White abalone
The white abalone, scientific name Haliotis sorenseni, is a species of large sea snail, a marine gastropod mollusk in the family Haliotidae, the abalones.
The white abalone is an endangered species in the United States; it may now have the smallest population of all eight of the abalone species on the west coast of North America.
Historically the white abalone ranged from Point Conception, California to Baja California, Mexico, and was found especially on the offshore islands.
In the most northerly part of the California range, white abalone were reported as being more common along the mainland coast. However, in the middle portion of the California range, they were noted to occur more frequently at the offshore islands, especially San Clemente and Santa Catalina Islands. At the more southerly end of the range, in Baja California, Mexico, white abalone were reported to occur more commonly along the mainland coast, but were also found at a number of islands including Isla Cedros and Isla Natividad.
It remains unknown whether this distribution pattern was a result of lack of suitable habitat along the mainland coast in the mid portion of the range, or was instead due to overfishing in these more accessible mainland regions.
Since the mid-1990s, extremely low numbers of isolated survivors have been identified along the mainland coast in Santa Barbara County and at some of the offshore islands and banks in the middle portion of the range, indicating the current range of white abalone in California may be similar to what it was historically.
No recent information on current range is available for Baja California. The white abalone population in Mexico is thought to be depleted based on commercial fishery data, but the status of the species in Mexico remains largely unknown.
The white abalone is the deepest dwelling of eight species of California abalones, living at depths from 80 to 200 ft (24–61 m).White abalone are found in open low and high relief rock or boulder habitat that is interspersed with sand channels. Sand channels may be important for the movement and concentration of drift macroalgae, and a variety of red algae, upon which white abalone are known to feed.
The white abalone is known to be a herbivore, grazing mainly on macroalgae, such as Laminaria farlowii and Agarum fimbriatum, and also several species of red algae. Other species it eats include Chondracanthus exasperatus, Laminaria farlowii, Macrocystis pyrifera , and Palmaria mollis.
Like many gastropods, white abalone have a complex life cycle involving larval stages. Fertilized eggs hatch into larvae; these larvae eventually metamorphose into the adult form and settle from the plankton to a hard substrate.As broadcast spawning gastropods, white abalone reproduce by releasing their eggs and sperm into the surrounding water. If fertilized, the eggs hatch after only one day, but high concentrations of sperm are required in order for an egg to be fertilized. Therefore, aggregations of adult male and female abalone are necessary for successful fertilization to occur.
