Atlantic Wolffish (Anarhichas lupus)
Abundance and Distribution in the Gulf of Maine
Fall Surveys, 1963-2004
How have wolffish populations changed through time? Are there any patterns in wolffish populations that may be correlated with habitat?
We compared the sampling effort and frequency of occurrence of Atlantic wolffish in the Gulf of Maine with the corresponding substrate and charted changes in their population over time within specific habitat areas.
- Significance
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This study demonstrates how the National Marine Fisheries Service (NMFS) database can be used to investigate the changing population of a single species through time. These data show wolffish abundance decreasing through time, and they indicate linkages between wolffish abundance and substrate as approximated by the World Wildlife Fund Gulf of Maine substrate layer.
Substrate
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The coarse resolution of the World Wildlife Fund substrate layer, shown above, provides an indication of basic substrate types in the Gulf of Maine.
Spring & Summer
Fall
Maps of Wolffish Abundance
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Maps of Wolffish Abundance Including the Zero Tows
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Graphs of Sampling Effort by Substrate
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This shows no sampling on bedrock and ample sampling on the other substrate types.
Graphs of the Distribution of Positive Tows by Substrate
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The positive tows for wolffish in the Gulf of Maine occurred in these substrates as shown by the above proportions. (E.g. approximately 50% of all tows positive for wolffish were taken on gravel and till.) There is no significant change between seasons.
Abundance
Map of Wolffish Abundance, Spring and Summer
1968-2005
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Map of Wolffish Abundance, Spring and Summer
1968-2005 including zero tows
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Map of Wolffish Abundance, Spring and Summer
2000-2005
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Map of Wolffish Abundance, Spring and Summer
2000-2005 including zero tows
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Habitat Regions
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The habitat regions represent areas where wolffish have been recorded by NMFS (National Marine Fisheries Service, United States) and DFO (Department of Fisheries and Oceans, Canada) surveys through time. We created the habitat region boundaries as a way of exploring wolffish abundance over time in specific areas in the Gulf.
Map of Positive Wolffish Tows
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Map of Sampling Effort
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Change in Positive Tows within the Habitat Regions
Data Sources: NMFS Spring Bottom Trawl Survey 1970-2004; DFO Spring and Summer Bottom Trawl Surveys 1970-2001
#1 Stellwagen Bank / Jeffreys Ledge
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#2 Great South Channel
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#3 Georges Bank, Northeast Peak
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#4 Western Scotian Shelf / Browns Bank
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#5 German Bank
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Other (Gulf of Maine outside of defined Habitat Regions)
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Average Number of Wolffish per tow within the Habitat Regions
(Average Number Based on All Tows)
#1 Stellwagen Bank / Jeffreys Ledge
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#2 Great South Channel
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#3 Georges Bank, Northeast Peak
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#4 Western Scotian Shelf / Browns Bank
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#5 German Bank
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Average Number of Wolffish per positive tow within the Habitat Regions
(Average Number Based on Positive Tows)
#1 Stellwagen Bank / Jeffreys Ledge
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#2 Great South Channel
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#3 Georges Bank, Northeast Peak
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#4 Western Scotian Shelf / Browns Bank
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#5 German Bank
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Western Gulf of Maine Closed Area
Map of Gulf of Maine Closed Area and Habitat Regions and Figures of the Number of Wolffish per Tow
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Maps of the Gulf of Maine Closed Area and Wolffish Distributions and Sampling Efforts
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Data Sources
Data
NMFS (National Marine Fisheries Service): The NMFS data were obtained by Erica Fuller through Chad Keith. The NMFS data were already separated into spring and fall surveys.
DFO (Department of Fisheries and Oceans, Canada): The DFO data were a lab copy.
Base maps
WWF Benthic Substrate:
The substrate layer is a product of a WWF-Canada and CLF project Classifying and Mapping Physical Habitat Types (Seascapes) in The Gulf Of Maine and The Scotian Shelf: Seascapes Version to May 2003 by Hussein Alidina and John Roff. The data were displayed by the substrate field and the colors reflect the substrate as illustrated in Figure 5.12 of the report: http://gmbis.iris.usm.maine.edu/Documents/FInal%20Seascapes%20Methods%20Report%20May%202003.pdf Metadata: http://gmbis.iris.usm.maine.edu/WWF%20Pelagic%20Seascapes%20Metadata.xml.
Canada:
Paskevich, Valerie, 20020401, CANADA: Eastern Canadian Provinces:, U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Field Center, Woods Hole, MA. http://pubs.usgs.gov/of/2003/of03-001/data/basemaps/canada/canada.htm.
USA:
Paskevich, Valerie, and Environmental Research Institute, Inc. (ESRI), 20010331, USA: United States basemap data layer for the Gulf of Maine surficial sediment GIS project.: U.S. Geological Survey, Coastal and Marine Geology Program, Woods Hole Field Center, Woods Hole, MA. http://pubs.usgs.gov/of/2003/of03-001/data/basemaps/usa/usa.htm.
Bathymetry:
USGS Digital bathymetry of the Gulf of Maine, constructed by Ed Roworth and Rich Signell, gom15dd. http://pubs.usgs.gov/of/1998/of98-801/bathy/index.htm.
U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Geophysical Data Center, 2001. 2-minute Gridded Global Relief Data (ETOPO2) http://www.ngdc.noaa.gov/mgg/fliers/01mgg04.html
Western Gulf of Maine Closed Area:
Center for Marine Conservation (Carol Baumann), 20010419, nmfs closures: part of the Marine and Coastal Protected Areas Mapping Project, Center for Marine Conservation, Washington DC.
NMFS NEFSC Bottom Trawl Survey 1963-2003
This bottom trawl survey data are provided by the Northeast Fisheries Science Center of the U.S. National Marine Fisheries Service in Woods Hole, MA, USA. This is the U.S. analog to the DFO Bottom Trawl Survey. Data is provided for 1963 through 2003.