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Chesapeake Bay Management Plan Workshop. The Vision (from 2004 OMP) Achieve a restored oyster resource…throughout the Chesapeake Bay, performing important ecological roles and supporting an oyster fishery. The Purpose

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Chesapeake Bay Management Plan Workshop

The Vision (from 2004 OMP)

Achieve a restored oyster resource…throughout the Chesapeake Bay, performing important ecological roles and supporting an oyster fishery.

The Purpose

Review management strategies and make preliminary recommendations for amending and/or supporting existing objectives.

The Recent Background

Virginia Blue Ribbon Panel (May 2007): Fishing industry and management dominated panel recommended enhanced state & private support of public and private hatchery-supported fisheries and aquaculture practices.

Oyster Disease Workgroup (June 2007): Confirms the emergence of MSX resistance & clarifies issues related to management for Dermo. Affirms the efficacy of intensive aquaculture strategies.

Genetics Workgroup (July 2007): Abandons the concept of “genetic rehabilitation” of wild stocks and clarifies genetic considerations for sanctuaries and hatchery-supported fisheries & aquaculture.

Maryland Oyster Advisory Commission (draft report Dec. 2007): Charged with recommending changes to the framework and strategies for rebuilding and managing oyster populations. Discussions to date have questioned the extent of public subsidy for the fishery.

E.I.S. (Sometime in 2008): I predict will shine a light on our inability to precisely model and therefore predict the outcome of any of the proposed scenarios.

A few of the big questions

Can we continue to support a fishery and achieve ecological restoration?

What is the proper role for public hatcheries? Or, for pubic investment in the fishery?

What is the return on investment in these activities?

What (if anything) can we do better in our restoration activities? What can we restore?

Could we actually do any better with a different species?

Recent Commentary

“Ecological and economic restoration are mutually exclusive…”R. Mann (last week)

“High activation energy is required to transition from one state [low biomass-low habitat] to the other [high biomass-high habitat].”E. Powell (2007 ERF presentation)

“Without [such high activation energy] restoration is arguably untenable.” R. Mann (this week)

“There is little economic justification for any State role in oyster restoration for industry.”D. Lipton (Nov. 2007 presentation to MD OAC)

“Oysters cannot, and could not, control spring blooms that are the ultimate cause of summer hypoxia.”L. Pomeroy et al. (2007 MEPS)

“I …would …like to know [the] costs to produce a bushel of [oysters from hatchery spat-on-shell], compared to the dockside value of about $30 a bushel.” R. Kobell (Baltimore Sun, Bayblog 11/30/07)



Hatchery seed grown in protective structures

Hatchery seed w Predator protection

Washington, New England

Atlantic Canada, Virginia

Hatchery seed planted onto unprotected public bottom

Hatchery seed w/o Predator protection

Hatchery seed planted onto unprotected leased bottom

Wild seed w/ Predator protection

Wild seed grown in structures on leases

Wild seed moved to un-protected public bottom

Wild seed moved to

unprotected leased bottom

Wild seed w/o Predator protection

Maryland -seeding

Gulf States, VA (historical)

Substrate addition

Mining Phase

Ostrea edulis –W. Europe

O. conchaphila – Pacific NW

Crassostrea gigas – Asia

C. virginica – N.E., mid-Atlantic S. Atlantic, Gulf



Public capture




Fully Private


Animal Husbandry

Economic Exploitation of Oysters

Maryland -Harvest plantings and managed reserves, Virginia – pilot project

Washington, British Columbia, Virginia (recent)




Romans, VA, MD, many others


So, can we restore oysters to Chesapeake Bay for the ecological services that they provide?

Historical harvest has certainly played a role in the decline of oyster populations.

There is debate and legitimate uncertainty about the current role of harvesting.

Mann & Powell suggest that F below 5% of standing stock has minimal impacts.

There are growing calls for a harvest moratorium in MD. My more radical suggestion…

Ending harvest alone is not likely to result in dramatic increases in oyster abundance.

Disease remains a significant obstacle to increasing oyster abundances in many regions.

The evidence for the emergence of disease tolerance in wild populations is compelling, but..

Dermo is likely to remain an impediment to enhancing abundances in many locations.

Recruitment is highly variable, and in most places below historical levels, hence the increasing use of hatchery production to supplement recruitment.

Cost effectiveness, efficacy & sustainability of this strategy have not been fully evaluated.

We have long known that substrate is limiting—hence shell repletion programs.

Mann & Powell have now explicitly and eloquently defined the role of shell budgets.

For Delaware Bay shell half life varies between 3 & 10 yrs. This range is important!

Shell matters.

Substrate matters.

We have not fully explored how we can best use non-shell substrates.

So, can we restore oysters to Chesapeake Bay for the ecological services that they provide?

Larval dispersal is far from uniform.

We knew this, watermen knew it too, but we’ve not been thoughtful about it in our restoration.

Especially important at low brood stock and larval abundances.

New modeling tools (North; Wang et al.) demonstrate this and offer options for optimization.

Larval dispersal matters.

Some predator populations appear to be increasing.

- Cownose rays

- Rapa whelks?

- Starfish?

Predators matter.

Harmful algal blooms have had demonstrably negative impacts on oysters.

- Prorocentrum blooms - Cochlodinium, Gyrodinium, Gymnodinium blooms

- Aureococcus blooms in the coastal bays

HABs matter.

Water Quality

- We’ve paid too little attention to toxics impacts on reproduction and larval survival.

- Endocrine disruptors? Impacts on C. gigas have recently been shown.

Water quality matters more for oysters than visa versa.

So, can we restore oysters to Chesapeake Bay for the ecological services that they provide?

We need to employ rigorous population models. R. Mann

Births-deaths, dN/dt, How hard can that be?

An example: Increasing R is one of the things we may need to do for restoration.

10bagillion eggs; we generally assumed that eggs=embryos=larvae

At low adult densities fertilization success is surely low.

Skewed sex ratios, esp. among single cohort populations, may affect fertilization success. Kellogg et al. (2007 ICSR presentation)

Need to understand and incorporate effective population size into the demographics models.

We need to understand the metapopulation structure and connectivity between spatially discrete oyster reefs.

Early life history matters.

So, can we restore oysters to Chesapeake Bay for the ecological services that they provide?

Even in the absence of harvesting we must pay heed to many other factors.

- Disease - Shell (stocks, production rates and degradation rates) - Sedimentation rate

- HAB dynamics - Predators - Brood stock densities - Sex ratios - Contaminants

We will surely need…

- Good population and meta-population models - Realistic time and cost estimates

We will almost assuredly have to spend more money to do (seemingly) less.

It will take a long time.

No one will look out from the dockside restaurant and see clearer water as a result of this.

So, can we restore oysters to Chesapeake Bay for the ecological services that they provide?

specified biogenic habitat characteristics






targeted production increases of other species

local water quality or benthic-pelagic coupling

Operational: promote disease resistance

I suggest that you consider amending the “throughout the Chesapeake Bay” part of the vision and set reasonable goals.

I further suggest that we would be better served by heeding the advice of Margaret Palmer, who recently noted that rarely can we truly restore highly degraded habitats. Rather, we need to identify specific ecological services that we wish to rehabilitate or enhance.

This will force us to set more specific functional metrics rather than structural ones, like a 10-fold increase, for the specific ecological functions that we wish to enhance.

I sugest that it is not sufficient to list all of the ecological services oysters can play and then say “we’ll restore oysters and restore all of those functions.”

Specific goals could include:

- Self sustaining or increasing biogenic habitat in a particular tributary (e.g. Lafayette R.), where by increasing R or decreasing shell loss, dN/dt and dS/dt could be ≥ 0, even if MD is high.

- Provide biogenic complex habitats in low salinity areas (e.g., Choptank, Chester or Patuxent R.) sufficient to support X standing stock or Y annual production of associated decapods and fish.

- Facilitate localized transfer of specified quantities of materials between the water column and benthos, either for water quality or trophic transfers.

- Operational goals: E.g. - Promote the development of disease tolerance in wild oysters through ongoing, but temporary, placement of substrate in consistently high disease areas.

In Summary ecological services that they provide?

There are no options for returning to and sustaining the mining phase of oyster production.

- We may maintain very small regional fisheries with minimal intervention.

- Even a decades-long moratorium would not get us there.

- Introducing another oyster species will not get us there. It has not worked anywhere else.

The only potential for expanding the economic production of oysters is through aquaculture.

- Seed from public hatcheries grown on public bars

- Seed from public hatcheries grown on private leases

- Seed from private hatcheries grown on private leases

Cost effectiveness? Policy implications?

Temporary activity at best

The most effective approach in U.S.

Baywide restoration of oysters populations is not a realistic goal at this time. We need to replace that goal with specific, regionally-based efforts to rehabilitate specific ecological functions formerly provided by oyster reefs.

We need more than just restoration projects followed by good monitoring and adaptive management. We need large-scale manipulative experiments that test approaches towards restoring specific ecological functions.

Comprehensive Everglades Restoration Plan ecological services that they provide?

The Plan must:

• Be based on the best available science;

• Contain sufficient information for…plan formulation and evaluation, environmental and/or economic benefits, engineering and design, costs…;

• Contain the information necessary to determine that the activity is justified by the environmental benefits derived …and/or that the benefits of the project are commensurate with costs, and that the project is cost-effective;

• Identify the appropriate quantity, timing, and distribution…necessary for restoration of the natural system…

• Include an assessment of the monetary and non-monetary benefits and costs, optimization and justification, cost-effectiveness, and engineering feasibility of the project.

Extracted from U.S. Army Corps of Engineers Decision Document for Central and South Florida Everglades Restoration.