Rates of Spawning and Mortality Using Contrasting Methods for Culling Pacific Crown-of-Thorns Starfish, Acanthaster...

Area of Science:

• Marine Biology
• Ecology
• Conservation Science

Background:

• Crown-of-thorns starfish (CoTS) outbreaks pose significant threats to coral reefs.
• Effective management strategies, including culling, are crucial for controlling CoTS populations.
• Concerns exist regarding the potential for culling methods to inadvertently induce spawning in CoTS.

Purpose of the Study:

• To evaluate the frequency and timing of spawning in Pacific CoTS (Acanthaster cf. solaris) after different culling treatments.
• To compare the efficacy of bile salts versus vinegar injections in managing CoTS populations.
• To assess the impact of culling methods on CoTS reproductive behavior.

Main Methods:

• Pacific CoTS were injected with either bile salts or vinegar.
• Spawning frequency and timing were monitored for up to 48 hours post-treatment.
• Experimental controls included handling, injection, and spawning controls.

Main Results:

• Male CoTS frequently spawned within 24 hours of culling treatments.
• Vinegar injections resulted in a higher incidence of male spawning (70%) compared to bile salts (36.4%).
• No female CoTS spawned after handling or injections; mortality rates varied significantly between treatments.

Conclusions:

• Bile salts are a more suitable culling agent than vinegar for managing CoTS, particularly during reproductive seasons, due to lower rates of induced spawning.
• Vinegar injections lead to higher male spawning rates and slower mortality, potentially exacerbating population issues.
• Sustained culling efforts remain the most direct method for suppressing CoTS densities and reproductive capacity.