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Whelk
Fishery
An important molluscan fishery in Georgia until
recent years, it was mainly a winter trawl fishery. Landings in
the past few years are reported to have declined to levels making
it currently uneconomical. This cyclical pattern of exploitation
and recovery is typical of whelk fisheries worldwide. Studies
have been completed by MAREX to develop trawling gear that reduces
turtle captures. Gear has also been tested to evaluate the
potential of developing a pot
based fishery, similar to whelk fisheries in the northeast.
We are currently examining the Georgia whelk population structure
(species, size) in both the offshore and intertidal environment.
Eighteen months of trawled samples from a commercially harvested
area have been processed and the population data is being analyzed.
The reproductive cycle has been elucidated through gonadal indices
based on reproductive organ weights expressed as a percentage
of the eviscerated weight, and also through a histological analysis
of the male’s seminal vesicle, which stores spermatozoa
prior to copulation. The reproductive cycle will be confirmed
through a histological analysis of the gonads. Egg capsule morphometrics
and the diets of hatchling whelks have been documented Power,
A.J., Covington, E., Recicar, T., & Eller, N., 2002. Observations
on the egg capsules and hatchlings of the knobbed whelk, Busycon
carica in coastal Georgia. Journal of Shellfish Research 21:769-776.
Data analysis of our intertidal component, a massive
mark and recapture effort involving the tagging of thousands of
specimens is also underway. This study will document growth, intertidal
population structure, and movement
patterns. Research into genetic parentage with our research
associates, Dr. John Avise, and Dr. DeEtte Walker from the UGA
Genetics Department has identified a sex associated microsatellite
marker which has been used to refute the theory that these whelks
are sequential protandrous hermaphrodites Avise,
J.C., Power, A.J. & Walker, D. Genetic sex determination,
gender identification and pseudohermaphroditism in the knobbed
whelk, Busycon carica (Mollusca: Melongenidae). Proceedings of
the Royal Society of London, Series B, 271: 641-646
and Walker, D., Power,
A.J. & Avise J.C. Sex linked markers facilitate genetic parentage
analysis in knobbed whelk broods. J. Heredity 96(2): 1-6.
A manuscript documenting the micro-spatial and temporal arrangements
of genetic paternity along egg-strings of the knobbed whelk is
currently being reviewed for publication in Molecular Ecology
Walker, D.,
Power, A.J., Sweeney-Reeves, M. and Avise, J.C. Multiple Paternity
and an “Almost-Smooth-Gravy” Model for Female Sperm
Usage along Egg-Case Strings of the Knobbed Whelk, Busycon carica
(Mollusca; Melongenidae).
It is hoped that the fundamental life history information
generated by these studies will assist the Georgia Department
of Natural Resources develop a sustainable management plan for
one of our most economically important shellfish species.
Georgia
Whelk Landings
Intertidal
Whelk Population Poster ppt (pdf)
Knobbed Whelk
Life History Poster ppt (pdf)
Whelk
Fishery Brochure |
