Conflict resolution in fisheries management using decision rules: an example using a mixed-stock Atlantic Canadian herring fishery

Abstract

The process of developing and implementing decision rules resolved a mixed-stock herring fishery crisis in Cape Breton, Nova Scotia, Canada. The fishery occurs in an area which receives a large migrating stock on a set of smaller local stocks. A purse seine fleet follows the migrating stock into the area as part of their autumn and winter fishery. Little is known about the smaller local stocks which are harvested as by-catch in the seiner fishery and in directed inshore fisheries by local boats. A situation of constantly shifting regulations during the 1996 fishing season led to a series of incidents that included a wharf occupation and prevention of seiner offloading. As a result of these conflicts it was decided to develop decision rules that would allow the fishery to continue in a safe manner and would clearly identify the information and analyses needed to change the rules.

The decision rules were developed by using computer simulations to estimate exploitation rate scenarios on each stock component. These simulations determined the following general guidelines for the decision rules. First, if fishing occurs where mixing of schools from stocks is random and proportional to their abundance, then average exploitation rates will be equal among stocks but exploitation rates will be more variable on the smaller stock(s). Second, if fishing occurs where small stocks are concentrated, then exploitation rates will be higher on the small stocks. A combination of data analysis and computer simulations was used to develop decision rules concerning catch allocations, when and where to start fishing, and size of fish to catch.

The decision rules were formulated in a series of workshops and stock assessment review meetings attended by industry, managers, and scientists. This process was successful because it broke down barriers among these groups and used quantitative general guidelines to develop the decision rules. The process is readily transferable to other fisheries and provides a means of avoiding or resolving fisheries management crises.