Regional-Scale Migrations and Habitat Use of Juvenile Lemon Sharks (Negaprion brevirostris) in the US South Atlantic

Abstract

Resolving the geographic extent and timing of coastal shark migrations, as well as their environmental cues, is essential for refining shark management strategies in anticipation of increasing anthropogenic stressors to coastal ecosystems. We employed a regional-scale passive acoustic telemetry array encompassing 300 km of the east Florida coast to assess what factors influence site fidelity of juvenile lemon sharks (Negaprion brevirostris) to an exposed coastal nursery at Cape Canaveral, and to document the timing and rate of their seasonal migrations. Movements of 54 juvenile lemon sharks were monitored for three years with individuals tracked for up to 751 days. While most sharks demonstrated site fidelity to the Cape Canaveral region December through February under typical winter water temperatures, historically extreme declines in ocean temperature were accompanied by rapid and often temporary, southward displacements of up to 190 km along the Florida east coast. From late February through April each year, most sharks initiated a northward migration at speeds of up to 64 km day−1 with several individuals then detected in compatible estuarine telemetry arrays in Georgia and South Carolina up to 472 km from release locations. Nineteen sharks returned for a second or even third consecutive winter, thus demonstrating strong seasonal philopatry to the Cape Canaveral region. The long distance movements and habitat associations of immature lemon sharks along the US southeast coast contrast sharply with the natal site fidelity observed in this species at other sites in the western Atlantic Ocean. These findings validate the existing multi-state management strategies now in place. Results also affirm the value of collaborative passive arrays for resolving seasonal movements and habitat preferences of migratory coastal shark species not easily studied with other tagging techniques.

Population structure and cryptic speciation in bonnethead sharks Sphyrna tiburo in the south‐eastern U.S.A. and Caribbean

“…Structure within the Gulf of Mexico coincides with differences in several reproductive variables observed in S. tiburo living in different estuaries in the region, including size at maturity and growth rates (Parsons, 1993 a , b ; Lombardi‐Carlson et al ., ) and the limited dispersal of S. tiburo (Heupel et al ., ; Ubeda et al ., ; Froeschke et al ., ). Sphyrna tiburo make seasonal migrations between the Carolinas and at least Cape Canaveral, FL, similar to other sharks (Driggers et al ., ; Reyier et al ., ), but dispersal from the Carolinas to the Gulf of Mexico or Bahamas appears to be minimal. This may be because migratory individuals are site‐faithful, returning to the same destinations each seasonal cycle without straying.…”

Juvenile Greenland sharks Somniosus microcephalus (Bloch & Schneider, 1801) in the Canadian Arctic

“…Juveniles B200 Polar Biol waters of exposed beaches and undertake seasonal movements of several hundred kilometers (Reyier et al 2008(Reyier et al , 2014. This demonstrates that birthing and nursery locations can be variable within a single species.…”

Philopatry and Regional Connectivity of the Great Hammerhead Shark, Sphyrna mokarran in the U.S. and Bahamas

“…For aquatic ectotherms, seasonal rises in water temperature can act as an important cue in the timing of migration (e.g., salmon [Salmo salar] smolts Jonsson and Ruud-Hansen, 1985;squid [Loliginid forbesi] Sims et al, 2001). All three great hammerheads that exhibited long-distance migrations departed Bimini April to early May when the water temperature began to rise above 26 • C. In the same region, water temperature was found to be a key predictor for the presence and absence of lemon and blacktip shark seasonal aggregations in Florida (Kessel et al, 2014a;Reyier et al, 2014;Kajiura and Tellman, 2016). Future studies on great hammerhead sharks should explore the timing, repeatability, and motivations for such long-distance movements, particularly as their travel routes cross various management and political boundaries.…”