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.

Implications of life history uncertainty when evaluating status in the Northwest Atlantic population of white shark (Carcharodon carcharias)

“…This is concerning given their widespread distribution throughout the Northwest Atlantic (Skomal et al, 2017) and their potential for interaction with multiple commercial fleets in both national and international waters (Queiroz et al, 2019). Incidental captures have occurred in many gear types: including trawl, gillnet, trap or weir, and longline fisheries (Curtis et al, 2014; DFO, 2017), and estimating total discards of white shark in the Northwest Atlantic has been flagged as a research priority (Curtis et al, 2018). Although incidental mortality from any one fleet might be expected to be rare and sporadic, there is currently no real method by which to track collective mortality from all fleets and fisheries affecting the population in the Northwest Atlantic.…”

“…White shark are a good example: For any given population, individuals are encountered infrequently over a vast geographical range (Bonfil et al, 2005; Skomal, Braun, Chisholm, & Thorrold, 2017), interact with diverse fisheries in national and international waters (Dewar et al, 2013; Queiroz et al, 2019), and thus have limited potential for using catches to monitor absolute (as opposed to relative) abundance (Baum et al, 2003; Burgess et al, 2005; Curtis et al, 2014). A reliable time‐series of total removals for white shark in the Northwest Atlantic is not available due to the need to identify and scale up observed interactions from multiple fleets where observation rates tend to be low (Curtis et al, 2018; Dulvy et al, 2008). Catch‐per‐unit‐effort (CPUE) indices of relative abundance coupled with life history information become the primary data sources that can be used to assess status.…”

Seasonal Presence of Atlantic Sturgeon and Sharks at Cape Hatteras, a Large Continental Shelf Constriction to Coastal Migration

“…Based on fishery capture and sightings data, White Sharks Carcharodon carcharias may occur in coastal North Carolina waters year-round but are most common during fall and spring migrations (Curtis et al 2014). More recent telemetry work has shown that the Hatteras Bight is a key SEASONAL PRESENCE OF ATLANTIC STURGEON AND SHARKS feature in the coastal portion of the annual migration of adult White Sharks (Skomal et al 2017); juveniles may overwinter on the continental shelf off North Carolina in considerable numbers (Curtis et al 2018). A wide variety of other shark species also occurs off Cape Hatteras during winter, where despite the closure of bottom longline fishing they can comprise a considerable amount of the targeted catch and bycatch in gill-net fisheries (Jensen and Hopkins 2001;Thorpe and Frierson 2009).…”

Future Research Directions on the “Elusive” White Shark

“…Numerous statistical approaches have been devised in recent years to model critical habitat based on environmental and presence-absence data sets (Valavanis et al, 2008), but this still needs to be done for many subpopulations of white sharks, and across all lifehistory stages. While the majority of published studies are on subadult and adult stages, some knowledge exists for juvenile and young-of-the-year stages (Dewar et al, 2004;Weng et al, 2007b;Bruce and Bradford, 2012;Lyons et al, 2013;White, 2016;Oñate-González et al, 2017;Curtis et al, 2018). Owing to the direct relationship between stock size and recruitment for sharks (Holden, 1974;Hoenig et al, 1990), it is imperative that new studies are implemented to better understand the preferred habitats frequented by juvenile sharks.…”