Difference between revisions of "Striped Bass Page"

Description: Striped bass are native to the Atlantic coastline of North America from the St. Lawrence River into the Gulf of Mexico to Louisiana. They are anadromous fish that migrate between fresh and salt water. Spawning takes place in fresh water.[2]

Location and Habitat: Self renewing inland stocks of striped bass generally require two major types of habitat: (1) riverine habitat for reproduction; and (2) lacustrine or estuarine habitat for foraging, growth, and development by the larvae, juveniles, and adults.[3]

Temperature: Spawning: Adults usually initiate spawning runs when temperatures reach 15 to 19° C (59 to 62° F). Both the initiation and duration of spawning are temperature-dependent, and sudden drops in water temperature may interrupt spawning. Larval: Mean time between hatching and yolk absorption was 5.1 days at 21° C (69.8° F) and 8.3 days at 15° C (59° F) The duration of larval development (finfold plus post-finfold state) was about 24 days at 21° C (69.8° F) and 68 days at 15° C (59° F). Larvae may live within a temperature range of 12.8 to 23.9° C (55 to 75° F), but high mortality can be expected at 23.9° C (75° F) and above. Temperatures below 10° C (50° F) and above 23° C (73.4° F) are apparently lethal to larvae. [4]

Turbidity and Dissolved Oxygen: Reports indicate that striped bass have a relatively high tolerance to silt-laden and turbid waters and that high concentrations of suspended sediments likely do not affect the eggs or larvae. Sediment levels up to 500 mg/1 did not affect the hatching success of eggs. However, sediment levels of 1,000 mg/1 significantly reduced hatching success. Levels over 100 mg/1 delayed hatching several hours. Hatch of striped eggs was not significantly affected by suspended sediment concentrations ranging from 20 to 2,300 mg/1, but embryo development was slowed significantly at concentrations above 1,300 mg/1.[5]

Salinity: Albrecht (1964) concluded that low salinity (920 to 948 mg/1 chlorides) enhanced egg and larval survival and that moderate salinity (4,595 to 4,740 mg/1 chlorides) was not detrimental. [6]

Reproduction: Streams suitable as striped bass reproductive habitat generally have a large volume of swift, turbulent water flowing over a substrate of rock and/or fine gravel. Eggs are deposited near the water surface. The incubation period is about 34 hours at 21° C (70° F), 51.8 hours and 62 hours at 18° C (64.4° F) and 15.0° C (59.0° F), respectively, and about 70 to 74 hours at 14.4 to 15.6° C (58 to 60° F). Eggs generally hatch in riverine habitat, initial growth and development of larvae take place in the stream, and subsequent growth and development of larvae, juveniles, and adults occur in lacustrine habitat.[7]

Food: Adults also tend to be opportunistic feeders, but landlocked populations usually select clupeids or soft-rayed fish over other available food items. Threadfin shad was the primary food item, both in frequency of occurrence and total volume, of adults from the lower Colorado River and Lake Powell. [8]

Risk:

• Nonnative Invasive Aquatic Species
• Habitat suitability index models and instream flow suitability curves: Inland stocks of striped bass
• 2019 National Park Service Expanded Non-native Aquatic Species Management Plan
• 2013 National Park Service Comprehensive Fisheries Management Plan

• Wayne Gustaveson and Georg Blommer, 2013, History of Striped Bass Management in the Colorado River, American Fisheries Society Symposium 80:15–23

Evidence of striped bass natural reproduction in Lake Powell was first discovered in 1979 and annually thereafter. Initially, it was thought that reproduction was confined to the Colorado River above the lake where river current could suspend eggs and larvae. The spawning site was in or below Cataract Canyon, a 19-km gorge containing 23 sets of rapids. Striped bass apparently used less than 20 km of river above the reservoir because ripe striped bass adults were 18 gustaveson and blommer collected below but not above Cataract Canyon during spawning season (Persons and Bulkley 1982).

During spring 1979, striped bass spawning was discovered in the lower reservoir near the dam. In spring of most years, prespawning striped bass aggregated near Glen Canyon Dam. These fish seemed attracted to the current created as water was drawn through the dam penstocks. With time and warming, the aggregation left the 165-m-deep dam forebay and moved to nearby coves where spawning occurred. Most fish left the prespawning staging area simultaneously during early May as water surface temperature reached 16–19°C, which is the generally accepted peak spawning temperature range (Setzler et al. 1980). Spawning sites were located near the dam where floating masses of dead (unfertilized) eggs were clearly visible. J. D. Bayless (South Carolina Wildlife and Marine Resources Department, personal communication) found that unfertilized eggs would float but that immediately after fertilization, eggs would sink 0.3 m in 27 s. Settling rate slowed with time, but eggs still descended 0.3 m every 60 s some 24 h after fertilization (Gustaveson et al. 1984).

An oxygen-temperature profile taken in spawning coves near the dam showed oxygen levels of 8.4 mg/L near the surface and 13.2 mg/L on the substrate in 9 m of water. Siltation was insignificant in these coves on the rock and sand substrate during the brief 48-h incubation period (Hardy 1978). Thus, eggs settling on the bottom of Lake Powell had adequate oxygen for normal development.

Collection of larval striped bass 18–22 mm total length (TL) with midwater trawl and meter tow net samples confirmed successful reproduction of striped bass near the dam. The collected larvae were determined not to be derived from the river upstream of the reservoir. Prolarvae are capable of swimming at 4 d of age and could be expected to travel great distances if assisted by strong mainstream reservoir currents. However, studies of density currents using total dissolved solids as an indicator showed a weak density current in the reservoir that could not have assisted in moving larvae from the inflow any closer to the dam than 190 km (D. Merritt, U.S. Bureau of Reclamation, personal communication). Instead, striped bass larvae were captured 295 km downstream from the inflow. If spawning occurred only at inflow areas and larval fish were distributed by reservoir currents, then larval fish should have been found throughout the reservoir. In contrast, there was a preponderance of young striped bass at two distinct locations, the inflow and again at the dam. It was evident from these analyses that these young striped bass found near the dam were the result of successful in-reservoir spawning (Gustaveson et al. 1984).

Over the years, it has been confirmed that striped bass spawning occurs annually in Lake Powell, Lake Mead, Lake Mohave (Liles 1985), and Lake Havasu. Eggs and larval striped bass also pass through the dams to provide additional recruits to downstream lakes and canals as water is delivered from the Colorado River to locations in California, Nevada and Arizona (Stewart and Burrell 2013).[9]