Ref. No. [UMCES CBL]

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1 Ref. No. [UMCES CBL] Potential impact of Site 104 dredging and sediment placement operations on fish eggs and larvae in the upper Chesapeake Bay January 5, 2000 E. W. North and E. D. Houde University of Maryland Center for Environmental Science Chesapeake Biological Laboratory Solomons, Maryland Introduction This report evaluates the potential impact of dredging and sediment placement operations on fish eggs and larvae in the upper Chesapeake Bay in relation to the proposed placement at Site 104. Direct impacts on ichthyoplankton may occur if there is an overlap between dredge and placement areas and fish spawning and nursery areas. This will be assessed by examining recent and historical data that describe spawning and nursery areas in the upper Bay during the proposed placement window, October 1 to April 15. Spawning and nursery areas are defined as locations where a high abundance of fish eggs (spawning area) and fish larvae (nursery area) have been found. Since the Site 104 operations entail both dredging 1 and placement, the occurrence of fish eggs and larvae in both areas during the placement window will be examined. Recent data on the abundance and distribution of fish eggs and larvae in the upper Chesapeake Bay have been collected as part of University of Maryland Center for Environmental Science s TIES program (Trophic Interactions in Estuarine Systems) sponsored by the National Science Foundation (NSF). Since 1995, the distribution and abundance of fish eggs and larvae in the Chesapeake Bay have been mapped during four-day surveys in the spring, summer and fall. In addition, the upper Chesapeake Bay was the focus of extensive ichthyoplankton collections during 1996 when researchers examined trophic interactions in the estuarine turbidity maximum (Boynton et al 1997). Ichthyoplankton data from the fall and spring surveys and the 1996 special study will be presented in this report. Spring sampling in the upper Bay was completed on 2-3 May 1995, 2-6 May 1996, and April Fall sampling was completed on 27 October - 3 November 1995, October 1996, and 1-5 November, A description of collection methods can be found in Boynton et al (1997). Preliminary findings from the NSF sponsored dissertation research of E. W. North with E. D. Houde as advisor are also presented in this report. The goal of this research is to determine whether fish eggs and larvae concentrate in the region of the estuarine turbidity maximum at the tip of the salt front and how the biological-physical interactions in this region affect their survival. The depth-distribution of fish eggs and larvae from a 4-5 May 1998 cruise are presented in this report. For further information regarding collection methods please contact E. W. North. Historical surveys of fish eggs and larvae in the upper Chesapeake Bay were completed in (Dovel 1971), in (Johnson and Koo, 1975), in (Kernehan et al 1981), and in (Rutherford and Houde 1995). Dovel (1971) was the only researcher to make collections near Site 104. Unfortunately, results from collections at this station are not reported in the literature and raw data from this sampling station are currently unavailable. In the following sections of the report, the occurrence of spawning and nursery areas at Site 104 and in the C&D Canal Approach Channel during the placement window is assessed. In accordance with the UMCES Science and Site 104 report, statements regarding potential impacts are labeled with an uncertainty rating of low, medium or high. 1 Channels proposed for dredging: Craighill Entrance, Craighill Channel, Craighill Angle, Craighill Upper Range, Cutoff Angle, Brewerton Channel Eastern Extension, Swan Point Channel, Tolchester Channel, and southern C&D Canal Approach Channel 1

2 Ref. No. [UMCES CBL] Site 104 as a spawning ground Two stations in the TIES program surveys are located near Site 104 (Figure 1). In collections from fall and spring of only eight pelagic fish eggs were found at the two stations near Site 104. One menhaden egg was found in October, Three striped bass eggs and three unidentified eggs were found in May, 1995 and one unidentifed egg was found in April, The paucity of eggs found near Site 104 indicates that Site 104 is not an important spawning ground for pelagic fish species in October and April/May (uncertainly: low). The eggs of fish which spawn demersal eggs (attached to the bottom) are not collected in the TIES program so the extent of demersal spawning at Site 104 cannot be assessed. Site 104 as a nursery area In 1996 and 1997, no larvae were captured near Site 104 during the fall collections. In 1995, 5 menhaden larvae and 9 silverside larvae were collected. The small number of larvae collected during the fall of indicates that Site 104 is not an important larval nursery area for pelagic fish species in October (uncertainly: low). The abundance of larvae captured during the spring near Site 104 and in the upper Bay can be found in Table 1. The abundance numbers are based on captures of 1 (0.06 larvae/m 2 ) to 62 larvae (3.69 larvae/m 2 ). Larvae at Site 104 constituted 0%, 0.19%, and 4.21% of larvae collected in the upper Bay in 1995, 1996, and 1997 respectively. Although it is notable that yellow perch larvae were captured near Site 104, only 3 larvae were captured in 3 years. This low abundance of larvae found near the mouth of the Magothy River matches past assertions of small spawning populations in this river (Dovel 1967, Piavis 1990). The low percentage of larvae captured at Site 104 as well as the small number of yellow perch larvae found there indicate that Site 104 is not an important nursery area for most species of fish in late April and early May (uncertainty low for white perch, striped bass, alosids; uncertainty moderate for yellow perch). Upper Chesapeake Bay as a spawning ground and nursery area TIES collections of anadromous fish eggs and larvae in the upper Chesapeake Bay indicate that the region south of Turkey Point was a spawning area for striped bass (Figure 1) in In addition, TIES data show that the region south of Turkey Point was an important nursery area for alosids (herrings), white perch, and striped bass larvae in late April or early May in 1995 (Figure 2), 1996 (Figure 3) and 1997 (Figure 4). Results of the NSF North/Houde research cruise in early May 1998 also demonstrate that the upper Bay south of Turkey Point is an important spawning area for striped bass and an important nursery area for striped bass and white perch larvae (Figure 5). Although there is some conflict in the historical literature regarding the major spawning and nursery area of striped bass in the upper Chesapeake Bay, results of the most recent studies substantiate the findings of the TIES and NSF programs. Based on egg collections, Kernehan et al (1981) found two distinct striped bass spawning areas, one in the C&D Canal and one in the lowermost part of the Elk River and the Chesapeake Bay south of Turkey Point. They concluded that the area south of Turkey Point was a much more important spawning and nursery ground than the C&D Canal since they found the highest densities of eggs and post yolk-sac larvae in that area. Rutherford et al 1997 also found two peaks in striped bass egg and larval abundances, one south of Turkey Point and one near the C&D Canal. Other historical studies that cite the C&D Canal as the only major spawning area for striped bass are at least three decades old and either did not sample south of Grove Point (Johnson and Koo 1975) or did not discuss the distribution of eggs south of Turkey Point (Dovel 1971). The conclusion that the upper Bay is an important spawning and nursery area is mostly based on recent ichthyoplankton collections located at stations that were in the shipping channel (TIES and NSF North/Houde research programs). The proposed dredging site, the C&D Canal Approach Channel, is an important spawning and nursery area for andromous fish (uncertainty: low). 2

3 Ref. No. [UMCES CBL] Although recent studies of fish eggs and larvae in the upper Bay have not been designed to determine the start of spawning, historical studies have documented the beginning of spawning in the upper Bay. Rutherford et al (1997) found striped bass eggs as early as 13 April in Kernehan et al (1981) found that striped bass spawning in the vicinity of the C&D Canal began as early as 3 April during Dovel (1971) reported that striped bass began spawning in early to mid-april while white perch and alewife began spawning in late March in Since historical evidence indicates that anadromous fish spawning begins as early as late March in the upper bay, dredging operations that extend beyond March 31 in the C&D Canal Approach Channel could overlap spawning and nursery areas (uncertainty: moderate). Indirect impacts Although speculative, it is important to consider the possibility that changing the bathymetery of the upper Bay may change the structure of the spawning and nursery areas of anadromous fish. Deepening the channel in the upper Bay and blocking the deep channel at Site 104 may modify the pattern of salinity intrusion into the upper Bay. As can be seen in Figure 5, white perch and striped bass larvae appear to be concentrated near the salt front, a physical feature that may be important for retention of larvae, for food concentration and for predator avoidance. Changes in bathymetery due to dredge and placement operations could affect salt intrusion and lead to an alteration of this important fish habitat (uncertainty: high). Table 1. Abundance of fish larvae (#/m^2) at two TIES stations near Site 104 in spring and comparison with abundance of larvae captured in upper Chesapeake Bay Alosids (Herrings) Cyprinids (Shiners) Striped Bass White Perch Yellow Perch Total Upper Bay Total Percent larvae in upper Bay captured near Site Acknowledgements Data were obtained in research supported by National Science Foundation Grants OCE and DEB Additional support for data analysis and report preparation were provided by EPA Science-To-Achieve-Results Fellowship Program (Fellowship No. U ). 3

4 Ref. No. [UMCES CBL] Literature Cited Boynton, W. C., W. Boicourt, S. Brant, J. Hagy, L. Harding, E. Houde, D. V. Holliday, M. Jech, W. M. Kemp, C. Lascara, S. D. Leach, A. P. Madden, M. Roman, L. Sanford, and E. M. Smith Interaction between physical and biology in the estuarine turbidity maximum (ETM) of Chesapeake Bay, USA. ICES CM 1997/S:11. Dovel, W Fish eggs and larvae of the Magothy River, Maryland. Chesapeake Science 8(2): Dovel, W Fish eggs and larvae of the upper Chesapeake Bay. Natural Resources Institute Contribution No. 460, NRI Special Report No. 4. Johnson, R. K. and T. S. Koo. Production and distribution of striped bass (Morone saxatilis) eggs in the Chesapeake and Delaware Canal. Chesapeake Science 16(1): Kernehan, R. J., M. R. Headrick, and R. E. Smith Early life history of striped bass in the Chesapeake and Delaware Canal and vicinity. Transactions of the American Fisheries Society 110: Piavis, P Yellow Perch, Perca flavescens. In: Funderburk, S. L., S. Jordan, J. A. Mihursky, and D. Riley, eds. Habitat Requirements for Chesapeake Bay Living Resources. Chespeake Bay Program, Living Resources Subcommittee. Rutherford, E. S., E. D. Houde, and R. M. Nyman Relationship of larval-stage growth and mortality to recruitment of striped bass, Morone saxatilis, in Chesapeake Bay. 4

5 Figure 1. TIES Striped bass egg abundance to to 0.80 May 2-3, 1995 Eggs 0.00 to to to to to to to 2.80 May 2-6, 1996 Eggs 0.00 to to 0.80 April 20-21, 1997 Eggs

6 Figure TIES Ichthyoplankton Survey, May to to to to to to 1.20 White Perch 0.00 to to to to to to 0.06 Striped Bass 0.00 to to to to to to 1.55 Herring

7 Figure TIES Ichthyoplankton Survey, May to 0 0 to to to to to to to to 600 White Perch 0 to 0 0 to to to to to to to 175 Striped Bass 0 to 0 0 to 3 3 to 6 6 to 9 9 to to to to 21 Herring

8 Figure TIES Ichthyoplankton Survey, April to to to to to to to 1.40 White Perch 0.00 to to to 0.04 Striped Bass 0.00 to to to to to to to 2.10 Herring

9 Figure NSF North/Houde icthyoplankton survey, 4-5 May. Station location map to the right. Egg and larval abundance at depth (y-axis) along the channel (x-axis) is below. Distance along channel is measured from Havre de Grace (0 km) south to the Bay Bridge (77 km). Small dots indicate mid-depth of the net tows at each station. Havre de Grace Striped Bass Eggs (#/m^3) with Salinity contour lines Striped Bass Yolk-sac Larvae (#/m^3) with Salinity contour lines Depth (m) White Perch Yolk-sac Larvae (#/m^3) with Salinity contour lines Striped Bass and White Perch Post-Yolk-sac Larvae (#/m^3) with Salinity contour lines Kilometers from Havre de Grace 0