Copyright # Blackwell Munksgaard 2003
Ecology of Freshwater Fish 2003: 12: 265±274 Printed in Denmark All rights reserved
Development and assessment of habitat suitability criteria for adult brown trout in southern New England rivers Strakosh TR, Neumann RM, Jacobson RA. Development and assessment of habitat suitability criteria for adult brown trout in southern New England rivers. Ecology of Freshwater Fish 2003: 12: 265±274. # Blackwell Munksgaard, 2003 Abstract ± Habitat suitability criteria (HSC) for depth, mean velocity, nose velocity, substrate, embeddedness, and cover were developed for brown trout 170 mm (Salmo trutta Linnaeus) on the West Branch Farmington River, CT, USA. Microhabitat data was collected by underwater observation using an equal effort habitat sampling design; HSC were constructed using nonparametric tolerance limits. Transferability of previously published HSC to the West Branch Farmington River was poor; only 1 of 13 HSC tested was considered transferable. The HSC developed for the West Branch Farmington River were tested for transferability to the East Branch West®eld River, Massachusetts. First, a composite suitability index (SI) score was calculated using the source HSC for each occupied and unoccupied location in the West®eld River. Then, x2-tests were used to determine if optimal or suitable locations were occupied in greater proportion than usable or unsuitable locations. Composite SI scores based on total depth, mean velocity, and cover were not transferable, but composite SI scores based only on total depth and mean velocity were. A multivariate pro®le analysis was also used to test for transferability. In each test, only total depth, ®sh depth, and mean velocity HSC were successfully transferred. Transferability of depth and velocity HSC between rivers shows promise for applications to similar systems where brown trout occur.
T. R. Strakosh1, R. M. Neumann1, R. A. Jacobson2 1
Department of Natural Resources Management and Engineering, University of Connecticut, Box U-4087, Storrs, CT 06269, USA, 2Inland Fisheries Division, Connecticut Department of Environmental Protection, 79 Elm Street, Hartford, CT 06106, USA
Key words: brown trout; HSC; instream flow; transferability; snorkeling; microhabitat Timothy R. Strakosh, Kansas Cooperative Fish and Wildlife Research Unit, Division of Biology, 205 Leasure Hall, Kansas State University, Manhattan, KS 66506, USA; tel.: 1785 532 1818; e-mail:
[email protected] Accepted for publication May 12, 2003
Un resumen en espanÄol se incluye detraÂs del texto principal de este artõÂ culo. Introduction Habitat suitability criteria (HSC) have been developed for many ®sh species and applied in numerous instream ¯ow studies; however, transferability of HSC among and within regions has been problematic. Several factors, including interand intraspeci®c competition (Fausch & White 1986), habitat availability, and food abundance, can in¯uence river-speci®c habitat selection patterns, resulting in poor transferability of HSC among systems (Shirvell & Dungey 1983; Moyle & Baltz 1985; Bovee 1986; Orth 1987; Bozek & Rahel 1992; Baker & Coon 1997; Freeman et al.
1997). Application of HSC among dissimilar systems could have detrimental outcomes by leading to incorrect ¯ow regime recommendations (Groshens & Orth 1994; Thomas & Bovee 1993). Therefore, development of site-speci®c HSC is often recommended (Moyle & Baltz 1985; Bozek & Rahel 1992; Groshens & Orth 1994; Newcomb et al. 1995; Glozier et al. 1997), but is not feasible in most cases because of time and cost constraints. Many agencies and managers of regulated systems develop ¯ow regimes based on HSC found in scienti®c literature. Therefore, it is important to develop and publish HSC for a variety of river systems in which a species may occur. 265
Strakosh et al. located in northwestern Connecticut. The study reach is designated as a National Wild and Scenic River and is managed as a Trout Management Area (TMA) with catch-and-release angling regulations. Flow is regulated by hypolimnetic releases from Goodwin Dam with ¯ow requirements to meet downriver riparian commitments. The approximate annual mean ¯ow for the study reach is 12.11 m3s 1 (Ranzau et al. 2000). The watershed is approximately 600 km2 and is primarily forested (Nosal 1997). The West Branch Farmington River is utilized for hydropower, waste assimilation, ¯ood control, irrigation, water supply, ®sheries, boating, tubing, esthetics, and additional recreation. The study reach included a large diversity of habitats, good water quality, abundant target species, and good underwater visibility (3.1± 5.2 m). The reach consisted of a series of alternating rif¯es and runs possessing a substrate of primarily gravel, cobble, and small boulders, shallow wide rif¯es with a cobble and small boulder substrate, deep run/pool habitat (maximum depths > 1.5 m), and long moderately deep runs (Normandeau Associates 1992). The study reach maintains good thermal characteristics for brown trout year round with mean summer temperatures
