Estimating allometric energy allocation between somatic and gonadic growth

1. Quantifying growth patterns and energy allocation strategies is essential to comprehend the biological characteristics of organisms and their interactions with broader biological communities in which they reside. Mathematical models, such as mono and di-phasic allometric energy-based growth models, play a pivotal role in delineating such body growth patterns. However, modelling approaches often face some major challenges that stem from both model nonlinearity and data limitation in practice.

2. The present study investigates the nature of the challenges and develops a flexible diphasic allometric growth model. The proposed modelling framework offers an effective parameter estimation approach directly built upon statistical smoothing techniques and numerical optimisation methods.

3. The simulation study undertaken demonstrates that the proposed approach can provide accurate parameter estimates. The illustrative example analyses the individual body and gonadic weight of subtropical cutlassfish (Trichiurus japonicus) from the cooler northern and warmer southern coasts of Taiwan. The results reveal the linear growth of fish in the south compared with those in the north, which distinctive growth pattern results from the lower dependency to body mass in the somatic and gonadic growth.

4. The proposed unified modelling framework offers new advances in growth modelling to shed light upon the intraspecific life-history strategies, quantifying growth patterns and energy allocation strategies.