MB: Worldwide Interconnections & Responsible Stewardship

Complementing Approaches to make decisions on improving human stewardship

• Top-down, science driven management: use population models, motitoring, gear rules

• Bottom-up, community-driven management: involve local stakeholders, traditional knowledge, user-rights, and co-management to increase compliance and sustainability.

• Why both? Science gives tools and targets; local involvement provides enforcement, context, and social legitimacy. Good stewardship mixes both.

Overfishing Increases vulnerability to other stresses

• Core idea: removing key species (predators, herbivores, large biomass) reduces ecosystem resilience so other stresses (pollution, warming, storms) cause bigger collapses.

• Examples to cite/explain:

  • Kelp forests: remove sea otters or large predatory fish → urchin explosion → kelp loss (less buffer against storm damage).

  • Coral reefs: overfish herbivores → algae overgrow corals → reefs are less able to recover from bleaching.

  • Seagrass & estuaries: remove consumers or engineers → altered nutrient cycling and sediment dynamics → lower resilience to eutrophication or storms.

examples from paper

Selected Recommendations from the 2003 Manila Symposium on Resposible Stewardship- 1. Integrated Coastal Management & MPAs (marine protected areas)

• ensure connections among MPAs: proetects key habitats, larval dispersal corridors

• involve all stakeholders (fishers, tourism, natives) and ensure transparency

• finance & policy: user fees, multilateral agreements, and cross-border cooperation improve enforcement and long-term success.

2. Sustainable Fishers

• Protect spawning aggregations (temporal closures, area closures).

• No wild-capture juveniles to seed mariculture — mariculture must be self-sufficient or use hatchery-produced juveniles.

• Alleviate poverty via alternative livelihoods so people don’t overexploit resources.

• Prevent habitat degradation (reefs, mangroves, seagrass) — habitat protection is fisheries protection (high priority)

3. Discouraging Marine Resource Crimes

-Effective deterrence: penalties must exceed the illegal profit.

• Enforcement capacity: funding, political will, and local buy-in improve compliance

4. Research and Monitoring

• continuous high quality monitoring programs (not relying solely on catch for estimating stock size

• clear documentation of effects of climate change on coral bleaching,
  mangrove health, disease, turtle and seabird nesting success, plankton
  community dynamics - good long term records are the only way to provide
  perspective on human influences on marine ecosystems

Small Fish (forage fish)

• Forage fish (anchovy, sardine, herring, menhaden) are ecologically crucial: they convert plankton into food for larger fish, seabirds, and marine mammals.

• Human use: direct harvest for fishmeal, aquafeed, and sometimes table fish.

• Management concern: removing too many forage fish can cascade up the food web (fewer seabirds, marine mammals, large predators). Stewardship must consider ecosystem role, not just single-species yield.

Do we already know enough about the science of the sea to be able to serve as effective stewards?

• Yes:

  • Ecology and fisheries science provide many effective tools (MPAs, gear changes, catch limits, seasonal/area closures, protected spawning sites, ecosystem-based management).

  • We understand key processes (trophic cascades, importance of herbivores, connectivity) well enough to design many successful interventions.

• No / caveats:

  • Social, economic, and political barriers often prevent application (lack of funding, poor governance, perverse incentives).

  • Climate change, novel diseases, and complex ecosystem thresholds mean uncertainty remains.

  • Continuous monitoring, adaptive management, and the precautionary principle are essential because surprises happen.

• Bottom line: We know enough to act effectively in many cases — but success depends on applying known measures, building social/political support, and maintaining long-term monitoring + adaptive management.

Jackson et al (2001) paper

Historical overfishing has been the first and most powerful human disturbance to coastal ecosystems, long before pollution, climate change, or habitat destruction.
By removing large predators, key herbivores, and ecologically important consumers, humans weakened the structure and resilience of marine ecosystems. Once weakened, these ecosystems became more vulnerable to modern stresses such as nutrient pollution, disease, storms, and warming.

In short:
Overfishing was the initial driver of collapse. Other stresses only became catastrophic after humans removed the species that kept the ecosystem stable.

Jackson calls this the “ecological collapse cascade”