A Workshop On Methods To Estimate Total And Natural Mortality Rates Using Mean Length Observations And Life History Parameters

A Workshop on Methods to Estimate Total and Natural Mortality Rates Using Mean Length Observations and Life History Parameters

"The Pacific Islands Fisheries Science Center (PIFSC) and the Southeast Fisheries Science Center (SEFSC) held a workshop on the topic of estimating total and natural mortality rates in data-limited stock assessment situations. The working group (WG) for this workshop consisted of Jon Brodziak, Dean Courtney, Joseph O'Malley and Benjamin Richards from the PIFSC and Todd Gedamke, Clay Porch, and John Walter from the SEFSC. The WG reviewed the survival estimation in non-equilibrium (SEINE) model which is based on the method of Gedamke and Hoenig (2006), and considered the application of this model for individual species. In particular, example applications of the SEINE model were developed for blacktip grouper, bluespine unicornfish, orangespine unicornfish, and blue shark. The WG also discussed and developed several extensions of the SEINE methodology. These extensions included: (i) multispecies extensions of the SEINE model; (ii) developing a random walk likelihood component for total mortality estimates; (iii) developing a simple Bayesian formulation of the SEINE model using a prior distribution for natural mortality under a two time-period application; (iv) developing an R-based shell application to create input files and execute the SEINE model; and (v) developing a hierarchical Bayesian formulation of the SEINE model for three island areas. The WG also developed a simple Bayesian version of the Beverton-Holt (or single-period SEINE) model and considered a formulation of this model using mean weight instead of mean length observations. Other conceptual extensions of the SEINE model, including potential applications to multiple fleets or fishing gears, were discussed"--Introduction.

Federal Register

Elasmobranch Biodiversity, Conservation and Management

The Darwin Elasmobranch Biodiversity Conservation and Management project in Sabah held a three-day international seminar that included a one-day workshop in order to highlight freshwater and coastal elasmobranch conservation issues in the region and worldwide, to disseminate the result of the project to other Malaysian states and countries, and to raise awareness of the importance of considering aspects of elasmobranch biodiversity in the context of nature conservation, commercial fisheries management, and for subsistence fishing communities. These proceedings contain numerous peer-reviewed papers originally presented at the seminar, which cover a wide range of topics, with particular reference to species from freshwater and estuarine habitats. The workshop served to develop recommendations concerning the future prospects of elasmobranch fisheries, biodiversity, conservation and management. This paper records those conclusions, which highlight the importance of elasmobranchs as top marine predators and keystone species, noting that permanent damage to shark and ray populations are likely to have serious and unexpected negative consequences for commercial and subsistence yields of other important fish stocks.