Local ecological knowledge, or the collective perceptions held by a particular group about their environment, results from the transmission of cultural knowledge from one generation to the next, combined with regular and persistent interactions between individuals and the biophysical environment. Management systems that limit access to certain natural resources likely have an effect on the quality of that knowledge. We explore the distribution of local ecological knowledge as it corresponds to different types of fishing activities and experience among fishermen in the eastern Gulf of Maine. We use a network approach to analyze cognitive maps of the ecosystem structure and dynamics described by fishermen during in-depth, open-ended interviews. The interviews reveal unique perspectives on complex interactions between species and their habitat, providing insights about local fluctuations in water temperature and weather patterns, predator-prey dynamics and interspecies competition, with a particular focus on species of commercial interest. We find a significant positive relationship between individuals’ diversification in fisheries and the scope of their knowledge. The preliminary findings suggest that fishermen with diversified fishing portfolios interact with a broader range of components in the system, resulting in a more holistic understanding of the marine environment and its dynamics. Because regulatory measures in fisheries management increasingly constrain the ability of individuals to enter diverse fisheries, these findings have significant implications for sustainability and understanding the role that institutions play in shaping local ecological knowledge more generally. A more systematic investigation of how institutional constraints affect the distribution of local ecological knowledge would be well-positioned to inform ecosystem-based approaches in fisheries management.