coasts. Information provided by these surveys was instrumental in decisions by the COE and the Environmental Protection Agency (EPA) on where to conduct dredging activities and locate dredged-material disposal sites.

The Division studied demersal fish and benthic invertebrate communities at four interim ocean dredged-material disposal (ODMD) sites along the Oregon coast, including sites off Tillamook, Depoe, Siuslaw, and Umpqua Bays. Two surveys (September 1984 and January 1985) indicated that the benthic invertebrate population was greater off Tillamook Bay than at the other three sites. The high concentrations of demersal fishes and benthic invertebrates found off Tillamook Bay led to a third survey in July 1985. The results of these three surveys suggested that very high densities of fishes, crabs, and benthic invertebrates occur annually at the Tillamook Bay ODMD site. Examination of additional sediment samples collected off Tillamook Bay in May 1988 indicated a possible reduction in benthic invertebrates 4 km offshore at an approximate depth of 60 m. Division personnel conducted a fourth survey at the extended Tillamook Bay offshore dredge-disposal site in September 1988. Results of this survey were used to aid in determining the suitability of the extended bay as a disposal site for bay sediments and to establish baseline data for future monitoring.

In 1985, at the request of EPA and the Seattle District COE, the Division surveyed a proposed interim ODMD site off Willapa Bay, Washington. The benthic invertebrate community, sampled with a box corer, was high in both numbers of species and densities of individuals. The benthic invertebrate densities off Willapa Bay were much higher than typically found in the Washington-Oregon nearshore environment and resembled those reported in studies of Grays Harbor, Washington, and Tillamook Bay, Oregon, ODMD sites. These three estuaries have extensive mud flats with abundant microalgae and eelgrass. The cause of high invertebrate densities is unknown, but the contribution of primary production from the adjacent estuaries is a probable factor. The Division recommended that these areas not be used for disposal of dredged materials until after more intensive studies are complete. These areas would not be suitable unless it could be shown there would be no severe impacts to estuarine and marine fisheries.

Additional studies concerning the impacts of dredging and dredge disposal on the benthic community were conducted near Westport and Coos Bay, Oregon. Each of these projects resulted in specific recommendations regarding the location of dredging activities and future research needs.

#### Bibliography

Coley, T. C., G. T. McCabe, Jr., R. L. Emmett, and R. J. McConnell.1986. Juvenile lingcod outer harbor field survey, Grays Harbor navigation improvement project. Final Report to U.S. Army Corps of Engineers, Contract E86-85-3308, 43 p. (Available from Northwest Fisheries Science Center, 2725 Montlake Blvd. E., Seattle, WA 98112-2097.)

Emmett, R. L., T. C. Coley, G. T. McCabe, Jr., and R. J. McConnell.1987. Demersal fishes and benthic invertebrates at four interim dredge disposal sites off the Oregon coast. Final Report to U.S. Army Corps of Engineers, Contract DACW57-85-0210, 69 p. (Available from Northwest Fisheries Science Center, 2725 Montlake Blvd. E., Seattle, WA 98112-2097.)

Emmett, R. L., T. C. Coley, G. T. McCabe, Jr., and R. J. McConnell.1988. Demersal fishes and benthic invertebrates off Tillamook Bay, Oregon, in July 1985. Report to U.S. Army Corps of Engineers, Contract DACW57-85-F-0210, 23 p. + Appendixes. (Available from Northwest Fisheries Science Center, 2725 Montlake Blvd. E., Seattle, WA 98112-2097.)

Emmett, R. L., S. A. Hinton, and D. R. Miller.1990. Benthic invertebrates, sediment structure, and demersal fishes off Tillamook Bay, Oregon, September-October 1988. Final Report to U.S. Army Corps of Engineers, Contract DACW57-85-H-0001, 69 p. (Available from Northwest Fisheries Science Center, 2725 Montlake Blvd. E., Seattle, WA 98112-2097.)

McCabe, G. T., Jr., and S. A. Hinton.1990. Benthic infauna and sediment characteristics in the Columbia River near Westport, Oregon, August 1989. Final Report to U.S. Army Corps of Engineers, Contract E86890154, 10 p. + Appendix. (Available from Northwest Fisheries Science Center, 2725 Montlake Blvd. E., Seattle, WA 98112-2097.)

Miller, D. R., R. L. Emmett, and S. A. Hinton.1990. A preliminary survey of benthic invertebrates in the vicinity of the Coos Bay, Oregon, navigation channel. Final Report to U.S. Army Corps of Engineers, Contract DACW57-8-F-0467, 9 p. + Appendix. (Available from Northwest Fisheries Science Center, 2725 Montlake Blvd. E., Seattle, WA 98112-2097.)

Miller, D. R., R. L. Emmett, and R. J. McConnell.1988. Benthic invertebrates and demersal fishes at an interim dredge-disposal site off Willapa Bay, Washington. Report to Environmental Protection Agency, Contract DW13931463-01-0, 20 p. + Appendixes. (Available from Northwest Fisheries Science Center, 2725 Montlake Blvd. E., Seattle, WA 98112-2097.)

Miller, D. R., R. L. Emmett, and R. J. McConnell.1989. Benthic invertebrates at a test dredged-material disposal site in the Umpqua River, Oregon. Final Report to U.S. Army Corps of Engineers, Contract E86880162, 11 p. + Appendixes. (Available from Northwest Fisheries Science Center, 2725 Montlake Blvd. E., Seattle, WA 98112-2097.)

#### Columbia River Estuary Data Development Program

The results of this study demonstrated that the Columbia River estuary is an important sanctuary for juvenile fish. Also, the composition of species-groups in the estuary is most influenced by seasonal cycles in the life history and migration of these fish. The most complex composition and distribution were noted in summer. River flow and estuarine salinity appeared to have a strong secondary effect on fish distributions. Finally, within salinity zones, distribution of fishes was related to habitat type. Nearshore, bay, pelagic, and near-bottom areas had slightly different fish assemblages. The maximum number of fish usually paralleled the maximum concentration of zooplankton and epibenthic organisms, the principal fish foods in the central estuary and protected bays. 

In addition to the final CREDDP report, another report was based on the CREDDP surveys and evaluated the diets of 25 fish species from demersal, pelagic, and intertidal habitats of the Columbia River estuary. The following are among the findings: groups of fishes with similar diets were distinct in every season; some fishes showed large seasonal variations in diet; and, in general, diets appeared to be determined by the seasonal abundance of prey. Despite the similarities in diet between species, little competition was indicated and this may have been the result of high concentrations of few species of prey. 

Also based on results of the CREDDP surveys was a separate report on the diet of juvenile white sturgeon (Acipenser transmontanus) in the lower Columbia River and estuary. Sturgeon lengths ranged from 5 to 130 cm (total length). Sturgeon diets varied with area of capture, season, and size. The amphipod Corophium salmonis was the most important food item, but it was less important for larger sturgeon (greater than 80 cm total length) and those from the lower estuary; these sturgeon consumed larger invertebrates and fish. In general, prey diversity increased with sturgeon size and nearness to the river mouth.

#### Bibliography

Durkin, J. T., T.H. Blahm, G. T. McCabe, Jr., T. C. Coley, R. J. McConnell, R. L. Emmett, and W. D. Muir.1981. Salmonid and non-salmonid fish. Columbia River Estuary Data Development Program, Completion Report, 129 p. Pac. Northwest River Basins Comm., Vancouver, WA. (Available from National Marine Fisheries Service, Point Adams Biological Station, P.O. Box 155, Hammond, OR 97121.)

Durkin, J. T., T. C. Coley, G. T. McCabe, Jr., W. D. Muir, K. Verner, and R. L. Emmett.1981. Non-salmonid, salmonid fishes. Columbia River Estuary Data Development Program. Annual Data Report, Vol. 2, 24 p. Pac. Northwest River Basins Comm., Vancouver, WA. (Available from National Marine Fisheries Service, Point Adams Biological Station, P.O. Box 155, Hammond, OR 97121.)

McCabe, G. T., Jr., W. D. Muir, R. L. Emmett, and J. T. Durkin.1983. Interrelationships between juvenile salmonids and nonsalmonid fish in the Columbia River estuary. Fish. Bull., U.S. 81:815-826.

McConnell, R. J., T. H. Blahm, G. T. McCabe, Jr., T. Clocksin, T. C. Coley, J. T. Durkin, and R. L. Emmett.1983. Columbia River Estuary Data Development Program report: Salmonid and non-salmonid fish. 4 volumes. Columbia River Estuary Data Development Program, Astoria, OR. (Available from National Marine Fisheries Service, Point Adams Biological Station, P.O. Box 155, Hammond, OR 97121.)

Muir, W. D., R. L. Emmett, and R. J. McConnell.1988. Diet of juvenile and subadult white sturgeon in the lower Columbia River and its estuary. Calif. Fish Game 74(1):49-54.

#### Columbia River White Sturgeon

The CZES Division is responsible in part for two of the four major objectives of the study: 1) to describe the reproduction and early life history characteristics of white sturgeon populations and 2) to define habitat requirements for spawning and rearing of white sturgeon and quantify the extent of habitat available. The Division's research is being conducted in the Columbia River downstream from Bonneville Dam (RKm 233). When the study began, this was the only reach in the Columbia River system known to support all developmental stages of white sturgeon in sufficient numbers to provide a control against which habitat use and availability in other reaches of the river could be compared. In addition, sturgeon downstream from Bonneville Dam have unrestricted access to the Pacific Ocean and, therefore, may exhibit characteristics of sturgeon stocks that existed prior to dam construction. 

Data collected by the CZES Division and WDF ("control data") will be compared to similar data collected by FWS in the impoundments upstream from Bonneville Dam. These comparisons will help determine the impact of hydropower development and operation on spawning, early life history stages, and juveniles of white sturgeon in the impoundments. Initial activities in the study included a literature review and the testing of sampling gear. Field work was conducted from 1987 through 1991 and will resume in 1993. 

Research conducted to date has yielded considerable information. Downstream from Bonneville Dam, white sturgeon typically spawn from late April through late June or early July at water temperatures ranging from 10o to 18oC. Spawning occurs from the dam to points at least several kilometers downstream, in areas with high water velocity and a cobble or boulder bottom. Stage 2 (freshly fertilized) white sturgeon eggs were collected in areas with mean water column velocities from 1.2 to 2.8 m/s at depths from 4.3 to 21.3 m. In 1987 and 1988, white sturgeon larvae were collected more than 48 km downstream from Bonneville Dam. In 1989, a higher flow year than 1987 and 1988, one larva was collected more than 56 km downstream from Bonneville Dam. Small young-of-the-year (YOY) white sturgeon were collected in the upper Columbia River estuary (River Km 50) in 1989; presumably these YOY had been transported as larvae to the upper estuary, a freshwater environment, before metamorphosing. 

Catches of juvenile white sturgeon in the Columbia River downstream from Bonneville Dam were patchy. Catch data indicated that juvenile white sturgeon tended to be more abundant in water 9.1 m and greater in depth, at least during daylight. Because of the protracted spawning period and different environmental conditions, there can be large variations in lengths of white sturgeon from a specific year class. These variations precluded separation of white sturgeon into year classes except for the very young. The YOY catches were relatively low from 1987 to 1989, ranging from 11 in 1988 (less than 1% of total catch) to 111 in 1989 (4% of total catch). Data from 1989 indicated YOY growth was relatively good, with mean fork length increasing from 85 mm in July to 234 mm in October. 

Since white sturgeon is a demersal species, benthic surveys were conducted in conjunction with juvenile sampling to determine the relationship between white sturgeon population densities and benthos. However, these survey data did not indicate a strong relationship between white sturgeon population densities and benthic invertebrate population densities. 

Feeding habits of juvenile white sturgeon were examined in 1988 from two locations in the Columbia River downstream from Bonneville Dam. Results from stomach analyses indicated that juvenile white sturgeon fed on benthic organisms, but not necessarily in proportion to the abundance of these invertebrates in the benthos. Corophium salmonis, a tube-dwelling amphipod, was overall the most important food item. Other important prey included the clam Corbicula manilensis and eulachon Thaleichthys pacificus eggs in May. Results from stomach analyses suggested that food may be limited for juveniles, at least in certain areas of the river, in September and October.

#### Bibliography

Brannon, E., A. Setter, M. Miller, S. Brewer, G. Winans, F. Utter, L. Carpenter, and W. Hershberger.1986. Columbia River white sturgeon Acipenser transmontanus population genetics and early life history study. Final Report to Bonneville Power Administration, Project 83-316, Contract DE-AI79-84BP18952, 42 p. + Appendixes. (Available from Northwest Fisheries Science Center, 2725 Montlake Blvd. E., Seattle, WA 98112-2097.)

McCabe, G. T., Jr., S. A. Hinton, and R. J. McConnell.1989. Report D. In A. A. Nigro (editor), Status and habitat requirements of white sturgeon populations in the Columbia River downstream from McNary Dam, p. 167-207. Report to Bonneville Power Administration, Project 86-50, Contract DE-AI79-86BP3584, 207 p. (Available from Bonneville Power Administration, Division of Fish and Wildlife, P.O. Box 3621, Portland, OR 97208.)

McCabe, G. T., Jr., and R. J. McConnell.1987. Appendix D. In A. A. Nigro (editor), Status and habitat requirements of white sturgeon populations in the Columbia River downstream from McNary Dam, p. 49-60. Report to Bonneville Power Administration, Project 86-50, Contract DE-AI79-86BP3584, 60 p. (Available from Bonneville Power Administration, Division of Fish and Wildlife, P.O. Box 3621, Portland, OR 97208.)

McCabe, G. T., Jr., and R. J. McConnell.1988. Appendix D. In A. A. Nigro (editor), Status and habitat requirements of white sturgeon populations in the Columbia River downstream from McNary Dam, p. 114-140. Report to Bonneville Power Administration, Project 86-50, Contract DE-AI79-86BP3584, 140 p. (Available from Bonneville Power Administration, Division of Fish and Wildlife, P.O. Box 3621, Portland, OR 97208.)

Muir, W. D., R. L. Emmett, and R. J. McConnell.1988. Diet of juvenile and subadult white sturgeon in the lower Columbia River and its estuary. Calif. Fish Game 74:49-54.

#### Dungeness Crab

Specific objectives of the study were to describe the Dungeness crab's estuarine distribution, abundance, size-class structure, and location and timing of movements across the Columbia River bar (entrance channel at the mouth of the river). Since crabs moving between the ocean and the Columbia River estuary must pass over the bar, the effects of dredging on crabs could be significantly detrimental. 

Sampling for the 2-year study began in November 1983 and was completed in October 1985. Results showed that crabs were generally distributed from the bar to River Km 27. Overall, crab densities on the bar were significantly less than densities in the area upstream from the bar. The YOY crabs were captured in the estuary beginning in May 1984 and 1985. During the late spring and summer, YOY densities increased on the bar, but there was no corresponding increase in YOY densities upstream from the bar. Dungeness crabs were collected only in subtidal areas of the estuary during the 2-year study. 

Because of large annual fluctuations in crab densities observed at some frequently dredged estuarine areas during the study period, the Division continues to sample at some of the established stations. The objective of the extended study was to describe the abundance and size-class structure of Dungeness crabs in or near frequently dredged areas in the Columbia River estuary, including the bar and three sites upstream from the bar. Results of these observations have expanded the overall data base on Dungeness crabs in the estuary, specifically in areas subject to frequent dredging. They have also provided additional information for crab entrainment studies. 

Results of the initial 2-year study and the extended study show that the Columbia River estuary provides valuable habitat for Dungeness crabs, and that crab densities fluctuate temporally and spatially. Densities of crabs on the bar are extremely dependent on the immigration of early instar crabs or megalops larvae into the estuary during spring and summer. Although densities fluctuated annually, seasonal patterns were identified at some sites. This information about the Columbia River estuary aids resource managers in making decisions about dredging schedules and methods to minimize impacts on Dungeness crabs. 

CZES Division personnel continue to sample regularly at three estuarine sites in or near frequently dredged areas.

#### Bibliography

Emmett, R. L., R. J. McConnell, G. T. McCabe, Jr., W. D. Muir, and T. C. Coley.1983. Distribution, abundance, size class structure, and migrations of Dungeness crab in the Columbia River estuary. Report to U.S. Army Corps of Engineers, Contract DACW57-83-F-0377, 20 p. (Available from Northwest Fisheries Science Center, 2725 Montlake Blvd. E., Seattle, WA 98112-2097.)

McCabe, G. T., Jr., R. L. Emmett, T. C. Coley, and R. J. McConnell.1986. Distribution, abundance, and size-class structure of Dungeness crabs in the Columbia River estuary. Report to U.S. Army Corps of Engineers, Contract DACW57-84-F-0178, 57 p. (Available from Northwest Fisheries Science Center, 2725 Montlake Blvd. E., Seattle, WA 98112-2097.)

McCabe, G. T., Jr., R. L. Emmett, T. C. Coley, and R. J. McConnell.1987. Effect of a river-dominated estuary on the prevalence of Carcinonemertes errans, an egg predator of the Dungeness crab, Cancer magister. Fish. Bull., U.S. 85(1):140-142.

McCabe, G. T., Jr., R. L. Emmett, T. C. Coley, and R. J. McConnell.1988. Distribution density, and size-class structure of Dungeness crabs in the river-dominated Columbia River estuary. Northwest Sci. 62(5):254-262.

McCabe, G. T., Jr., R. L. Emmett, and R. J. McConnell.1987a. Abundance and size-class structure of Dungeness crabs in or near frequently-dredged areas in the Columbia River estuary. Report to U.S. Army Corps of Engineers, Contracts DACW57-86-F-0581 and DACW57-87-F-0127, 31 p. (Available from Northwest Fisheries Science Center, 2725 Montlake Blvd. E., Seattle, WA 98112-2097.)

McCabe, G. T., Jr., R. L. Emmett, and R. J. McConnell.1987b. Abundance and size-class structure of Dungeness crabs in or near frequently-dredged areas in the Columbia River estuary. Report to U.S. Army Corps of Engineers, Contract DACW57-87-F-0127, 29 p. (Available from Northwest Fisheries Science Center, 2725 Montlake Blvd. E., Seattle, WA 98112-2097.)

McCabe, G. T., Jr., R. L. Emmett, R. J. McConnell, T. C. Coley, and W. D. Muir.1985. Distribution, abundance, size class structure, and migrations of Dungeness crab in and to the Columbia River estuary. Report to U.S. Army Corps of Engineers, Contract DACW57-84-F-0178, 20 p. (Available from Northwest Fisheries Science Center, 2725 Montlake Blvd. E., Seattle, WA 98112-2097.)

McCabe, G. T., Jr., and R. J. McConnell.1989a. Abundance and size-class structure of Dungeness crabs in or near frequently-dredged areas in the Columbia River estuary. Report to U.S. Army Corps of Engineers, Contract DACW57-88-F-0461, 10 p. + Appendix. (Available from Northwest Fisheries Science Center, 2725 Montlake Blvd. E., Seattle, WA 98112-2097.)

McCabe, G. T., Jr., and R. J. McConnell.1989b. Abundance and size-class structure of Dungeness crabs in or near frequently-dredged areas in the Columbia River estuary. Final report to U.S. Army Corps of Engineers, Contract DACW57-88-F-0461, 22 p. (Available from Northwest Fisheries Science Center, 2725 Montlake Blvd. E., Seattle, WA 98112-2097.)

#### Parasitic Copepod

#### Bibliography

Heron, G. A., and D. M. Damkaer.1986. A new nicothoid copepod parasitic on mysids from northwestern North America. J. Crust. Biol. 6(4):652-665.

Table of Contents