Jenkins, W.E., Bridgham, C.B., Smith, T.I.J.
Abstract:
Red drum are an important recreational species in the southeast US
and are spawned in several states to support stock-enhancement
programs and research. In addition red drum are being commercially
cultured in many parts of the world including the US, south and
central America and the Far East. Controlled spawning of red drum
has been well documented since the late 1970's however methods
described to date do not allow precise prediction of spawning date. In
order for culturists with limited conditioning tanks and broodstock to
optimize air shipment and stocking schedules fish must be
programmed to spawn on specific days of the week.
Fish (3 females and 5 males) were subjected to a standard 6 month
conditioning cycle using photothermal cues. Once fish began to
spawn temperature and photoperiod remained constant (25 C, 13 hrs.
light) until fish spawning became extremely unpredictable (elapsed
time = about 3 months). Eggs were collected and estimated daily. Egg
production during this period was highly variable and ranged from 0 -
1.7 million/day (73 spawns, 649,000 eggs/spawn). Total egg
production during the 3 months was 47 million (68.4% viable). Once
spawning became unpredictable fish were put into a cycle in which
water temperature was manipulated as follows: 25 C for 4 days
followed by 21 C for 3 days. Fish would spawn the day after
temperature was raised and continue spawning until temperature was
lowered. This could be used to schedule pond preparation or
shipments to other facilities weeks in advance. Using this technique
fish were spawned on schedule weekly for 14 months. During that
time fish spawned 154 times (570,000 eggs/spawn) producing 87
million eggs (74.7% viable).
(South Carolina Department of Natural Resources, Marine Resources
Research Institute, P. O. Box 12559, Charleston, South Carolina,
USA 29422-2550)