Despite a wealth of information on the growth and population dynamics of sub-adult and 
adult Caribbean spiny lobsters (Panulirus argus), there is far less information about 
younger juveniles under natural conditions. Growth and population dynamics of juvenile 
spiny lobsters (12 - 68 mm carapace length, CL) that were studied for 14 months 
(October 1988 - December 1989) are described using mark-recapture techniques in a 
hardbottom community in Florida Bay. The supply of postlarvae into the region in 1988 
and 1989 was monitored using Witham-type surface collectors in an effort to link peak 
periods of settlement of postlarvae with subsequent cohorts of juveniles. Field 
estimates of growth were the highest ever reported for this species, averaging 0.95 
mm CL wk' 1 (range: 0.35 - 1.25 mm CL wk* 1 for individuals 2 - 25 mm CL and 40 - 45 
mm CL, respectively). These results indicate that lobsters in some areas in Florida Bay 
can reach Florida's legal harvestable size (76 mm CL) 1.5 yrs after settlement. Season 
and lobster size had significant effects on growth rates; less growth occurred during 
the winter and among small individuals. Differences in growth among size classes 
resulted from changes in molt increment, whereas seasonal differences were a result 
of changes in intermolt interval. Using mark-recapture techniques, we estimate that 
the density of juvenile spiny lobsters <45 mm CL in this prime nursery habitat was 454 
ha' 1 , that the mean monthly probability of survival (reflecting actual mortality plus 
emigration) was 0.51, and that an average of 131 lobsters entered the population 
through re-recruitment and immigration each month. Recruitment of juveniles was 
significantly correlated (r = 0.83) with the supply of postlarvae to the region 8 months 
earlier. This relationship is stronger than was previously believed, and may only be 
manifested in areas with superior nursery habitat. Sampling took place in Fiesta Key 
from 1988 to 1989. 
1988 - 1989 
Ley, J. A., and C. Montague (1989) Influence on changes in freshwater flow to northeast 
Florida Bay on use of mangrove prop root habitat by fish. Pilot study submitted to the South 
Florida Water Management District. University of Florida, Gainesville, FL. 42 pp + 
appendices. 
The objective of this study was to measure quantitatively the fish communities in the 
fringing red mangrove habitat of Florida Bay over a broad range of mean salinity and 
salinity variation conditions and determine if corresponding fish community differences 
exist. To accomplish this objective, upstream, mid-bay and downstream stations 
across a salinity gradient were located in two tributary creek systems, Snook Creek in 
Joe Bay and Highway Creek in Long Sound, that carry freshwater to northeast Florida 
Bay. Comparisons were made between upstream and downstream over a period of 
transition from along dry season (winter and spring) to wet (summer and fall). Also 
sampled were sites in Little Blackwater Sound, Duck Key and Pelican Key. Eight 
methods were used to sample fish, three visual and five collecting methods. Overall, 
more than 43,000 fish and invertebrates were observed at 71 station/dates. All data 
is included in the citation. 
1988 - 1990 
Manire, C. A., and S. H. Gruber (1991) Effect of M-type tags on field growth of juvenile 
lemon sharks. Trans. Amer. Fish. Soc. . 120:776-80. 
Previous experience with M-type dart tags suggested that their implantation causes 
trauma and retards growth of small sharks. To test this hypothesis, a group of 76 
Juvenile lemon sharks Negaprion brevirostris of a precaudal length of l 9 ss than 80 cm, 
were marked with tiny (2 mm x 11 mm), passive integrated transponder (PIT) 
microtags, implanted intramuscularly. A second group of 563 lemon sharks of the same 
size range was marked with M-type dart tags, and both groups were released around 
Big Pine Key in Florida Bay. Growth of 10 recaptured fish with the M-type tag averaged 
320 
