Applications of Biochemical Genetics to Aquaculture

Abstract

American lobster (Homarus americanus) catches are diminishing. More than 90% of the annual catch is 2.2-kg (1-lb) minimum legal size. Females of this size may have produced 10,000 eggs prior to catch, but, with an estimated larval survival of 1/100,000, 10 females are required to reproduce 1 female. The prognosis for the lobster fishery appears poor.Laboratory culture of larval lobsters can achieve more than 60% survival at a cost of about 2¢ per postlarval juvenile. The effectiveness of restocking has never been evaluated.Starch-gel electrophoresis reveals protein differences among individual lobsters: progeny studies confirm Mendelian inheritance of allozymes encoded by five independent genes, Est-2, Idh, Pgi-3, Pgi-4, and Pgm-1. Genetic markers may be determined by biochemical analysis of pereiopod tissue, without killing. Allozyme frequencies have been measured in natural populations (e.g. Pgm-1103 is absent in lobsters from Martha’s Vineyard (MVS), but occurs elsewhere in frequencies of 0.C2). Larvae with rare allozyme genotypes (e.g. Pgm-1100/103 or Pgm-1103/103 at MVS) may be obtained from selected females or produced by appropriate matings. These may be released, and their survival at selected times after release monitored by leg sampling from lobsters of the appropriate age-class. This technique is being used to select diverse parental stocks and produce progeny which may show hybrid vigor. These stocks will be used in developing lobster farming.