Atlantic Menhaden

1. Atlantic Menhaden An update of the issues and scienceGood science and multiple perspectives Bob Wood NOAA’s director for the Cooperative Oxford Laboratory

2. Atlantic menhaden population status and management is ahot topic • http://www.chesbay.org/ (Chesapeake Bay Ecological Foundation) “Atlantic menhaden … have the ability to filter a volume of water equal to the entire Chesapeake Bay in less than one day ... However, since there is no quota to limit or control the harvest, this intensive fishery for Atlantic menhaden seasonally depletes the Bay's most valuable living resource.” • http://www.menhadenmatter.org (an NGO “alliance”) “Simply put, striped bass and a number of other predators are competing with the industrial-scale menhaden fishery for food, and they are losing the fight.” • http://baytruth.org “As of now (1/05) there are no laws on the books protecting menhaden.  Omega Protein is free to wipe out this species with no legal consequences or financial risk.”

3. Localized Depletion is a term that has arisen over … concerns that the annual abundance and distribution of Atlantic menhaden in Chesapeake Bay is less than optimal with respect to the ecosystem services the population provides: as a forage fish, and as a filter feeder. “Localized Depletion”(what does that mean?)

4. What do we know - concerns • A pronounced and prolonged decline in Atlantic menhaden recruitment to the Bay • Chesapeake Bay striped bass “symptoms” • Disease/lesions • poor condition / “starving” fish

5. Conceptual model of Atlantic menhaden population dynamics 4) Management 1) Food Web 3) Recruitment 2) The fishery

6. Food web concerns

7. What we know • Menhaden – striped bass trophic linkages • signs of stress in the striped bass stock: are they related to declining menhaden abundance? • Disease • Low weight/length

8. Ecological importance 40-75% of a young Striped bass’s diet piscivorous fishes forage fishes Atlantic menhaden bayanchovy zooplankton phytoplankton

9. menhaden+anchovy Comprise a large proportion of the striped bass diet Data pertains to 150 - 450mm striped bass Provided by John Walter & Anthony Overton

10. Are striped bass “menhaden limited” ? • Some facts • Observations of thin and diseased striped bass appear to be on the rise…some theorize this is related to declining forage. • From 1982-95, Striped bass consumption demand increased 8x ! • Age 3-6 striped bass eat a lot of menhaden in spring & summer • As early as 1991, age 3 striped bass had periods of negative growth • Dietary energy cost of switching from menhaden to other prey is not very high high

11. About thin striped bass? • studies have shown some # of thin / poor condition striped bass in the population • this number varies from year to year • Representative sampling to determine the real extent of the problem is VERY difficult • Extent and yr-to-yr persistence UNKOWN

12. Ulcerative Dermatitis Syndrome Multiple red sores, often coalescing to cover large areas of the dermis. Multiple pathogens isolated from infected fish, none consistent Affecting 10 -30% of fish sampled in Chesapeake waters

13. Mycobacteriosis • Slow progressing, systemic disease, caused by several species of bacteria of the genus Mycobacterium (1897 – First report of “fish tuberculosis”) • Clinical signs may include dermal lesions, pigmentary changes, emaciation, stunted growth, exophthalmia, or no external signs • Detected in 50-75% of striped bass (Morone saxatilis) sampled in Chesapeake waters depending on technique • Usually results in mortality (in fish), as there is no known cure

14. Oxford Lab Archives • Examination of several hundred archived tissue blocks from 1970 – present • Few records prior to late 80’s • Wild caught striped bass only [research by John Jacobs] Fishery declared “recovered” First reports of unhealthy fish from watermen Limited Fishery Re-opened Fishery Closed

15. The Fishery

16. About the fishery • currently no catch limits [new limits just proposed] • very low to no by-catch (efficient catch relative to wasted fish & energy) • Coastal fishing grounds in are closed • in many northeastern state waters • targets age 1-3 (prefer older) which may have limited fish forage potential in Chesapeake Bay • Does catch significant levels of age • 1’s in some years

17. Trends in Reduction and Bait Landings, 1985-2002

18. Threshold Threshold 1.18 13.3 Management Benchmarks Coastal stock meets management objectives and is “healthy” (relative to sustainability) Fecundity Benchmarks (egg biomass) Target Worse Better 26.6 40.6 Note: Stock values are for 2002 Fishing Mortality (M) Benchmarks Target Better Worse 0.75 0.79

19. Atlantic menhaden fishing mortality (F)[for ages 2+] management threshold (action if exceeded) management target

20. Bubble plot for Atlantic menhaden reduction fishery catch-at-age (Ricker model output)

21. Recruitment

22. How is recruitment? Not good in Chesapeake Bay and points south positive trends in northern range recruitment trends are limiting available forage for game fish Climate variability is a strong candidate as an important reason

23. 1970 1980 1990 2000 1980 1990 2000 1970 1970 1970 1980 1990 2000 1980 1990 2000 1980 1990 2000 1980 1990 2000 Recruitment MDNR seine Upper Bay VIMS seine VIMS Bay trawl 1970 1980 1990 2000 VIMS river trawl Choptank River 1970 1980 1990 2000 Nanticoke River Potomac River Rappahannock River Chesapeake York Bay River 1970 1980 1990 2000 James River 1970

24. Spring weather conditions appear to influence recruitment Azores-Bermuda high in March = favorable menhaden habitat & prey conditions for in Chesapeake Bay Azores-Bermuda High warm subtropical air advected northward Gulf moisture & storm track Azores-Bermuda high predicted Atlantic menhaden recruitment Menhaden recruitment r-squared = 0.44 20000 Model fitted recruitment Ricker curve residuals 0 -20000 65 70 75 80 85 90 95

25. Weather conditions in strong Menhaden recruitment years Temperature anomalies Precipitation anomalies Precipitation inches Fahrenheit degrees

26. Chesapeake Bay Anadromous / Shelf Spawner recruitment pattern (CBASS) Shelf Spawners Common nursery areas - different spawning behaviors Annual young-of-the-year abundance scatter plots Anadromous fishes Anadromous fish spawning areas Coastal shelf spawner nursery areas

27. Management

28. Atlantic menhaden management Atlantic Menhaden Fisheries Management Plan Goal: To manage the Atlantic menhaden fishery in a manner that is biologically, economically, socially and ecologically sound, while protecting the resource and those who benefit from it.

29. Atlantic menhaden managment • http://www.asmfc.org/Draft Addendum II to the Atlantic Menhaden FMP • Just a few of the stated Objectives: • Protect and maintain the Atlantic menhaden stock at levels to maintain viable fisheries and the forage base with sufficient spawning stock biomass to prevent stock depletion and guard against recruitment failure. • Maintain existing social and cultural features of the fishery to the extent possible. • Protect and maintain the important ecological role Atlantic menhaden play along the coast. • Develop options or programs to control or limit effort, and regulate fishing mortality by time or area.

30. Different stakeholders and user groups Recreational Fishers Commercial Fishers Omega Protein ASMFC NGO groups State management agencies Coastal stock versus Chesapeake Bay menhaden status

31. Atlantic menhaden management Draft Addendum II to the Atlantic Menhaden FMP 110,400 metric ton cap vs. 135,000 volunteered by Omega • States will be conducting public hearings on the Addendum this summer • presents a suite of management options to limit the catch menhaden in both the Chesapeake Bay and coastwide • proposes a research program to assess whether localized depletion is occurring and identifies the following research priorities: • determine menhaden abundance in the Chesapeake Bay • determine estimates of menhaden removal by predators • evaluate the rate of exchange of menhaden between the Bay and coastal systems • conduct larval studies to determine recruitment to the Bay.

32. ASMFC Expert panel Consensus (excerpts from ASMFC special report 83) • There may be a relative imbalance between the prey needs of an increased striped bass population and a decreased abundance of menhaden juveniles (age zeros and ones) in Chesapeake Bay. • The abundance of Atlantic menhaden in Chesapeake Bay remains unknown. • There is an ongoing concern of the decade-long decline in recruitment in Chesapeake Bay.

33. Brief Conclusions • We have reason to be concerned • Stock assessments seem to rule out a problem with spawning stock biomass • Recruitment has been declining for decades • - env’l forcing appears to be influential • Striped bass population is showing signs of stress

35. ASMFC Expert panel Advice (excerpts from ASMFC special report 83) • Time and space closures/openings have potential as a management tool. • Develop reference points specific to Chesapeake Bay • Need to quantify predation mortality and produce estimates of abundance of menhaden to develop ecologically based reference points • Confront the need and potential mechanisms for management that cross single species management boundaries. • Establish values and goals for population utilization that acknowledge ecosystem services and fisheries support provided by the menhaden population. • Investigate the issue of low recruitment in the Chesapeake Bay and what is causing it.

36. The latest developments (as of March 10, 2005) • The ASMFC’s “localized depletion” workshop report (ASMFC special report 83) • ASMFC Atlantic Menhaden Plan Addendum II [ http://www.asmfc.org/speciesDocuments/menhaden/reports/menhadenWorkshopReportDec04.pdf ] • “options to limit the catch of menhaden, including restricting the Chesapeake Bay purse seine harvest to no more than 110,400 mt annually in 2006 and 2007” • “initiating a research program to … assess whether localized depletion is occurring in the Bay”