POND CARRYING CAPACITY Concepts of Carrying capacity Must

POND CARRYING CAPACITY Concepts of Carrying capacity – • Must be careful of overloading • •

POND CARRYING CAPACITY Concepts of Carrying capacity • Flow index: • Density Index:

POND CARRYING CAPACITY Concepts: 1. Density 2. Oxygen 3. Ammonia 4. Suspended solids Factors

POND CARRYING CAPACITY Data needed: 1. Physical parameters • • • Pond dimensions Water use Elevation above sea level Daily mean water temperature Water inflow rates

POND CARRYING CAPACITY 2. Chemical parameters: 3. Water discharge permit specifications: • ammonia • Solids • • • phosphate

POND CARRYING CAPACITY 4. Feed quality • metabolizeable energy (kcal/kg) • • Density Carrying Capacity (spatial requirements) Wden = V*Di Wden: Biomass (kg) per unit length (cm) Di: Density index (kg/cm/m 3)

POND CARRYING CAPACITY Species RBT Steelhead Chinook salmon Coho salmon Atlantic salmon kg/cm/m 3 3. 0 1. 5 1. 8 2. 4 1. 8

POND CARRYING CAPACITY Density-based permissible biomass in the rearing unit Bio = Wden*L Bio: permissible biomass (kg) Wden: biomass per unit body length (kg/cm)

POND CARRYING CAPACITY Oxygen carrying capacity Single-pass system W = F*L*I W: permissible biomass F: flow index (see table) L: length I: water inflow F value:

POND CARRYING CAPACITY Multiple-pass system (w/o aeration) Increases potential of fish health problems: • • accumulation of waste products • Reduction in DO available • Dependent on fall ht, water temp, elev. , etc. • Simple method - Life support index (from tables 14/15) should be reduced by 25% for first use and 30% for additional ponds

POND CARRYING CAPACITY Multiple-pass system (with aeration) • Pumped air or pure O 2 • Treat as single-pass (be careful) • Risk of nitrogen supersaturation (acute >110%, chronic 102%) • Water quality

POND CARRYING CAPACITY Circulating water systems - Similar concepts, but lower water flows - Generally need supplemental aeration - May remove dependency of fish on DO

POND CARRYING CAPACITY Ammonia carrying capacity - Ammonia in unionized form (NH 3) is harmful - End-product of protein metabolism Single-pass – Multiple-pass – may exceed limit of 0. 03 - Accumulation with each reuse of water - Must reduce feeding rate

POND CARRYING CAPACITY Circulating systems - Accumulation due to increases water retention time - Recirculating systems -

POND CARRYING CAPACITY Suspended solids carrying capacity – no reliable method to calculate Depends on: 1. Digestibility of feed (FCR) 2. Feeding techniques If solids accumulate – fish health problems

POND CARRYING CAPACITY Application of CC: Stock pond for “take-out” - number of fish (plus mortality) that are to be removed at a specified time 1. Establish date 2. 3. Calculate temp. -based daily growth rate (table 4) 4. 5. 6. Nat. mortality (0. 02 -0. 03% per day) 7.

PRODUCT DEFINITION Product potential/planning The 5 W’s: 1. 2. 3. 4. 5. Who What Where When Why