Fish Habitat: Essential Fish Habitat and Rehabilitation

<em>Abstract.</em> —The magnitude of changes occurring in Louisiana’s estuaries creates a unique set of challenges in fish habitat management. Louisiana leads the nation in rate of coastal land loss, with some 70% of national losses. Both natural and anthropogenic factors are involved in coastal land loss in Louisiana: subsidence, erosion, sediment and freshwater deficits, channelization, and rising mean sea level. Disruption of the natural deltaic cycles of the Mississippi River has been particularly detrimental to estuarine fish habitat. Navigation and flood control needs have resulted in the near-total leveeing of the river, preventing normal overbank flooding, channel filling and switching, delta and subdelta development, and sediment nourishment of adjacent and down-current marshes. The resulting system is one in which the quantity and quality of estuarine habitat are linked to rapidly degrading wetland environments. Although the relative production value of subsiding marsh surfaces is often very high, this condition is not sustainable. Steep declines in fish production have been forecast for the next century. Federal, state, and local coastal restoration projects are attempting to address the loss of estuarine habitat with a number of techniques that may produce localized changes in fisheries production and distributions. Temporary resource displacements can result in increased harvest costs, and basin-scale changes may be particularly hard to accept for resource users who are satisfied with current conditions. Harvesters have demonstrated reluctance, and may lack the financial flexibility, to forfeit expected current catches for predicted enhancement of long-term fisheries production. In some instances, both sportfishers and commercial resource users have expressed concern over estuarine freshening and turbidity from restoration inputs from riverine sources. Additional public perception difficulties with restoration efforts arise from misunderstandings of the nature of estuarine functions, particularly of the importance of nursery habitat and of the value of low-salinity marshes as nursery habitat. Significant improvement in the outlook for estuarine fish habitat in Louisiana will require long-term and large-area vision from resource managers and the public.