275
0-8493-1123-3/03/$0.00+$1.50
© 2003 by CRC Press LLC
11 Sea Turtle Population
Ecology
Selina S. Heppell, Melissa L. Snover, and
Larry B. Crowder
CONTENTS
11.1 Introduction: What Drives Sea Turtle Population Dynamics? ...................275
11.2 Life History .................................................................................................277
11.2.1 Life Stages and Ontogenetic Shifts ................................................277
11.2.2 Growth Rates and Stage Lengths ...................................................280
11.2.3 Age at Sexual Maturation ................................................................285
11.2.4 Growth Rate Variability ..................................................................286
11.2.5 Survival Rates .................................................................................286
11.2.6 Reproduction ...................................................................................290
11.3 Population Structure ...................................................................................291
11.4 Assessing Population Change through Time .............................................292
11.5 Population Models as Tools for Testing Hypotheses about Population
Dynamics ....................................................................................................297
References ............................................................................................................299
11.1 INTRODUCTION: WHAT DRIVES SEA TURTLE
POPULATION DYNAMICS?
Sea turtle population demographics reflect the effects of natural and anthropogenic
stressors that include environmental variability, terrestrial habitat loss, terrestrial
and aquatic habitat degradation, and direct and indirect fishing mortality (National
Research Council, 1990; Lutcavage et al., 1997). New threats include increases in
egg incubation temperatures (further skewing sex ratios, which are defined by
incubation temperature) caused by global warming and loss of nesting habitat to
rising sea levels on developed and armored beaches. In the marine system, accumulation of pollutants such as plastics, heavy metals, environmental estrogens,
and oil products in pelagic nursery and demersal coastal habitats threaten juvenile
and adult turtles of all species. In addition, sea turtles swim a gauntlet of fishing
gear, including trawls, gill nets, pound nets, and longlines, as they migrate across
1123 book.book Page 275 Tuesday, November 12, 2002 7:43 AM
0-8493-1123-3/03/$0.00+$1.50
© 2003 by CRC Press LLC
11 Sea Turtle Population
Ecology
Selina S. Heppell, Melissa L. Snover, and
Larry B. Crowder
CONTENTS
11.1 Introduction: What Drives Sea Turtle Population Dynamics? ...................275
11.2 Life History .................................................................................................277
11.2.1 Life Stages and Ontogenetic Shifts ................................................277
11.2.2 Growth Rates and Stage Lengths ...................................................280
11.2.3 Age at Sexual Maturation ................................................................285
11.2.4 Growth Rate Variability ..................................................................286
11.2.5 Survival Rates .................................................................................286
11.2.6 Reproduction ...................................................................................290
11.3 Population Structure ...................................................................................291
11.4 Assessing Population Change through Time .............................................292
11.5 Population Models as Tools for Testing Hypotheses about Population
Dynamics ....................................................................................................297
References ............................................................................................................299
11.1 INTRODUCTION: WHAT DRIVES SEA TURTLE
POPULATION DYNAMICS?
Sea turtle population demographics reflect the effects of natural and anthropogenic
stressors that include environmental variability, terrestrial habitat loss, terrestrial
and aquatic habitat degradation, and direct and indirect fishing mortality (National
Research Council, 1990; Lutcavage et al., 1997). New threats include increases in
egg incubation temperatures (further skewing sex ratios, which are defined by
incubation temperature) caused by global warming and loss of nesting habitat to
rising sea levels on developed and armored beaches. In the marine system, accumulation of pollutants such as plastics, heavy metals, environmental estrogens,
and oil products in pelagic nursery and demersal coastal habitats threaten juvenile
and adult turtles of all species. In addition, sea turtles swim a gauntlet of fishing
gear, including trawls, gill nets, pound nets, and longlines, as they migrate across
1123 book.book Page 275 Tuesday, November 12, 2002 7:43 AM