Geography 316: Biogeography
In progress
01/19/2005
Geography
316: Biogeography
In progress
01/19/2005
The Biogeography of the Red Abalone (Haliotis
rufescens).
by Adrienne Priselac, student in
Geography 316 Fall 2003
Thank you for visiting
our site. This web pages was written by a student in Geography 316: Biogeography
and edited by the instructor, Barbara Holzman, PhD. All photos and maps
are posted with specific copyright permission for the express use of education
on these web pages. The students have tried to be as accurate as possible with
the information provided and sources and references are cited at the end of each
page.
Species Name: Haliotis rufescens
| Kingdom: Animalia Phylum: Mollusca Class: Gastropoda Subclass: Prosobranchia Order: Archaeogastropoda Superfamily: Pleurotomariacea Family: Haliotidae Genus: Haliotis Species: Haliotis rufescens |
|
| Figure 1: The Red abalone. Source: Haaker et al. 1986. |
Description of Species:
Abalone are marine mollusks, they have a soft body surrounded by a mantle, an anterior head, and a large, muscular foot (see Figure 1). Abalone shells are rounded or oval with a large dome towards one end and a row of respiratory pores. The muscular foot has strong suction power enabling the abalone to cling to rocky surfaces. An epipodium is a sensory structure and extension of the foot that has tentacles, it circles the foot and extends outside the edge of the shell (see Figure 2). The red abalone can reach sizes upwards of a foot but commonly sizes range from 6 to 8 inches. A red abalone can be identified in the field usually by the brick red surface of its shell, although color can be masked at times by encrusted organisms. Red abalones generally have 3 to 4 moderately elevated pores on the surface of its shell. that are moderately elevated. The epipodium, foot and tentacles are all black.
Figure 2. Abalone anatomy
Source: Haaker et al., 1986.
Red abalones have separate sexes and fertilize externally. To reproduce, they release sperm and eggs into the water through their pores and rely on the high egg and sperm densities for successful fertilization, which requires large adult populations in close proximity. Upon successful fertilization the abalone eggs hatch into free-swimming larvae that feed on plankton until their shells begin to form. As their shells form they sink to the bottom and cling to rocky surfaces. Settling rates for all species are believed to be variable. After settling, abalones change their diet and feed on macroalgae. Most California abalones mature at between 3 and 7 years of age and may live for 35 to 54 years (Haaker et al., 1986). Red abalones are one of the longest living species and typically weigh between 1 and 2 kilograms. Fecundity increases exponentially with size, therefore the large size of the red abalone is to its advantage compared to other abalone species. Newly mature females produce a few hundred thousand eggs each year, and older individuals produce 10-15 million eggs annually. Most abalone species spawn between spring and fall, although red abalone can spawn all year long in certain locations (Haaker et al., 1986).
Natural History:
Abalones are members of a large class of mollusks that have one-piece shells. They belong to the family Haliotidae and the genus Haliotis, which means sea ear and refers to the flattened shape of the shell. Abalone are native to California and have lived along the Pacific Coast for millions of years. Abalone, sometimes referred to as marine snails, have over 70 modern species occurring throughout the world. Abalone fossils have been dated back to over 100 million years ago, with the first abalone fossil dating from about 70 million years ago in what now is California (Lindberg 1992). Many believe that the name abalone is derived from the Spanish-American word “aulone”.
Human exploitation of abalone has occurred for centuries and mainly has been for food, tools, and jewelry (Shepherd et al. 1992). Some of the eastern Pacific abalones were abundant enough to support multimillion-dollar fisheries through most of the twentieth century. However, abalone populations in southern California have been less successful and flawed management strategies recently caused a collapse in the population whereby closing the majority of fisheries (Davis et al. 1994). The red abalone are the largest of all abalone species, and this in conjunction with their light meat color makes them the most commercially desirable. Many red abalone populations have been known to recolonize depleted areas rapidly and have been successfully grown in fisheries. Red abalone are the only abalone species that still support fisheries in California. Between 1950 and 1995, red abalone made up about 46% of all abalone catches in California (Davis et al. 1994). Since 1993, only red abalones have been taken commercially, and the State Fish and Game Commission closed all red abalone catching south of San Francisco in May 1997 (SNIC, 2003). After this closure the State Fish and Game Commission instituted a red abalone management plan to help the populations south of San Francisco recover. The red abalone fishery in northern California still has annually successful production and although it is generally stable, continued productivity is threatened by poaching.
The abalones of the Pacific Coast are found on rocky intertidal and subtidal areas and cling to rocks along the shore down to depths of 65 meters. The main source of nutrition for the red abalone is kelp and other algae. Red abalones position themselves in places where they can catch this drifting food, mostly in intertidal zones. In California, most species are separated by depth and latitude (Haaker et al. 1986). The red abalone has the largest range, from tidal pools in Oregon to deep reefs in southern Baja California. Abalone also prefer dark areas which protect them from predators, although as they grow larger and less susceptible to most predators, they venture out into more open and visible spots where food is easily available. Filter feeding fish and some shellfish eat abalone eggs and larvae. Predators of young abalones include crabs, lobsters, other gastropods, octopuses, sea stars, and fishes. The bat ray in southern California and the sea otter in central California are both red abalones predators.
Movement
Red abalones, as well as most other abalone species, are nocturnal feeding and
most of their movement is associated with this activity (Haaker et al. 1986), In
addition to this type of common movement the red abalone also move seasonally
depending algal growth and to avoid predation. During the life cycle of abalone
there is also movement that occurs when the abalone moves from the shallow
juvenile habitat to deeper and darker waters as it matures to an adult (Haaker
et al. 1986, see Figure 3). The amount of movement of any abalone species is therefore a
combination of size, availability of food and shelter, and presence of
predation. Interestingly Ault and DeMartini (1987) observed a trend in red
abalone that was dependent on seasons. They were able to observe distinct
patterns of movement by the red abalone in northern California, which included
them moving from shallow water in spring to deep water in summer, and from deep
water in fall to shallow water in winter. Ault and DeMartini concluded that
these movements were in response to highly seasonal variations in algal growth,
which changed in abundance at varying depths in this area depending on the
season.
Figure 3. Lifecycle of the abalone.
Source: Haaker et al., 1986.
Distribution:
Biological Species Distribution
There are seven different abalone species found in California (Lindberg, 1992):
• red abalone, Haliotis rufescens
• pink abalone, H. corrugata
• green abalone, H. fulgens
• black abalone, H. cracherodii
• white abalone, H. sorenseni
• pinto abalone, H. kamtschatkana
• flat abalone, H. walallenis
The red abalone species is the most common as well as the largest of the seven
native California abalone species. All of the Pacific Coast abalone are found on
rocky intertidal and subtidal areas clinging to rocks along the shore down to
depths of 65 meters. In California, several of the
native abalone species may
be found occupying the same coastal regions, although most are separated by
depth and latitude (Haaker et al. 1986). Abalone tend to prefer boulder and
rock habitats, and are commonly associated with kelp forests. The red abalone
has the largest range, from tidal pools in Oregon to deep reefs in southern Baja
California, Mexico (see Figure 4) (Haaker et al., 1986). Red abalone can be found
to occur along the entire California
coastline, while pink, green, and white abalones are found in the mild warm
waters south of Pt. Conception, Santa Barbara County (Fanshawe et al., 2003).
Black abalone have a more similar coverage to red abalone living from just
north of San Francisco to Baja California, Mexico. Flat and pinto abalones,
which are much less common, generally inhabit the cooler waters generally north
of Point Conception (Tegner and Butler, 1985).
Figure 4. Map of CA Abalone distribution. Source: Cook, Peter, 2003.
Evolution:
Red abalone are part of the large Class Gastropoda. The gastropods, which includes snails and slugs, contain almost 100,000 living species (Lindberg, 1992). There is a rich fossil record for gastropods extending back into the Cambrian [about 510 million years ago(mya)], see the cladogram (Figure 5) below which outlines the evolution of the mollusk classes including the gastropods. This cladogram dates back to the early Paleozoic (over 550 mya), the period that many gastropods are believed to have evolved. Since then the Gastropods have been a stable and constant part of marine benthic ecosystems. Like the cephalopods (octopuses, squids) that also appeared at this time, gastropods radiated very quickly, but unlike the cephalopods, they made it through the Cambrian mass extinction events successfully (Tokyo University, 2003). Although like most other organisms, the gastropods were affected by late Permian (about 260 mya) mass extinction event, and a number of groups died out at this time. However many survived through to the Mesozoic (about 240 mya) (Tokyo University, 2003). By Carboniferous times gastropods were diverse. There were a large number of marine forms and also some lineages had adapted to fresh water. Additionally the first terrestrial forms appeared during this time (Kazlev, 2003).
Abalone are part of the Order Archaeogastropoda. Archaeogastropoda is a large gastropod group with a long and successful history from the late Cambrian to today. There have been over eighty families (extinct and existing) described as archaeogastropods (Knight et al., 1960), with recent species assigned to about forty families. Archaeogastropods have been thought to exhibit many primitive anatomical features within Gastropoda (Knight et al., 1960). These features include symmetry of some internal organs, no presence of a larval shell and importance of the shell structure (Lindberg 1992). Archaeogastropoda, with its primitive features and long and successful past plays an important role in phylogenetic studies when considering the origin and subsequent radiation of gastropod groups (Lindberg, 1992). In addition it is well believed that archaeogastropod evolution has been independent from that of other gastropods since the beginning of the Ordovician and that archaeogastropods were richly diversified in the Triassic (Kazlev, 2003). Some researchers (Hickman, 1988 and Voltzow, 1994) have even argued that the "Archaeogastropoda" is an invalid modern taxon because it is too simplistic and should be discarded (Kazlev, 2003). However there is a lack of scientific evidence for this change and ongoing gastropod phylogeny research is concerned with the evolution, comparative anatomy, zoogeography and reproductive biology of these “Archaeogastropoda” species.
Other interesting issues:
Abalone populations in trouble
Abalone populations have been decreasing for the past 60 years and most markedly over the past 40 years. This population decline lead to the closure of many abalone fisheries in the late 1990's (DFG, 2003). As part of those closures the Fish and Game Commission was required to develop "The Abalone Recovery and Management Plan" (ARMP). The ARMP provides a cohesive framework for the recovery of depleted stocks in southern California, and for the management of the northern California fishery and future fisheries (DFG,2003). All of California’s abalone species are included in this Plan. The California Fish and Game is instituting a recovery and management plan for these species to manage and prevent further population declines throughout California, and to ensure that current and future populations will be sustainable. The decline and, in most cases, closure of California’s abalone fisheries in the late 1990’s is due to a variety of factors, primarily commercial and recreational fishing, disease, and natural predation (DFG, 2003). Commercial and recreational fishing have most dramatically reduced abalone populations. Advances in diving technology during the mid-1900s, including scuba, gave birth to a sport-based fishery in southern California that placed even more pressure on a limited number of fishing areas. In northern California, using scuba gear to take abalone is illegal and there remain limits on the size and numbers of abalone that divers are permitted to take every year (DFG,2003).
The six major reasons for abalone population decline
According to a two-year study in 1974-75 by the California Department of Fish and Game, six major reasons for the decline in the abalone populations along the California Coast were identified (Burd, 1997):
Mendocino County (in northern California) Annual Abalone Festival
Mendocino County holds an annual Abalone festival that includes an abalone cookoff, arts and crafts, and educational booths to help promote abalone management programs. The Abalone Festival is usually held the second weekend in October. The Festival is sponsored by the Medocino County Parks District, the District can be contacted at (707) 937-5397 or check out their website at http://www.mendocinoguide.com/pages/calendar-events.html
Interesting Links:
4th International Abalone Symposium
California Department of Fish & Game Abalone Page
http://www.dfg.ca.gov/Mrd/abindex0.html
California's Abalone Recovery and Management Plan
http://www.dfg.ca.gov/mrd/armp/index.html
Western Australia’s Abalone Conservation Guide
http://www.wa.gov.au/westfish/rec/broc/fishcard/abalone.html
University Of Cape Town, Abalone Network
http://www.uct.ac.za/depts/zoology/abnet/
California Abalone Guide
http://www.abalone.net/guide.htm
University of California at Davis, Seafood Network Information
http://seafood.ucdavis.edu/pubs/abalone.htm
Bibliography
Ault J.S., and DeMartini J.D. 1987. Movement and Dispersion of Red Abalone, Haliotis rufescens, in Northern California. State of California, The Resources Agency, Department of Fish and Game, Marine Resources Division, Long Beach, CA. 73(4):196-213.
Burd, E. 1997. Comparing red abalone populations on the Sonoma County, California coast. Section on Statistics and the Environment poster session Joint Statistical Meetings, Anaheim, California, August 12, 1997. http://www.erikburd.org/projects/abalone/
Cook, P. 2003. CA Abalone Distribution Map. University of Cape Town, South Africa. http://web.uct.ac.za/depts/zoology/abnet/namer.html
Davis, G. E., K. R. Faulkner,
and W. L. Halvorson. 1994. “Ecological monitoring in Channel Islands National
Park, California” in The fourth California islands symposium: update on the
status of resources, W. L. Halvorson, editor. Santa Barbara Museum of
Natural History, Santa Barbara, CA, pp.465-482.
http://www.nature.nps.gov/im/
Department of Fish and Game (DFG). 2003. "Abalone Recovery and Management Plan".
State of California, Resources Agency.
http://www.dfg.ca.gov/mrd/armp/index.html, December 7,2003. Fanshawe, S., G. Vanblaricom and A. Shelly. 2003. “Restored
Top Carnivores as Determints to the Performance of Marine Protected Areas
Intended for Fishery Sustainability: a Case Study with red Abalone and Sea
Otters”. Conservation Biology. v17 n1 pp. 273-283. FishTech, Inc. October13, 2003. http://www.fishtech.com Haaker, P.L., Henderson, K.C.,
and Parker, D.O. 1986. California Abalone, Marine Resources Leaflet
No. 11. State of California, The Resources Agency, Department of Fish and
Game, Marine Resources Division, Long Beach, CA. Hickman, C.S. 1988. “Archaeogastropod evolution, phylogeny
and systematics: a re-evaluation”. Prosobranch Phylogeny, Malacology
Review. Supplement 4. pp. 17-34. Kazlev, M.A. 2003.
“Relationships and Evolutionary History”.
Knight, J. B., Cox, L. R., Keen, A. M., Batten, R. L., Yochelson, E. L., and Robertson, R. 1960. “Systematic descriptions: Archaeogastropoda”. In Moore, R. C. (ed.) Treatise on Invertebrate Paleontology. Part I. Mollusca. Geological Society of America, Colorado.
Lindberg, D. R. 1992. “Evolution, distribution and systematics of Haliotidae” in Abalone of the world. A. Shepherd, M. J. Tegner, and S. A. Guzmán del Próo, editors. Blackwell Scientific Publications, Oxford, England, pp. 318.
Shepherd S.A., M.J. Tegner, and S.A. Guzmán del Próo (eds.).(1992) Abalone of the world - Biology, fishery and culture. Blackwell Scientific Publications, Oxford, England.
Seafood Network Information Center Publications (SNIC). October 13, 2003. Abalone. University of California, Davis. Davis, CA. http://www.seafood.ucdavis.edu/pubs/abalone.htm
Tegner M.J., and Butler R. 1985. The Survival and Mortality of Seeded and Native Red Abalones, Haliotis rufescens, on the Palos Verdes Peninsula. . State of California, The Resources Agency, Department of Fish and Game, Marine Resources Division, Long Beach, CA. 71(3):150-163.
Tokyo University. 2003. “Gastropod Evolution”. Tokyo University Digital Museum. http://www.um.u-tokyo.ac.jp/publish_db/Bulletin/no38/no38004.html
Voltzow, J. 1994. “Gastropoda: Prosobranchia”. In Harrison, F. W. and Kohn, A. J. (eds.) Microscopic Anatomy of Invertebrates. Vol. 5. Mollusca, pp. 111-252. Wiley-Liss, New York.
Yochelson, E.L. 1978. An alternative approach to the interpretation of the phylogeny of ancient mollusks, Malacologica, 17 (2): 165:191.
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