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27 <br />State of Texas for joint management of the entire island (60.8 km long by 1.2 to 7.2 km in <br />width) is awaiting signature. <br />Construction of the GIWW in the early 1940's, through the heart of the marshes on Aransas <br />NWR, and subsequent erosion by wind and boat wakes, resulted in 11 percent loss of <br />wintering habitat (Sherrod and Medina 1992). Boats and barges plying the GIWW create <br />wakes and surges which continuously erode the marsh back from the channel (U.S. Army <br />Corps of Engineers [Corps] 1988). Between 1959 -1992, volunteers placed over 57,000 <br />sacks of cement to protect 2,652 m. of shoreline. In 1992, the Corps placed 610 m of <br />interlocking cement mats to stop erosion. Stehn (pers. comm 1993) reported erosion <br />occurring along 8.5 miles of critical habitat shoreline. The Corps agreed in 1993 to armor <br />approximately 3 miles of the most critically eroding shoreline in 1993 and 1994. Thereafter, <br />the Corps will continue to armor 2,000 feet annually until all areas are adequately protected <br />by the means identified in the Corps' Section 216 Study which is to provide a permanent <br />solution to the habitat erosion problem. <br />Deposition of dredged material from periodic maintenance dredging of the channel has <br />destroyed additional marsh and, unintentionally, created some new marsh. Dredged material <br />disposal sites along the GIWW which would cause little or no damage to whooping crane <br />habitat have all been utilized and the problem of future disposal of spoil is critical. <br />The Corps is now evaluating beneficial uses of dredge spoil to create new whooping crane <br />coastal marsh habitat similar to that created by Mitchell Energy and Development <br />Corporation in Mesquite Bay. In the summer of 1991 Mitchell Energy created a dike around <br />4 ha of open shallow bay and filled the area with dredge spoil. The area was then planted <br />with vegetation and the first whooping crane use was documented in January 1992. <br />Captive Propagation <br />Research and Propagation at PWRC: Before research was carried out at PWRC, successful <br />attempts to propagate whooping cranes involved only four birds - -two females (Josephine <br />and Rosie) and two males (Crip and Pete) (McNulty 1966, Doughty 1989). Josephine was <br />the last survivor of the nonmigratory, southwestern Louisiana population. Crip, Pete, and <br />Rosie, flightless due to injuries, were from the migratory population (McNulty 1966, Maroldo <br />1980)., <br />Erickson (1961) analyzed the Aransas winter population counts from 1938 -1960, and <br />prepared an administrative report entitled "Production and Survival Of The Whooping <br />Crane ". This analysis revealed three important characteristics of the wild population that <br />were later confirmed by Novakowski (1966): (1) principal production was apparently <br />derived from a fairly stable cohort of long -lived adults, (2) among birds returning to Canada, <br />mortality was highest in the subadult cohort, and (3) because subadult mortality was <br />apparently limiting recruitment into the breeding population, the population would remain <br />insecure until this mortality was reduced. Based on these findings, Erickson proposed to <br />bolster the wild population through captive propagation and the release of captive- produced <br />stock. However, he cautioned that before stock was obtained from the wild, safe and <br />effective procedures should be developed using sandhill cranes as research surrogates. <br />