Natural mortality estimates throughout the life history of the sea cucumber Isostichopus Badionotus (Holothuroidea: Aspidochirotida).

The Natural Mortality coefficient (M) is a key parameter for stock assessments. The need to establish age-specific natural mortality coefficients is widely recognized because M decreases rapidly over the early stages of the life cycle until it reaches a stable M value around the age-at-maturity. The aim of this study was to estimate M during the life cycle of the sea cucumber Isostichopus badionotus, a species under heavy fishing exploitation in the Caribbean Sea and the Gulf of Mexico. Coefficients M at age were estimated using two models: The Gnomonic Interval Model (GIM) and the Chen & Watanabe model. Two different scenarios were simulated considering early and late age-at-maturity. Estimated M values using the GIM model for the early maturity scenario were 2.15 to 2.35 year-1 (interquartile range) for the juvenile stage and 0.39 to 0.43 year-1 for the adult stage; for the late maturity scenario were 0.65 to 0.71 year-1 for the juvenile stage and 0.68 to 0.74 year-1 for the adult stage. The Chen & Watanabe model M estimates for juvenile stage were between 0.85 and 2.23 year-1 and 0.39 and 2.23 year-1 for the early and late maturity scenarios respectively; for adult stage were between 0.97 and 0.21 year-1 and 0.62 and 0.43 year-1 respectively. The GIM estimated high natural mortality rates during larval stages. These estimates provided a higher level of certainty for the population models to more effectively manage a fishery and improve stock assessments.

Annotated checklist of the coastal ichthyofauna from Michoacán State, Mexico.

This study is the first to complete an intensive and comprehensive list of the ichthyofauna of nearly all ecosystems of the Michoacán coast, Mexico. The resulting systematic checklist, supplemented with information from the literature and scientific collections, comprises 440 species belonging to two classes, 31 orders, 104 families, and 264 genera. The families with the highest number of species were Sciaenidae (30 spp.), Carangidae (26), Haemulidae (24), Serranidae (21), Paralichthyidae, and Gobiidae (13). Of the total species list, 134 represent first records for the Michoacán State, and one is a first record for Mexico. The results expand the number of known fish species of the Michoacán coast by almost one third and will help to develop conservation and management plans for this coastal zone.