Spawning Ethology and Egg-Substrate Preference of Bigfin Reef Squid on Rope Attractors in Coastal Indonesia

Ardianta Selasa, September 08, 2026
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FORMOSA NEWS

Shaded Rope Attractors Provide Effective Artificial Spawning Habitat for Bigfin Reef Squid in Coastal Indonesia

Pute Anging, Indonesia — Recruitment of the economically important bigfin reef squid (Sepioteuthis lessoniana) relies heavily on the availability of suitable egg-attachment substrates in vulnerable coastal environments. To address the degradation of natural spawning grounds, marine scientists from State Agricultural Polytechnic of Pangkajene Islands (Polipangkep) designed and tested a low-cost artificial spawning structure made of polyethylene rope topped with a protective rubber shade.

The field study was led by Muhammad Aras and Irawan Alham from the Fishing Technology Study Program, alongside Syamsul Hadi from the Fishing Port Management Study Program, all within the Department of Maritime Technology at Polipangkep. Direct underwater observations confirmed that wild squid readily accepted the artificial structure as a functional egg-laying habitat. Their findings were published in the peer-reviewed journal International Journal of Contemporary Sciences (IJCS) in 2026.

Background and Environmental Relevance

Bigfin reef squid represent a critical fishery resource across tropical and subtropical coastal waters in the Indo-Pacific region. Due to their rapid growth, short lifespans, and reliance on shallow nearshore habitats, local squid populations are highly vulnerable to overfishing and habitat destruction.

In coastal Indonesia, commercial and artisanal squid fishing frequently overlaps with adult aggregation and spawning periods. As coastal development and climate impacts degrade natural habitats such as coral reefs and seagrass beds, females face a shortage of stable surfaces to attach their egg capsules. Providing artificial spawning habitats offers a practical conservation tool to support egg survival and maintain wild squid stocks without relying on complex, expensive technologies.

Research Methodology

The researchers conducted a 60-day field case study in the clear coastal waters of Pute Anging Island, Barru Regency, South Sulawesi, Indonesia. They deployed a box-shaped frame made of polyethylene rope, anchored 3 to 4 meters deep over a seabed of sand and coral debris.

To create a favorable microhabitat, the team fitted the top of the frame with a black rubber sheet that provided interior shade, while a sealed PVC pipe and concrete weights kept the structure stable against local currents. Inside the frame, 32 vertical polyethylene rope strands (10 mm in diameter and 35 cm long) hung down to serve as attachment points.

Scuba divers monitored the attractor twice daily during designated one-hour windows in the early morning (06:00–07:00) and late afternoon (17:00–18:00). The team recorded squid arrival, courtship behavior, deposition duration, strand utilization, and egg development without capturing or disturbing the spawning adults.

Key Research Findings

Throughout the 60-day monitoring period, the research team gathered detailed behavioral and biological data on how bigfin reef squid interact with artificial rope structures:

  • Delayed Discovery Phase: The first egg deposition occurred 35 days after deployment, indicating that squid required a discovery and inspection period before actively utilizing the new structure through day 60.
  • Substantial Egg Accumulation: A total of 16 egg colonies accumulated on the attractor, containing 566 individual egg pods and 1,698 recorded egg units, averaging three egg units per pod.
  • Morning Spawning Periodicity: All observed egg-laying events took place exclusively during the 06:00–07:00 morning observation window. Spawning involved groups of 1 to 4 pairs and lasted approximately 15 minutes per bout, with individual egg capsules attached every 10 to 30 seconds.
  • Specific Substrate Preference: Squid used 13 out of the 32 available rope strands, resulting in a corrected substrate utilization rate of 40.6%. Egg masses clustered densely on the upper portions of the ropes directly under the shaded rubber sheet.
  • Successful Development: Eggs developed successfully to hatching over a 28-day incubation period. Sampled egg pods measured 64 mm in length by 13 mm in diameter at day 14, and newly hatched squid emerged at an average length of 7.7 mm.

Real-World Impact and Policy Implications

This research demonstrates that simple, community-deployable artificial structures can effectively support the reproductive cycles of cephalopods in degraded marine environments. Because polyethylene ropes and rubber sheets are inexpensive and locally available, fishing communities, coastal managers, and conservation agencies can easily replicate the design.

However, the authors emphasize that artificial attractors must be managed responsibly. If deployed openly without catch restrictions, attractors risk acting as aggregation devices that make spawning adults easier to catch, worsening overfishing. To maximize ecological benefits, policymakers and local communities should install these structures inside designated marine protected areas or seasonal no-take zones, ensuring that hatchlings can safely recruit into the wild population.

"The covered polyethylene-rope attractor was repeatedly used by bigfin reef squid as an egg-deposition substrate in shallow waters," stated Lead Author Muhammad Aras and Co-Author Irawan Alham from State Agricultural Polytechnic of Pangkajene Islands. "These observations add behavior-level evidence that shade, elevation within the structure, and flexible rope surfaces are relevant design attributes for artificial squid spawning habitat."

Author Profiles

  1. Muhammad Aras, S.St.Pi., M.Si. — Researcher and lecturer in the Fishing Technology Study Program, Department of Maritime Technology, State Agricultural Polytechnic of Pangkajene Islands (Polipangkep). His research focuses on fishing technology, artificial habitats, and coastal resource management.
  2. Irawan Alham, S.St.Pi., M.Si. — Researcher and lecturer in the Fishing Technology Study Program, Department of Maritime Technology, State Agricultural Polytechnic of Pangkajene Islands (Polipangkep). He specializes in marine animal behavior, gear technology, and fisheries conservation.
  3. Syamsul Hadi, S.St.Pi., M.Si. — Researcher and lecturer in the Fishing Port Management Study Program, Department of Maritime Technology, State Agricultural Polytechnic of Pangkajene Islands (Polipangkep). His expertise covers fisheries harbor management and marine policy.

Research Source

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