Presentation on theme: "The Importance of Pelagic Processes in determining Habitat in the Sea SeaScape Meeting Sandy Hook March 2, 2012 Donald B. Olson With major input from Jerry."— Presentation transcript:
The Importance of Pelagic Processes in determining Habitat in the Sea SeaScape Meeting Sandy Hook March 2, 2012 Donald B. Olson With major input from Jerry Ault, Ashley McCrea-Strub, Jing-Gang Luo, and William Harford
Regional Oceanography Bathymetry & CurrentsSea Surface Temperature 1 June 2011 Bottom topography and SST
Retrograde fronts: Density surfaces are perpendicular to the bottom topography Examples: Mid- Atlantic Bight Prograde fronts: Density surfaces parallel to bottom topography. Examples: Gulf Stream along U.S. coast or Kuroshio off China See Mooers et al. 1978 or Olson 2001
Small boney fish. Oily High protein Detrital diet is rich in terrestrial nutrients
Americas First and Foremost Fishery: Menhaden or Mossbunker Early visitors to America came for cod; but the early colonists were not fishermen per see. Capt. John Smith noted on his first trip to Virginia that a small fish formed massive shoals in the shallow bays. Squanto (Tisquantum) taught the Pilgrims to place these small fish in mounds of corn to act as fertilizer.
The Menhaden Industry Early Long Island and New England fishery involved groups of farmers covering their fields with fish. In 1850s this gave way to industrial trying and processing oil and meal separately. Meal becomes easily shipped fertilizer and later animal feed. Oil becomes prime replacement for whale oil following the fall of the whale fishery after the early 1860s.
Shortfin mako - Bluefish Interactions in the Western North Atlantic Ocean A large fraction (>80%) of mako diet consists of bluefish during part of the year; Food web model developed using Ecopath with Ecosim; Emphasis on indirect effects of fishing. Shortfin makoBluefish Fishery Indirect Effects William Harford
Multispecies Yield Surfaces Resource-driven control by bluefish was strongly evident; Mako fishery had little effect on bluefish (right), whereas bluefish fishery had notable effect on mako (left); Suggestive of competition for shared bluefish prey between mako & fisheries.
Chlorophyll aSea Surface Temperature Small prey (Spring) < 200 mm Small prey (Fall) Prey Abundance
Factors affecting fish “spatial growth rate potential” components of “essential habitat”. August Age 0 Menhaden August Age 4 Menhaden (X,Y) Bluefish October 1 Transport and Movements of Predator & Prey April 15
What are the effects of schooling affinities? Bakun’s Red fish/Blue fish hypothesis: Obligations to remain in schools shift fish populations towards different geographic locations based on metapopulation density within schools. Selection and genetics? The MacCall hypothesis: Fish make use of their ability to migrate as schools to exploit changes in mesoscale habitat linked to larger scale climate variations.
Fisheries yield and yield vs costs N₂N₂ N₁N₁ Cost N₂N₂ Olson et al. (In prep)
Summary Fisheries habitat is at the highest level set by the physical factors: Climatological postions of front and circulations and their dynamics; seasonal progression of S, T,… Trophic interactions between species and the adaptation to each other and the environment. The use of habitat by fishermen is a crucial factor in terms of understanding fisheries.