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Induced Spawning of the Margined Madtom
Author(s) -
Stoeckel Joseph N.,
Neves Richard J.
Publication year - 2001
Publication title -
north american journal of aquaculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 41
eISSN - 1548-8454
pISSN - 1522-2055
DOI - 10.1577/1548-8454(2001)063<0099:isotmm>2.0.co;2
Subject(s) - germinal vesicle , biology , oocyte , yolk , ovulation , human chorionic gonadotropin , carp , human fertilization , andrology , follicle , zoology , fish <actinopterygii> , hormone , fishery , medicine , endocrinology , embryo , anatomy
Daily hormonal injections of male and female margined madtoms Noturus insignis induced captive spawning of 59 of 77 fish. Two injection treatments proved effective. Mean total dosage for one of the treatments was 5,372 IU human chorionic gonadotropin/kg plus 56 mg carp pituitary extract/kg; the other treatment was 572 μg LHRHa/kg plus 57 mg domperidone/kg. Of the 59 females induced to ovulate by the two hormonal treatments, 47% of them ovulated approximately 2 d after the first hormonal injection and 92% of them had ovulated within 4 d of the first injection. Inclusion of more than one breeding pair of margined madtoms per tank inhibited tank spawning, but females in tanks containing multiple pairs of fish ovulated and could be stripped. Embryos did not develop in 6 of 11 tank‐spawned egg masses or from any of 19 strip‐spawned egg masses. Margined madtoms consumed tank‐spawned egg masses when spawners were not removed from the nest. Oocyte diameter (≥3.5 mm) and germinal vesicle position (>90% toward the edge of the oocyte) can be used to determine which females will respond to hormonal treatments. However, catheterization to determine oocyte stage inhibited ovulation. Critical topics of research, before these techniques are applied to rare species, include refinement of oocyte staging methods and greater assurance that spawned eggs are fertilized.