Adapted from the Coastal Artificial Reef Planning Guide (49KB pdf)
Site selection is vital to the overall success of Taylor County’s artificial reef program.
Determining the best site starts with a purpose. The initial focus should be to enhance or create good habitat that will benefit local fisheries. We then must consider the various social, economic, environmental and biological concerns. Reefs that are improperly sited and do not take all of these factors into consideration during the planning phase will result in wasted time, money and effort and will not fully realize the purpose. Most importantly, they will not be permitted. The following guidelines are provided to help make the best decision during the critical site-selection stage of artificial reef development.
Traditionally, the majority of artificial reefs in US coastal marine waters have been sited and built to support and enhance recreational fishing. Properly sited, constructed and managed reef sites can meet a variety of other uses, such as fisheries conservation and scuba diving enhancement. However, all of these uses should share the common purpose of enhancing the marine habitat for associated fishes and other organisms. The fundamental issue dictating the design and location of an artificial reef is its intended purpose and objective. State and federal fishery management agencies and other natural resource management organizations have established essential protocols for siting artificial reefs. In Florida, the Florida Fish and Wildlife Conservation Commission (FWC) works as counsel and intermediary for the Army Corps of Engineers. The Corps is the organization that ultimately supplies the permit for an artificial reef (See Taylor County Reef Site Permitting for more information about the process).
The following factors should be considered in siting reefs to accommodate fishing and diving activities, and to enhance fish:
Prospective reef builders should have an understanding of the limiting factors involving the plants and animals that will utilize an artificial reef site. Builders must identify the habitat type and/or species targeted for enhancement and determine which biological, physical, and chemical site conditions will be most effective in accomplishing our goal. Once these criteria are determined they should be used in identifying potential construction sites and materials to be used.
Artificial reefs should NOT be constructed on many types of natural habitats, including:
- existing coral reefs,
- significant beds of aquatic grasses or macroalgae,
- oyster reefs (except for shell stock replenishment),
- scallop, mussel, or clam beds, or
- existing “live bottom” (marine areas supporting growth of sponges, sea fans, corals, and other sessile invertebrates generally associated with rock outcrops).
Prospective reef builders should understand the nature and extent of recreational fishing in the area when planning artificial reefs for recreational fishing enhancement. The national Marine Recreational Fishery Statistics Survey (MRFSS) can help with such information. Other factors that must be considered include:
- location of shoreline access points (e.g. ramps, piers, marinas, bridges, and charter and party boat docks),
- general fishing methods and use patterns (e.g. trolling versus bottom fishing, vessel sizes, distances traveled offshore, skin and SCUBA diving), and
- potential conflicts with other users (e.g. commercial fishermen, divers, shipping, general navigation, military, mineral and energy extraction, historic wrecks and sites, etc.).
The Taylor County artificial reef program should attempt to accommodate the full range of recreational fishing needs, but will focus primarily on recreational bottom-fishing enhancement.
Sport divers represent a growing number of artificial reef users. The development of new technology and the increased availability of diver training and access has led to a tremendous increase in the number of sport divers in the US. The economic impact of sport divers frequenting artificial reefs often rivals that of recreational fishing activities in some regions. If Taylor County wishes to propose artificial reefs constructed for diving, there may be specific siting and construction considerations for that application.
Reefs proposed for divers should be sited and constructed at depths that will provide reasonable bottom time and minimize the decompression hazard. Factors such as water clarity, proximity to other popular dive areas, average current velocities, depth, and possible conflicts with other user groups (e.g. recreational hook and line and/or commercial fishing, navigation, etc.) should be considered.
The use of artificial reefs as marine sanctuaries for fisheries management areas has been applied in very few areas to date. Taylor County is fortunate enough to be in the early stages of a major project that seeks to develop "essential fish habitat" for gag grouper and other related species (see Steinhatchee Fisheries Management Area (SFMA) for more information). While the SFMA is NOT off-limits to divers, fisherman and other coastal activities, Taylor County artificial reef sites must be developed outside of this 100-square mile area centered off the Steinhatchee River.
Recognizing that the majority of artificial reefs will continue to be built to support fishing and diving activities, artificial reef development should be located in geographic areas with the greatest user needs, demand, and constituency support. Artificial reefs constructed for recreational use normally will be near major population centers. Due to the undeveloped, rural nature of Taylor County and the fact that there are relatively few artificial reefs in the area, this issue is not as important to our reef program, although efforts will be made to develop artificial reefs in proximity to public boat ramps.
Before beginning the site selection process, reef planners will determine existing fishing patterns and conditions offshore of each identified demand center in question. Such information will include:
- an estimate of reef use,
- preferred target species,
- distances from nearest navigable inlet or harbor,
- traditional fishing areas and methods, and
- existing or future fishery management issues which may affect the reef site or users (e.g., stock status problems, user conflicts, closures, etc.).
Analysis of this information should enable prospective reef builders to delineate broad geographical areas adjacent to identified demand centers within which to begin a more detailed site selection process and should help determine reef size and management needs. The size (aerial extent) of a reef can be important, depending on the type and quantity of material to be used and the number of boats expected on a reef at any one time.
The goals and priorities of the reef managers should direct overall site selection. Within the identified target area, existing artificial reefs and known bottom obstructions should be identified. Exclusion areas should include, but need not be limited to:
- shipping lanes,
- restricted military areas,
- areas of poor water quality (e.g., low DO, dredge spoil sites etc.),
- traditional trawling grounds,
- unstable bottoms, existing rights-of-way (e.g., oil and gas pipelines and telecommunication cables), and
- sites for other purposes that are incompatible with artificial reef development.
When the intended artificial reef construction purpose is clearly established, the following should be established and addressed:
- evaluation of social and economic siting concerns,
- definition of a general reef construction target area,
- delineation of known exclusion areas, and
- assessment of proposed site geology, hydrology and water quality.
Information and assistance useful to these assessments can be obtained from state and local natural resource management agencies, academic institutions, private consulting firms, not for-profit organizations, and local residents. Specific attention should be given to the points covered below.
The bottom composition and character at an artificial reef site has a pronounced effect on reef stability and longevity and must be carefully evaluated in the site selection process. In most cases, soft sediments such as clays, silts, and loosely packed sands should be avoided. Over time, most reef materials may sink into these sediments or become partially covered, thereby losing their utility as fish habitat.
Bottoms consisting of hard rock or hardpan with a veneer of sand cover provide excellent substrate for most types of reef construction. Dense materials such as concrete cannot settle or scour excessively on these substrate types. Reef planners should be aware however, that bottom sediments shift and may change radically during storms, hurricanes, and geologic events. Materials that present large amounts of surface area may scour deeply into almost any bottom type, depending upon storm events, current, or wave. Excessive silt and sand may become detrimental to the epibenthic organisms associated with artificial reef structures, covering or burying them. Water column sediment loads may reduce the fouling community by reducing light penetration.
Estimations of depth and bottom type using NOS charts are recommended only in the planning stages for a new reef site. Detailed information about bottom type and water depth should be obtained before a site is actually permitted for development of artificial reef construction.
Principal hydrographic factors to be considered in selecting sites for artificial reef construction include water depth, potential wave height, currents, and tides. Water depth is significant as a criterion for siting, for several reasons. First, reefs must be built in water sufficiently deep to avoid creating a hazard to navigation. Minimum clearance above the reef should accommodate the draft of the vessels expected to operate in the vicinity. The USCG and the Corps will review the merits of each reef construction proposal in light of local circumstances (see Regulatory Requirements section). Factors considered in these cases include water depths at and near the site, type of construction materials to be used, reef clearance, nature and extent of vessel traffic in the area, and proposed marking methods. Second, water depth has implications for reef users. In many coastal areas, water depth is a function of the distance offshore. This relationship must be considered when making tradeoffs between reef stability, clearance requirements, target species, and reef accessibility to various user groups (e.g., small versus large boat fishermen, commercial versus recreational fishermen, fishermen versus divers).
Third, water depth affects species composition at the reef site. This includes all sessile and motile invertebrates associated with the reef as well as plant life and fish assemblages. Reef materials placed in clear or shallow water with good light penetration generally will provide the best results in meeting the typical biological objectives of most artificial reef projects. Water depth is a key factor in determining the likely presence of desired life history stages of target fish species. Also, water depth at the reef site may critically affect reef material stability and long-term structural integrity. In this case, average wave energy in large, open bodies of water as a function of water depth is the major concern. The magnitude of wave interaction with a reef is difficult to predict but it can be destructive. It is primarily dependent on wave height, wave speed, depth of the reef, and density and shape of the reef material.
This force can resuspend bottom sediments causing siltation on the reef or destabilization of reef materials allowing them to move short distances or entirely off the site. Reef materials -20-and designs should be properly matched to water depths and predicted wave conditions to ensure their stability. Planning for worst-case storms may need to be considered on sites where movement of materials would be detrimental or hazardous. Predicted currents (tidal or wave-generated) for a possible reef site can greatly influence reef effectiveness as well as necessitate inclusion of certain critical design parameters in the selection of reef materials. Reefs should be designed to resist breakup, movement or burial that might result from the effects of currents. Detailed engineering studies may be required in some cases to ensure reef success in some areas.
Currents also influence reef effectiveness and the number of boats that can fish a reef at one time. Fishing reefs constructed across prevailing currents will allow the maximum flow of nutrient/food-laden, well oxygenated water through the reef and increase the availability of food for reef organisms and may improve hatching success of adhesive egg masses. This design orientation also helps create nutrient upwelling over the reef which, if large enough, attracts and concentrates baitfish and their predators which are often targeted by fishermen. In spite of the possible advantages of orienting reefs perpendicular to general current directions, there are cases (exceptionally strong currents or predictable storm surge) where restrictions to water flow should be minimized. In these cases, structures might function better if oriented parallel to or at shallow angles to predominant current flow or direction of storm surge.
General water quality is another important reef siting consideration. Water turbidity, salinity (in estuarine and coastal areas), dissolved oxygen, biological oxygen demand, water temperature, nutrient loads, pollution levels, and other water quality factors affect both the biological productivity and use value of artificial reefs. For example, benthic reefs built in areas with low dissolved oxygen levels (generally below 3mg/l) or where anoxic (oxygen depleted) conditions periodically occur will not achieve desired biological productivity levels and will probably not achieve management goals. Similarly, reefs built in highly turbid water would have limited value to the diving community, but may be valuable as fish habitat. Polluted areas and areas affected by treated sewage effluent should be avoided to minimize resource exposure and possible human health risk. In site planning, information and assistance can be obtained from federal, state, and local resource management, environmental quality, and scientific research agencies (see Sources of Information section). If sufficient background information does not exist to permit an adequate water quality assessment, prospective reef builders should ensure that this information is obtained through whatever means necessary, especially if some questions exist as to the suitability of a site based on water quality factors.
Artificial reef effectiveness is largely determined by the biological processes that enhance habitat for associated invertebrate and fish species or the ability of the reef to improve recreational fishing. Specific biological criteria for reef siting are not appropriate in a national plan due to variations that exist in the biological requirements of reef communities in different geographical areas. This discussion, therefore, focuses on general procedure that should be used in isolating and accommodating key biological siting factors. State and federal fishery management agencies, and other knowledgeable parties have the capability to determine the nature of fishery resources and fishing activities in the geographical areas targeted for reef construction. Objectives of the proposed reef should be compatible with fisheries conservation and management programs of the pertinent fishery management entities. Clear objectives for the proposed reef should be based on an assessment of public need and existing shore-based infrastructure. In addition, reef builders should select the target species, species groups, or life stages that they wish to enhance or rebuild. Critical habitat and environmental requirements of those species also must be identified. If selected target species are particularly sensitive to water temperature, salinity, dissolved oxygen levels, water turbidity, and contaminants, or if they have stringent habitat or food requirements, these parameters should be used as artificial reef site selection and design criteria. For example, in building reefs for snapper, grouper, black sea bass, rockfish, and other marine demersal species, low and medium profile reefs should be constructed from different sized materials which will create numerous holes and crevices of varying sizes, providing shelter for juveniles and adults.
Prospective reef builders should be aware of existing and proposed fishery management plans and regulations for the species that may be significantly affected. They should site or construct artificial reefs that would complement fishery management goals.