florida striped bass
TRANSCRIPT
Striped bass scales and
life history tales:
fish and physics in the St. John’s
River
Appearance
Striped bass are quick powerful fish with silvery sides and white belly. They have seven or eight black stripes along the sides. Stripes are absent on young fish of less than six inches
Habitat
In Florida, striped bass are found primarily in the St. Johns River and its tributaries, and a few panhandle rivers. Striped bass need long stretches of flowing water to reproduce successfully. These conditions are rare in Florida.
Behavior
Stripers do not tolerate water temperatures over 75˚F for long. During Florida summers, striped bass become less active and must find cool water to survive. Striped bass populations depend on annual stockings from FWC and federal hatcheries.
State Record
42.25 lbs.
Big Catch: 30 inches or 12 lbs.
Striped bass scales
http://www.mdsg.umd.edu/MarineNotes/Sep-Oct98/
EggsSize: 1.8 – 3.7 mmDuration: 2 days
AdultsSize: 0.5-2.0 m
Duration: 35 years
http://www.dnr.state.md.us/fisheries/education/rockfish/rockfish.html
Note: Source for images is listed the first time the image is used.
Life history tales
Fish photographs by D. Flescher, downloaded from www.fishbase.org
Fish illustrations from: Lippson, A. J. and R. L. Moran. 1974. Manual for identification of early developmental stages of fishes of the Potomac River Estuary. Prepared for MD DNR Power Plant Siting Program. PPSP-MP-13. 282 pp.
Larvae
http://www.dnr.state.md.us/fisheries/juvindex/index.html
Juveniles
Adults
Eggs
http://www.mdsg.umd.edu/MarineNotes/Sep-Oct98/
Striped bassdistribution
http://seawifs.gsfc.nasa.gov/SEAWIFS/
St. John’s River
Jacksonville
http://seawifs.gsfc.nasa.gov/SEAWIFS/
The Lower St. John’s River
To understand how physical conditions affect striped bass in the St. John’s River, we need to:
determine how physical conditions change in the St. John’s River
identify how striped bass respond to physical conditions
Physical conditions affect all life stages
Water temperature, salinity, dissolved oxygen concentrations, and currents influence:
survival (heat shock, winter mortality)
growth rates
location, movement, migration
Outline
1. Water temperature2. Salinity 3. Dissolved oxygen
Water Temperature
Chesapeake Bay Program Monitoring Data
http://tidesandcurrents.noaa.gov/ofs/sjofs/fore_temp.shtml
Striped bass and water temperature: lethal limits and optimal ranges
Juveniles Adults
Stress/Mortality
Optimal
oCoC
Optimal
Stress/Mortality
Setzler-Hamilton and Hall 1991
http://tidesandcurrents.noaa.gov/ofs/sjofs/sjofs.html
The St. John’s River is in the optimal temperature range, so Striped Bass move throughout thesystem during fall and winter.
http://tidesandcurrents.noaa.gov/ofs/sjofs/sjofs.html
Striped Bass congregate in large cold water springs, such as Croaker Hole during the summer.
Croaker Hole
Outline
1. Water temperature2. Salinity 3. Dissolved oxygen
Find current salinity at http://tidesandcurrents.noaa.gov/ofs/sjofs/now_sal.shtml
Salinity measures the amount of salts dissolved in water. An estuary can exhibit a change in salinity throughout its length as fresh water entering from the tributaries mixes with seawater from the ocean.
Striped bass are migratory fish which spend most of their life in bays and the ocean, but travel up tidal freshwater rivers in the spring to spawn.
Outline
1. Water temperature2. Salinity3. Dissolved oxygen
Dissolved Oxygen (DO) is one of the most important indicators of water quality. It is essential for the survival of fish and other aquatic organisms.
The DO test tells how much oxygen is dissolved in the water.
Factors that effect the amount of dissolved oxygen in the water
Water Temperature: Colder water holds more oxygen.Warmer water holds less oxygen.
Salinity:Fresher water holds more oxygen.Saltier water holds less oxygen,
too many bacteria or algae in the water may reduce oxygen levels.
The DO test tells how much oxygen is dissolved in the water.
Striped bass and dissolved oxygen concentrations: lethal limits
Juveniles Adults
Stress
Mortality
Preferred
Setzler-Hamilton and Hall 1991
Dissolved Oxygen
Helpful LinksWater Quality St. John’s Riverhttp://www.lake.wateratlas.usf.edu/river/waterquality.asp?wbodyid=1025&wbodyatlas=river
St. John’s River Operational Forecast System: Get current data at specific parts of the St.John’s using Nowcasthttp://tidesandcurrents.noaa.gov/ofs/sjofs/sjofs.html
SummaryPhysical conditions affect all life stages of striped bass
Understanding changes to striped bass habitat is important for fisheries management
Habitat quality is determined by a suite of physical conditions