Physical Sciences and Mathematics Commons^™

Design And Field Methods For Sighting Surveys Of Cetaceans In Coastal And Riverine Habitats, Steve Dawson, Paul Wade, Elisabeth Slooten, Jay Barlow

United States Department of Commerce: Staff Publications

1. Dolphins and porpoises in coastal and/or riverine habitats face serious conservation threats, yet surveys of their abundance are often especially difficult due to the challenges imposed by the habitats. Because many of these species occur in developing countries, lack of resources imposes a further set of challenges.

2. We offer advice on designing and conducting line-transect surveys with a focus on sound, practical, design rather than analytical sophistication, and we attempt, where possible, to offer simple, inexpensive solutions.

3. We guide the reader through the questions of what kind of survey should be done, whether by boat or aircraft, …

Lessons From Monitoring Trends In Abundance Of Marine Mammals, Barbara L. Taylor, Melissa Martinez, Tim Gerrodette, Jay Barlow, Yvana N. Hrovat

United States Department of Commerce: Staff Publications

We assessed scientists’ ability to detect declines of marine mammal stocks based on recent levels of survey effort, when the actual decline is precipitous. We defined a precipitous decline as a 50% decrease in abundance in 15 yr, at which point a stock could be legally classified as “depleted” under the U.S. Marine Mammal Protection Act.We assessed stocks for three categories of cetaceans: large whales (n = 23, most of which are listed as endangered), beaked whales (n = 11, potentially vulnerable to anthropogenic noise), and small whales/dolphins/porpoises (n = 69, bycatch in fisheries and important abundant …

First Estimates Of Vaquita Abundance, Jay Barlow, Tim Gerrodette, Greg Silber

United States Department of Commerce: Staff Publications

The abundance of the only population of vaquitas, Gulf of California harbor porpoise (Phocoena sinus), is estimated from four surveys conducted in Mexico between 1986 and 1993, using a variety of methods. A line-transect approach was applied, using some parameters estimated from a related species, the harbor porpoise (Phocoena phocoena). Vaquita abundance is estimated as 503 (CV = 0.63) from 1986-1988 boat surveys, 885 (CV = 0.50) from 1988-- 1989 aerial surveys, 572 (CV = 1.43) from a 1991 aerial survey, and 224 (CV = 0.39) from a 1993 ship survey. A weighted log-linear regression in …

Changes In The Freshwater Mussel Community Of Lake St. Clair: From Unionidae To Dreissena Polymorpha In Eight Years, Thomas F. Nalepa, David J. Hartson, Gerald W. Gostenik, David L. Fanslow, Gregory A. Lang

United States Department of Commerce: Staff Publications

To determine density changes in both the zebra mussel, Dreissena polymorpha, and native mussels, Unionidae, in Lake St. Clair, surveys were conducted in 1990, 1992, and 1994 and compared to a similar survey in 1986 when no D. polymorpha was found. Collection methods were the same each year; divers used the quadrat method to collect 10 replicate samples at 29 sites located throughout the lake. The total number of unionids collected declined from 281 in 1986, to 248 in 1990, 99 in 1992, and 6 in 1994, while the number of species collected in each of the four respective …