Presentation on theme: "River Herring: Status and Threats Overview Karin E. Limburg SUNY College of Environmental Science & Forestry, Syracuse, NY."— Presentation transcript:
River Herring: Status and Threats Overview Karin E. Limburg SUNY College of Environmental Science & Forestry, Syracuse, NY
Outline of todays talk: A bit of river herring biology and ecology A look at r.h. in the past The present situation
Two separate herring species in the subfamily Alosinae – blueback herring (Alosa aestivalis) and alewife (A. pseudoharengus) Closely related – capable of hybridizing Anadromous – spawn in fresh waters in spring Migrate to sea to grow and mature – largely a big black box at present Broad geographic ranges Biology & Ecology
NYS Canal Authority River Herring in New York State
Part of the lock and canal system on the Mohawk River (NYS Barge Canal). Every time the locks open and close, there are opportunities for fish passage.
River herring composed vast fisheries up and down coast (C. Hall will talk about Maine) NMFS
57 Systems on Atlantic coast –9 categories of FI &FD data 54% are blank Only 26% of remaining have good or complete (green) data –Most occurs in NE states From the stock assessment report: River herring Stock Assessment Subcommittee (SASC)
Reported NAFO landings – large foreign fleet catches in late 60s – early 70s
Stock assessment looked into current sources of mortality for r.h. For some time, bycatch (incidental catch) in marine fisheries has been suspected to be a large problem…SASC did 1 st thorough assessment Photo: Stephen McGowan, Marine PhotoBank
Relative abundance data (size of the spawning runs) - A mixed bag. Depends in part on length of dataset. Trends most clear in longer data sets.
Mean size of adults, size at age, and amount of repeat spawning is going down
Also from the stock assessment report: mortality rates are higher than most stocks can support directed fisheries exploitation rates are little to none therefore, something else is going on (e.g., bycatch, watershed impacts)
Recommendations from the stock assessment (some of many) Determine impacts of bycatch: Determine who is getting caught in bycatch Determine which stocks are vulnerable to mixed stock fisheries Reduce mortality! Monitor success of river restoration efforts Improve understanding of juvenile requirements
River herring distinct population segments Data: E. Palkovacs, E. Argo, D. Hasselman
Complementary project under-way – river herring stock discrimination in NYS and rest of coast Carlls River Carmans River Big Fresh Pond Peconic River Coxsackie (rkm 201) Newburgh (rkm 96) Peebles Isl, (Mohawk mouth, rkm 240) Sponsored by HRF, thank you!
Water -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 -0.500.000.501.00 Re-scaled Canonical Variate 1 (64.5%) Re-scaled Canonical Variate 2 (34.9%) Lower HR 2009 Lower HR 2010 Upper HR 2009 Upper HR 2010 Tribs 2009 Tribs 2010 LI 2009 LI 2010 87/86 Sr 18 O Ba:Ca Sr:Ca 1 mm Mn:Ca
Conowingo Dam (Susquehanna) Holyoke Dam (CT River) Watershed impacts: dams Small dam on Quassaick Creek
2000 Maps (top left, clockwise): Dittman et al. unpub.; Hall et al. 2010; Swaney et al. 2006; damsafety.org; Wikipedia
Merrimack R. 20% 40% 60% 80% 100% 1st to last dam 1st to 2nd dam Connecticut R. 20% 40% 60% 80% 100% Susquehanna 0% 20% 40% 60% 80% 100% 19801985199019952000200520102015 Passage efficiency between dams Passage efficiency from sea to upstream spawning grounds is not good… Brown et al. in revision. Stats for American shad. And where shad cannot go, neither can river herring…unless theyre trucked
Urbanization and sprawl growth Watershed impacts:
1988: Studied 16 tribs, in 4 reaches of the estuary: 1 st to 9 th order
2009: Growth and condition of YOY alewives reduced by urbanized watersheds (R. Monteiro et al. in revision)
Endangered Species Act (ESA) listing process Initiated by the NRDC 3 workshops this past summer Decision will be made later this fall or early next year.
River herring down around historic lows – is this a critical point? Is depensation occurring? Efforts really needed to re-build biomass this means we need to reduce mortality and increase recruitment – need to address both marine and inland concerns Take-homes: