Landry Jr, A.M.

LONG-TERM MOVEMENTS OF AN ADULT MALE KEMP’S RIDLEY SEA TURTLE (LEPI- DOCHELYS KEMPII) IN THE NORTHWEST- ERN GULF OF MEXICO—Despite recent insights into the spatial ecology of juvenile (Morreale and Standora, 2005; Renaud and Williams, 2005; Mansfield, 2006; McClellan, 2009; Seney and Landry, 2011; Lyn et al., 2012) and postnesting female Kemp’s ridleys (Lepi- dochelys kempii) (Seney and Landry, 2008, 2011; Shaver and Rubio, 2008; Shaver et al., 2013, 2016), the breeding, migratory, and foraging behaviors of adult male Kemp’s ridleys remain largely unknown (Shaver et al., 2005).

The current paradigm suggests that adult male Kemp’s ridleys primarily reside in neritic forag- ing habitats near nesting beaches year round and engage in courtship and mating activities in March, immediately before the April–July nest- ing season (Owens, 1980; Rostal et al., 1998; Rostal, 1991, 2005; Shaver et al., 2005). Field observations of mounted pairs near known nesting beaches have occurred between October and May in Mexico (Rancho Nuevo) and in early June in Texas [Padre Island National Seashore (PAIS)], although confirmation of copulation is lacking (Pritchard and Ma ́rquez, 1973; Shaver et al., 2005). This tendency for male Kemp’s ridleys to establish year-round residency near nesting beaches is behaviorally disparate from seasonal migratory movements displayed by adult female conspecifics (Seney and Landry, 2008, 2011; Shaver and Rubio, 2008; Shaver et al., 2016; Hughes and Landry, unpubl. data) and males of other species (Lepidochelys olivacea: Beavers and Cassano, 1996; Plotkin et al., 1996; Caretta caretta: Arendt et al., 2012; Casale et al., 2013; Chelonia mydas: Limpus, 1993; Hays et al., 2001; Der- mochelys coriacea: James et al., 2005).

Identification of spatially and temporally defined areas frequented by adult male Kemp’s ridleys for breeding, migrating, or foraging is necessary to accomplish a Priority 1 Recovery Task in the Kemp’s Ridley Recovery Plan mandating protection and management of im- portant marine habitats (National Marine Fish- eries Service, 2011). Implementation of marine protected areas and other conservation measures to facilitate protection of adult males utilizing

critical habitats will require a comprehensive effort to better delineate habitat boundaries, assess localized sources of mortality, and, in foraging areas, to quantify and qualify prey resources and physical site characteristics. Infor- mation on adult male Kemp’s ridley migratory behavior is currently limited to a single source describing the movements of 11 individuals incidentally captured from waters near Rancho Nuevo (Shaver et al., 2005). Our analysis herein of a single adult male Kemp’s ridley’s long-term movements in northwestern Gulf of Mexico (GOM) waters, which recently have been identi- fied as critical foraging (Shaver et al., 2013) and migratory (Shaver et al., 2016) habitat for adult female conspecifics, is the longest time series of information to date for a male sea turtle. This study provides valuable insight into the behavior of an individual male Kemp’s ridley and has implications for the management and conserva- tion of the species. 

Long-term monitoring of in-water life history stages of the critically endangered Kemp’s ridley sea turtle (Lepidochelys kempii) is essential for management because it generates information on the species’ at-sea abundance, size composition, distribution, and habitat requirements. We documented trends in Kemp’s ridley size, relative abundance, and distribution using entanglement netting surveys at three study areas adjacent to tidal passes in the northwestern Gulf of Mexico (NWGOM) during intermittent sampling periods from 1991 to 2013. A total of 656 Kemp’s ridley sea turtles were captured ranging in size from 19.5 to 66.3 cm straight carapace length (SCL) (mean 1⁄4 35.0 cm SCL). The dominance of juveniles (25–40 cm SCL) captured during sampling suggests the nearshore waters of the NWGOM are an important developmental foraging ground for Kemp’s ridley. Characterization of Kemp’s ridley long-term relative abundance reveals a generally stable trend in catch- per-unit-effort (CPUE) across all study areas combined. Based on the increasing trend in the number of hatchlings released from the species’ primary nesting beach, Rancho Nuevo, Mexico, since the early 1990s, the lack of a corresponding overall increase in juvenile abundance at nearshore sampling locations is puzzling. This disparity is most likely an artifact of the present study’s sampling design, but could also indicate shifts in Kemp’s ridley recruitment away from the NWGOM. While conservation efforts have contributed to this species’ overall growth since the 1980s, as measured by the increasing number of nests, recent declines in this rate of increase are a concern and call for a more comprehensive approach to managing Kemp’s ridley recovery efforts.