FISHERY BULLETIN; VOL. 83, NO. 4 



Tagging Trial C 



Similar procedures were followed as for trials A 

 and B, but only the 1,830 m and a new 3,660 m 

 transects were set and exposure categories of 0, 15, 

 30, 60 min were used. Because parasite infection was 

 observed on some animals (6.3% of releases), its 

 presence was recorded as it could affect growth. The 

 infection is a combination of a fungus {Fusarium sp.) 

 and a bacteria {Vibrio sp.), which causes black lesions 

 in the exoskeleton, usually in areas that have been 

 damaged (e.g., tail fans and appendages). Infections 

 were scored on an ordered scale of 0-6, with in- 

 dicating no infection. About 2,900 tagged animals 

 were released. 



Results 



Figure 1 shows mean size (carapace) increment 

 related to month of recapture for each of three tag- 

 ging trials. In tagging trials A and C (November- 

 December releases), February was the first month 

 when there was evidence of molting in animals 

 recaptured (Fig. 1); therefore, subsequent analyses 

 on size increment only used recaptures from 

 February onwards. In tagging trial B (February- 

 March releases). May was the first month when there 

 was evidence of molting (Fig. 1), so only data from 

 this month onwards was used for the analyses. 



The results of an analysis of variance (ANOVA) on 

 size increment for each of three tagging trials is 

 shown in Tkble 1. In this analysis recapture month, 

 sex, color, displacement, and exposure were treated 

 as factors while size at release, damage, and level of 

 parasite infection were treated as covariates. The 

 analysis enables the significance of these factors and 

 covariates to be determined after effects of other fac- 

 tors and covariates are taken into account. 



In tagging trial A, after taking the effects of other 

 factors into account (eg., sex, recapture month, etc.), 

 the size increment per appendage missing was 

 smaller by 0.48 mm wdth standard error of 0.04. This 

 is also evident from Figure 2 which shows the rela- 

 tionship between mean size increment and numbers 

 of appendages missing for all recaptures from 

 February to June 1979. Size increment in tagging 

 trial C was also smaller by 0.48 mm per appendage 

 missing with standard error of 0.004 (see Figure 3), 

 while that for tagging trial B was 0.33 mm smaller 

 (standard error of 0.07). 



From the ANOVA, size increments of displaced 

 compared with nondisplaced animals were smaller 

 by 0.32, 0.65, and 0.27 mm for tagging trials A, B, 

 and C respectively. 



Exposure in tagging trial C, after other factors 

 were taken into account by the ANOVA, resulted in 

 increments smaller by 0.83, 1.34, and 2.30 mm for 

 15-, 30-, and 60-min exposure respectively, when com- 

 pared with the zero exposure category. This can also 

 be seen from Figure 3 which shows the mean size 

 increment for animals recaptured after February 

 1980 related to exposure and number of appendages 

 missing. While the effect of exposure on growth was 

 not significant for the February-March 1979 trial B, 

 size increments were smaller by 0.62 and 0.73 mm 

 for 30- and 60-min exposures respectively, compared 

 with unexposed animals. 



Mean size increment of males was larger than 

 females by 0.95, 1.34, and 0.76 mm for the three tag- 

 ging trials. Although the size at release of all animals 

 was between 66 and 76 mm, there was still a highly 

 significant decrease in size increment due to size at 

 release of 0.25, 0.36, and 0.20 mm for every 1 mm 

 increase in size at release Difference in color, i.e, 

 dark-shelled vs. pale-shelled animals, was significant 

 in tagging trial A with pale-shelled animals having 

 a greater size increment by 0.65 mm, but this was 

 not evident in tagging trial C. In tagging trial C, level 

 of parasite infection of the animals was found to have 

 had a detrimental effect on growth. 



DISCUSSION AND CONCLUSIONS 



Exposure 



Exposing undersize rock lobsters to the at- 

 mosphere was detrimental to their growth increment 

 at the first molt after exposure in both laboratory 

 and field tagging trials. In the December laboratory 

 experiment (Group II) the effect of exposure was still 

 significant at the second molt after exposure "Eg- 

 ging trial B (February-March 1979) resulted in ex- 

 posure not having a significant effect on growth 

 despite the presence of a negative trend between ex- 

 posure and size increment. This may have been due 

 to the fact that only 7 of the 110 animals recaptured 

 in May- June 1979 had been exposed; this is the 

 period when many of the undersize lobsters would 

 have undergone their first postexposure molt (Fig. 

 1). Since there is a closed season from 1 July to 14 

 November, no recaptures were made until the time 

 of the second postexposure molt in November- 

 December 1979, by which time the combined effects 

 of two molts may have masked the effect of the ex- 

 posure treatment. However, this was not the case in 

 tagging trial C (November-December 1979), which 

 was held at the start of the fishing season, where 

 the effect of exposure on the first molt which occurs 



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