Beach Seining Project for
Young-Of-the-Year Bonefish and Permit
Bonefish support an economically-important recreational fishery in south Florida . Despite their ecological and economic relevance, there is little scientific knowledge on early life history, recruitment and juvenile population dynamics of bonefish. To develop an understanding of the early life history and recruitment of juvenile bonefish we started a monthly seining study on the oceanside of Key Biscayne to understand the seasonality and settlement habitats of juvenile bonefish.
A stratified random sampling methodology was utilized to assess habitat requirements and recruitment dynamics of YOY bonefish. The stratification was based on NOAA benthic habitat maps for Key Biscayne generated from high resolution aerial photographic surveys (far left ). All habitats, with the exception of hard bottom, were randomly sampled each month for a period of one year (September 2003 to August 2004).
The seining gear used was a 21.3 m center-bag seine that was deployed parallel to the beach at a distance of 9.1 m and then hauled in an arc towards shore. The large size of the net reduced net avoidance which is common due to the bonefish's fast swimming speed.
Surface area covered by the net is 377 m2. Environmental data on water quality (temperature, dissolved oxygen, and salinity) was recorded for each sample. In addition, habitat characteristics (shore vegetation, bottom vegetation, and percent bottom cover), the lunar phase, tidal cycle and climatic parameters, such as wind speed/direction, cloud coverage and coastal oceanographic conditions, were recorded for each sample.
The study revealed that the recruitment of YOY bonefish to Key Biscayne occurred between October and June (far right).
Thirty-seven young-of-the-year bonefish (<370 mm total length as defined by Crabtree et al. 1996) and 3 bonefish leptocephali were captured (photos below) in the first year of the project.
Bonefish leptocephalus
captured in the beach seine.
Juvenile bonefish
caught in the beach seine.
The following table below shows the average total length and numbers of juvenile bonefish and permit collected in a monthly stratified-random-sampling beach-seining project. The sampling for the month of April did not produce any juvenile bonefish but it did produce two Bonefish leptocephalus*.
The project not only collected YOY bonefish but also YOY permit (185 mm TL as defined by Crabtree et al. 2002).
A total of 371 permit were collected which showed a bimodal distribution with peaks in September to November and May to June (far right ).
Crabtree et al. (2002) define the spawning period of permit it Florida to be from May to July, however, this project has caught YOY of the year permit in every month of the year.
This suggests that the permit
spawning period may be more extended than previously believed.
Young-of-the-year
permit caught in the beach seine.
Literature Cited
Crabtree, R.E., Harnden, C. W., and D. Snodgrass 1996 Age, growth, and mortality of bonefish, Albula vulpes , from the waters of the Florida Keys . Fish. Bull. 94(3):442-52.
Crabtree, R.E., Hood, P.B., and D. Snodgrass. 2002. Age, growth, and reproduction of permit , Trachinotus falcatus , in Florida waters. Fish. Bull. 100:26-34.