Since 2000, virtually every major assessment of ocean policy has called for implementing an ecosystem approach to managing marine resources, yet crafting such an approach has proved difficult. Ecosystems today exhibit little of the abundance and complexity found in the past, and populations of over‐fished species have declined dramatically world‐wide, yet historical evidence has been difficult to assimilate into complex ecosystem models. Here, we look to the testimony of Gulf of Maine fishermen for insights on the abundance of Atlantic cod (Gadus morhua) and the environment that once supported such large numbers of them. Using logbook data from Frenchman’s Bay, Maine, and other New England communities at the time of the Civil War, we estimate cod landings in the Gulf of Maine in 1861, establish a population structure for cod at that time, and map the geographical distribution of fishing effort of a fleet that minimized risk and cut expenses by fishing inshore where cod and bait species were plentiful. Log entries list the pelagic and bottom‐dwelling invertebrate species these fishermen used for bait, when and how they acquired it, and what species they looked for in the water to signify the presence of cod. Ranked descriptions of both cod and bait abundance were found to be statistically significant indicators of cod catch. Frenchman’s Bay fishermen 140 years ago provided a minimum set of ecosystem requirements for abundant cod, conditions that may inform management plans aimed at restoring both the species and the Gulf of Maine marine ecosystem.

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Anadromous Alewives Alosa pseudoharengus and Blueback Herring A. aestivalis, collectively known as “river herring,” provide ecosystem services to coastal communities in the Eastern United States. Despite traditions of community‐based stewardship, many populations exhibit long‐term declines. Their name notwithstanding, river herring spend most of their lives at sea and stray among natal rivers. Therefore, absence of management above individual rivers can compromise population viability, local conservation investments, and ecosystem services. Large‐scale management in the USA was achieved for the first time during 2007–2015 by amending three Fishery Management Plans and creating a broader River Herring Conservation Plan following an Endangered Species Act petition. Concurrently, an international restoration plan for river herring in the St. Croix River on the USA–Canada border was adopted. A survey of stakeholder organizations in New England during this period revealed widespread concern for stressors managed at different scales, but that most action was directed locally. Stakeholder collaboration networks were clustered within states and around loose regional hubs, matching the scales of stakeholder concerns and actions. Unfortunately, river herring face growing threats linked to climate change, effects of which will be felt at local and regional scales, while effective mitigation will require actions at national and global scales.

Age-based stock assessments are sometimes rejected by review panels due to large retrospective patterns. When this occurs, data-limited approaches are often used to set catch advice, under the assumption that these simpler methods will not be impacted by the problems causing retrospective patterns in the age-based assessment. This assumption has never been formally evaluated. Closed-loop simulations were conducted where a known source of error caused a retrospective pattern in an age-based assessment. Twelve index-based methods, an ensemble of a subset of these methods, and a statistical catch-at-age model with retrospective adjustment were all evaluated to examine their ability to prevent overfishing and rebuild overfished stocks. Overall, none of the methods evaluated performed best across the scenarios. A number of methods performed consistently poorly, resulting in frequent and intense overfishing and low stock sizes. The retrospective adjusted statistical catch-at-age assessment performed better than a number of the alternatives explored. Thus, using a data-limited approach to set catch advice will not necessarily result in better performance than relying on the age-based assessment with a retrospective adjustment.

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