The analytical framework used throughout most of this study is directly inspired from transaction-cost economics, implying that a lot of attention is devoted to monitoring and enforcement costs involved in collective schemes. One of its most important contributions is to show that, with the help of these tools combined with conventional market power considerations, successes and failures of different groups of fishermen according to their technique and site of operation can be well accounted for. The first part of the document provides background information regarding Senegalese small-scale marine fisheries is provided and the methodology of the study based on cross-section data is briefly described. In Section 2, an historical sketch of all recent effort-limiting schemes attempted along the Senegalese coast is presented. The methods used to limit fishing efforts, which vary according to the fishery concerned, are discussed with a view to understanding their rationales in the light of the specific circumstances surrounding them. In the third section, the incidence of rule violations as perceived by the fishermen themselves is addressed and is also tackled by using the multinomial logit approach on the basis of survey data. Section 4 is devoted to fitting a time-series econometric model to price and output data. Section 5 summarizes the main results of the study. It is found that many of the factors shown to have a significant impact are of a rather structural character, namely, market conditions, features of fishing techniques which bear upon enforcement costs of a collective scheme, nature of relationships between fishermen and fish merchants, and history-determined patterns of authority and leadership. By overlooking such critical parameters, one incurs a high risk of setting up control measures that will be short-lived. The same parameters are also susceptible of evolving and, as a result, measures that worked rather well in a given period may prove difficult to sustain in a different set of circumstances. This dynamic aspect of reality, is probably the most difficult to accept by leaders who have played a major role in the initiation and enforcement of local-level regulation of fishing effort.