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,,-t;____ 27 State of Texas for joint management of the entire island (60.8 km long by 1.2 to 7.2 km in width) is awaiting signature. Construction of the GIWW in the early 1940's, through the heart of the marshes on Aransas NWR, and subsequent erosion by wind and boat wakes, resulted in 11 percent loss of wintering habitat (Sherrod and Medina 1992). Boats and barges plying the GIWW create wakes and surges which continuously erode the marsh back from the channel (U,S. Army Corps of Engineers [Corps) 1988). Between 1959-1992, volunteers placed over 57,000 sacks of cement to protect 2,652 m. of shoreline. In 1992, the Corps placed 610 m of interlocking cement mats to stop erosion. Stehn (pers. comm 1993) reported erosion occurring along 8.5 miles of critical habitat shoreline. The Corps agreed in 1993 to armor approximately 3 miles of the most critically eroding shoreline in 1993 and 1994. Thereafter, the Corps will continue to armor 2,000 feet annually until all areas are adequately protected by the means identified in the Corps' Section 216 Study which is to provide a permanent solution to the habitat erosion problem. Deposition of dredged material from periodic maintenance dredging of the channel has destroyed additional marsh and, unintentionally, created some new marsh. Dredged material disposal sites along the GIWW which would cause little or no damage to whooping crane habitat have all bel3n utilized and the problem of future disposal of spoil is critical. The Corps is now evaluating beneficial uses of dredge spoil to create new whooping crane coastal marsh habitat similar to that created by Mitchell Energy and Development Corporation in Mesquite Bay, In the summer of 1991 Mitchell Energy created a dike around 4 ha of open shallow bay and filled the area with dredge spoil. The area was then planted with vegetation arid the first whooping crane use was documented in January 1992. I. Captive Propagation Research and Prollaaation at PWRC: Before research was carried out at PWRC, successful attempts to propagate whooping cranes involved only four birds--two females (Josephine and Rosie) and two males (Crip and Petel (McNulty 1966, Doughty 1989). Josephine was the last survivor of the nonmigratory, southwestern Louisiana population. Crip, Pete, and Rosie, flightless due to injuries, were from the migratory population (McNulty 1966, Maroldo 1980). Erickson (1961) aoalyzed the Aransas winter population counts from 1938-1960,and prepared an administrative report entitled "Production and Survival Of The Whooping Crane". This analysis revealed three important characteristics of the wild population that were later confirmed by Novakowski (1966): (1) principal production was apparently derived from a fairly stable cohort of long-lived adults, (2) among birds returning to Canada, mortality was highest in the subadult cohort, and (3) because subadult mortality was apparently limiting recruitment into the breeding population, the population would remain insecure until this mortality was reduced. Based on these findings, Erickson proposed to bolster the wild population through captive propagation and the release of captive-produced stock, However, he cautioned that before stock was obtained from the wild, safe and effective procedures should be developed using sandhill cranes as research surrogates.