Dear Colleagues,
On behalf of my co-authors, I am pleased to announce the following publication: Campbell, G.S., Thomas, L., Whitacker, K., Douglas, A.B., Calambokidis, J. and J.A. Hildebrand. 2014. Inter-annual and seasonal trends in cetacean distribution, density and abundance off southern California. Deep Sea Research II: Topical Studies in Oceanography. http://dx.doi.org/10.1016/j.dsr2.2014.10.008. ABSTRACT Trends in cetacean density and distribution off southern California were assessed through visual line-transect surveys during thirty-seven California Cooperative Oceanic Fisheries Investigations (CalCOFI) cruises from July 2004-November 2013. From sightings of the six most commonly encountered cetacean species, seasonal, annual and overall density estimates were calculated. Blue whales (*Balaenoptera musculus*), fin whales (*Balaenoptera physalus*) and humpback whales (*Megaptera novaeangliae*) were the most frequently sighted baleen whales with overall densities of 0.91/1000 km2 (CV=0.27), 2.73/1000 km2 (CV=0.19), and 1.17/1000 km2 (CV=0.21) respectively. Species specific density estimates, stratified by cruise, were analyzed using a Generalized Additive Model to estimate long-term trends and correct for seasonal imbalances. Variances were estimated using a non-parametric bootstrap with one day of effort as the sampling unit. Blue whales were primarily observed during summer and fall while fin and humpback whales were observed year-round with peaks in density during summer and spring respectively. Short-beaked common dolphins (*Delphinus delphis*), Pacific white-sided dolphins (*Lagenorhynchus obliquidens*) and Dall’s porpoise (*Phocoenoides dalli*) were the most frequently encountered small cetaceans with overall densities of 705.83/1000 km2 (CV=0.22), 51.98/1000 km2 (CV=0.27), and 21.37/1000 km2 (CV=0.19) respectively. Seasonally, short-beaked common dolphins were most abundant in winter whereas Pacific white-sided dolphins and Dall’s porpoise were most abundant during spring. There were no significant long-term changes in blue whale, fin whale, humpback whale, short-beaked common dolphin or Dall’s porpoise densities while Pacific white-sided dolphins exhibited a significant decrease in density across the ten-year study. The results from this study were fundamentally consistent with earlier studies, but provide greater temporal and seasonal resolution. The full-text open access .pdf of the paper can be downloaded at http://www.sciencedirect.com/science/article/pii/S0967064514002690 or contact me via email at [email protected] for a copy. Cheers, Greg Campbell -- Greg Campbell Marine Mammal Behavioral Ecology Group Department of Marine Biology Texas A&M University Galveston [email protected] http://www.tamug.edu/mmbeg/
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