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

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

POND CARRYING CAPACITY Concepts: Factors Density Oxygen Ammonia Suspended solids

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/m3)

POND CARRYING CAPACITY Species kg/cm/m3 RBT 3.0 Steelhead 1.5 Chinook salmon 1.8 Coho salmon 2.4 Atlantic salmon 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 O2 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 (NH3) 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: Who What Where When Why