Elasmobranch fisheries: status, assessment and management
department or school: Science, Faculty of
department or school: Resources, Environment and Sustainability (IRES), Institute for
data provider: DSpace
degree campus: UBCV
creator: Bonfil-Sanders, Ramon
issued: 2009-03-19T22:23:11Z
issued: 1996
related degree: Doctor of Philosophy - PhD
degree grantor: University of British Columbia
description: An overview of the situation of elasmobranch fisheries around the world and problems for their assessment and management are presented. Four different studies are carried out, each attacking a particular problem under this general topic. The first, is an in-depth review of recent trends in elasmobranch exploitation and management on a worldwide basis aimed at closing the gap in baseline information about these fisheries on a global scale. In the second study, a deterministic age-structured simulation model is developed to analyse density-dependent changes in fecundity as a response to increased fishing mortality in a hypothetical shark population. The use of the model as an aid in management decision-making is exemplified with a case from a tropical shark fishery. Monte Carlo analysis is used in the third study, to evaluate the Schaefer and Fox surplus production models and the delay-difference model of Deriso-Schnute for the estimation of assessment and management parameters of elasmobranch fisheries. The fishery models are evaluated by comparing their estimates of stock assessment a n d management parameters against the known values of a full age-structured stochastic simulation model of a shark population. Different scenarios of stock recruitment relationship, fishable stock size, spatial behaviour of the sharks, and data quality are used for testing robustness. None of the fishery models performs satisfactorily under situations of density-dependent catchability. When catchability remains constant, the Deriso-Schnute model outperforms the Schaefer or Fox models, both for biomass and management parameter estimation. In the final study, the multispecies shark fishery of Yucatan, Mexico, is used as an example of the problems for elasmobranch stock assessment in the real world. The fishery is analysed by fitting the Schaefer model to catch and cpue data. The results highlight severe deficiencies in the data available for assessment which are characterised by a lack o…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/6233
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note: Elasmobranch Fisheries: Status, Assessment and Management by Ramon Bonfil-Sanders B.Sc. (Hons), Universidad Autonoma de Baja California (Mexico), 1983 M.Sc, University College of North Wales (UK), 1991 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in THE FACULTY OF GRADUATE STUDIES (Resource Management and Environmental Studies) We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA February 1996 © Ramon Bonfil-Sanders 1996 In presenting this thesis in partial fulfilment of the requirements for an advanced degree at the University of British Columbia, I agree that the Library shall make it freely available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission. Department of 2&t/£&M^MMr/hW£m£0MtV7?rl S7l»/£S The University of British Columbia Vancouver, Canada Date ^B3-X9-DE-6 (2/88) II A b s t r a c t . A n o v e r v i e w of the s i tuat ion of e l a s m o b r a n c h f i sher ies a r o u n d the w o r l d a n d p r o b l e m s for thei r a s s e s s m e n t a n d m a n a g e m e n t a re p r e s e n t e d . F o u r different s tud ie s a r e ca r r i ed out, e a c h a t t ack ing a par t icu lar p r o b l e m u n d e r this g e n e r a l top ic . T h e first, is a n in-depth r ev i ew of recent t r ends in e l a s m o b r a n c h explo i ta t ion a n d m a n a g e m e n t o n a w o r l d w i d e b a s i s a i m e d at c l o s i n g the g a p in b a s e l i n e informat ion abou t t h e s e f i she r i es o n a g l o b a l s c a l e . In the s e c o n d s tudy, a de te rmin i s t i c age - s t ruc tu red s imula t ion m o d e l is d e v e l o p e d to a n a l y s e d e n s i t y - d e p e n d e n t c h a n…
has type: Thesis/Dissertation
date issued: 1996-05
is shown at: 10.14288/1.0074816
language: eng
degree discipline: Resource Management and Environmental Studies
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/6233