HUSBANDRY · CONTROLLED DOCUMENT
AE-SOP-0102 — Larval Rearing & Grow-Out
To govern the rearing of larvae from spawn through metamorphosis to grow-out stock at the GreenSky Breeding Station, where the first feeding window and water-quality discipline decide whether a cohort survives at all. The procedure guarantees that live-feed culture stays ahead of demand, that larval density never outruns the system's carrying capacity, and that every cohort is graded and split before crowding triggers a die-off — because a hatchery cohort lost in its first week cannot be recovered.
ActiveHusbandryRev C
Doc Control AE-SOP-0102Revision CEffective 2090-04-02Next Review 2091-04-02Owner Breeding Program LeadApprover Marine ScienceStatus ActiveClass RESTRICTED // TIDEWATER-EYES-ONLY
1. Purpose
To govern the rearing of larvae from spawn through metamorphosis to grow-out stock at the GreenSky Breeding Station, where the first feeding window and water-quality discipline decide whether a cohort survives at all. The procedure guarantees that live-feed culture stays ahead of demand, that larval density never outruns the system's carrying capacity, and that every cohort is graded and split before crowding triggers a die-off — because a hatchery cohort lost in its first week cannot be recovered.
2. Scope
All larval and juvenile rearing from spawn capture to grow-out transfer.
- In scope: First-feed timing, live-feed enrichment, density management, stage grading, and grow-out transfer of captive-bred cohorts.
- Out of scope: Spawn induction and gamete handling, which follow AE-SOP-0230; release conditioning of grow-out stock, which follows AE-SOP-0410.
3. Definitions
| Term | Definition |
|---|
| First-Feed Window | The narrow interval after yolk-sac absorption in which larvae must accept live feed or starve. |
| Live-Feed Culture | The standing rotifer, copepod, and microalgae cultures kept ahead of larval demand. |
| Enrichment | The fortification of live feed with lipids and pigments before it is offered to larvae. |
| Stage Grading | Sorting a cohort by size at metamorphosis to split fast and slow growers before cannibalism begins. |
| Carrying Density | The maximum larvae per litre a rearing system can hold in band before water quality fails. |
4. Responsibilities
| Role | Responsibility |
|---|
| Breeding Program Lead (Owner) | Owns the procedure; approves cohort splits and signs grow-out transfer. |
| Hatchery Technician | Runs live-feed culture, executes feeds and grading, and maintains the cohort log. |
| Marine Science | Sets species first-feed timing and enrichment specification. |
| NEREID | Tracks larval density against carrying capacity and flags any tank trending toward overcrowding before grading is due. |
5. Larval Stage Rearing Targets
| Stage | Larval Density | Feed Regime | Grade / Split Trigger |
|---|
| Yolk-sac (pre-feed) | ≤ 80 /L | None — endogenous | On yolk absorption |
| First feed | ≤ 60 /L | Enriched rotifers, 4×/day | Survival < 50 % by day 5 |
| Post-metamorphosis | ≤ 30 /L | Enriched copepods + microalgae | Size spread > 25 % |
| Grow-out juvenile | ≤ 12 /L | Weaning to formulated feed | On transfer clearance |
Note. Density is reduced at every stage before crowding forces it; a cohort is split on the size-spread trigger, not on the calendar, because cannibalism follows the spread, not the date.
6. Materials & Equipment
- Larval rearing tanks with gentle laminar flow and dim staging
- Standing rotifer, copepod, and microalgae culture lines
- Lipid and pigment enrichment media
- Calibrated larval-counting and sizing station
- Graded mesh sorters for stage splitting
- Weaning diet and automated feeders for grow-out
7. Procedure
7.1 First Feed
- Confirm yolk-sac absorption before introducing any live feed.
- Offer enriched rotifers within the species first-feed window; never miss the window.
- Hold larval density at or below the first-feed target and log survival by day 5.
7.2 Grow & Grade
- Step the feed from rotifers to enriched copepods through metamorphosis.
- Grade and split the cohort when size spread exceeds the trigger.
- Reduce density at each stage ahead of crowding, never after.
7.3 Weaning & Transfer
- Wean juveniles onto formulated feed at the grow-out stage.
- Confirm health-screen status before any transfer out of the hatchery.
- Sign grow-out transfer only on the Breeding Program Lead's authorisation.
8. Records
- Cohort rearing log with daily survival and density (retained 3 years)
- Live-feed culture and enrichment batch records
- Stage-grading and split log
- Weaning and feed-conversion record
- Grow-out transfer clearance
9. References
10. Revision History
| Rev | Date | Author | Summary |
|---|
| A | 2088-07-14 | Breeding Program Lead | Initial issue; first-feed window and live-feed culture discipline established. |
| B | 2089-09-22 | Breeding Program Lead | Added stage-density targets and size-spread split trigger. |
| C | 2090-04-02 | Breeding Program Lead | NEREID carrying-capacity tracking and weaning feed-conversion record added. |