Growth and Maturation of Plectropomus spp. in the Saudi Arabian Red Sea

Handle URI:
http://hdl.handle.net/10754/209394
Title:
Growth and Maturation of Plectropomus spp. in the Saudi Arabian Red Sea
Authors:
DesRosiers, Noah
Abstract:
Two species of plectropomid grouper (Plectropomus areolatus and P. pessuliferus) are found in the Red Sea. In Saudi Arabia these are the most valuable fishes by weight, averaging wholesale prices around US $15 per kilogram (personal observation). Over the past two decades, the number of fishing vessels in the Saudi Arabian Red Sea has tripled. Despite this increase in fishing effort Saudi Arabia has not implemented any marine resource management for Red Sea fisheries. Little biological data are currently available to inform managers. The research presented here addresses knowledge gaps on the growth pattern, longevity and sexual ontogeny of Plectropomus spp. in the Red Sea. Collections of each species were established by purchasing landed individuals from fishermen and fish markets distributed evenly between three latitudinal regions around the country. The total length of each fish was measured to the nearest millimeter. Age was estimated by enumerating annual bands visualized in transverse sections of sagittal otoliths. Sexual stage was determined via histological examination of gonadal tissue. Plots of total length versus age were fitted with reparameterized von Bertalanffy growth functions constrained to a size-at-settlement estimate of 20 mm. P. pessuliferus achieved a larger size (maximum 960 mm) and an older age (maximum 19 years) than P. areolatus (maximum size 570 mm, maximum age 9 years). While no regional patterns were found for P. pesuliferus, likelihood ratio tests revealed regional differences in growth pattern for P. areolatus, finding an increasing mean age, increasing mean length, and decreasing growth rate with decreasing latitude. In addition, males of P. areolatus were more abundant in the Southern region. These findings contradict existing theories about the effects of latitudinal temperature gradients on life history. It is hypothesized that the broader continental shelf in the Southern region may be providing a haven for these species in the form of reduced fishing pressure, increased habitat, and increased abundance of prey organisms due to greater regional productivity. Given all of this information, it is recommended that a comprehensive fisheries management regime be implemented, starting with an immediate return to previously-used spawning season closures and working towards spatial closures and size limits.
Advisors:
Berumen, Michael L. ( 0000-0003-2463-2742 )
Committee Member:
Choat, John; Luyten, James
KAUST Department:
Biological and Environmental Sciences and Engineering (BESE) Division
Program:
Marine Science
Issue Date:
May-2011
Type:
Thesis
Appears in Collections:
Marine Science Program; Theses; Biological and Environmental Sciences and Engineering (BESE) Division

Full metadata record

DC FieldValue Language
dc.contributor.advisorBerumen, Michael L.en
dc.contributor.authorDesRosiers, Noahen
dc.date.accessioned2012-02-04T08:22:30Z-
dc.date.available2012-02-04T08:22:30Z-
dc.date.issued2011-05en
dc.identifier.urihttp://hdl.handle.net/10754/209394en
dc.description.abstractTwo species of plectropomid grouper (Plectropomus areolatus and P. pessuliferus) are found in the Red Sea. In Saudi Arabia these are the most valuable fishes by weight, averaging wholesale prices around US $15 per kilogram (personal observation). Over the past two decades, the number of fishing vessels in the Saudi Arabian Red Sea has tripled. Despite this increase in fishing effort Saudi Arabia has not implemented any marine resource management for Red Sea fisheries. Little biological data are currently available to inform managers. The research presented here addresses knowledge gaps on the growth pattern, longevity and sexual ontogeny of Plectropomus spp. in the Red Sea. Collections of each species were established by purchasing landed individuals from fishermen and fish markets distributed evenly between three latitudinal regions around the country. The total length of each fish was measured to the nearest millimeter. Age was estimated by enumerating annual bands visualized in transverse sections of sagittal otoliths. Sexual stage was determined via histological examination of gonadal tissue. Plots of total length versus age were fitted with reparameterized von Bertalanffy growth functions constrained to a size-at-settlement estimate of 20 mm. P. pessuliferus achieved a larger size (maximum 960 mm) and an older age (maximum 19 years) than P. areolatus (maximum size 570 mm, maximum age 9 years). While no regional patterns were found for P. pesuliferus, likelihood ratio tests revealed regional differences in growth pattern for P. areolatus, finding an increasing mean age, increasing mean length, and decreasing growth rate with decreasing latitude. In addition, males of P. areolatus were more abundant in the Southern region. These findings contradict existing theories about the effects of latitudinal temperature gradients on life history. It is hypothesized that the broader continental shelf in the Southern region may be providing a haven for these species in the form of reduced fishing pressure, increased habitat, and increased abundance of prey organisms due to greater regional productivity. Given all of this information, it is recommended that a comprehensive fisheries management regime be implemented, starting with an immediate return to previously-used spawning season closures and working towards spatial closures and size limits.en
dc.language.isoenen
dc.titleGrowth and Maturation of Plectropomus spp. in the Saudi Arabian Red Seaen
dc.typeThesisen
dc.contributor.departmentBiological and Environmental Sciences and Engineering (BESE) Divisionen
thesis.degree.grantorKing Abdullah University of Science and Technologyen_GB
dc.contributor.committeememberChoat, Johnen
dc.contributor.committeememberLuyten, Jamesen
thesis.degree.disciplineMarine Scienceen
thesis.degree.nameMaster of Scienceen
dc.person.id102046en
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