Transdisciplinary science and stakeholder engagement: A before-after-control-impact study on learning for sustainable stocking in German recreational fisheries

Fish stocking is the most widespread management tool for freshwater fisheries, but stocking can be economically wasteful and ecologically harmful. This project evaluated two educational interventions that taught sustainable... [ view full abstract ]

Fish stocking is the most widespread management tool for freshwater fisheries, but stocking can be economically wasteful and ecologically harmful. This project evaluated two educational interventions that taught sustainable stocking practices in one of the largest educational randomized experiments of its kind involving stakeholders who have a direct say in management. In Germany, anglers are leaseholders of fishing rights and are responsible for management actions in their water bodies, including stocking. Seventeen angler clubs from the German state of Lower Saxony were randomly assigned to three groups: placebo lecture (control group), stocking lecture, or transdisciplinary cooperation. We assessed the efficacy of the seminar and transdisciplinary interventions at changing knowledge, behavioral antecedents, and intentions relative to the control using questionnaires. Lecture group anglers received a presentation on sustainable stocking. The transdisciplinary group, in addition to the same stocking lecture, participated in workshops where anglers and scientists collaborated to design, conduct, and evaluate stocking experiments on different species in diverse club water bodies. Transdisciplinary group anglers actively experimented and observed effective and ineffective stocking outcomes. Results of the two educational interventions were analyzed by Before-After-Control-Impact analysis with club-level random effects. We found that anglers absorbed information from the lectures in the short-term, but had forgotten all but one topic (i.e., that stocking does not always work to enhance catch) 8-10 months later. Transdisciplinary group anglers retained four knowledge domains 8-10 months later, including complex genetic concepts (the previously mentioned domain plus the potential negative impacts of stocking, advantages of locally adapted stocks, and potential genetic risks of stocking). Further, unlike in the stocking seminar group, a functional belief in the efficacy of stocking was altered. Transdisciplinary anglers reduced their behavioral intention relative to the control group to stock a naturally recruiting species (pike) that they had experimentally observed a lack of stocking success with, as well as a reduced intention to stock ‘other’ species (not currently stocked). Transdisciplinary cooperation performed much better than lectures in imparting knowledge and changing behavioral intentions, in addition to building relationships with stakeholders and facilitating two-way knowledge transfer.