Offshore Wind Power Projects in the Great Lakes - Ministry of ...

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Offshore wind power projects in the Great Lakes: Background and science considerations for fish and fish habitat Previous experiences within the Great Lakes have demonstrated that artificial reefs located in 4 - 7.5 m of water are ideal for many centrarchid species including bass, bluegill and crappie (Creque et al. 2006; Lynch & Johnson 1988). Conversely, artificial reefs that are situated further offshore are susceptible to unstable thermal habitats making them unsuitable as habitat for these species (Creque et al. 2006). To keep warm water fish concentrated around a reef complex even when thermal stratification occurs in deeper areas, it has been suggested that artificial structures could be placed in rows that extend from shallow to deeper water so that fish can move into shallower or more oxygenated waters as necessary (Bolding et al. 2004). These examples demonstrate that knowledge of local and seasonal conditions, as well as an understanding of the physiological tolerances of target fish species to different temperature or dissolved oxygen conditions will be essential in selecting suitable sites for artificial habitat enhancement projects. Artificial structures generally work best to concentrate bottom and structure-oriented species, territorial species, or obligate reef spawners. Through monitoring studies of nearshore artificial structures, Great Lakes fish species that have been found to be attracted to habitat modifications that include riprap, steel piling, concrete or rock rubble, cobble and other materials include walleye, mottled sculpins, yellow perch, smallmouth bass, rock bass, largemouth bass, lake trout, lake whitefish, spottail shiner, white sucker, white crappie and round gobies, among others (Bolding et al. 2004; Fitzsimons 1996; Herdendorf 1985; Jude & DeBoe 1996; Rutherford et al. 2004). In contrast, structure in nearshore environments doesn’t usually drive the presence of open-water or pelagic species like salmonids, for example. Clearly, prior knowledge of which fish species exist within the system and are likely to inhabit or utilize specific project areas is necessary in order to ensure greater chances of success in attracting fish to the artificial structures (Wills et al. 2004). Similarly, an understanding of the specific life history and habitat requirements of possible inhabitants will be important in the selection of appropriate scour protection material type, size and design, as well as in the design or layout, and location of turbine arrays. Lake trout habitat restoration Because there has been a lot of emphasis in recent years to restore spawning populations of lake trout throughout the Great Lakes, and because offshore wind turbine foundations and scour protection materials might be located in areas suitable for lake trout spawning habitat, it is worth Aquatic Research and Development Section 50
Offshore wind power projects in the Great Lakes: Background and science considerations for fish and fish habitat highlighting some of the critical habitat requirements for this particular species. Lake trout require coarse, cobble-like substrate with interstitial spaces for successful spawning and egg incubation. Ideal substrates are angular to subangular in shape (Fitzsimons 1995), with sizes ranging between 10-20 cm (Fitzsimons 1996). Substrates smaller than this are more prone to sediment infilling, which should be avoided as lake trout require clean substrate clear of fouling or fine sediment in order to incubate their eggs (Marsden et al. 1995; Rutherford et al. 2004). For this reason, locating artificial lake trout spawning habitat in areas surrounded by fine or sandy substrates might not be ideal in some areas as currents could sweep these sediments onto incubating eggs. Having a significant influence on the movement of sediments, lakebed relief and local current regimes around a reef could play a more critical role in dictating the integrity of reef spawning sites than the nature of the surrounding sediment, however. While many historical lake trout spawning shoals were located on offshore reefs at a variety of water depths (Fitzsimons 1996), current populations of stocked lake trout appear to spawn primarily on shallow, nearshore reefs (
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Offshore Wind Power Projects in the Great Lakes - Ministry of ...

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