The corvina reina (Cynoscion albus) is an important part of the artisanal fishery
in the Gulf of Nicoya, Costa Rica. Stock assessment on this sciaenid species has been
restricted to the use of length-based methods because of the lack of age data. Direct age
determination methodologies for tropical species often encounter serious difficulties
such as poorly defined hyaline and opaque zones and lack of adequate techniques of
ageing. This thesis presents the results of an age-determination study of Cynoscion
albus based on otolith surface readings and microincrement analysis. Age estimates
were obtained from counts of hyaline zones from surface readings using the light
microscope and from microincrement readings from cross sections of the otolith using
the scanning electron microscope. Validation of age estimates from surface readings
was based on a linear regression of the age estimates from surface readings on age
estimates from integrated daily increment readings. Growth of the otolith was studied
using linear and multivariate regression methods and the results were used to construct
multivariate models for prediction of age. Consistent estimates of age and fish growth
parameters were obtained from surface and microincrement analysis. This study showed
that Cynoscion albus is a slow-growing fish (K = 0.121) and reaches a large size (L∞ =
127.5 cm) and therefore is likely to suffer overfishing in the Gulf of Nicoya fishery. / Graduation date: 1993
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/37253 |
| Date | 22 January 1993 |
| Creators | Mug-Villanueva, Moises |
| Contributors | Gallucci, Vincent F., Hall, James D. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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