Long-Term Change in the Biodiversity and Biocomplexity of Gulf of Maine Fisheries

Once known for abundant and diverse fisheries, the Gulf of Maine today mostly supports invertebrate fishing industries. Scallop and lobster are profitable while groundfishermen receive Federal disaster relief. The historical and present abundance of cod, lobster and alewives have been compared, but few studies have explored the role of biodiversity and biocomplexity in long-term fisheries success and ecosystem resilience. Here, data from US Fish Commission, Bureau of Fisheries and Fish and Wildlife reports before 1950 allow us to examine changes over time and by gear type in the biodiversity and biocomplexity of fisheries, and compare these trends to conditions today. Gulf of Maine fisheries before 1950 were diverse (as many as 52 different species commercially fished), closer to shore (more small boats and fixed gear catch, particularly north of Massachusetts), and complex (higher trophic level combined with catch more evenly distributed across species groups).  Catch from coastal fisheries resembled food webs, with prey species one to several orders of magnitude more abundant than predators. Conversely, offshore otter trawls captured slices of the water column and high-graded predatory species. We suggest that trophic highgrading accelerated the deterioration of the Gulf of Maine by undercutting biocomplexity and system resilience.