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How can we use the past for managing the present and the future? Enric Sala CMBC, SIO

How can we use the past for managing the present and the future? Enric Sala CMBC, SIO. How can we use knowledge about the past to manage the present and improve the future? The collapse of fisheries. Tegner & Dayton. Pauly & Maclean 2003. Tuna fishing in the Mediterranean.

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How can we use the past for managing the present and the future? Enric Sala CMBC, SIO

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  1. How can we use the past for managing the present and the future? Enric Sala CMBC, SIO

  2. How can we use knowledge about the past to manage the present and improve the future? The collapse of fisheries Tegner & Dayton

  3. Pauly & Maclean 2003

  4. Tuna fishing in the Mediterranean

  5. Marine systems are historical systems • Knowledge of the past can help us to: • Understand how and why we arrived here • The past must be used to understand the present • Marine ecosystems are historical systems whose present state depends on processes acting at different time scales • Change is continuous

  6. Knowledge of the past can help us to: • Determine where we want to go • Using historical baselines as references for management and conservation goals • What is the “best” environment we want?

  7. Knowledge of the past can help us to: • Predict future change • Understanding past trajectories can help us predict next changes

  8. How can we use knowledge about the past to understand why we are here and what is next? • Obtain a reasonable sample of one ecosystem over thousands of years, to obtain a statistical measure of change • We looked at: • 14 coral reef regions • 7 times, from pre-human to present • 7 guilds of organisms • and asked how their states changed

  9. Cultural Periods Pre-human (40,000 bp – 1503) Hunter-gatherer (20,000 bp – 1824) Agricultural based (1400 – 1800) Colonial occupation (1500 – 1850) Colonial development (up to 1900) Modern I: 1900-1950 Modern II: 1950-2002

  10. Communities surveyed • I) Megafauna • Large and small carnivores • Large and small herbivores • II) Architects • Corals • Seagrasses • Suspension feeders (eg. oysters)

  11. Pristine Detailed historical record of marine resource lacks any evidence of human use or damage. Example: Fossil corals Abundant/ Common Human use with no evidence of reduction of marine resource. Example: No reduction in size of fish vertebrae in middens Depleted/ Uncommon Human use and evidence of reduced abundance (number, size, biomass, etc.). Example: Shift to smaller sized fish, decrease in abundance, size, or species proportional representation Ecosystem State

  12. Rare Human use and evidence of severe impact. Examples: Truncated geographic range; greatly reduced population size; harvesting of pre-reproductive individuals; CPUE significantly decreased. Ecosystem State (con’t) Ecologically extinct So rare that there are few direct observations of its presence…OR…if numbers were zero there would be no further environmental effect. Human observation is newsworthy and a novelty. Examples: Turtles. Globally extinct Forever extinct. Example: Caribbean Monk seal

  13. Pandolfi et al. 2003

  14. Pandolfi et al. 2003

  15. Reef degradation was not due solely to an increase in human population (60%) Coral decline Grouper depletion Monk seal extinct Manatee depletion G. Paredes, unpublished

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