Spatfall of pearl oyster, Pteria sterna (Gould), on experimental collectors at Bahía de La Paz, South Baja California, Mexico

Abstract

Spatfall of pearl oyster, Pteria sterna (Gould), was analysed at two sites, stations Gaviota and Merito, at Bahía de La Paz, South Baja California, Mexico, during an annual cycle in 1991‐1992. and from surface to 15 m depth. Sampling was carried out monthly using experimental collectors which remained immersed for 60‐65 days. Four different substrates were tested for spat settlement preference: a native bush called ‘chivato’, dry palm leaves, and red and yellow plastic onion bags: temporal variations, and horizontal and vertical spatfall distribution patterns were evaluated between and within stations. Spat settlement showed significant differences depending on the structure and texture of the substrate type. Chivato bush was in general the best spat collector, but was difficult to handle for large‐scale operations; plastic onion bags were more suitable and spat yield was adequate; palm leaves were poor spat collectors. There was no evidence for colour preference of spat settlement between red and yellow onion bags. Pteria sterna spat were present throughout almost all of the study period. Main spatfall was detected in winter‐spring, coinciding with low temperatures; most spat then occurred from surface to 4‐5 m depth. Few spat were present in summer and most then occurred below 7‐9 m depth. The distribution patterns of spat within substrate replicates were apparently influenced by the abundance of spatfall. Aggregated spatial patterns were evident in shallow water during months of maximum spatfall but not when spat was less abundant. These events did not occur in the same substrate type, and differences were also detected between stations. Trends were related to oceanographic conditions prevailing at each site. Two patterns of spatfall abundance and vertical distribution were evident, one for winter‐spring, and the other for summer. Samples at station Gaviota were grouped by spatfall abundance and spat vertical distribution patterns, while the latter defined better the grouping of samples at station Merito. Geographical variations of spatfall characteristics for Pteria sterna itself, and in comparison with Pinctada mazatlanka (Hanley) in the Gulf of California, are discussed.

Spat availability of commercial bivalve species recruited on artificial collectors from the northern Gulf of California. Seasonal changes in species composition

“…The general pattern resembles the winter–spring recruitment season described for the species in La Paz, Baja California Sur (Cáceres‐Martínez et al . ; Monteforte, Kappelman‐Piña & Lopez‐Espinosa ; Cáceres‐Puig ). In the southern portion of the Gulf of California, P. sterna is characterized by continuous gametogenesis throughout the year, with winter and spring spawning peaks (Díaz & Buckle‐Ramírez ; Saucedo & Monteforte ; Vite‐García & Saucedo ).…”

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

“…They also pointed out the necessity to further study the stock density and cleaning effects on P. mazatlantica. However, for Pinctada mazatlantica, as well as for Pteria sterna, preliminary studies indicated that the collectors should be recovered not later than 3 months after immersion, otherwise high seed mortality can occur as a result of predation and competition among associated species (Monteforte and Garcia-Gasca, 1994;Monteforte and Wright, 1994;Monteforte et al, 1995;Wright, 1997).…”

“…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.…”

Growth and survival of the Calafia mother-of-pearl oyster Pinctada mazatlanica (Hanley 1856) under different sequences of nursery culture-late culture at Bahía de La Paz, Baja California Sur, México

“…Usually, spat remain in the collectors for as long as 6 months after which they are removed and placed into different kinds of rearing containers where the culture process takes place until the time of pearl induction operations (Wada 1973;Coeroli et al 1984;Gervis & Sims 1992). However, for P. mazatlanica, as well as for P. sterna, earlier works have demonstrated that collectors must be recovered no later than 3 months after immersion, otherwise high mortality of spat can arise as a result of predation and competition with associated species (Monteforte & Garcõ Âa-Gasca 1994;Monteforte & Wright 1994;Monteforte, Kappelman & Espinoza 1995;Wright 1997). Because the harvested spat is still small and fragile, the nursery culture constitutes a well-de®ned stage in the culture process of our local pearl oyster species.…”