5. Interpret
5.3.1 Inseason management
Low-harvest-rate fisheries can be managed with very indirect and imprecise methods, but fisheries with high harvest rates require active inseason management to be sustained. This active control is made up of three components. First, there must be a direct assessment of the effect of the fishery on the stock over very short time intervals. Second, there must be a set of fishery management objectives. Third, there must be a management mechanism that can increase or decrease fishing pressure so as to reach the management objectives of the fishery.
In Alaska and Canada, managers frequently observe either direct or indirect measure of salmon escapement and harvest during the run. Direct measurements of escapement are often accomplished with counting weirs, where fish are literally counted one by one as they move upstream, or with sonars or counting towers with passage rates sampled in time or space and then statistically expanded to estimates of total fish passage over a unit of time. Indirect measures of escapement include subjective aerial assessments of the buildup of salmon during the course of the run, or measurement of salmon in a few systems which are assumed to be representative of other systems in the area. Using the STRIDe terms, inseason measurements, such as escapement counts over a few days, can be summarized into metrics of salmon escapement using the response design. If management has maintained a history of these inseason metrics, by date, management can project whether its objectives will be met with and without adjustments to the harvest intensity. If the fishery is on a trajectory to miss the escapement objectives without adjustments, then management will make the appropriate adjustments by means of instituting fishery closures or, alternatively, allowing additional fishing time within a time period.
Run timing chart for escapement showing available values of an escapement metric (blue dots) up to time step 19 relative to the management objective (found between upper and lower curves). In this case, it appears that the fishery will end with escapement near the upper end of the management objective. Early in the season (say, between time step 10 and 15), if the escapement metric is below the lower curve management will close times and areas to fishing to increase escapement. Similarly, if the escapement metric is above the upper curve early in the season, management will increase fishing opportunity by opening more time and area for fishing.
At the conclusion of a season, the various metrics will be converted to what we are calling indicators, to use the STRIDe term. Most importantly, fishery objectives will be stated in a way that will allow an observer to examine post-season indicators to know if the objectives were met.
Examples
Southeast Alaska pink salmon
- Seining. Credit Hal Geiger/ADF&G
In Southeast Alaska, pink salmon originate from over 2,500 short coastal streams before migrating to the ocean. These streams are largely located in inaccessible wilderness areas. Large numbers of pink salmon are harvested, principally by a purse seine fleet. From 1995 to 2005, an average of 49 million pink salmon were harvested in Southeast Alaska commercial fisheries, with an average ex-vessel value of $21 million over that same period. The streams in Southeast Alaska are divided into three subregions, and these sub-regions are further divided into 52 stock groups for management purposes. The fishery is managed through a system of intensive harvest monitoring, fishing-effort monitoring, and escapement monitoring that begins at the time fishing starts in July of each season and ends after the fishing has ceased for the year. Managers are assigned escapement goals for each of the sub-regions, with less formal harvest guidelines for each of the stock groups. Harvests are monitored through a "fish ticket" system. A formal fish ticket is required by law at the time of each ex-vessel sale. The fish tickets are entered into a computer-based fish system so that cumulative catch can be estimated up to the minute. Through this system, the cumulative catch can be forecasted to the end of the season, as a function of increased or decreased fishing effort. Fishing effort can also be computed through the fish tickets system. Additionally, fishing effort -- and the spatial distribution of fishing effort -- is monitored by occasional aerial overflights of the fishery by fishery managers. During these aerial overflights, managers record their visual impressions of escapement in 718 "index" pink salmon streams. It is not clear how these streams were originally selected, but these "index streams" are widely distributed through most of the important pink salmon-producing habitat. The index streams tend to be large and more important streams with good visual access. That is to say, glacial streams or streams extensively obscured by forest canopy are not in the index set. On these aerial overflights, managers record their impression of the number of pink salmon staging near spawning areas and the number of pink salmon present in the spawning areas. These impressions are combined into what ADF&G calls an index of escapement for each of the 52 stock groups, and ADF&G maintains a computer system so that managers can view values of these indices, by date, for each year since 1960. This system allows managers to forecast year-end values of the indices as a function of fishing effort. Managers can control fishing effort by a system of what are called "emergency orders." The season begins with a series of scheduled fishing periods and closed periods defined for specific fishing areas or districts. If managers want to increase fishing effort they can extend the time of a fishing period or add additional fishing periods. Similarly, on short notice, managers can eliminate fishing periods. In some cases they can add to or restrict the size of fishing areas to fine tune the effort exerted on different stocks and substocks. Managers have a very wide latitude to control fishing effort during the season, and they are evaluated based on their ability to permit orderly fisheries and to have the escapement indices fall within pre-season escapement goal ranges, which are specified in regulations. Notably, preseason forecasts have very little to do with the management of these fisheries, and the preseason forecasts only affect the fishing intensity very early in the season, before many fish are present. This style of management is almost entirely based on measured and observed harvest and a measured and observed proxy for escapement.
Bristol Bay Sockeye Fishery
The management of the Bristol Bay sockeye fishery is similar to the style of management of pink salmon in Southeast Alaska, Prince William Sound, and Kodiak. There are several important differences, especially having to do with the intensity of the fisheries, the measurement of the escapement, and the value of the commercial product. In Bristol Bay the commercial fishing season is very compressed, with much of the harvest being taken in a little over a week. For example, in 2009 commercial fishing started to pick up around June 17, but by July 13--less than a month later--many fishing operations had ended for the year. Also, in 2009, the commercial harvest of sockeye salmon topped 30 million fish, worth over $128 million U.S. dollars, yet the managers were able to meet most of the escapement goals. Managers slightly exceeded the upper end of the escapement goal range for the Ugashik River, although the escapement into the Igushik River was substantially above the upper end of the escapement goal range. Escapements into the other seven major river systems were within goal ranges. Once again, this was achieved by controlling fishing effort by means of "emergency orders," which added or reduced fishing time and area in response to observed harvest rates and observed escapement. In Bristol Bay, in the clear-water systems, much of the sockeye escapement is measured by means of counting towers, since sockeye salmon are bank-oriented during their up-river migrations. In other areas, side-looking sonars are used in rivers that are visually occluded.
Fraser River Sockeye Fishery
The annual management of the sockeye fishery relies on pre-season and inseason information. Pre-season abundance and run timing forecasts are estimated using naïve and biological models and used to prepare pre-season fishing plans for several abundance and timing scenarios. Inseason management is based on a combination of indicators of in-season run size, river entry timing, river environmental conditions influencing survival, and pre-season forecasts of run size and run timing. The CDFO and Pacific Salmon Commission (PSC) estimate run size in-season at several points along the migration corridor using metrics from the most seaward locations as sockeye migrate around Vancourver Island to the most terminal point at the spawning grounds. Daily test fishing measurements occur where the fish migrate around Vancouver Island through Johnstone and Juan de Fuca Straits, and near the Fraser River mouth at the Cottonwood and Whonnock test fisheries. At the tidal boundary, abundance is measured more precisely using hydroacoustic methods and daily measurements of migrating sockeye past Mission, B.C. At the most terminal location the spawner abundances are estimated for each stock and management unit, typically using census methods such as mark-recapture. Metrics at each location contribute to an indicator of in-season run size.
The PSC is responsible for decisions to conduct fisheries in the Fraser River Panel Area waters. Each week, fishery decisions are made using the abundance estimates, catch estimates, and predictions of natural mortalities during adverse environmental conditions in the Fraser River. Inseason fishery harvests are estimated by fishers self-reporting catches to a call center, by on-water hail surveys, and by creel survey methods relying on surveys of fishing effort and catch rate. Fraser River environmental conditions have produced poor survival conditions for migrating sockeye, so water temperature and flow are monitored daily and forecast in advance of each week. These environmental data are used to predict natural mortalities of Fraser River sockeye salmon. Post-season estimates of run size are based on estimates of harvest, spawner abundance, and natural mortality in the Fraser River using a run reconstruction model.
Additional Canadian Resources
Fraser sockeye forecast methods
Fraser River Environmental Conditions
