A Low Intensity Sampling Method for Assessing Blue Crab Abundance at Aransas National Wildlife Refuge and Preliminary Results on the Relationship of Blue Crab Abundance to Whooping Crane Winter Mortality

Authors

Bruce H. Pugesek, U. S. Geological Survey, Northern Rocky Mountain Research Center
Michael J. Baldwin, U. S. Geological Survey, National Wetlands Research Center
Thomas V. Stehn, Aransas-Matagorda Island National Wildlife Refuge Complex

Date of this Version

2008

Document Type

Article

Citation

Pugesek, B.H., M.J. Baldwin, and T.V. Stehn. A low intensity sampling method for assessing blue crab abundance at Aransas National Wildlife Refuge and preliminary results on the relationship of blue crab abundance to whooping crane winter mortality. In: Folk, MJ and SA Nesbitt, eds. 2008. Proceedings of the Tenth North American Crane Workshop, Feb. 7-10, 2006, Zacatecas City, Zacatecas, Mexico: North American Crane Working Group. pp. 13-24.

Comments

Reproduced by permission of the North American Crane Working Group.

Abstract

We sampled blue crabs (Callinectes sapidus) in marshes on the Aransas National Wildlife Refuge, Texas from 1997 to 2005 to determine whether whooping crane (Grus americana) mortality was related to the availability of this food source. For four years, 1997 - 2001, we sampled monthly from the fall through the spring. From these data, we developed a reduced sampling effort method that adequately characterized crab abundance and reduced the potential for disturbance to the cranes. Four additional years of data were collected with the reduced sampling effort methods. Yearly variation in crab numbers was high, ranging from a low of 0.1 crabs to a high of 3.4 crabs per 100-m transect section. Mortality among adult cranes was inversely related to crab abundance. We found no relationship between crab abundance and mortality among juvenile cranes, possibly as a result of a smaller population size of juveniles compared to adults.