Geography 316:  Biogeography     In progress  05/22/2005

The Biogeography of the Striped Bass.
 

by Kin Lee student in Geography 316  Spring 2005

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: Morone saxatilis 

Kingdom: Animailia Phylum: Craniata Class: Actinopterygii Order: Perciformes Family: Percichthyidae Genus: Morone Species: Morone saxatilis
	Photo By Author 2005

  Description of Species:

             One of the most easily identifiable traits of the striped bass is by its six to nine black stripes on its side found on adults.  Its mouth does not extend past its eye (see Fig. 1).  It has two dorsal fins, the largest being the first, has nine spines, typical of all members of the genus Morone of the fish family (Page 2001).  Adults also typically have a white edge on their anal fin and a white, silvery color on their sides while being dark olive to gray blue on top and completely white on their bellies. The body is elongated and slightly compressed (football shaped), the deepest part is found between the two dorsal fins.  The head is narrow and cone shaped with a large mouth that does not extend past its eye (California Department of Fish and Game 2001). They are anadramous fish the tend to spend most of their time in salt water.  However, some of them do stay in fresh water and estuaries for long periods of time (Jones 2004).

Figure 1: Note the mouth of the fish when closed does not go past the eye. Photo by Author 2005

General Information

            Native to the east coast of North America, their range never goes south the state of South Carolina but extends past the northern border of the state of Maine slightly into Canada.  However, in 1879, they were introduced into the San Francisco Bay to start a new fishing industry.  Their recorded range extends from northern Baja California to Barkley Sound, British Columbia.  However, they are mostly concentrated around the San Francisco Bay and the Sacramento, San Joaquin Delta (Page 1991).  Their diet consists of multiple fish and crustaceans ranging from anchovies to shrimp.  They can reach the size of 79 inches and even rumored to grow larger as told by the commercial fishing industry.  During their peek periods in numbers, the fish rely heavily on the large supply of food (mainly baitfish) that follows the nutrients of provided by the Gulf Stream (Cragin 2005).  During these months, the fish enter freshwater rivers and streams to spawn.  After the spawning season ends and the ocean temperatures begin to cool, the fish migrate back south to warmer waters.  However, it must be noted that not all fish migrate south in warmer water, but in fact, stay in local bays and estuaries (Cragin 2005).

            Known for their ability to withstand stressors, they have been introduced across the continental United States as well as other countries in lakes and reservoirs by commercial and private fishing interests.  The first ones to be introduced into the San Francisco Bay Estuary were in 1879.  Since then, their population has increased dramatically peaking in early 1970s at an estimated 1.7 million to the last official estimate by the California Department of Fish and game was roughly 650,000 adult fish in 1992.  Their range is mainly concentrated along  the central coast of California (most of which is made up of the San Francisco Bay Delta region but as stated previously, are found all along the western seaboard from the Southwestern coast of Canada to Northern Baja California.

            The recent drop of numbers are related to the more recent actions of the state’s water department to supply “drier” parts of the state with fresh water needed for the correct salinity levels to spawn.  Also, with the movement of large amounts of water, key spawning areas have been lost due to increased sedimentation and less and increase of average temperature of the water (US Fish and Wildlife Service 2004).  However, the decline of the striper population on the east coast has been connected with heavy over fishing as well as large amounts of pollutants in their spawning grounds.

            Males become sexually mature at about the age of two compared to age five for females.  However, the amount of eggs produced by the female goes up exponentially to its age.  The largest proven breeders can produce more than ten million eggs whereas the youngest produce a mere 25 thousand.  It is believed that they are only able to breed in fresh water. (Jones 2004)

 

 Figure 2:
This map shows in light blue where Striped Bass are most commonly found.  Their prime spawning grounds are seen in the areas to the right of the red border where they are still found. *Map courtesy of California Department of Fish and Game, edited by author. http://www.delta.dfg.ca.gov/baydelta/sturdis.gif

           During the spawning season, the correct conditions must be present. In the spawning months, the correct conditions must be present, this includes a temperature range of 61-69 degrees Fahrenheit from mid April to mid-June .  The most critical areas for spawning in California are the San Joaquin River (where an estimated 1/3 of the population spawns) and the Sacramento River (where the other 2/3 spawns) (see figure 2 above).  After spawning, the eggs become free floating and after hatching, develop rapidly while feeding on the abundance of micro-organisms and invertebrates in these areas.

            During their peek periods, many fisherman seek to capture these fish.  They offer good table fair because they are very meaty as well as have a very mild taste.  Their flesh is flakey white when cooked and often times, fisherman like to bake the fish.  However, due to poor mining practices as well as industrial practices from the past inhabitants of the shoreline, many of these fish have some degree of contamination in their flesh so they should be consumed in moderation.  Currently, they have a minimum size requirement of at least 18 inches in order to be legally taken as catch and only two may be possessed at any time.  Any fish below this size limit must be released regardless of its condition.

            However, as more and more fisherman are beginning to pay attention to their catch, they notice that the stripes of these fish are not always in perfect condition and at times, they almost have no identifiable continuous stripes.  Some people believe that those fish with non continuous lateral lines are not as good as those with straight continuous ones.  Not many people understand why this occurs.  Some say that it is due to their environment while others say that this is due to just genetic differences.  However, fish with continuous stripes are more often larger fish that can be found in the oceans and those with broken stripes are found more within estuaries and fresh water confinements.  Also, the larger ones can be found more readily in freshwater confinements because of the more abundance of food such as state planted trout.  More interesting information can be found at http://stripers247.com.     

Figure 3: This fish succumbed to the hook of an angler at the jetty located at the end of First Street in the town of Benicia, California.  This specimen is a good example of the typical amount of lateral lines on the side of the fish. Photo by Author 2004

 Evolution:

            The gradual evolution of Morone saxatilis dates back to about 480 million years ago where the first life forms developed a skull like structure that enclosed the important parts of the central nervous system such as the brain, inner ear, olfactory system and eyes.  This structure was found on primitive jawless fishes and is classified under the phylum Craniata (Kraft 2003).  From here, they began to further the evolution of their skeletal structure and jaw structure and other important organs such as the swim bladder and lateral line eventually to the point where the evolution of the Osteichthyes (Vertebrate 2004).  From here in the Devonian times (roughly 415-350 million years) branched out the ancestors of all modern fish belonging to the class Actinopterygii (ray finned fish) (Vertebrate 2004).  Some of the fish in this class are more primitive such as the paddlefish to the more complex flounder and sailfish.

The closest relatives of Morone saxatilis are White bass (Morone chrysops) and White Perch (Morone americana), both of which also belong to the family Percichthyidae (Kraft 2003).  Morone saxatilis are sometimes interbred with Morone chrysops (with human help) for both recreation as well as a food supply (Leffler 2005).  This hybrid is very popular among the fisherman of the central United States and dubbed them with the time “Wipers” after a combination of Striped Bass and White Bass.  However, this hybrid is unable to reproduce therefore, their continuous existence is only made possible by artificial means.

Bibliography
Cragin, Mike. (2005, April 7).  Angling Lore, by Striper Mike. [Online] Available:
http://www.stripermike.com/ [April 10, 2005].

Department of Fish and Game.  2001 March 21.  [Online]. Available:
http://www.dfg.ca.gov/mrd/mspcont9.html#top [March 1, 2005]

Hammerson, G., and L. Master. (2003 March 23). NatureServe Explorer.
[Online]. Available: http://www.natureserve.org/explorer/servlet/NatureServe?searchName=Morone%20saxatilis [March 1, 2005]

 Janvier, Philippe. (2005, April 13). Craniata. [Online]. Available:
http://tolweb.org/tree?group=Craniata. [April 13 2005]

Jones, Ken. Pier Fishing in California 2^nd Edition. Roseville, California.  Publishers Design Group
2004

Kraft, Clifford E.. (2003 January 1) Temperate Bass Family Percichthyidae. [Online].
Available: http://fish.dnr.cornell.edu/nyfish/Moronidae/Percichthyidae.html [April 24
2005]

Leffler, Merrill. (2005, April 13). Maryland Marine Notes: Online. [Online]. Available:
http://www.mdsg.umd.edu/MarineNotes/Sep-Oct98/ [April 13 2005]

 Vertebrate Evolution. (2004, March 22) [Online]. Available:    
http://www.anselm.edu/homepage/jpitocch/genbios/vertevol.html [April 17, 2005]

Page, Lawrence M. and Brooks M. Burr. Peterson Field Guides: Freshwater Fishes
Boston, Massachusetts.  Houghton Mifflin Company 1991.

US Fish and Wildlife Service. 2004, August 2. [Online]. Available:
http://www.fws.gov/r5crc/Fish/zh_mosa.html [April 4, 2005].

  send comments to bholzman@sfsu.edu
 

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