Defining habitat preferences of pelagic loggerhead sea turtles (Caretta caretta) in the North Atlantic through analysis of behavior and bycatch
For many species of marine turtle the characteristics that define pelagic habitat have yet to be fully identified. A better understanding of these habitat characteristics is critical to reduce high seas fisheries interactions with turtles, especially as the status of many turtle populations has plac...
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Online Access: | https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/0r967674h |
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ftoregonstate:ir.library.oregonstate.edu:0r967674h 2024-09-15T18:21:27+00:00 Defining habitat preferences of pelagic loggerhead sea turtles (Caretta caretta) in the North Atlantic through analysis of behavior and bycatch McCarthy, Abigail L. Heppell, Selina S. Strub, P. Ted Krueger, William Boehlert, George Fisheries and Wildlife Oregon State University. Graduate School 1404428 bytes application/pdf https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/0r967674h English [eng] eng unknown Oregon State University https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/0r967674h All rights reserved Loggerhead turtles -- Habitat -- North Atlantic Ocean -- Remote sensing Loggerhead turtles -- Behavior -- North Atlantic Ocean Sea turtles -- Habitat -- North Atlantic Ocean -- Remote sensing Sea turtles -- Behavior -- North Atlantic Ocean Masters Thesis ftoregonstate 2024-07-22T18:06:06Z For many species of marine turtle the characteristics that define pelagic habitat have yet to be fully identified. A better understanding of these habitat characteristics is critical to reduce high seas fisheries interactions with turtles, especially as the status of many turtle populations has placed them on the threatened or endangered species list. The combination of high-resolution satellite-tracking data with remotely sensed oceanographic data makes it possible to identify habitat for loggerhead turtles by analyzing the behavior of individual animals. Bycatch of loggerhead turtles in longline fisheries can also be examined using the same high-resolution oceanographic data to determine if there are identifiable habitat differences in high- and low- bycatch areas. I analyzed the tracks of ten loggerhead turtles tagged in the spring and fall of 1998 near Madeira, Portugal in relation to the marine environment they occupied. To determine the relationship between an individual turtle and its environment, some measure of behavior was necessary. I calculated the straightness index (SI), the ratio of the displacement of the animal to the total distance traveled, for individual weekly segments of the ten tracks as a measure of individual behavior. I then extracted information about the chlorophyll, sea-surface temperature (SST), bathymetry, and geostrophic current of the ocean in a 20km buffer surrounding the tracks, and examined the relationship between the straightness index and those characteristics using logistic regression. Chlorophyll a value, bathymetry, and movement of the turtle with geostrophic currents were consistently related to the straightness index of the tracks of all ten animals (two-sided p-value from Wald's test: 0.005, 0.0017, and 0.0018, respectively). Tracks were less straight in high chlorophyll regions and in shallower ocean areas, and animals were more likely to be moving with prevailing geostrophic currents during straighter track segments. These results confirm comparable analyses of ... Master Thesis North Atlantic ScholarsArchive@OSU (Oregon State University) |
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ScholarsArchive@OSU (Oregon State University) |
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ftoregonstate |
language |
English unknown |
topic |
Loggerhead turtles -- Habitat -- North Atlantic Ocean -- Remote sensing Loggerhead turtles -- Behavior -- North Atlantic Ocean Sea turtles -- Habitat -- North Atlantic Ocean -- Remote sensing Sea turtles -- Behavior -- North Atlantic Ocean |
spellingShingle |
Loggerhead turtles -- Habitat -- North Atlantic Ocean -- Remote sensing Loggerhead turtles -- Behavior -- North Atlantic Ocean Sea turtles -- Habitat -- North Atlantic Ocean -- Remote sensing Sea turtles -- Behavior -- North Atlantic Ocean McCarthy, Abigail L. Defining habitat preferences of pelagic loggerhead sea turtles (Caretta caretta) in the North Atlantic through analysis of behavior and bycatch |
topic_facet |
Loggerhead turtles -- Habitat -- North Atlantic Ocean -- Remote sensing Loggerhead turtles -- Behavior -- North Atlantic Ocean Sea turtles -- Habitat -- North Atlantic Ocean -- Remote sensing Sea turtles -- Behavior -- North Atlantic Ocean |
description |
For many species of marine turtle the characteristics that define pelagic habitat have yet to be fully identified. A better understanding of these habitat characteristics is critical to reduce high seas fisheries interactions with turtles, especially as the status of many turtle populations has placed them on the threatened or endangered species list. The combination of high-resolution satellite-tracking data with remotely sensed oceanographic data makes it possible to identify habitat for loggerhead turtles by analyzing the behavior of individual animals. Bycatch of loggerhead turtles in longline fisheries can also be examined using the same high-resolution oceanographic data to determine if there are identifiable habitat differences in high- and low- bycatch areas. I analyzed the tracks of ten loggerhead turtles tagged in the spring and fall of 1998 near Madeira, Portugal in relation to the marine environment they occupied. To determine the relationship between an individual turtle and its environment, some measure of behavior was necessary. I calculated the straightness index (SI), the ratio of the displacement of the animal to the total distance traveled, for individual weekly segments of the ten tracks as a measure of individual behavior. I then extracted information about the chlorophyll, sea-surface temperature (SST), bathymetry, and geostrophic current of the ocean in a 20km buffer surrounding the tracks, and examined the relationship between the straightness index and those characteristics using logistic regression. Chlorophyll a value, bathymetry, and movement of the turtle with geostrophic currents were consistently related to the straightness index of the tracks of all ten animals (two-sided p-value from Wald's test: 0.005, 0.0017, and 0.0018, respectively). Tracks were less straight in high chlorophyll regions and in shallower ocean areas, and animals were more likely to be moving with prevailing geostrophic currents during straighter track segments. These results confirm comparable analyses of ... |
author2 |
Heppell, Selina S. Strub, P. Ted Krueger, William Boehlert, George Fisheries and Wildlife Oregon State University. Graduate School |
format |
Master Thesis |
author |
McCarthy, Abigail L. |
author_facet |
McCarthy, Abigail L. |
author_sort |
McCarthy, Abigail L. |
title |
Defining habitat preferences of pelagic loggerhead sea turtles (Caretta caretta) in the North Atlantic through analysis of behavior and bycatch |
title_short |
Defining habitat preferences of pelagic loggerhead sea turtles (Caretta caretta) in the North Atlantic through analysis of behavior and bycatch |
title_full |
Defining habitat preferences of pelagic loggerhead sea turtles (Caretta caretta) in the North Atlantic through analysis of behavior and bycatch |
title_fullStr |
Defining habitat preferences of pelagic loggerhead sea turtles (Caretta caretta) in the North Atlantic through analysis of behavior and bycatch |
title_full_unstemmed |
Defining habitat preferences of pelagic loggerhead sea turtles (Caretta caretta) in the North Atlantic through analysis of behavior and bycatch |
title_sort |
defining habitat preferences of pelagic loggerhead sea turtles (caretta caretta) in the north atlantic through analysis of behavior and bycatch |
publisher |
Oregon State University |
url |
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/0r967674h |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/0r967674h |
op_rights |
All rights reserved |
_version_ |
1810460022149218304 |