Offshore egg production and vertical distribution of the Centropages furcatus (Copepoda) in the Gulf of California

Abstract

Temperature, chlorophyll-a concentration, egg production rates (EPR, Sep-Oct 2010) and vertical distribution (January and July 2007) of the calanoid copepod Centropages furcatus were measured in the central and northern region of the Gulf of California. C. furcatus was the most abundant copepod species in the Gulf of California during summer spawning in a wide sea surface temperature range (15.7-25.8 °C). This is the first offshore EPR estimation of C. furcatus in the Gulf of California because previous EPR measurements were done in several bays located at both coasts of Baja California peninsula (Magdalena, La Paz, and Concepción) and Navidad, Jalisco. During Sep-Oct 2010, the mean and maximum daily EPR increased in regions with high chlorophyll-a concentrations and well-mixed water column. Mean daily egg production rate in offshore waters measured during Sep-Oct 2010 was 18.8 eggs female-1 d-1 , near the lower range of mean EPR known for C. furcatus in other regions. The EPR in Gulf of California were of similar magnitude to Feb 1998 and Oct 2002 in Magdalena bay and about half of EPR values measured in Feb 2002 and autumn-winter 2000-2001 in La Paz bay. This confirms that C. furcatus is a neritic tropical species that can reproduce offshore in lower rates than in bays, thus autumn conditions in the Gulf of California represented stressing environmental conditions that limited it EPR