2025/09/10 by Miguel Ángel Cisneros‐Mata, Marcelo Vidal Curiel-Bernal · 1 voice
Agricultural and Biological Sciences · Environmental Science · #Fish Biology and Ecology Studies #Fish Ecology and Management Studies #Marine and fisheries research
paper · doi:10.1111/jfb.70159
openalex publication_date 2025/09/10 · openalex created_date 2025/09/12 · openalex updated_date 2026/05/21
Natural mortality rate (M) is a crucial parameter for fish and other species. In fisheries management it is common practice to obtain estimates of M using one of several empirical formulas available in the literature. However, when using these formulas, an important question arises: for which life stage or age does the estimated rate pertain to? In the present work, gnomonic stage-specific mortality rates are estimated for Totoaba macdonaldi, a vulnerable fish species of the gulf of California. The gnomonic method is based on knowledge of the species life cycle; it tracks numbers surviving during exponential decay of a cohort under specific restrictions. An average weighted mortality rate of 0.108/year is then computed for adults and senescent fish subjected to poaching. This allowed us to ascertain status of the population calculating exploitation rate (80%). It is concluded that the totoaba population is under heavy overexploitation.