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1. Using Site-specific, Biological Data to Evaluate the Protective Value of Seasonal Dredging Restrictions for Winter Flounder in New York / New Jersey Harbor • Douglas Clarke1, Dara Wilber2, David Davis3, Sarah Zappala3, • Laura Csoboth3, Catherine Mulvey4, Ann Marie Dilorenzo4, and Jenine Gallo4 • 1 U.S. Army Engineer Research and Development Center, • 2Bowhead Information Technology Services • 3Henningson, Durham and Richardson Engineering, Inc. (HDR) • 4United States Army Corps of Engineers – New York District www.cleanoceanaction.org

2. “the committee found that the scientific evidence used in setting windows varies greatly. Some decisions appear to be based on outdated data and information, others on the authority of the resource agency, and only a few on scientific observation.”

3. Seasonal dredging restrictions are designed to protect eggs and larvae www.cleanoceanaction.org

4. Rationale - Temporally isolate the impact in response to the regulatory requirement to avoid, minimize, and/or mitigate for navigation construction projects. Winter Flounder – Seasonal Dredging Restriction February 1 – May 31st

5. Impacts of Seasonal Dredging Restrictions • Increase project costs • Decrease navigation safety • Reduce construction efficiency • Prolong adverse effects on the environment

6. Aquatic Biological Survey • 1998 – 2011 • Over 3,000 ichthyoplanktontows since 2002 when sampling began in Lower Bay • 26 – 29 stations throughout the harbor Photo credit: Schultz et al. 2007 epibenthicsled-mounted 0.5-m plankton nets (0.5-mm mesh)

7. Station Locations in New York / New Jersey Harbor

8. Temporal Pattern of Egg and Larval Occurrences 90% Conceptual 10% Jan. Feb. Mar. Apr. May June July 2001 Conservation Recommendation dredging restriction February 1st to May 31st

9. When are 10% of winter flounder eggs collected in NY/NJ Harbor? Dredging restriction would start earlier 90% Conceptual Dredging restriction can start later 10% Jan. Feb. Mar. Apr. May June July 2001 Conservation Recommendation dredging restriction February 1st to May 31st

10. <10% of eggs were collected before February 1st each year Actual Data

11. When are 90% of winter flounder larvae collected in NY/NJ Harbor? Dredging restriction wouldend later Dredging restriction would end earlier 90% Conceptual 10% Jan. Feb. Mar. Apr. May June July 2001 Conservation Recommendation dredging restriction February 1st to May 31st

12. >90% of larvae were collected before May 31st each year Actual Data

13. Actual Data ColderWarmer

14. Low value spawning habitat Actual Data

15. Conclusions The existing winter flounder dredging restriction (February 1st – May 31st) broadly brackets the timing of winter flounder spawning in New York/New Jersey harbor. In many cases, the dredging restriction is too conservative and can be shortened by several weeks in February (front end) and in May (back end) without increasing risks of adverse impacts on winter flounder larvae. The occurrence of larvae in the harbor later in the spring during cold years allows adaptive management of dredging restrictions, although logistical considerations, such as contracting constraints, may be a limitation.

16. Special thanks to Captain Mike Marcello and the crew of the USACE Hudson