Effects of water depth on survival and growth of

Authors: Miguel Avendaño Marcela Cantillánez Gérard Thouzeau

Publish Date: 2007/11/28

Volume: 16, Issue: 5, Pages: 377-391

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Abstract

Collection and suspended culture of Argopecten purpuratus spat in Japanesetype collectors was undertaken in the Rinconada Marine Reserve Antofagasta Chile to determine growth variations between surface and bottom waters Scallop spat was collected at 16m depth and grown at 1 and 16m depths An initial settlement of ca 13000 postlarvae per bottom collector 2 cohorts was observed on 3 February 2001 Two new cohorts settled in bottom collectors on 3 March while no spat settlement occurred in surface collectors The four cohorts exhibited substantial and different mortality rates over the study period depending on the cohort and ongrowing depth The first and second cohorts exhibited mortality rates of 803 and 531 in bottom collectors respectively versus 29 and 436 in surface structures The third and fourth cohorts exhibited mortality rates of 214 and 597 in bottom collectors respectively Mean shell height of scallop spat after 88 days of culture was 646 mm for the first cohort and 437 mm for the second cohort in bottom collectors versus 1033 and 731 mm in surface collectors respectively Mean postlarval growth rate in bottom collectors 86 μm day−1 was significantly lower than growth rate in surface collectors 146 μm day−1 Factors explaining the depthrelated mortality and growth rates are discussed to improve scallop culture in the Reserve It was concluded from the results that culture improvement in Antofagasta Bay would require collecting spat in bottom waters and raising it near the surface during initial cultivation stages

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