Methods for Improving Settlement and Metamorphosis of Shelled Marine Mollusks in Aquaculture: A Review

ABSTRACT Settlement and metamorphosis are critical life stages for marine mollusks that transition larvae to their adult forms. Often acting as bottlenecks in aquaculture production, as it is the most difficult step in a hatchery due to the changes in anatomical structures, for example, loss of velum and gain of adult shell structures. With various methods for induction explored through the years, this review explores the use of synthetic compounds, endogenous neurotransmitters, native‐inducing compounds and genomics in larval settlement and metamorphosis. Synthetic compounds typically lead to higher mortality and reduced effectiveness than native compounds. However, they produce varied effects across many marine mollusks, serving as valuable tools for studying behaviour and morphology during this transition. In contrast, native‐inducing compounds from environmental factors have species‐specific effects, demonstrating high efficacy and low mortality. Although native larval inducers are often unknown, difficult to identify and highly specific to individual species, understanding trends in other organisms may provide insights into methodologies, especially with the increasingly significant role of genomics. Genomics has the potential to aid in identifying valuable life history information to streamline and increase the effectiveness of grow‐out techniques in production settings. This understanding has the potential to significantly influence aquaculture by exemplifying multidisciplinary strategies, refining future initiatives and encouraging similar research efforts.