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Stochastic Transport Generates Coexistence in a Nearshore Multi-Species Fishery

Stochastic Transport Generates Coexistence in a Nearshore Multi-Species Fishery. Heather Berkley, Satoshi Mitarai, Bruce Kendall, David Siegel, Robert Warner. NSF Biocomplexity Project - Flow, Fish and Fishing. Multi-species Model. Stochastic dispersal as a mechanism for coexistence

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Stochastic Transport Generates Coexistence in a Nearshore Multi-Species Fishery

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  1. Stochastic Transport Generates Coexistence in a Nearshore Multi-Species Fishery Heather Berkley, Satoshi Mitarai, Bruce Kendall, David Siegel, Robert Warner NSF Biocomplexity Project - Flow, Fish and Fishing

  2. Multi-species Model • Stochastic dispersal as a mechanism for coexistence • What is impact of stochastic dispersal on interactions? • What factors will influence coexistence? • Diffusive Dispersal: competitive exclusion • Stochastic Dispersal: can coexist

  3. Packet Model N larval packets • Larval settlement as arrival of N packets • L = domain size • l = eddy size (50 km) • T = Spawning time • t = eddy turnover rate (14 d) eddy size (l)

  4. Modeling 2 Species w/ Different Spawning Times • Considering 2 species with similar life histories (Life span, Fecundity, PLD, etc) • Differences in when and how long they release larvae will impact where their larvae settle • Packets released within 14 days will end up in the same location

  5. Spawning Window Overlap • Specify how many days of overlap between spawning times for both species • Makes some packets perfectly correlated for both species and others independent Packets will have same settlement locations Species A Spawning Window Species B Spawning Window TIME

  6. Distribution of Packets • ~Half of spawning windows overlap Species ASpecies B 2 2 1 1

  7. Distribution of Packets • ~Half of spawning windows overlap • ~Half of the packets settle in the same locations Species ASpecies B 2 2 1 1

  8. Parameters • spawning time= 30 days for both • Vary amount of overlap • Fecundity of Sp.A = 0.5 • Fecundity of Sp.A = 0.45 • Adult Mortality = 0.09 • Run time = 500 yrs; • Patch size = 5 km; • Domain size = 500 km; • Larvae on larvae DD (total # of both sp) • Averaged over 10 simulations

  9. Adult Population • Single run • No overlap in spawning times • Packet transport => patchy distribution • Coexistence Species ASpecies B

  10. Mean Adult Abundance Species ASpecies B

  11. 0 days of overlap Species ASpecies B

  12. 10 days of overlap Species ASpecies B

  13. 20 days of overlap Species ASpecies B

  14. 25 days of overlap Species ASpecies B

  15. 30 days of overlap Species ASpecies B

  16. Summary • Coexistence breaks down as settlement events become more correlated between species • Increasing the number of independent packets accomplishes the same result • By chance more packets => more concurrent settlement between species

  17. Future Work • Quantify how much overlap in spawning time can occur and still get coexistence • Deal with partial correlation at edges of overlap?? • Statistics from flow simulations on overlapping spawning windows (Satoshi)

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