Human impacts on salmon stocks can be grouped into two broad categories-those that affect production and those that affect harvest. Production impacts include a broad range of watershed activities. A few examples are hatcheries and spawning channels that enhance reproductive success, dams that increase mortality of both upstream adult migrants and downstream smolt migrants, fish ladders that help improve upstream survival, bypass systems that help reduce downstream mortalities at dams, and logging practices that reduce available spawning habitat.
Harvest management involves both long- and short-term decisions. Over the long term, managers must decide on a general harvesting strategy. There are three basic types of harvest strategies-fixed catch, fixed harvest rate, and fixed escapement. Fixed catch means setting a quota for a fishery and keeping the same quota for several years. A fixed harvest rate policy takes a fixed percentage of the available run each year. Finally, a fixed escapement policy adjusts catches such that a given number of spawners return to the spawning grounds each year. Each type of long-term strategy usually involves establishing size limits, also. Within each long-term strategy are the annual decisions regarding specific times and areas where fishing can occur in order to meet the specific long-term strategy.
Each management action (e.g., setting catch ceilings, adjusting size limits, changing hatchery production) affects the fisheries and stocks in CRiSP Harvest. Some of these are easier to simulate than others. In practice, it is often most useful to compare alternatives to a "base case" or "status quo" scenario specified by the default *.opt file.
In the sections that follow, management actions are discussed in greater detail. Production alternatives include:
Fishery alternatives include: There are two different methods for modeling management alternatives: the "Interactive Method" and the "Input File Method". The Interactive Method uses the CRiSP Harvest toolbars, dialog boxes and menus for altering the parameters and assumes that you are familiar with these controls. Review the appropriate sections of the manual before following the procedures for this method.Input File Methods require manipulating the files used by CRiSP Harvest before launching the model from the "Run" dialog box. This enables you to specify a particular *.opt file (see "File Structure") which has detailed instructions on which files the model should use for each alternative. For more information on these files consult the appropriate sections of this manual (especially "Files used by CRiSP Harvest").
Comparison of alternatives is done by creating output files for the different alternatives and/or comparing graphs of different output. For this reason, users who prefer the Interactive methods should be familiar with the file structure used by CRiSP Harvest and in particular be able to (see "Graph Windows").
As noted in previous sections, many CRiSP Harvest parameters can not be changed while modeling alternative management strategies. These parameters are valid only when used in concert with other parameters from the same calibration run.
The following tables detail some of the limitations to Modeling Management alternatives:
| Fishery | Fishery Alternatives | ||||
|---|---|---|---|---|---|
| Fixed Catch | Fixed HR | Fixed Esc | Size Limits | ||
| 1 | Alaska Troll | x | |||
| 2 | Northern B.C. Troll | x | x | ||
| 3 | Central B.C. Troll | x | x | ||
| 4 | West Coast Vancouver Island Troll | x | x | ||
| 5 | Washington/Oregon Troll | x | |||
| 6 | Strait of Georgia Troll | x | x | ||
| 7 | Alaska Net | x | x | ||
| 8 | Northern B.C. Net | x | |||
| 9 | Central B.C. Net | x | |||
| 10 | West Coast Vancouver Island Net | x | |||
| 11 | Juan de Fuca Net | x | |||
| 12 | North Puget Sound Net | x | |||
| 13 | South Puget Sound Net | x | |||
| 14 | Washington Coast Net | x | |||
| 15 | Columbia River Net | x | x | ||
| 16 | Johnstone Strait Net | x | |||
| 17 | Fraser River Net | x | |||
| 18 | Alaska Sport | x | |||
| 19 | North/Central B.C. Sport | x | |||
| 20 | West Coast Vancouver Island Sport | x | |||
| 21 | Washington Ocean Sport | x | |||
| 22 | North Puget Sound Sport | x | |||
| 23 | South Puget Sound Sport | x | |||
| 24 | Strait of Georgia Sport | x | x | ||
| 25 | Columbia River Sport | x | |||
| Stock | Production Alternative | |||
|---|---|---|---|---|
| EV | Enh | IDL | ||
| 1 | Alaska South SE | x | ||
| 2 | Northern/Central B.C. | x | ||
| 3 | Fraser River Early | x | ||
| 4 | Fraser River Late | x | ||
| 5 | West Coast Vancouver Island Hatchery | x | x | |
| 6 | West Coast Vancouver Island Natural | x | ||
| 7 | Upper Strait of Georgia | x | ||
| 8 | Lower Strait of Georgia Natural | x | x | |
| 9 | Lower Strait of Georgia Hatchery | x | x | |
| 10 | Nooksack River Fall | x | x | |
| 11 | Puget Sound Fingerling | x | x | |
| 12 | Puget Sound Natural Fingerling | x | ||
| 13 | Puget Sound Yearling | x | x | |
| 14 | Nooksack River Spring | x | ||
| 15 | Skagit River Wild | x | ||
| 16 | Stillaguamish River Wild | x | ||
| 17 | Snohomish River Wild | x | ||
| 18 | Washington Coastal Hatchery | x | x | |
| 19 | Columbia River Upriver Brights | x | x | |
| 20 | Spring Creek Hatchery | x | x | |
| 21 | Lower Bonneville Hatchery | x | ||
| 22 | Fall Cowlitz River Hatchery | x | ||
| 23 | Lewis River Wild | x | ||
| 24 | Willamette River | x | ||
| 25 | Spring Cowlitz Hatchery | x | ||
| 26 | Columbia River Summers | x | ||
| 27 | Oregon Coastal | x | ||
| 28 | Washington Coastal Wild | x | ||
| 29 | Snake River Wild Fall | x | x | |
| 30 | Mid Columbia River Brights | x | x | x |
| Fixed Parameters | Years |
|---|---|
| Environmental Variability (EV) Scalars | 1979-1994 |
| Enhancement | 1979-1994 |
| IDL (Inter-Dam Losses, or pre-spawning mortality) | 1979-1994 |
| Catch Ceilings | 1979-1994 |
| Harvest Rate Scalars | 1979-1994 |
| PNV (Percent Non-Vulnerable) | 1979-1994 |