FISHERY BULLETIN: VOL. 84, NO. 1 



deeper water (~8 m) just inside the reef tract; the 

 bottom consisted of a mosaic of scattered seagrasses, 

 small patch reefs, and open areas of coarse sand. 

 Salinities at both sites ranged from 34%o to 36%o 

 and water temperature ranged seasonally from 17° 

 to 29°C. 



The effect of exposure was examined at both sites. 

 Lobsters were held in shaded boxes for l k, 1, 2, and 

 4 h and then placed in traps. Entrances were sealed, 

 and no lobsters were added after treatments were 

 established. Each treatment utilized 5 standard 

 wooden slat lobster traps; each trap contained 3 

 lobsters (total 15 lobsters/ treatment) for each ex- 

 posure period. Control treatments (minimum ex- 

 posure) also consisted of 5 traps each containing 3 

 lobsters, but these lobsters remained in traps in 

 which they were originally captured and were ex- 

 posed only for the time required to clean, seal, and 

 return a trap to the water. Intent was to place 

 sublegal lobsters in all traps, but use of some larger 

 lobsters was necessary to conduct experiments. 

 Traps in oceanside experiments were reinforced with 

 wire mesh sides to reduce damage by loggerhead 

 turtles, Caretta caretta; traps in Florida Bay were 

 not reinforced with wire sides. 



In Florida Bay, all lobsters exposed >1 h were 

 dampened every x k h by pouring a bucket of seawater 

 into the porous holding box, whereas equal numbers 

 of lobsters exposed >1 h in oceanside tests were 

 always treated with and without seawater dampen- 

 ing every V2 h to test the effect of dampening. Con- 

 trol and V2-h treatments were the same in dampened 

 (wet) and undampened (dry) tests because their total 



exposure periods were less than or equal to the 

 period between dampenings. 



After initiation, all experiments were sampled at 

 1-wk intervals for 4 wk by pulling each trap and 

 counting remaining live lobsters. The mortality 

 estimate is a combination of missing lobsters and 

 those observed to be dead. Several lines of evidence 

 indicate that missing lobsters died and did not 

 escape Only lobsters too large to fit between trap 

 slats were used in experiments, and trap entrances 

 were boarded shut to seal the ordinary avenue of 

 departure Additionally, observations made during 

 frequent dives at traps where lobsters died during 

 other experiments indicated that carcasses could be 

 broken up sufficiently by scavengers within 24 h 

 after death to wash through slats when traps were 

 pulled. 



All original data, taken as number of living 

 lobsters remaining in a trap each week, were con- 

 verted to weekly mortality rates calculated as the 

 number of lobsters that died during that week divid- 

 ed by the initial density during that week. This 

 method provided the only independent, non- 

 cumulative estimate of mortality. All other methods 

 biased the data by either increasing the weight given 

 to deaths later in the experiment or altering mor- 

 tality estimates because of trap losses. Although this 

 method provided unbiased estimates of mortality, 

 data still were not normally distributed, so all testing 

 of treatment means used nonparametric Wilcoxon 

 Two Sample Tests (Sokal and Rohlf 1969) to deter- 

 mine where the differences of significance occurred. 

 Standard notations are used to designate signi- 



Table 1.— Average weekly spiny lobster mortality (%) for each location, exposure period, and 

 wet or dry treatment. N = number of traps; x = mean; SE = standard error; W = wet; D 

 = dry. 



70 



