What are striped bass?

Striped bass. Striper.  Rockfish.  Each of these common names describes the same popular fish, Morone saxatilis. Native all along the Atlantic coast from Florida to Nova Scotia, striped bass can grow longer than five feet and can weigh as much as 125 pounds. Known to put up a good fight, they are popular among sportfishermen. Striped bass are also harvested commercially, typically with gill nets and pound nets. They can live up to thirty years but most are caught by fishermen when they are less than eight years old.

How do striped bass grow?

Striped bass are anadromous, meaning they live in the coastal ocean but return to fresh water to spawn, or release eggs. Striped bass have been known to migrate as far north as Canada, then return to the estuary, or body of water where fresh water meets salt water, in which they were spawned.

Throughout their range, striped bass spawn when water temperatures begin to rise in the spring. Peak spawning occurs when water temperatures reach 55-68 °F (13-20 °C). As the eggs hatch, they release larvae, which eventually grow into juveniles, then adult striped bass.

The Chesapeake Bay is an important estuary where a large portion of Atlantic coast striped bass are born and many stages of a striped bass' life take place.

Egg

Striped bass eggs hatch about 29-80 hours after they are fertilized, depending on water temperature. Older and larger striped bass tend to produce more eggs than younger and smaller striped bass. In addition, striped bass females which weigh 10 pounds or more produce eggs that are larger, have greater amounts of yolk, and have a greater chance of hatching than eggs produced by smaller females.

---

Yolk-sac Larvae

When they hatch, striped bass larvae are 2.0-3.7 mm long and have a large yolk-sac that provides them with nourishment. They don't have a mouth, bones, scales, or pigment in their eyes. As they absorb their yolk-sac, they develop eye pigment, a mouth and a gut, and immediately must begin feeding. If they don't eat, they won't have energy to grow.

---

Feeding Larvae

Striped bass larvae begin feeding on zooplankton (tiny floating animals) about five days after hatching at a size of 5 mm. If they find enough food to eat, they start to grow soft fins and bones, longer guts, stronger muscles and better eyes. If water temperatures are warm and they have plenty of food, they grow faster than if water temperatures are cooler. If temperatures are too hot (> 23°C or 73.4°F) or too cold (< 11°C or 51.8°F), they will die.

---

Juvenile

Striped bass larvae begin metamorphosis to the juvenile stage when they are about 20 mm in length. Juveniles look like tiny adults, with fully developed eyes, hard bones, spines in their fins, scales and stripes. As juveniles grow, they leave the nursery area and move progressively downriver towards saltier water, feeding on larger prey like mysids (shrimp-like creatures) and worms. Shallow, nearshore areas are the preferred habitat of juvenile striped bass. The growth of striped bass depends on how much food they can find as well as properties of the water like salinity (amount of salt), temperature, and dissolved oxygen.

---

Adult

Adult striped bass migrate out of the estuary and into the coastal ocean. When spring arrives, the fish will migrate back into estuaries to spawn. Each year until they are three years old, striped bass grow about 120 mm (the size of a hot dog). In their first few years, striped bass swim in schools while pursuing food: small fish such as spot and menhaden. As the fish age, they become more independent hunters. Female striped bass live longer and grow larger than males. Most fish age eleven and older are females. Large striped bass, which may weigh as much as 125 pounds and be up to 59 inches long, are almost exclusively females.

---

• Try It - Life Cycle

What affects striped bass survival?

Like many aquatic organisms, striped bass produce millions of eggs. The eggs hatch into tiny larvae, but only a few out of the many produced survive to become adults.

Survival of larvae and young depends on several biotic and abiotic factors in their surrounding environment. They need plenty of food for nutrition, a good hiding place to avoid predators, salinity less than 10, and water temperature between 18-21°C (64-70°F).

One place where these conditions are met is an estuary, specifically the region where fresh water meets salt water. Here, currents cause particles including sediment and detritus to remain suspended in the water. Scientists have named this region the Estuarine Turbidity Maximum (ETM) because turbidity (cloudiness of the water) is very high. This dark murky water provides refuge from predators, who hunt the larvae by sight.

• More Info - Secchi Disk

• More Info - Nursery Area Physics

Activity: Water Clarity

Currents in the ETM not only trap sediment and detritus, but also tiny organisms like zooplankton, striped bass eggs, and larvae.

Copepods (pronounced cope-uh-pod), a type of zooplankton, are found here in world-record numbers and are a great food source for striped bass larvae. Cladocerans (pronounced clah-doss-ur-ans) are another type of zooplankton and important prey item.

Activity: Larvae Feeding

(Hint:  Select each organism to learn more about why it is found in the ETM)

Copepods

Larvae

---

• More Info and Try It - Nursery Area Food Web

• Try It - Striped Bass Survivor

Activity: Learn About Anticipation Guide