Spatiotemporal variation of benthic communities on weathervane scallop (Patinopecten caurinus) beds with socioeconomic considerations of the commercial fishery off the coast of Alaska

Thesis (M.S.) University of Alaska Fairbanks, 2014.Weathervane scallops (Patinopecten caurinus [Gould, 1850]) off Alaska are commercially harvested in areas that contain commercially important groundfish and crabs. Using observer bycatch data collected during 1996-2012, we analyzed spatial and temporal patterns in community composition on weathervane scallop beds and explored whether observed patterns related to environmental variables (sediment, depth, bottom water temperature, and freshwater discharge) and anthropogenic variables (trawling and dredging effort). Significant (P<0.05) differences in community structure were observed at the scale of state fishery registration districts, as well as among individual scallop beds. Spatial differences were most strongly correlated with sediment, depth, and dredging effort. Sequential changes over time were also detected, as was a split between 1996-1999 and 2000-2012. Temporal changes were weakly yet significantly correlated with freshwater discharge and dredging effort. We also conducted a socioeconomic assessment of the commercial weathervane scallop fishery, structured within the framework of a SWOT (strengths, weaknesses, opportunities, threats) analysis. Specifically, we focused on five categories: social, technological, economic, environmental, and regulatory. Whereas the data-poor status of the stock appears to be the fishery's biggest weakness, the largest strengths are conservative management, industry self-regulation, and the fishery's small footprint. Impending threats include stock declines, effects of dredging, and changes in the structure of the fishery. These analyses provide a baseline of benthic community composition on weathervane scallop beds, as well as socioeconomic information to contribute to the environmental, economic, and social sustainability of the Alaska scallop fishery.General Introduction -- Chapter 1: Spatiotemporal variation of benthic communities associated with weathervane scallop (Patinopecten caurinus) beds off Alaska -- Chapter 2: Socioeconomic considerations of the commercial weathervane scallop fishery off Alaska using a SWOT analysis -- General Conclusions

Spatiotemporal Variability of Benthic Communities on Weathervane Scallop Beds off Alaska

<p>Marine benthic communities are critical biotic components of habitat due to their roles in ecosystem function and health and as indicators of ecosystem change. Benthic communities are receiving increasing attention as institutions adopt ecosystem-oriented research approaches. We conducted a multidecadal analysis of benthic communities in areas targeted by a commercial weathervane scallop <i>Patinopecten caurinus</i> fishery on the continental shelf off Alaska. Using bycatch data collected by onboard observers during 1996–2012, we analyzed spatiotemporal patterns in community composition on weathervane scallop beds. We also explored whether spatiotemporal differences were related to environmental (sediment and depth) and anthropogenic (dredging effort) variables. Statistically significant (<i>P</i> < 0.05) temporal changes in community composition occurred during 1996–2012, with a split between 1996 and 1999 and subsequent years. Taxa contributing to temporal changes were not consistent across fishery registration areas. Significant spatial differences in community structure were detected both at the scale of registration areas (200–2,000 km) and individual scallop beds (<50 km). We also found significant correlations between benthic species composition and environmental and anthropogenic variables over space and time. Although the relationships were generally weak, the ecological associations were consistent with expected depth and sediment relationships in this region. Our results are directly relevant to the habitat objective of the scallop fishery management plan, inform essential fish habitat designations for weathervane scallops and other commercially important species, and serve as a baseline against which to compare future changes associated with fishing and climate change. Ensuing research should include the collection of environmental data at the spatial scale of individual scallop beds as well as controlled experiments on the impacts of fishing on benthic communities and their recovery.</p> <p>Received August 19, 2016; accepted August 8, 2017</p