Ecosystem Concepts for Sustainable Bivalve Mariculture (2010) / Chapter Skim
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4 Bivalve Mariculture Contrasted with Wild Fisheries
4 Bivalve Mariculture Contrasted with Wild Fisheries
Pages 73-86
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From page 73... ...
. The effects of harvesting bivalves for mariculture operations on the benthic community are similar to those of wild fisheries harvest in (1)
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From page 74... ...
and is typically more concentrated in local areas favorable for growth than wild-stock molluscs. Impacts to wild oyster and mussel reefs are thus potentially more severe and longer lasting than mariculture harvest impacts, and both clam and oyster harvests from these reefs have been shown to cause reef degradation and more substantial losses to oyster resources than clams (Lenihan and Micheli, 1999; Lenihan and Peterson, 2004)
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From page 75... ...
marina were undetectable, but digging clams with shovels reduced eelgrass cover and biomass over the short term, although recovery occurred fairly rapidly (months) in Yaquina Bay, Oregon (Boese, 2002)
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From page 76... ...
They are viewed as having aphrodisiacal properties in Asia and support an $80 million a year mariculture industry in Washington State and a $35 million one in British Columbia. There is a lucrative, illegal subtidal harvest of wild stocks as well.
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From page 77... ...
Issues in Chapter 6 for further discussion of aesthetics and NIMBY issues.) Because it is a relatively new practice, few data exist on the ecological effects of these PVC plantations, and this exacerbated the public debate to the point that the Washington State Legislature held a sympo sium and appropriated funds through Washington Sea Grant to study the issue in 2007.
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From page 78... ...
Integrated coastal governance and management systems of the complex natural, fisheries, and social and political milieu of the Wadden Sea began with the first Trilateral Governmental Conference in 1978, which led to the Trilateral Wadden Sea Coop eration as the focal point for coordination among governments of the three coun tries (Olsen and Nickerson, 2003)
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From page 79... ...
appeared to be sustainable with very little impact, while the impacts of dredge harvesting of wild stocks of mussels and cockles in intertidal areas of the Dutch Wadden Sea at much larger scales are highly debated (Piersma et al., 2001; Verhulst et al., 2004; Kraan et al., 2007; Box 4.2)
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From page 80... ...
Carbon Footprint No published work has addressed the relative carbon footprint (net carbon emissions per kilogram of harvest) or energy use of wild-stock bivalve exploitation versus bivalve culture; however, this comparison has been made for finfish (see Troell et al., 2004; Tyedmers, 2004)
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From page 81... ...
. EFFECT OF MARICuLTuRE ON WILD POPuLATION FISHING PRESSuRE Defining "Fishing Pressure" There is no universally accepted definition of "fishing pressure" in fisheries management literature; the term is used in a variety of ways to describe the level of fishing effort or catch (landings)
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From page 82... ...
Management of the wild fishery may limit fishing effort or landings, thereby capping physical fishing pressure.1 As a result, it is possible for the economic factors underlying fishing pressure to change without a change in the fishing pressure exerted on the wild stock. For example, a highly profitable fishery that is operating near MSY, and in which catch and effort are carefully managed, may not see any significant shift in fishing pressure despite an increase in market price (because increased fishing is proscribed by management)
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From page 83... ...
(Refer to the genetics section in Chapter 3 for more information on the genetic impacts of interactions between farmed molluscs and wild stocks.) Although bivalve mariculture generally produces effects that in theory will lead to a decrease in fishing pressure on wild populations, it is possible that no reduction in wild-capture landings or fishing pressure will occur despite increasing mariculture production.
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From page 84... ...
(2005) examined market integration of farmed and wild salmon and found that the increase in mariculture production was
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From page 85... ...
As a consequence of lower prices, the economic incentives to harvest wild populations will tend to be reduced. The extent to which this change in economic incen tives reduces fishing pressure depends on the condition and management of the wild fishery.
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From page 86... ...
Studies at larger spatial scales and over longer periods of time should also be undertaken. Finding: Economic theory suggests that mariculture production will tend to increase supply and reduce the price of the cultured species, thereby reducing economic incentives to harvest wild populations.
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