Larval growth and survival of two catarina scallop ( Argopecten circularis, Sowerby, 1835) populations and their reciprocal crosses

Abstract

Populations of catarina scallop are distributed along both coasts of the Baja California Peninsula, Mexico. Those populations represent potentially different genetic resources for aquaculture, and the evaluation of their genetic and production characteristics is important. To determine those characteristics, intra- and intercrosses of two populations were produced and their phenotypic response to growth and survival at the hatchery were compared, determining the relative magnitude of maternal effects and heterosis. There was a clear maternal effect for survival, evidenced by a difference between the reciprocal crosses. Larvae from the Magdalena (M) population and the reciprocal cross produced with those eggs had a higher survival (45.8% and 47.5%) than larvae from the Concepción (C) population and its maternal reciprocal cross (32.5% and 28.9%). Average growth during the larval period indicated larvae derived from Bahı́a Magdalena spawners had a larger size (±half width confidence intervals) (166.8±7.9 μm) than those derived from Bahı́a Concepción spawners (140.4±6.7 μm). Both reciprocal crosses (F1-paternal–maternal) larvae grew (160.1±7.7 and 153.3±7.3 μm, F1-CM and F1-MC) as well as the Magdalena larvae. When length was analyzed at age to determine the effects of egg origin and mating strategy on growth, a significant maternal effect was revealed on the reciprocal crosses' growth up to day 11, which decreased by day 15, and disappeared by day 17. The dissipation of maternal effects was coincident with the first appearance of a heterosis value by day 15 (3.5%), increasing to day 17 (6.8%). The presence of maternal effects is explained because egg energy reserves are different between the two populations despite the simultaneous conditioning for 15 days for both groups of spawners prior to spawning induction. The importance of stock selection is emphasized not only for juvenile or adult phenotypic traits of artificially-produced progeny, but also on the maternal quality of the spawners producing that progeny.