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Regional-scale migrations and habitat use of juvenile lemon sharks (Negaprion brevirostris) in the US South Atlantic.

Reyier EA, Franks BR, Chapman DD, Scheidt DM, Stolen ED, Gruber SH - PLoS ONE (2014)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Kennedy Space Center Ecological Program and InoMedic Health Applications, Kennedy Space Center, Florida, United States of America.

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.

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Nomogram depicting effect sizes for the best supported lemon shark residency model.To use the nomogram, locate the desired level of each variable and follow the position vertically up to the Points Scale. Repeat this for all variables and add up the points, then find that value on the Total Points Scale. Finally follow that position directly down to the Fitted Probability Scale which gives the predicted probability of daily detection.
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pone-0088470-g003: Nomogram depicting effect sizes for the best supported lemon shark residency model.To use the nomogram, locate the desired level of each variable and follow the position vertically up to the Points Scale. Repeat this for all variables and add up the points, then find that value on the Total Points Scale. Finally follow that position directly down to the Fitted Probability Scale which gives the predicted probability of daily detection.

Mentions: The best-supported residency model (AICc weight  = 0.87; Table 2) determined that day length, categorical days at liberty, and the magnitude of water temperature change over the previous three days (i.e., Δ3temp) helped predict daily detection probability of lemon sharks at Cape Canaveral. In this model, day length had the greatest (negative) effect size with individuals most likely to be present on the shortest days of the year (Table 3; Fig.3). Δ3temp also had a negative effect meaning that cooling trends resulted in higher predicted probability of shark detection, while warming trends resulted in lower predicted probability. The effect size for days at liberty was also negative meaning that sharks were more often detected on dates nearer their release date. Neither sex nor size helped predict lemon shark presence at Canaveral. Further, an effect of wave height on detection probability, shown during range testing to reduce receiver performance, was not supported, confirming that sharks were detected at least sporadically when present in the Canaveral Array, even during periods of high seas.


Regional-scale migrations and habitat use of juvenile lemon sharks (Negaprion brevirostris) in the US South Atlantic.

Reyier EA, Franks BR, Chapman DD, Scheidt DM, Stolen ED, Gruber SH - PLoS ONE (2014)

Nomogram depicting effect sizes for the best supported lemon shark residency model.To use the nomogram, locate the desired level of each variable and follow the position vertically up to the Points Scale. Repeat this for all variables and add up the points, then find that value on the Total Points Scale. Finally follow that position directly down to the Fitted Probability Scale which gives the predicted probability of daily detection.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3935833&req=5

pone-0088470-g003: Nomogram depicting effect sizes for the best supported lemon shark residency model.To use the nomogram, locate the desired level of each variable and follow the position vertically up to the Points Scale. Repeat this for all variables and add up the points, then find that value on the Total Points Scale. Finally follow that position directly down to the Fitted Probability Scale which gives the predicted probability of daily detection.
Mentions: The best-supported residency model (AICc weight  = 0.87; Table 2) determined that day length, categorical days at liberty, and the magnitude of water temperature change over the previous three days (i.e., Δ3temp) helped predict daily detection probability of lemon sharks at Cape Canaveral. In this model, day length had the greatest (negative) effect size with individuals most likely to be present on the shortest days of the year (Table 3; Fig.3). Δ3temp also had a negative effect meaning that cooling trends resulted in higher predicted probability of shark detection, while warming trends resulted in lower predicted probability. The effect size for days at liberty was also negative meaning that sharks were more often detected on dates nearer their release date. Neither sex nor size helped predict lemon shark presence at Canaveral. Further, an effect of wave height on detection probability, shown during range testing to reduce receiver performance, was not supported, confirming that sharks were detected at least sporadically when present in the Canaveral Array, even during periods of high seas.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Kennedy Space Center Ecological Program and InoMedic Health Applications, Kennedy Space Center, Florida, United States of America.

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.

Show MeSH