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Full-Text Articles in Physical Sciences and Mathematics
Sperm Competition In Grey Whales, Katherine Ralls, Robert L. Brownell Jr.
Sperm Competition In Grey Whales, Katherine Ralls, Robert L. Brownell Jr.
United States Department of Commerce: Staff Publications
SIR-Your legend for the drawing of grey whales taken from Cyall Watson's book Whales of the World, perpetuates the myth that a 'helper' male is necessary for successful mating in this species. The legend states that: "Only one male is involved in the actual mating; the other takes an upright position on the far side of the female, acting as a prop or wedge". This description of grey whale mating behavior. paraphrased from Watson's book, can he traced to Samaras.
Distribution, Abundance, And Biomass Of Freshwater Mussels (Bivalvia: Unionidae) In Lake St. Clair, Thomas F. Nalepa, Jeffrey M. Gauvin
Distribution, Abundance, And Biomass Of Freshwater Mussels (Bivalvia: Unionidae) In Lake St. Clair, Thomas F. Nalepa, Jeffrey M. Gauvin
United States Department of Commerce: Staff Publications
A mussel population survey was conducted in Lake St. Clair with divers using SCUBA to sample at 29 stations throughout the lake. Mean abundance was 2 m-2 and mean biomass was 4.4 g dry wt m-2. Of the 18 species collected, Lampsilis radiata siliquoidea was by far the most abundant, accounting for 45% of all individuals. The age-frequency distribution of L. r. siliquoidea was dominated by individuals between 9 and 12 years old. In contrast, the second most abundant species, Leptodea fragilis, showed yearly variation in recruitment with no apparent trends in year class strength. Annual …
The Vaquita: Can It Survive?, Robert L. Brownell Jr.
The Vaquita: Can It Survive?, Robert L. Brownell Jr.
United States Department of Commerce: Staff Publications
The vaquita (Spanish for "little cow"), or Gulf of California harbor porpoise (Phocoena sinus), has the most limited range of any marine cetacean and is probably the rarest. It has been caught incidentally in gill nets set commercially for totoaba (Totoaba macdonaldi), large fish that were over-exploited in the upper Gulf of California until they, too, were endangered. In 1975. the Mexican Government announced a total indefinite closure on fishing for totoaba, Between the time this porpoise was described as new to science (1958) and its listing by the U.S. Fish and Wildlife Service as Endangered …