Spat collection studies on pearl oysters Pinctada mazatlanica and Pteria sterna (Bivalvia, Pteriidae) in Bahia de La Paz, South Baja California, Mexico

Abstract

The present work deals with the temporal and bathymetrical variations of the epifaunal community associated with two species of pearl oysters (Pinctada mazatlanica and Pteria sterna) during a seed collecting season from June to November 1989 . A total of 63 items (species, genera and/or families) were recorded ; their variations in presence and abundance were followed during three periods (June-July, August-September and October-November) . The collectors were examined for different immersion times (2, 4, 6 and 8 weeks) for each period . Community structure was compared through the Brillouin Index, the Morisita Index and the Importance Value .We define the chronology of spatfall for both species of pearl oysters and their bathymetrical distribution . Relationships between these species and the epifaunal community present into the collectors were analysed, searching for possible noxious effects on the survival of juvenile pearl oysters, and identifying index species related with their spatfall . A strategy for starting massive seed collection of both species is established, particularly for P. mazatlanica .

Growth and survival of the pearl oyster Pteria hirundo (L.,1758) in an intermediate stage of culture in Santa Catarina, Brazil

“…In Mexico, there are several studies with Pteria sterna (Gould, 1851) and Pinctada mazatlantica (Hanley, 1846) (Monteforte and Cariño, 1992;Monteforte and Garcýa-Gasca, 1994;Monteforte and Wright, 1994;Monteforte, et al, 1995;Monteforte et al, 1996;Monteforte and Morales-Mulia, 2000). Pinctada imbricata (Roding, 1758) is studied in Venezuela, Colombia (Borrero, 1994;Pico et al, 1999), andAustralia (O'Connor andLawler, 2004), showing good culture potential.…”

History of Pearling in La Paz Bay, South Baja California

“…The incubators remained under water from May t o October, t h e reproductive season of Pinctada mzcitlanica (Monteforte and GarciaGasca, 1994;Monteforte and Bervera, 1994). Vives claimed that spawning and fertilization took place inside the incubators, and that the spat would settle on the substrates provided.…”

“…Vives claimed that spawning and fertilization took place inside the incubators, and that the spat would settle on the substrates provided. However, it is liighly unlikely that this is entirely accurate given the reproduction process for mollusks (Alagarswami, 1970;Monteforte and Garcia-Gasca, 1994).' Nevertl~eless, the average spat yield was about 10,000 individuals per box.…”

“…Since Gaston Vives's delineation of these essential conditions for La Paz Bay, there have been many failed attempts to reinstate mother-of-pearl farming and pearl culturing in Baja California. However, the recently established Pearl Oyster Research Group of the Northwestern Center of Biological Research (Grupo Ostras Perleras, Centre de Investigaciones Biologicas del Noroeste-CIBNOR) has succeeded in applying extensive cultivation techniques and repopulation strategies, to accomplish the production of cultured pearls, the first positive results in 90 years (Monteforte and Aldana, 1994;Monteforte and Bervera, 1994;Monteforte and Wright, 1994;Monteforte et al, 1994a and b). We believe that this recent success is due to our focus on the bioecology of the species and their response to different cultivation manipulations-the same factors that Vives had considered critical (Vives, 1908).…”

Abundancia y estructura poblacional de la madreperla Pinctada mazatlanica (Hanley, 1856) (Bivalvia: Pteriidae) en el litoral oriental de Baja California Sur, México

“…Su periodo reproductivo ocurre durante los meses de altas temperaturas en verano, cuando las ostras alcanzan el estado de madurez a partir de junio, pero los años con influencia del fenómeno de El Niño muestran un aumento del número de periodos de desove (García-Domínguez et al 1996, García-Cuellar et al 2004). La recolecta de la semilla de madreperla (definida como la larva pedivelígera que se ha fijado permanentemente a la superficie de algún objeto u organismo vivo, así como también se considera a los bivalvos entre 2 y 5 mm de altura de la concha, Saucedo 1995) en años típicos, se realiza durante agosto y septiembre (Monteforte & García-Gasca 1994) El presente estudio aporta información sobre el estado de las poblaciones de la madreperla Pinctada mazatlanica en el litoral oriental de Baja California Sur en términos de la variación geográfica de la abundancia y la estructura de alturas en los bancos naturales.…”