Table 1.
Summary of spiny dogfish (Squalus acanthias) PSAT tag deployments and pop-up date, locations, and time at liberty.
Figure 1.
Northern aggregate geolocation points (A) span the area between Rockland, ME (∼44°N) and the Virginia/North Carolina line (∼36°N), with the majority (67%) between Rockland, ME and Cape Cod, MA and few (33%) south of Cape Cod.
The majority (73%) of southern aggregate geolocation points (B) span the area between Albemarle Sound, VA (∼36°N) and New Smyrna Beach, FL (∼29°N), while the remaining points (27%) reach as far as Cape Cod. Tag deployment sites are marked in the Gulf of Maine (northern tags) and off the coast of North Carolina (southern tags).
Figure 2.
Pop-up points for northern (A) and southern (B) spiny dogfish tags.
Each point represents one tag pop-up point. The numbers inside of the triangles represent the month in which the tag popped. The green circle represents the point of deployment for both the northern (A) and southern (B) tags. Estimated 95% and 50% UDs for northern (A) and southern (B) spiny dogfish tags. 95% UD or total home range (light red bounding area) for the northern dogfish extends from Maine to Maryland, while the 50% UD or concentrated usage core space (dark red central area) lies between approximately Rockland, ME and Cape Cod, MA. The red points are the geolocations used to calculate the UDs. 95% UD (light grey bounding area) for the southern dogfish lies between approximately Cape Cod, MA and Georgia, while the 50% UD (black central area) extends from the Delaware/Maryland line and Outer Banks, NC. The black points are the geolocations used to calculate the UDs.
Figure 3.
Two representative 365-day tracks for one northern (triangles) spiny dogfish and one southern (squares) spiny dogfish.
Deployment sites (north = Maine, south = North Carolina) are indicated by green circles. Colors of points represent different months throughout the year.
Figure 4.
Geolocations for mature females (> = 88 cm) from both the northern (triangles) and southern (squares) tags.
Colors of points represent different months of proposed parturition.
Figure 5.
Circular (directional) seasonal histograms show the direction and magnitude of the majority of movement from individual geolocation points for the northern (A) and southern (B) tags.
Figure 6.
Estimated 95% and 50% UDs for northern (A) and southern (B) spiny dogfish tags.
95% UD or total home range (light red bounding area) for the northern dogfish extends from Maine to Maryland, while the 50% UD or concentrated usage core space (dark red central area) lies between approximately Rockland, ME and Cape Cod, MA. The red points are the geolocations used to calculate the UDs. 95% UD (light grey bounding area) for the southern dogfish lies between approximately Cape Cod, MA and Georgia, while the 50% UD (black central area) extends from the Delaware/Maryland line and Outer Banks, NC. The black points are the geolocations used to calculate the UDs.
Figure 7.
Seasonal 50% UDs for both the northern (A) and southern (B) deployed dogfish.
The 50% spring UDs are represented in green, summer in yellow, autumn in orange, and winter in blue. Autumn was the only season that showed spatial overlap between the northern group and southern group (C).
Figure 8.
Mean differences between hourly diel depths and mean daily depths for the northern tags (red) and southern tags (black) to reveal distinctly different diel patterns.
The northern tags show a larger change in mean diel depths than the southern tags. Error bars represent standard error.
Figure 9.
Mean daily depth time series for the northern (red) and southern (black) tags, ranging from 10/2/2009 to 7/17/2011 for the north and 4/13/2011 to 4/13/2012 for the south.
Error bars represent standard error.
Figure 10.
Mean daily temperature time series for the northern (red) and southern (black) tags, ranging from 10/2/2009 to 7/17/2011 for the north and 4/13/2011 to 4/13/2012 for the south.
Error bars represent standard error.
Figure 11.
NMFS bottom-trawl data of survey station bottom temperatures for autumn (A. 2009, C. 2010, E. 2011) and spring (B. 2010, D. 2011, F. 2012) trawls overlaid with corresponding northern and southern geolocations of current study.