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Adult Age‐Specific Embryonic Viability of the Northern Quahog
Author(s) -
Walker Randal L.,
Heffernan Peter B.
Publication year - 1996
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1577/1548-8675(1996)016<0633:aasevo>2.3.co;2
Subject(s) - biology , gamete , senescence , zoology , age groups , ecology , anatomy , human fertilization , demography , sociology , microbiology and biotechnology
This study assesses the viability of gametes produced by various age‐classes of the northern quahog Mercenaria mercenaria (Linnaeus, 1758). Using weight of gonadal material, previous investigators concluded that reproductive senescence did not occur in older northern quahogs. However, the viability of the gonadal material in older clams was not determined in those studies. We established two replicates of eight age‐groups (2–5, 6–10, …, 26–30, 31–34, and >34 years of age) and tested gamete viability. Age of clams had no significant effect on embryonic survival at 48 h. For all ages of parents, embryonic survival to day 2 was 20% with a range of 2. 1% to 32.8%. Within and among age‐class groups, variability in survival levels was similar. Unfertilized egg size (mean ± SE) was 87.97 ± 0.25 um, and the size‐frequency of eggs was normal. Individual unfertilized egg sizes (mean ± SE) ranged from 77.3 ± 1.07 to 100.5 + 1.19 μm. No linear relationship was evident between mean egg size and northern quahog age. These results show that older northern quahogs, although of little or no commercial value because of size, are a valuable reproductive resource and should be protected to ensure the continuation of the fishery.