A species-specific fish passage model based on hydraulic conditions and water temperature

Highlights

• A fish passage model for 13 migratory species predicted presence-absence above 159 barriers in New Jersey with 92% accuracy.

• All locations with possible barriers were predicted to block at least two species.

• Approximately 89% of locations with possible barriers were predicted to block all species.

• Alewife (A. pseudoharengus) and blueback herring (A. aestivalis) were predicted to be blocked the most at potential barriers.

• Predicted blockages were mostly due to weak jumpers and water temperatures outside the acceptable range during migration.

Abstract

Stream corridors contain many features that act as barriers to fish during migration. We built a model to determine the likelihood that each of 776 dams, culverts and waterfalls in New Jersey act as barriers to each of thirteen fish species during migration. We assessed each fish species at each potential barrier to determine if the fish could jump high enough to clear the barrier, swim fast enough to overcome the velocity of water to reach the barrier, dive deep enough in the plunge pool to reach maximum jump height, and persist with migration given predicted water temperatures. If all four were possible, the potential barrier was deemed passable. Blockages were mostly the result of predicted weak jumping abilities and water temperatures outside the acceptable range during migration. The model successfully predicted presence and absence above potential barriers for all species except the ubiquitous white sucker (C. commersonii). All locations with possible barriers were predicted to block at least two migratory fish species; 89% were predicted to block all species. Alewife (A. pseudoharengus) and blueback herring (A. aestivalis) were predicted to be blocked the most. Results allow prediction of which potential barriers block passage for each species, the length of waterways blocked by each barrier, and the reasons each barrier is predicted to block each species. We present our fish passage model as a tool for identifying possible barriers which if restored or removed, given appropriate field assessment, might reconnect migratory fish species with additional spawning habitat.

Introduction

Extensive dam construction in the early and mid parts of the twentieth century resulted in over 90,000 barriers across United States waters (American Rivres, 2021; Hossain et al., 2009). Dams provide valuable services for humans such as hydroelectric power, reservoirs for drinking water, irrigation for crops, flood protection, invasive species blockage, upstream contaminant and disease transfer prevention, and recreation (Graf, 1999; Great Lakes Fishery Commission, 2021). More recently, ecological impacts have been recognized (Ho et al., 2017) as ubiquitous dams have resulted in widespread altered stream flow (Peñas and Barquín, 2019), increasing water temperatures, altered sediment transport (Great Lakes Fishery Commission, 2021), fragmented stream habitat (Graf, 1993; Graf, 1999) and severe reductions in migratory fish populations (Larinier, 2001). Culverts with outlet drops can similarly fragment stream habitats and, coupled with dams and other anthropogenic modifications of waterways, have led to the decline of freshwater fish populations worldwide (Goodrich et al., 2018). In fact, the fragmentation of river habitats through dams and poorly designed culverts is one of the primary threats to aquatic species in the United States (Graf, 1999). Likewise, natural obstructions, like waterfalls, also cause habitat fragmentation of waterbodies (Kondratieff and Myrick, 2005).

A natural flow regime is important in determining the biotic composition, structure and function of river ecosystems (Poff et al., 1997; Richter et al., 1996). Thus, disruption of natural flow is considered one the most widespread and damaging impacts for river ecosystems (Peñas and Barquín, 2019; Vitousek et al., 1997). Likewise, fragmented stream habitat, through loss of connectivity, disrupts the movement of fish species (Thalinger et al., 2019). Many aquatic species need to move between habitat patches along the entire stream network in order to feed, seek refuge (e.g. overwintering), avoid predation, overcome the effects of competition, and spawn (Harris et al., 2017; Katopodis, 1992; Thalinger et al., 2019; Winemiller et al., 2016; Wohl, 2017). In particular, for migratory species, connectivity is essential to reach upstream portions of waterbodies in order to spawn and maintain sustainable populations (Thalinger et al., 2019). Disruption of migration patterns can lead to injury of fish (Larinier, 2000) and the decline or even extinction of populations (Arthington et al., 1995; Gehrke et al., 2002; Larinier, 2000; Penczak and Kruk, 2000).

Barriers to migration occur through the presence of natural or artificial stream features and the timing and magnitude of precipitation and stream flows (Bartson, 1997). Fish passage success is thus based on physical parameters (height of the potential barrier), hydraulic conditions (velocity, plunge pool depth) and the darting and jumping abilities of fish species during migration (Bartson, 1997; Larinier, 2000; Reiser et al., 2006). Some potential barriers may be permanently insurmountable for all fish species but others may be passable by some or all fish species at certain times of the year under favorable hydrological conditions (Larinier, 2000).

A non-structural variety of habitat fragmentation may come in the form of increased water temperature as a result of climate change (Kwak et al., 2017). Water temperature is one of the most important factors defining the physical, chemical, and biological properties of aquatic habitats, fish growth, water quality, and spawning rate (Kwak et al., 2017). Migratory fish are highly vulnerable to climate change (Hare et al., 2016) and related increases in water temperatures will most likely result in habitat contraction (Morales-Marín et al., 2019) and disruption of migration patterns if water temperatures are outside the acceptable range during the migration window (Jonsson, 1991). Sustained water temperature over certain thresholds can be lethal for certain species (Bouck et al., 1975).

Improving the ability of migratory fish populations to adapt to our changing climate will depend on significantly increasing their population sizes, and thus their resilience, by opening corridors to high-quality spawning habitat. Some of the potential barriers blocking access to spawning habitat no longer serve their intended purpose; others were not designed to withstand the increase in stormwater runoff associated with climate change, coupled with urbanization, and thus pose risks to downstream local communities. Much work is being done to address the issue of reconnecting stream habitat through removal of dams (Bellmore et al., 2017; Foley et al., 2017), restoration of culverts (Erkinaro et al., 2017; Wood et al., 2018), and implementation of managed relocation projects for freshwater species (Olden et al., 2011). Such projects have become more socially acceptable in recent decades and have proven successful at quickly restoring species to the area (Birnie-Gauvin et al., 2020; Catalano et al., 2007). Successes have spurred even greater interest in river restoration projects locally, regionally, and nationally (Bellmore et al., 2017, Foley et al., 2017).

Techniques for assessing the impact of potential barriers on fish passage and for prioritizing actions are important to inform restoration efforts (Kemp and O'hanley, 2010, Katopodis, 2005, McKay et al., 2017, Noonan et al., 2012). Several regional or national programs have been developed for this purpose including: The National Fish Passage Program, 2021 (https://www.fws.gov/fisheries/fish-passage.html) which works with local communities to assess fish passage and restore rivers; The Stream Continuity Portal, 2021 (https://streamcontinuity.org/), a regional collaborative, which has tools focused on aquatic organism passage and fragmentation of river and stream ecosystems; FishXing, 2021 (https://www.fs.fed.us/biology/nsaec/fishxing/index.html) which focuses on fish passage through culverts; and The Great Lakes Fishery Commission (2021) FishPass Project (http://www.glfc.org/fishpass.php) which is pioneering avenues to provide up- and down-stream passage of desirable fishes while simultaneously blocking undesirable fishes. Field assessment is imperative but models have become useful to ascertain where to focus attention given the many thousands of dams and millions of culverts to monitor across the United States (Chelgren and Dunham, 2015; Fukushima et al., 2007; Hirsch et al., 2017; Jager et al., 2001; Labonne and Gaudin, 2006; Sheer and Steel, 2006). Fish passage models have been improving in recent years (King and O'Hanley, 2016; Kraft et al., 2019; McKay et al., 2013; McManamay et al., 2019; Meixler et al., 2009). The common theme running through the literature on this topic is an attempt to simplify and optimize barrier removal decision-making. These models generally are focused on single species or families of fish instead of all the migratory species in a region (Kemp and O'hanley, 2010) and many do not carefully consider how passability was measured (Bourne et al., 2011).

Meixler et al., 2009 looked at fish passage for dams and waterfalls for a variety of common species. Though the model predominantly was able to predict passage for most fish species with significant accuracy, it predicted species to occur in places much more commonly than they were actually found in fish surveys. Thus we suspected that one or several important factors were not included in the original model. It has been established that water temperature during migration is an important factor in migratory success (Haro et al., 2004; Jonsson, 1991). To date, no studies have attempted a comprehensive, regional perspective of fish passage success for a variety of potential barrier types and fish species coupled with hydraulic conditions and water temperature model components. The location of potential barriers, the effect of potential barriers and water temperature on migratory fish passage success, and the cumulative stream length predicted to be blocked are all important pieces of information when prioritizing restoration activities (Roni et al., 2002).

In this paper, we use a geospatial model to examine fish passage for 13 native and non-native, warm water and cold water migratory species using information on physical parameters (height of natural and artificial potential barriers), fish darting and jumping abilities, hydraulic conditions (velocity and plunge pool depth), and water temperature during migration. Results from our model allow us to predict which potential barriers block passage for each species, the combined length of the streams blocked by each barrier, and the reasons each barrier is predicted to block each species (barrier height, plunge pool depth too shallow, velocity during migration too strong, and/or water temperatures during migration too extreme). We present this fish passage model as a tool for identifying locations that act as barriers to migratory fish species and whose restoration or removal, given appropriate field assessment, might be beneficial to reconnect migratory fish species with additional spawning habitat.