Record Details
Age determination of corvina reina (Cynoscion albus) in the Gulf of Nicoya, based on otolith surface readings and microincrement analysis
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Age determination of corvina reina (Cynoscion albus) in the Gulf of Nicoya, based on otolith surface readings and microincrement analysis |
| Names |
Mug-Villanueva, Moises
(creator) Gallucci, Vincent F. (advisor) Hall, James D. (advisor) |
| Date Issued | 1993-01-22 (iso8601) |
| Note | Graduation date: 1993 |
| Abstract | 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. |
| Genre | Thesis/Dissertation |
| Topic | Cynoscion -- Costa Rica -- Nicoya, Gulf of -- Age determination |
| Identifier | http://hdl.handle.net/1957/37253 |
