|
3.5Hawksbill Sea Turtle 3.5.1Description of the Species
The hawksbill (Eretomchelys imbricate) is one of the smaller sea turtles, it has overlapping scutes (plates) that are thicker than those of other sea turtles. This protects them from being battered against sharp coral and rocks during storm events. Adults range in size from 30 to 36 in (0.8-1.0 m) carapace length, and weigh 100 to 200 lbs (45-90 kg). Its carapace (upper shell) is an attractive dark brown with faint yellow streaks and blotches and a yellow plastron (under shell). There are two pairs of pre-frontal scales on the top of the head and usually two claws on each flipper (NOAA Fisheries 2011a).
3.5.2Species Habitat and Distribution
The name "hawksbill" refers to the turtle's prominent hooked beak. The hawksbill sea turtle is one of the most infrequently encountered sea turtles in offshore Louisiana. However, a hawksbill was reported near Calcasieu Lake in 1986. Hawksbills generally inhabit coastal reefs, bays, rocky areas, passes, estuaries, and lagoons, where they are found at depths of less than seventy feet. The hawksbill turtle is omnivorous, feeding on aquatic vegetation, jellyfish, and other marine animals. Nesting occurs on undisturbed, deep-sand beaches, from high-energy ocean beaches to tiny pocket beaches several meters wide bounded by crevices of cliff walls; these beaches are typically low-energy, with woody vegetation near the waterline.
In the continental United States, nesting sites are restricted to Florida where nesting is sporadic at best (NMFS /USFWS 1993). Due to the lack of suitable foraging and nesting habitats, there is a low probability of this species occurring within the Project area.
3.5.3Status and Cause of Decline
The hawksbill sea turtle was listed as an endangered species throughout its range on June 2, 1970. It is one of seven species of sea turtles found throughout the world. Commercial harvest, habitat degradation, coastal development, disease, and predation have contributed to the decline of this species.
3.6Kemp’s Ridley Sea Turtle 3.6.1Description of the Species
The Kemp’s ridley turtle (Lepidochelys kempii) is the smallest of the sea turtles; adults are approximately 2 to 2½ feet long and weigh 100 pounds (Dundee and Rossman 1989). This species has a single claw on the front flippers and one to two claws on the rear flippers (NOAA Fisheries 2017b). Kemp’s ridley turtles are carnivorous and usually feed on crabs, clams, and mollusks in shallow coastal waters (Dundee and Rossman 1989).
3.6.2Species Habitat and Distribution
The Kemp's ridley has the most limited distribution of any sea turtles except the Australian flatback (Perrine 2003). For the most part, breeding is confined to a limited stretch of beach on the Gulf coast of Mexico. The known range of this species includes the GOM and the Atlantic Ocean. The current range for Kemp’s ridley in the United States includes marine habitat of the following coastal states: Georgia, Florida, Alabama, Mississippi, Louisiana, and Texas.
Inshore areas of the GOM appear to be important habitat for Kemp’s ridleys, as they tend to concentrate around the mouths of major rivers (Frazier 1980). Members of this genus are characteristically found in waters of low salinity and high turbidity and organic content, where shrimp are abundant (Zwinenberg 1977; Hughes 1972 as cited in Frazier 1980). Kemp’s ridleys have been collected in Louisiana from Lake Borgne, Barataria and Terrebonne Bays, and near Calcasieu Pass (Dundee and Rossman 1989).
Occurrence of these sea turtles in bays and estuaries along the Louisiana coast would not be unexpected, as many of their primary food items occur there. Stomach analyses of specimens collected in shrimp trawls off Louisiana revealed crabs, gastropods, and clams (Dobie et al. 1961). Although Kemp’s ridleys are considered primarily carnivorous benthic feeders (Ernst and Barbour 1972), jellyfish as well as by-catch from shrimp trawlers have been reported as part of their diet (Landry 1986).
During the construction of the Caminada Headland Beach and Dune Restoration Project (BA-45), turtle trawling and relocation was conducted in conjunction with hopper dredging activities in the South Pelto Borrow Area. The relocation trawling effort as a whole represented approximately 111 days of 12 hour trawling with 1,582 tows being completed. This netted 154 relocations of 154 different sea turtles. A total of 83 Kemp’s Ridley Sea Turtles were relocated as a part of the project activities (Coastwise Consulting, 2014). There were no turtle mortalities or injuries associated with relocation trawling on this Project (REMSA 2014).
During the construction of the Caminada Headland Beach and Dune Restoration Increment II Project (BA-143), turtle trawling and relocation was conducted in conjunction with hopper dredging activities in the South Pelto Borrow Area. The relocation trawling effort as a whole represented approximately 68 days of 12 hour trawling with 808 tows being completed. This netted 40 relocations of 40 different sea turtles. A total of 33 Kemp’s Ridley Sea Turtles were relocated as a part of the project activities. There were no turtle mortalities or injuries associated with relocation trawling on this Project (East Coast Observers, 2016). There were zero incidental takes during the hopper dredge operation of the BA-143 Project (REMSA 2016).
The Caminada Headland Beach and Dune Restoration Projects clearly established the presence and high abundance of Kemp’s Ridley Sea Turtles in the South Pelto portion of Ship Shoal.
3.6.3Status and Cause of Decline
On December 2, 1970, the Kemp's ridley sea turtle was designated as endangered across its entire range (35 FR 18319). Critical habitat has been proposed, but has not been finalized to date.
The greatest cause of decline and the continuing primary threat to Kemp's ridleys is incidental capture in fishing gear, primarily in shrimp trawls, but also in gill nets, longlines, traps and pots, and dredges in the GOM and North Atlantic (NOAA Fisheris 2017b).
The Kemp's ridley is the rarest, most endangered, and enigmatic of all sea turtles world-wide (Perrine 2003; Spotila 2004). During the mid-20th century however, tens of thousands of ridleys nested near Rancho Nuevo, suggesting the Kemp's ridley was abundant in the Gulf of Mexico (NOAA Fisheries 2017b). According to NOAA, the population experienced a devastating decline between the late 1940s and the mid-1980s, however due to intensive conservation actions, the Kemp's ridley began to slowly rebound during the 1990s. The number of nests increased about 15% each year through 2009 but since 2010 the number of nests has decreased causing concern that the positive growth in the population seen over the last decades may have stalled or reversed (NOAA Fisheries 2017b). Although this small sea turtle has continued to decline in Louisiana, it is still believed to be the most frequently encountered (Dundee and Rossman 1989), if not the most abundant sea turtle, off the Louisiana coast (Viosca 1961).
Do'stlaringiz bilan baham: |
