Sea Cage Daily Inspection Checklist: Nets, Moorings, Predator Damage and Mortality

A net breach that goes unnoticed for a day can empty a cage; the same breach caught on a routine inspection is a patch repair. The gap between those two outcomes is almost entirely about whether a structured daily check happens, not about how dramatic the failure eventually becomes.

The checklist, in inspection order

1. Net integrity, above and below the waterline. Walk the full cage perimeter checking for visible holes, chafing points (particularly where the net contacts mooring lines or frame structures), and any area showing unusual deformation that might indicate a developing tear. See escapes and containment integrity for the specific failure modes this check is targeting.
2. Mooring lines, shackles and anchor points. Confirm tension looks normal across all lines, check shackles for visible wear or corrosion, and note any line showing chafing at a contact point — see the HDPE cage design and mooring reference for the specifications a healthy mooring system should maintain.
3. Predator netting and anti-bird systems. Confirm predator exclusion netting is intact and properly tensioned, with particular attention to known weak points (corners, access-hatch seams) where previous damage has occurred — see predator netting systems for design standards.
4. Surface and feed-barge equipment. Check feed lines, camera systems and any surface infrastructure for damage or malfunction before the day's feeding begins, catching an equipment problem before it affects the feeding schedule rather than during it.
5. Mortality count and removal. Count and remove any dead fish, logging the number against the cage ID — a sudden increase in daily mortality is one of the earliest signals of a developing health or water-quality problem, and only shows up as a signal if counted consistently every day.
6. General behavior observation. Note feeding response, swimming behavior and any fish showing visible distress or abnormal appearance — this qualitative check often catches problems before any single quantitative measurement would.

Timing and sequencing

Run the full inspection before the first feed of the day, not after — a problem found before feeding (a net breach, for instance) can be addressed before fish have further opportunity to escape or before feed is wasted on a compromised cage. Where staffing allows, pair the net and mooring check with the predator-netting check in the same pass, since both benefit from the same perimeter walk, while mortality counting and behavior observation can follow once the structural check is complete.

What counts as an immediate-escalation finding versus a logged note

• Immediate escalation: any net breach regardless of size, visible mooring line failure or severe chafing, or a mortality count significantly above the cage's recent baseline.
• Logged for scheduled follow-up: minor fouling not yet affecting flow, cosmetic wear on predator netting not compromising its function, equipment issues not affecting current feeding capability.

Distinguishing these two categories in the daily checklist itself — rather than leaving severity judgment entirely to whoever is performing the inspection that day — keeps response consistent regardless of which staff member is on duty.

Worked example

A routine morning inspection at a salmon cage site finds a small chafe point on the net where it contacts a mooring line bracket — not yet a breach, but visibly thinning mesh at a single contact point. Because the checklist's escalation criteria treat "severe chafing" as immediate-escalation rather than logged-for-later, the inspector flags it for same-day attention rather than noting it for the next scheduled maintenance pass. A technician patches the thinning section that afternoon, before it progresses to an actual tear. Three weeks later, a different cage at a neighboring, less rigorously inspected site develops an undetected chafe point at a similar contact location that is not caught until it has become a small but active breach — the fish loss from that incident, and the emergency repair response it required, is exactly what the daily checklist's escalation discipline is designed to prevent.

Adapting the checklist to site-specific risk factors

• High-current sites see faster mooring-line wear and more aggressive net chafing at contact points, warranting closer attention to those specific items even within a standard daily routine.
• Sites with known predator pressure (seals, birds) should weight the predator-netting check more heavily and track any near-miss or confirmed predator interaction as its own logged category, since patterns of attempted breach attempts at specific points often precede an eventual successful one.
• Sites with a history of specific equipment issues (a feed-barge component with a known failure pattern, for instance) benefit from a site-specific checklist addendum covering that equipment's particular failure signs, beyond the generic items every site shares.

Documenting the inspection

Log every inspection, not just ones that find a problem — a consistent record of clean inspections is itself valuable evidence of a well-maintained site, both for internal trend tracking and for certification audits that specifically look for routine, not just reactive, inspection practice. See the cage farm logbook standards guide for the full record-keeping structure this daily checklist feeds into.

Common mistakes

• Running the inspection after feeding rather than before, missing the chance to catch a problem before it compounds through the feeding cycle.
• Logging only problems found, with no record of routine clean inspections, undermining the ability to demonstrate consistent practice later.
• Leaving severity judgment entirely inconsistent between staff members with no defined escalation criteria.
• Skipping predator-netting checks on days when net and mooring checks look fine, treating it as a lower priority rather than an equally scheduled item.

Frequently asked questions

How long should a thorough daily inspection take for a typical cage site?

This varies with site size and number of cages, but a well-practiced routine for a moderate-sized site typically runs well under an hour — sites where inspection regularly takes much longer may benefit from reviewing whether the checklist sequence or staffing allocation is genuinely efficient.

Should inspection frequency increase during storm season or after severe weather?

Yes — an additional inspection immediately after any significant weather event, beyond the standard daily routine, catches storm-related damage before the next scheduled check would, and is standard practice on sites with meaningful weather exposure.

What's the right response if a net breach is found?

Isolate and assess the extent immediately, begin temporary containment measures if fish loss risk is active, and follow the full repair procedure in the companion net changing and repair SOP rather than attempting an ad hoc fix that might not hold.

Does this checklist apply the same way to submersible cage systems?

The core categories carry over, but submersible systems add depth-control and ballast-system checks specific to that design — see submersible-cage-specific operational guidance for those additional items, which a standard surface-cage checklist does not cover.

Who should be responsible for the daily inspection — a dedicated role or rotating staff?

A dedicated or consistently assigned inspector, even on a rotating schedule with clear handoff, tends to catch subtle changes (a gradually developing chafe point, for instance) more reliably than fully ad hoc assignment, since familiarity with the site's normal baseline condition is part of what makes the inspection effective.

Can underwater drone or camera inspection replace the physical walk-round checklist?

It can supplement and extend visibility to areas a surface walk-round cannot see well (deeper net sections, mooring points below the waterline), but it generally works best as an addition to, not a replacement for, the surface and surface-level checks described here — the two methods catch different failure modes and are more reliable combined than either alone.

How should a new cage site establish its initial inspection baseline?

Run the full checklist daily for an initial settling-in period while documenting what "normal" looks like for that specific site's fouling rate, mooring tension behavior and typical conditions — this baseline is what later inspections get compared against to catch a genuine deviation rather than normal site-specific variation being mistaken for a problem.