Chapter 1 -- Introduction (continued)
For the Smith River watershed, the Institute for River Ecosystems is developing a strategy for understanding and restoring 1) stream ecosystem integrity and 2) anadromous fisheries. Methods for understanding and restoring stream ecosystem integrity also contribute to understanding and restoration of anadromous salmonid populations. Most fisheries biologists agree that the most effective approach for maintaining stream ecosystems and species is to maintain or reinstate ecosystem processes that create habitat. However, in addition to renewal of general ecosystem processes, specific investigations into fish population and fish habitat are also important. These specific investigations are necessary to determine the deficiencies in ecosystem integrity that are most important for anadromous fisheries. Therefore this proposed strategy has two threads of research and action: Thread 1) a program for understanding and restoring overall stream ecosystem integrity Thread 2) a program for understanding and restoring anadromous salmonids. Fisheries restoration should simultaneously work toward both these aims.
These two threads are overlapping and interwoven because anadromous salmonids are corelated with ecosystem integrity. Anadromous salmonids provide one of the best indicators of ecosystem integrity in coastal streams of northwestern California. Therefore, by developing and implementing management policies that ensure survival of anadromous salmonids, these policies will probably also maintain the entire spectrum of components, processes, and amenities of the river ecosystem. One of the foremost challenges in restoration of ecosystems and fisheries is developing procedures for thinking and communicating about the entire river basin as a whole. For each of the threads, particular methods are recommended for envisioning the relevant processes across the entire watershed and over time.
The primary method recommended for assessing ecosystem integrity employs "indicators" that provide insights into key ecosystem processes (Table 4). Although each individual indicator by itself has limited utility, consideration of a constellation of indicators provides a useful assessment of stream ecosystem integrity and overall fish habitat quality. Futhermore, these indicators must be considered in the context of the watershed context. In the watershed perspective, the first priority for maintaining and renewing ecosystem integrity is identifying and reducing activities throughout the watershed that degrade streams. This approach recognizes that it is usually more effective to restore the ecosystem processes that create stream habitat rather than improve habitat artificially. This reduces the root causes of stream habitat degradation. Another priority is protection of relatively undisturbed habitats (biotic refuges) and connecting links in the stream system. A biotic refuge is a habitat in which organisms can survive during disturbance in the ecosystem. During recovery periods, organisms in the biotic refuge are a source population for recolonizing adjacent habitat. In the Smith River watershed, stream habitat occupied by sensitive species such as coho salmon and summer steelhead may be important as biotic refuges. Over longer periods, degraded areas adjacent to biotic refuges are candidates for restoration so as to allow recolonization by sensitive species. Restoration of important degraded ecosystem components, such as estuaries and floodplains, if feasible, would occur over several to many decades.
In the regional scale, the entire Smith River basin is a biotic refuge. This river system has been designated as a key watershed in the Northwest Forest Plan. It is the only key watershed that encompasses an entire river basin. Key watersheds are designated due to their importance to survival of anadromous fisheries in the regional (interstate) perspective. Therefore, maintaining the anadromous fisheries of the Smith River is important for ensuring the survival of anadromous fisheries throughout the region.
The most important actions for anadromous fisheries restoration are the same as for restoring ecosystem integrity: protecting biotic refuges and preventing actions that further degrade stream habitat. Simultaneous with actions to protect the overall ecosystem, there is a second tier of analysis and restoration actions aimed more specifically at anadromous fisheries. The second tier actions must be based on an understanding of fish population dynamics and habitat needs. In a watershed context, this requires visualization of the timing and distribution of habitat needs of anadromous fish as they migrate through the river network.
Anadromous salmonid species known to be well established in the Smith River are steelhead, chinook salmon, coho salmon, and coastal cutthroat trout, and each of these species has one or more life history patterns. Each unique life history pattern follows a series of developmental stages that have evolved to coincide with the timing of habitat availability in the river network. Because these life history patterns are adapted to the unmodified river system, human changes that remove a single link in the chain of required habitats can make a particular life history pattern non-viable. Conversely, by restoring the missing habitat link, it is sometimes possible to increase the success of particular life history patterns. To detect habitat changes that limit the success of life history patterns, information must be gathered not only about present river habitat conditions but also about conditions that fish are adapted to, that is, conditions prior to extensive human modification.
"Critical habitat" is an area that provides essential functions in the life cycle of a species. The population of species can be limited by a shortage of a particular type of habitat that is needed at some point in the life cycle of the species. The abundance of anadromous salmonids depends on certain habitats for each stage of life from egg to adult. Critical habitat for anadromous fish may include deep pools with cooler water that allow fish to survive through the summer, and riffle habitat which is necessary for spawning and incubation.
For anadromous salmonids, the geographic arrangement (spatial distribution) of habitat is crucial. An important aspect of habitat distribution is "connectivity." Connectivity is the capacity of an ecosystem to allow a species "to migrate at the appropriate time between links in the habitat chain" to complete their life cycle (Lichatowich et al. 1995). Through the eyes of a fish, connectivity in streams is influenced by predation risk, temperature barriers, low flow barriers, and leaping barriers such as cascades. When patches of high quality habitat are surrounded by poor habitat or other barriers, a species may be excluded from the high quality habitat due to poor connectivity. In the case of anadromous salmonids, poor connectivity can restrict the timing of upstream or downstream migration and thereby limit spawning success and future population size. Therefore, the timing of connectivity throughout the stream system in a particular year greatly influences the reproductive success of the various anadromous fisheries stocks during that period.
Table 5 presents an array of potential activities for understanding and restoring the Smith River ecosystem and its fisheries.
Table 5. Preliminary list of suggested actions for restoring the Smith River ecosystem and its fisheries. Obviously it is not practical to pursue all the listed actions. Through dialogue among concerned parties the most feasible and urgent actions should be selected for implementation. |
A) Stratify the watershed using various procedures including: |
1) ecological subsections based on geology and other factors |
2) the river continuum concept based on upstream/downstream changes in stream ecosystems |
3) the "rapid biotic and ecological response" strategy based on conservation biology principles, including identification of biotic refuges. |
B) Disturbance-recovery cycles |
1) Estimate the historical range of variability for disturbance-recovery cycles. |
2) Investigate recent disturbance-recovery cycles. |
3) Identify "after the disturbance" policies to protect beneficial changes. |
4) Through a combination of indicators, develop an index to rate the disturbance-recovery status for each area. |
C) Geomorphic processes |
1) Estimate the historical range of variability for geomorphic processes. |
2) Investigate short- and long-term trends in sediment production, transport, and storage, especially human influences on these trends. |
3) Investigate the use of lag time between rainfall and runoff as a monitoring tool. |
4) Investigate the use of bedload transport rate as a monitoring tool. |
5) Investigate the use of fine sediment supply as a monitoring tool. |
6) Investigate pool/riffle ratios, width-to-depth ratios, channel stability, and channel sinuosity as monitoring tools. |
7) Study gravel mining as a tool for increasing habitat diversity in the lower river. |
8) Identify "loaded guns", areas of the watershed that are high risk for future mass wasting. |
D) Riparian vegetation |
1) Compare the past and present extent of riparian forests. |
2) Identify and prioritize potential riparian restoration projects. |
3) Create incentives for improved riparian conditions on private timberlands. |
E) Large woody debris |
1) Estimate the status and trends of large woody debris throughout the stream network. |
2) Identify potential projects for increasing quantities of large woody debris in streams. |
3) Create incentives for improved retention of large woody debris on timberlands. |
4) Investigate the use of large woody debris surveys as a monitoring tool. |
F) Benthic macroinvertebrates: Investigate their use as an indicator of stream ecosystem conditions. |
G) Relating habitat conditions to anadromous salmonid populations and life history patterns. |
1) Use patient-template analysis to organize information about anadromous salmonids. |
2) Investigate the characteristics of anadromous life history patterns of the Smith River. |
3) Identify indices of anadromous salmonid abundance. |
4) Investigate the distribution and abundance of anadromous salmonids. |
5) Study how habitat complexity affects anadromous salmonid populations. |
6) Study the effects of predators on anadromous salmonid populations, including seals, otters, and birds. |
7) Estimate the effects of fishing on anadromous salmonid populations. |
8) Study how connectivity in the river network affects anadromous salmonid populations. |
9) Estimate historic changes in connectivity and how connectivity can be improved. |
10) Study how geomorphic processes and disturbance-recovery cycles affect anadromous salmonid populations. |
11) Identify critical habitat for anadromous salmonids. |
H) The floodplain |
1) Determine the present extent of the floodplain. |
2) Estimate the dimensions of the floodplain prior to human modification. |
3) Investigate the ecological importance of floodplain processes and habitats especially for anadromous fish. |
4) Investigate opportunities for restoring the floodplain. |
I) The estuary |
1) Study existing estuary habitats and their ecological importance. |
2) Estimate the dimensions of the estuary prior to human modification. |
3) Investigate estuary restoration options and their ecological effects especially on anadromous fish. |
J) The lower tributaries |
Synthesis |
A) Evaluate future trends and proposed actions. |
B) Identify adaptive management learning opportunities. |
C) Synthesize a restoration strategy. |
The Institute for River Ecosystems began addressing several of the above tasks in 1991 with the initiation of studies examining life history patterns, habitat use, and abundance of anadromous fish throughout different segments of the river network. In cooperation with the Smith River National Recreation Area, there have been snorkeling surveys, spawning surveys, and downstream migrant trapping in the mainstem, Middle Fork, and several tributaries of the Smith River. These efforts represent the first basin-wide study of anadromous fish use of the Smith River; they provide data on species composition, growth rates of downstream migrants, indices of abundance, and life history patterns.
A study by Jason White, in progress, focuses on the life history of fall chinook in the Smith River. In addition to data from downstream migrant traps, he is analyzing scales collected from smolts and adults for possible inference regarding estuarine rearing, growth patterns, and age characteristics of the population.
A study by Gary Reedy investigates the abundance and distribution of juvenile chinook salmon and steelhead in the Middle Fork Smith River. To describe spatial variability in juvenile fish abundance within a ten kilometer study segment, (1995) developed a modified habitat classification scheme that is more appropriate for medium to large rivers. He quantified temporal variation in habitat use by monitoring downstream migrant traps and by snorkel sampling in June, July, and August. The Middle Fork drains more than twelve anadromous fish bearing tributaries and an annual index of fish abundance in such a large branch could more reliably track basin-wide population trends than small stream surveys. Whereas electrofishing is impossible in the deep waters of a large stream, and downstream migrant trapping is very expensive, snorkel surveys were evaluated as a method for monitoring annual variation in population abundance. This cost-effective technique could permit long-term monitoring of juvenile fish abundance at the basin level, an important step in understanding fish population dynamics and assessing ecological integrity.
A thesis project by Smokey Pittman, in progress, investigates chinook salmon spawning in the mainstem Smith River with respect to fluvial geomorphic processes. Spawning surveys indicate that the mainstem may host an important component of total spawning by chinook salmon (Reedy personal communication 1997). Pittmans preliminary results indicate that despite greater bedload mobility rates in the mainstem than in other spawning streams, mainstem redds often survive annual peak flows. Pittmans work contributes to our understanding of habitat needs for salmon by making a rare and important link between geomorphic processes and habitat quality. His work also initiates inquiry into the effect of gravel mining on salmon habitat, and the development of new land use techniques that allow for the coexistence of both.
A thesis project by Joe Scriven, in progress, provides a methodology for determining the presence and abundance of coho salmon in streams using snorkeling and direct observation. The study provides information about the pattern of coho distribution in the Smith River tributaries. This study helps identify areas of critical habitat for coho. A related study by Chris Moyer develops quantitative estimates of coho and juvenile steelhead populations in tributaries of the Smith River.
Various additional studies are conducted under the auspices of the Institute for River Ecosystems. A study by Dave Manning investigates factors that limit anadromous salmonid populations in several areas including Mill Creek, a tributary of the lower Smith River. Studies by Todd Buxton and Sam Flanagan investigate the influence of roads on geomorphic processes and hydrology in the watersheds of Goose Creek and Hurdygurdy Creek, tributaries of the South Fork of the Smith River. They present improved methods for identifying culverts that are likely to fail. Goals of this project are to identify opportunities to improve culvert maintenance, reduce sediment loads, and improve fish access. Several studies investigate the influence of human activities on stream ecosystems and fish populations. A study by Bill Lydgate investigates the relationship between land management and stream characteristics. Jim Simondet is studying the response of land-locked coastal cutthroat trout to habitat manipulations.