Publication Date

Spring 2015

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Moss Landing Marine Laboratories

Advisor

Richard M. Starr

Keywords

biogeography, California Halibut, fecundity, growth, maturity, mortality

Subject Areas

Fisheries and aquatic sciences; Physiology; Biology

Abstract

Differences in key biological processes, such as growth and reproduction, can greatly influence localized population dynamics. Thus, it is important to evaluate intraspecific variation at several spatial scales to better understand biological limitations and develop management plans that maximize fishery sustainability. In 2011, the California Department of Fish and Wildlife (CDFW) conducted its first comprehensive stock assessment for California Halibut, Paralichthys californicus. However, limited life history data were available north of Point Conception. To improve our understanding of central California Halibut biology, 704 fish were collected during 2012 and 2013. Von Bertalanffy growth parameters were estimated at L∞ = 1041 mm and K = 0.25 for females and L∞ = 824 mm and K = 0.22 for males. Catch curve analysis indicated total mortality at 0.32 for females and 0.47 for males. Incidence of spawning females was used to estimate a seasonal spawning duration of 79 d, and temporal variation in gonadosomatic index identified peak spawning activity in July. The gravimetric method was used to estimate batch fecundity for an average-sized female (850 mm) at 6.0 x 105 eggs ± 6.7 x 104 (SE). Batch fecundity was multiplied by a spawning frequency of 25 to approximate seasonal fecundity at 1.4 x 107 eggs ± 1.3 x 106 (SE). When possible, comparisons were made with southern California Halibut using CDFW-collected data or results from the scientific literature. The information presented enhances our knowledge of California Halibut life history and provides region-specific estimates for future stock assessments.

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