| Abstract/Description or Keywords |
The long term survival of salmon depends on maintaining genetic diversity, which in turn depends on adequate numbers of salmon returning to natal spawning grounds. DFO’s ability to assess and manage for genetic diversity and nutrient returns were evaluated by posing 3 questions: • Is escapement adequately monitored? • Has DFO met its own target escapements? • Are these escapement targets adequate to sustain ecosystem and predator requirements? Answers to these questions will reveal DFO’s successes or failure in managing for genetic diversity and nutrient returns. The most practical way to assess fishery managers’ understanding of salmon diversity is to review DFO’s own database on salmon presence and trends in river systems. Such information reflects the level of on-the-ground field knowledge of metapopulations and demes. We analyze and discuss the database that contains enumerations of salmon returning to their natal streams, namely DFO’s salmon escapement database system (SEDS). Although there are limitations to the SEDS (discussed below), there are no alternative databases for the type of assessment attempted here. DFO attempts to enumerate salmon annually, an enormous undertaking given the size and geography of the north and central coasts, and the multiple species and river systems. Coho, for example, are elusive and can stay in a given river over a long period of time. The size and depth of larger systems and the turbid nature of glacially fed rivers makes observation of fish complicated. Methods used to count fish include permanent fences, observation/visual estimations (creek-walks), fish wheels, aerial counts and swims by divers. Escapement enumeration is an important tool used by DFO in the assessment of salmon returns and in determining harvest yields (PFRCC 1999). While DFO also uses other data to make management decisions, escapement data remain the backbone of salmon management. While the escapement database is important, it has limitations. Knowledge of particular systems and species ranges from extensive to virtually absent. Creekwalker reports exist for some systems as far back as the turn of the century; however, these records are not in the SEDS. The present database contains escapement estimates for anadromous salmon from the 1950s to the present. The Salmon Escapement Database System (SEDS). The fact that the database starts in 1950 is unfortunate, because activities such as commercial fishing, logging and watershed development were already extensive by then. Adverse weather, changes in personnel, and inconsistent methodology can all lead to misrepresentation of the real trends in escapement, and may mask the effects of other influences such as logging and land use, over-fishing, climatic and natural variations. When enumeration data are inconsistent and incomplete, their value for precise management and assessment purposes is limited. As a result, the escapement database cannot be viewed as a truly accurate representation of salmon trends in coastal rivers and streams. However, it embodies the only collection of enumeration data on individual river runs. Our analysis covers SEDS data from stream and river systems with DFO watershed codes in the central and north coasts (Fisheries Management Areas 3-10). The total number of systems that historically supported each species of salmon was determined using the DFO BC16 reports that catalogue spawning streams and escapements. The number so derived can only be viewed as an estimate; the actual number may be lower due to population extirpation or higher due to absence of some smaller systems and tributaries. |
