Decline of the Sea Turtles Causes and Prevention (1990) / Chapter Skim
Currently Skimming:
7. Conservation Measures
7. Conservation Measures
Pages 118-143
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From page 118... ...
Strategies to increase reproduction and reduce mortality will be discussed in this section after we describe the general rationale and objectives of recovery plans.
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From page 119... ...
An endangered species is "any species, subspecies, or distinct population of fish, or wildlife, or plant which is in danger of extinction throughout all or a significant portion of its range." A threatened species is "any species, subspecies, or distinct population of fish or wildlife, or plant which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range." The status of discrete breeding populations of listed species must be reviewed every 5 years, and recommendations, if warranted by the biological data, for Relisting or reclassification must be made to the secretaries of the Departments of the Interior and Commerce, who jointly administer jurisdictional responsibilities for sea turtles. The leatherback and hawksbill were listed as endangered throughout their ranges on.June 2, 1970.
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From page 120... ...
to captive breeding and programs of delayed release of young turtles. Increasing Protection of Critical Nesting Habihts Land Use A joint state, federal, and private effort is under way to provide permanent protection for 15 km of the approximately 34 km of high-density sea turtle nesting habitat between Melbourne Beach and Wabasso Beach, on the Atlantic coast of east-central Florida (Possardt and Jackson, 19891.
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From page 121... ...
Most zoning ordinances are at the county level. Beach Nourishment Beach nourishment is less destructive of sea turtle nesting habitat than is beach armoring, but it can cause problems for nesting females and nests if not done properly.
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From page 122... ...
Huff, Florida Department of Natural Resources, 19891. Becch Clecning, Pedestrian and Vehicular Traffic, and Recrec fional Equipment Beach-cleaning equipment, pedestrian traffic, off-road vehicles, and other human activities disturb nesting sea turtles considerably and can destroy eggs and hatchlings.
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From page 123... ...
They also suggested that increase in public awareness of the sea turtle situation and the development of strong international collaborative ties between the United States and Mexico were both worthwhile aspects of this particular headstart experiment. We found no adequate sample of natural hatchling survival against which to judge the success of headstarting.
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From page 124... ...
Of the three "experimental conservation" practices most commonly attempted with sea turtles (headstarting, artificial imprinting, and captive breeding) , only captive breeding has actually been shown to be successful.
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From page 125... ...
Moreover, turtle eggs receive legal protection in many countries, including Mexico, where sea turtle eggs of all kinds first received legal protection in the Tabla General de Vedas (General Schedule of Closed Seasons) , which has been strengthened and extended several times by laws that protect turtles or establish closed seasons for them.
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From page 126... ...
A less extreme approach is to implement time and area closures to reduce the impact of trawling as turtles occupy an area or are especially vulnerable to trawl-related death; this approach has already been used off Rancho Nuevo in Mexico during the nesting season of Kemp's ridleys. "Area" could be defined to include depth zones, as well as more conven The greatest disadvantage of time and area closures is that their broad application on fine time/space scales might require more and better information than is available on the distribution of sea turtles (see Chapter 41.
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From page 127... ...
First, there is a great deal of overlap in the distribution of sea turtles and fishing effort throughout the year. Second, most measures of turtle abundance are not independent of fishing effort; for example, sea turtle strandings are the result of a complex interaction between sea turtle abundance and shrimp trawling (Chapter 61.
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From page 128... ...
In announcing the June 27, 1987, regulation that required use of TEDs by shrimp trawlers in most shrimping grounds during most of the shrimping season in the Southeast, NMFS referred to its own test data on the effectiveness of the NMFS TED in excluding sea turtles in offshore waters around Cape Canaveral and v ~ ~ , l ~ _ _ ~ 1 _ ~ retaining shrimp under commercial shrimp trawling In most sournea~ern states (Federal Register, Vol.
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From page 129... ...
, working on the Texas coast, demonstrated that shrimp catch with a Morrison soft TED was reduced by 16% in the presence of abundant sticks and bottom debris that had been naturally deposited from riverine runoff after a rainstorm (Table 7-11. Controlled tests of the Georgia jumper TED recently completed in inshore waters of Core Sound, North Carolina, under normal inshore conditions of abundant seagrass debris and tunicate clumps, demonstrated shrimp losses of 26% by weight (one-tailed paired t test, n = 15; p = 0.016)
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From page 130... ...
But it is clear that conclusions based on specific TED design used under a particular set of conditions cannot be extrapolated to all TEDs and all conditions. NMFS has tested alternative TEDs off Cape Canaveral, an area with high densities of sea turtles and low concentrations of debris and shrimp.
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From page 131... ...
show that the average rate of mortality of sea turtles captured in trawls is reduced to a negligible point (less than 1%) as tow time is reduced to 60 minutes or less (Figure 6-3~.
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From page 132... ...
Second, we could detect no large difference between the two size classes of sea turtles: a tow-time limit of about 60 minutes produced negligible mortality in each. Third, there is a suggestion of only a small difference between the daytime and nighttime curves: for tow times less than about 60 minutes, turtle mortality is negligible.
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From page 133... ...
. Top: dead turtles; bottom: dead plus comatose turtles.
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From page 134... ...
Specifically, winter tows might need to be restricted to 60 minutes or less, instead of less than 90 minutes, whereas the 40-minute restriction in the summer seems sufficient. Tow-time limitation could be as effective as TEDs in reducing the mortality of sea turtles in shrimp trawls, but might be extremely complex as a management option, because of differences in seasons and locations.
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From page 135... ...
Much more could be learned about the physiological condition of sea turtle populations and the possible interactive effects of multiple stresses, if more professional necropsies are performed on fresh car casses. Other Commercial Fishing Activities Various commercial fishing activities besides shrimp trawling kill sea turtles.
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From page 136... ...
However, the take of sea turtles with the California draghead in the Port Canaveral Entrance Channel since 1980 has been found unacceptable by NMFS (pers. comm., T
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From page 137... ...
· Determination of the frequency and distribution of sea turtles in key navigation channels of Flor~da's coast and elsewhere. Several censuses of sea turtle populations in the Port Canaveral Entrance Channel have been conducted since 1980 (Henwood, 1987)
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From page 138... ...
Oil-Rig Removal Sea turtle species and turtles in different life stages within species often segregate by habitat preference. The deployment of underwater structures (oil-platform tripods, towers, anchors, sediment-control devices, ocean cables, and the like)
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From page 139... ...
Fritts and McGehee (1981) found that sea turtle eggs contaminated with fresh crude oil, as might occur after an oil spill, yielded a lower hatch rate and a higher percentage of deformities.
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From page 140... ...
, sea turtle biology and ecology, and Kemp's ridley headstarting (Oravetz, 19891. NMFS sea turtle program funding since 1977 has averaged $890,400 a year, starting at $250,000 in 1977 and with a high of $1,150,000 in 1982.
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From page 141... ...
and are being used to coordinate industry and Sea Grant efforts in TED testing, development, and technology transfer. The responsibilities of at least 21 NMFS employees include some aspect of TEDs or educating the public about sea turtle conservation.
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From page 142... ...
CONSERVATION EFFORTS IN OTHER JURISDICTIONS Mexico Measures taken by Mexico to conserve sea turtles have involved academics, nongovernmental private groups, and governmental agencies. Since 1966, government turtle biologists, fisheries inspectors, and armed Mexican marines have maintained a presence at Rancho Nuevo to protect nesting Kemp's ridleys, their nests, and eggs.
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From page 143... ...
Throughout most of their ranges, sea turtles continue to be under threats of decline from human activities, and are the continuing subject of intense study, regulation, and international action and concern. This is well demonstrated by recent statements and action at the World Herpetological Congress in Canterbury, England (September 1989)
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