First insights into the movements of young-of-the-year white sharks (Carcharodon carcharias) in the western North Atlantic Ocean

Abstract

In recent years, white sharks (Carcharodon carcharias) have become more accessible to researchers off the northeastern U.S. as feeding aggregation sites have emerged and the population has increased. However, there has been limited research on young-of-the-year (YOY) sharks relative to older age classes in this region. Previous research indicated that YOY white sharks were most frequently observed in the New York Bight, suggesting the region serves a nursery role. To further examine the species' use of this area, we deployed satellite and acoustic tags on ten YOY white sharks (138-166 cm total length) off Long Island, New York. The sharks remained resident in New York Bight waters through summer (August through October), further supporting the notion that the region is a nursery area. Southward movements were observed during fall, with overwintering habitat identified off North and South Carolina shelf waters. Return migrations toward the New York Bight were observed in some individuals the following spring. YOY white sharks in this heavily-populated region are exposed to anthropogenic impacts such as fisheries bycatch and coastal habitat degradation. As juvenile survival rates are important for long-term population sustainability, further research is necessary to assess the potential impacts of these activities on the western North Atlantic white shark population.

Figure 1

Map of the study site off Long Island, New York in the western North Atlantic (a) and photograph of a satellite tagged YOY white shark (WS2) on the M/V OCEARCH boat lift tagging platform (b). CT = Connecticut; NY = New York; NYC = New York City; NJ = New Jersey. Image copyright OCEARCH.

Figure 2

Tracks of eight YOY white sharks (a) and kernel utilization distributions (blue = 95%; yellow = 75%; orange = 50%; red = 25%) of the tagged sharks (b) off Long Island, New York, during August through October, 2016. The arrow indicates the tagging location. Diamond symbols represent locations of acoustic receivers where YOY white sharks were detected. Bathymetric contours (gray lines) are in 10 m increments.

Figure 3

Late-fall and overwinter (October through April) tracking positions of five YOY white sharks tagged off Long Island, New York. The arrow indicates the August 2016 tagging location. NY = New York; NJ = New Jersey; DE = Delaware; MD = Maryland; VA = Virginia; NC = North Carolina; SC = South Carolina. Solid black lines are the 100 and 200 m bathymetric contours denoting the edge of the continental shelf.

Figure 4

Complete 305-day track of a single YOY white shark (WS9), August 2016 to June 2017. The white arrow indicates the tagging location (August 23, 2016). Black arrows denote the directions of movement. Solid black lines are the 100 and 200 m bathymetric contours denoting the edge of the continental shelf.