Assessing Fisheries Management - Context
In a simple sense, the results of harvest management decisions can be directly inferred from assessing the numbers of fish caught, the numbers of fish spawning and the rate of harvest allowed in relation to the population size and the desired level of spawning escapement.
Salmon management might be a straightforward endeavor if salmon populations were like forests – if they were described mostly by their species composition, and if they reproduced and grew in finite areas where their numbers could be simply measured and their harvest could be easily planned to leave the desired numbers to sustain future production.
But, in contrast, salmon management is complex. Consider the number of unique, locally adapted populations that comprise the biological structure of salmon species and the fact that salmon migrate thousands of miles across many geo-political boundaries. Their harvest and status can be affected by myriad fisheries that are regulated by different management jurisdictions and systems. Understanding the impacts of harvest and its effects on populations typically requires extensive monitoring and the use of sophisticated stock identification tools.
So harvest management is a complex business, not usually transparent to the general public or even easily understood by a person who lives in a river basin and is concerned about the condition of the watershed and its salmon populations.
Hatcheries (and the related harvest of hatchery-origin fish) only add to the complexity of the management system since hatchery and wild salmon have different allowable exploitation rates such that when they are harvested together in mixed groups it can be difficult to ensure adequate protection of wild stocks while harvesting hatchery surpluses. Also, hatchery fish can affect the reproductive performance and long-term productivity of wild populations through interbreeding and other ecological interactions (disease, competition and predation).
The tools presented here focus on outlining principles and best practice performance standards that can be used to assess the adequacy of salmon management systems and describe a case study application of such standards.