Morone saxatilis
Rock
(Also: Rockfish; Striped bass; Striped sea bass; Striped sea-bass; Striper bass)

Striped bass can be found on the Atlantic coast of the United States, from northern Florida to the St. Lawrence estuary in southeastern Canada. This species has been introduced to many inland lakes and reservoirs in the Midwest, as well as, the Pacific coast of the United States. (Harrell, 1997; Ross and Brenneman, 2001; Shepherd, 2000)

Striped bass thrive in large bodies of deep, clear water. Ideal temperatures range from 18.3 to 21.1 °C, and evidence suggests a lower temperature limit of 9.0 °C. Mature fish can be found living inshore, in estuaries, and in freshwater habitats, depending on season and location, and most individuals are found more within five miles from the coast. Juvenile fish are normally found in rivers, which provide critical habitat for spawning. (Argentieri, 2002; Nelson, et al., 2010)

Striped bass have a laterally compressed body, large terminal mouth, separate dorsal fins and six to nine continuous lateral stripes on both sides of its body. The third anal spine is longer and thinner than the second anal spine. Adult striped bass typically weigh 3.6 to 6.8 kg, however, bass exceeding 22 kg are recorded on an annual basis. Adults range in length from 46 to 140 cm. Striped bass tend to be light green, olive, steel blue, black or brown on their dorsum, with a white or silver iridescent venter. Individuals greater than 25 years of age have been recorded, and sexual maturity is attained between the ages of 2 and 4 for males, and between the ages of 5 and 8 for females. (Argentieri, 2002; Schultz, 2004; Shepherd, 2006)

Striped bass eggs hatch 29 to 80 hours after fertilization. Newly hatched larvae remain suspended in the water column and tend to suffocate if they spend and extended period of time in oxygen poor water. Larvae measure about 3.1 mm long. As larvae, nourishment comes from the large yolk mass the females released with her eggs, and after two to four days their mouth forms. Once larvae begin feeding, primary prey consists of microscopic organisms that occupy the same area of water column. Juveniles are highly sensitive to their environment and can be greatly affected by changes in temperature or salinity. About 1 week after hatching, juveniles begin feeding on small crustaceans, such as copepods. Once they reach about 2 inches in length, juveniles begin feeding primarily on mysid shrimp and amphipods. During their first year of life, striped bass reach anywhere from 10 to 12 inches in length. Males reach sexual maturity by 3 years of age, and females reach sexual maturity within 4 to 6 years of age. Striped bass can live for up to 20 years in the wild. (Sanders, 2010)

Morone saxatilis is polyandrous. A group of 7 to 8 males surround a single larger female, and once surrounded, males bump the female to the waters surface. This act is often referred to as “rock fights,” due to the splashing that occurs on the surface of the water. Once at the surface, males continue bumping the female until she releases her eggs into the water. Once the eggs are discharged into the water, males release their sperm. (Sanders, 2010)

Striped bass begin spawning when temperatures warm to about 18 degrees C. They tend to spawn in rivers and in brackish estuaries. Major spawning locations include the Hudson River, the Chesapeake Bay and the Roanoke River-Albermarle Sound watershed. Once fertilized, embryos drift in the current for 1.5 to 3 days. Female can release between 500,000 and 3 million eggs during a single spawning event; however, less than one percent of embryos survive for more than a couple of months after hatching. Male striped bass typically reach sexual maturity at 2 to 3 years of age, and females reach sexual maturity at 5 to 6 years of age. (Diodati, 2007; Sanders, 2010)

Striped bass are broadcast spawners and embryos developed while suspended in the water column. As a result, parental care is nonexistent in this species. (Sanders, 2010)

Most striped bass live between 10 and 12 years; however, individuals older than 30 years have been recorded in the wild. (Sanders, 2010; Schultz, 2004)

For the first 2 years of life, striped bass move in small groups and tends not to migrate. Once large enough, they congregate in larger schools and begin following annual migrations patterns. Striped bass an perform upriver spawning migration, which lasts from late winter to early spring, and coastal migration, which is not associated with spawning. Although this species is generally social, females exceeding 30 pounds have been found as solitary individuals. (Diodati, 2007; Sanders, 2010)

There is no information available regarding the average home range size of striped bass. (Shepherd, 2006)

Sensory perception in striped bass occurs via the lateral line, a keen sense of smell and marginal vision. The lateral line gives them the ability to detect sound waves, as well as information related velocity and pressure. It also allows them to sense vibrations which is useful in predation and predator avoidance. Striped bass possess an acute sense of smell, which helps guide them to natal spawning grounds as well as detect potential prey. While striped bass have marginal vision, the number of rods and cones in their retinas allow for vision similar to that in humans. Rods allow them to see in low light conditions whereas cones make color vision possible. Vision is primarily used during close encounters with prey. (Bell, 2005; NEKF, 2007)

The dietary habits of striped bass change throughout their life. As larvae, striped bass feed on zooplankton, and as juveniles they mostly feed on insect larvae, small crustaceans, mayflies, and larval fish. Adult striped bass are piscivorous, feeding on bay anchovy, Atlantic silversides and yellow perch; however, a vast majority of their diet consists of Atlantic menhaden. Striped bass do most of their feeding at night in benthic habitats, but chase prey to the water's surface when necessary, typically during fall when trying to build winter fat reserves. (Argentieri, 2002; BUCKEL, et al., 2005; Burnley, 2006)

With the exception of humans, seals, and sharks, adult striped bass have few natural predators. Juveniles, however, are preyed upon by many larger fish, such as Atlantic tomcod, Atlantic cod, bluefish, silver hake, and larger striped bass have been known consume juveniles as well. ("Atlantic Striped Bass", 2010; Banck, 2009)

Striped bass are important predators on Atlantic menhaden and help maintain prey populations at sustainable levels. Major parasites of striped bass include copepods (e.g., Ergasilus labracid), tapeworms, cestode worms (e.g., Proteocephalid larvae), protists (e.g., Colponema, Trichodina, and Glossatella), myxozoans (e.g., Myxosoma morone), roundworms (e.g., Philometra rubra), and spiny-headed worms (e.g., Pomphorhynchus rocci larvae). For a complete account of parasites specific to this species, please reference Paperna and Zwerner (1976). ("Atlantic Striped Bass", 2010; Paperna and Zwerner, 1976; Paperna and Zwerner, 1982)

Striped bass are one of the most highly sought after sport fish along the Atlantic coast of the United States. Many fishermen take note of the migratory patterns of these fish and use this knowledge to catch them during different parts of the year, especially spring, when the fish are on their way to their natal spawning grounds. In addition to recreational fishing, a major commercial fishery for striped bass exists off the coast of Virginia and Maryland, which has accounted for nearly 56% of total catch since the year 2000. In 1974, commercial landings totaled 6,000 megatons. Due to severe population declines, these numbers have decreased dramatically, and in 2004, commercial landings totaled 3,290 mega tons. (Shepherd, 2006)

Striped bass introduced into the California Delta prey upon salmon and delta smelt and are now considered an invasive species. Salmon and delta smelt are important prey for a number of piscivorous fish species, which have experienced significant declines since the introduction of striped bass. ("Federal Judge To Approve Settlement In Striped Bass Predation Case", 2011; Shepherd, 2006)

Although this species has not been evaluated by the International Union for Conservation of Nature (IUCN), landing totals over the last 20 years have exhibited significant decreases in abundance. One of the primary conservation efforts for this species is the Interstate Fishery Management Plan for Atlantic Striped Bass, developed by the Atlantic States Marine Fisheries Commission under the authority of the Striped Bass Conservation Act. Under the conservation and management directives of this plan, striped bass populations have made the biggest comeback of any finfish species on record, with estimates as high as 1 to 1.5 million in the Connecticut River every spring. Despite their rebound, striped bass face a number of challenges. For example, mycobacteriosis, a bacterial infection that results in skin lesions, stunted growth, inflammation, tissue destruction, and formation of scare tissue in organs, poses a significant threat to the overall health of this species. Unfortunately, little is known of this disease, and research is currently underway to investigate this pathogen and its impact on the species as a whole. ("Atlantic Striped Bass", 2010)