Essential Fish Habitat (EFH) are bodies of water and substrate required for fish spawning, breeding, feeding, and a place they can grow to maturity. Bodies of water (freshwater, estuaries and saltwater systems) that fishes use as habitat have physical, chemical, and biological components and also include historical aquatic environments that fish have always used.[1]
Important essential fish habitat characteristics include sediment type, type of bottoms (sand, silly and clay), structures underlying the water surface, and aquatic community structures. These habitats and environments are essential for fish and a fisheries health in an ecosystem. Sediment in relation to essential fish habitat is a place where essential habitat begins; primary productivity takes place here because benthic photosynthetic algae provide food, nutrients and help stabilize the sediment from erosion in aquatic environments. Erosion is also stabilized by the size of the grain size (sand, silt and clay). There are two main types of bottoms, hard and soft.[2]
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A study by Christensen at el. (2004) looked at three bottom types (vegetated marsh edge, submerged aquatic vegetation, and shallow non-vegetated bottom) in relation to juvenile brown shrimp (Farfantepenaeus aztecus). The results from the study showed that brown shrimp selected vegetated areas in salinities 15-25 ppt and they would select vegetated areas over marsh edges when they co-occurred. Finding the areas that had the highest abundance, helped to identify essential habitat of juvenile brown shrimp.[3]
Hard bottom refers to coral reef communities, exposed areas or consolidated sediments and manmade reefs that occur in temperate, subtropical and tropical geographic locations. Hard bottoms are sometimes referred to as live rock or live bottom because of the living plants and invertebra, and fish that are present, attach or border hard bottoms. These include coral, hard coral, bryozoans, ploychaete worms, tunicates, a variety of fin-fishes, alga, and sponges. Areas of compacted or sheered mud and sediment are also a form of hard bottom.[4]
Around the world, soft bottom consist of unconsolidated sediment and unvegetated areas. It also has only one habitat requirement which is sediment supplied. In some regions soft bottoms are not protected even though they may be primary nursery areas, anadromous fish spawning areas, and andaromous nursery areas. Characteristics that affect soft bottom in relation to organisms that utilize them include sediment grain size, salinity, dissolved oxygen and flow.[5]
In 1996, the Magnuson-Stevens Fishery Conservation and Management Act were amended to incorporate essential fish habitat and final rules were published in the Federal Register on December 19, 1997. The Magnuson-Stevens Act has jurisdiction over the management and conservation of marine fish species. Congress has created councils to classify unfavorable impacts on fishes in relation to types of fishing gear, coastal developments and nonpoint and point source pollution, as well as, evaluating how well each one is managed. Essential fish habitat still face big issues like, budget limits in research fields, lawsuits, and some essential fish habitat has yet to be discovered. In the U.S. essential fish habitat is examined and studied by fishery-independent surveys. The fish surveys are standardized, for instance, catch per tow and tow location, to look at spatial relative abundance of fish species.[6]
Marine reserves (no fishing areas of a marine environment) have emerged, as the forefront of resource policy and management reasons. First, they can protect habitat that has been overharvested and restored. Second, they can help maintain and increase species diversity. Last, they could possibly help enhance harvest of fish species outside of the reserve.[7][8]
Artificial reefs are one of best ways to create essential habitat for fish species and are normally created in large bodies of water, like the Great Lakes and the marine environment. They should be created with clean boulders or riprap material and should also be submerged in waters at least three meters or deeper. In some states like North Carolina, surplus vessels, steel boxcars, concrete pipe, concrete rubble, boat molds, tires, and surplus military aircraft are used to create artificial reefs in marine environments. This is carried out through a program that was developed in 1988, the DMF Artificial Reef Master Plan. Placement of artificial reefs should be placed near drop-offs and beds of submerge aquatic vegetation (SAV), to provide better utilization by fishes. All of these structures can provide protection from predators and injury from fast moving water bodies. These areas also give fish species a place to rest, hide, feed, and spawn [9]