Forage Fish in Chesapeake Bay: Status, Trends, Science and Monitoring GIT Meeting Chesapeake Biological Lab Solomons, MD 4 December 2013 Chesapeake Bay Watershed Agreement, Draft 11/3/13 Forage Fish Outcome: By 2016 develop a strategy for assessing the forage fish base available as food for predatory species in the Chesapeake Bay.
What Are Forage Fish? Crucial species in food webs Small, often schooling pelagic species Sardines, anchovies, sand eels, krill, herring (Lenfest did not include squids) Because fish are hatched at small size, almost all fishes are prey for larger fishes and other predators. But, we generally don t consider species that have large adult size and non-schooling behavior as forage species. Feed on plankton and transfer energy to upper trophic levels From Lenfest 2012
Economic Value of Forage Fish Direct value of commercial catch Supportive commercial value Total global commercial value Value in 2006 dollars = $5.6 billion = $11.3 billion = $16.9 billion First ever estimate of total value of forage fish to all fisheries FORAGE FISH DIRECT VALUE FORAGE FISH SUPPORTIVE VALUE Lenfest 2012
Striped Bass Fishes of Chesapeake Bay Spot Atlantic menhaden Mummichog White Perch Atlantic Croaker Summer Flounder Hogchoker Bay anchovy Atlantic silverside Yellow Perch Weakfish American Shad Alewife Cownose Ray Bluefish Northern Snakehead Blueback Herring American Eel Atlantic Sturgeon Blue Catfish
Forage Fishes in Chesapeake Bay Bay Anchovy Atlantic Menhaden Atlantic Silverside Striped Anchovy Gizzard Shad Mummichog YOY Alosines Spottail Shiner Other small fishes (gobies, blennies, etc.)
Forage fish are valuable as prey Many predators are highly dependent on forage fish... and decline when forage fish decline. Predators that have a higher proportion of forage fish in their diet generally exhibit greater declines as forage fish abundance decreases. Forage fishes support a diverse spectrum of predators, not only exploitable, piscivorous fishes. Research and monitoring of the predators also is needed. Lenfest 2012
SSC National Workshop IV: EBFM and Forage Fish Issues Need better ways to estimate forage biomasses Need better ways to estimate predator demand Determining M2 is important Ecosystem forage buffers vs singlespecies buffers? MAFMC Forage Fish Workshop, April 2013
For consideration Indicators and reference points Are there any rules of thumb, e.g., F < M, Biomass threshold, hockey-stick (Restrepo, Lenfest) rules, appropriate F and B levels. Can predator demand be indexed from stock assessments of predators? What indices of ecosystem state are available that are indicative of predator demand and prey availability? Can energetics modeling be useful to estimate demand? What about ecosystem modeling? Strategic or tactical?
Leave one third for the birds Cury et al. 2011
Atlantic Menhaden
Young-of-the-Year Abundances Atlantic Silverside Bay-wide Geometric Mean Catch per Haul GM 18 16 14 12 10 8 6 4 2 0 Atlantic Menhaden Bay-wide Geometric Mean Catch per Haul GM 40 35 30 25 20 15 10 5 0 1959 1962 1965 1968 1971 1974 1977 1980 1983 1986 Year 1989 Mummichog 1992 1995 1998 Bay-wide Geometric Mean Catch per Haul 2001 2004 2007 2010 2013 1959 1962 1965 1968 1971 1974 1977 1980 1983 1986 Year 1989 1992 1995 1998 2001 2004 2007 2010 2013 2.5 2.0 GM 1.5 1.0 Bay Anchovy Bay-wide Geometric Mean Catch per Haul 0.5 0.0 1959 1962 1965 1968 1971 1974 1977 1980 1983 1986 1989 1992 1995 1998 2001 2004 2007 2010 2013 Year GM 8 7 6 5 4 3 2 1 0 1959 1962 1965 1968 1971 1974 1977 1980 1983 1986 Year Maryland DNR Juvenile Fish Seine Survey 1989 1992 1995 1998 2001 2004 2007 2010 2013 GM Spottail Shiner Bay-wide Geometric Mean Catch per Haul 3.0 2.5 2.0 1.5 1.0 0.5 0.0 1959 1962 1965 1968 1971 1974 1977 1980 1983 1986 Year 1989 1992 1995 1998 2001 2004 2007 2010 2013
VIMS Juvenile Fish Trawl Survey Houde et al. 2006. Progress Report to MD Sea Grant
Menhaden: Allocation and EBFM Bluefish Commercial Fishery Predators/Piscivores Striped Bass Weakfish Osprey What is a Fair Allocation Plan? Can Humans Cause Localized Depletion? Recreational Striped Bass Fishing
Research Needs Abundance Estimates Predator Demand Connectivity: Ocean & Estuary Forecasting Long-term Trends Energetics and Productivity Environment and Habitat Climate Effects
Monitoring Needs Continue Juvenile Index Surveys Baywide Trawl Survey Ingress Monitoring Predators Abundances Predators Stomach Analyses