release sites to zones of moderate to high fishing intensity. For 

 instance, at Boothbay Harbor tagged lobsters were released 

 more seaward than at the other areas and were therefore more 

 removed from immediate fishing pressure. Also, based on our 

 sightings of boats towing their nets near the release area shortly 

 after liberating tagged lobsters and rumors of trawlers catching 

 tagged lobsters but not reporting them (unlawful for trawlermen 

 to land lobsters in Maine), there is reason to believe that perhaps 

 several of the Boothbay Harbor releases were removed from the 

 fishery by trawlers. In Jonesport, where returns were the 

 highest, even though releases were in an area with very few 

 traps, substantial concentrations of traps were only about 1 

 n.mi. (1.9 km) away in all directions; whereas, at 

 Kennebunkport, where returns were intermediate to the other 

 two areas, the proximity of the area's release site to the trap 

 fields would be ranked between that of Jonesport and Boothbay 

 Harbor. 



Because differences in tag recoveries by area might be par- 

 tially due to any variations in the tagging adeptness of the two 

 biologists who applied the tags in this study, we evaluated this 

 possibility by comparing the proportions of the number of 

 lobsters returned with those tagged by biologists at each release 

 site (Table 2). As there were no significant differences (chi- 

 square test, P>0.05) between these proportions, it appears that 

 the biologists applied the sphyrion tags with nearly equal skill; 

 thus any major variations in returns from different areas could 

 not be related to differences in numbers of lobsters marked by 

 any one tagger. 



Table 2. — Comparison of the proportions of American lobsters recaptured with 

 those tagged by two biologists at each release area, 1975-77. Chi-square values 

 indicating no significant difference (P>0.05) between proportions are denoted 

 by NS. 



Table 3. — Mean sizes (carapace length) of tagged American lobsters recaptured 

 along with those lobsters not recaptured, 1975-77. 



Kennebunkport 



Boothbay 

 Harbor 



Jonesport 



Total 



Number la re- Number la re- Number °!a re- Number la re- 

 Tagger tagged turned tagged turned tagged turned tagged turned 



A 



560 79 



514 70 



490 85 



1,564 78 



B 



394 69 



428 64 



493 84 



1,315 73 



*-' 



1.61 NS 



0.58 NS 



0.0001 NS 



1.03 NS 



Four months after release, 53-81 % (67% combined) of the tagged 

 lobsters had been returned in each area, and after 1 yr 66-85% (75% 

 combined) had been recaptured. These high rates of return, 

 which corroborate the lobster fishery's high exploitation rate, 

 have undoubtedly been reduced by tag loss, incomplete report- 

 ing of recaptures, and natural and tag induced mortality. Based 

 on our observations of lobsters following tagging until time of 

 release and our close familiarity with the fishing community, it 

 appears that only a negligible number of lobsters died as a result 

 of tagging or were captured and not reported (exclusive of 

 Boothbay Harbor). Thus, in this study, tag loss and natural 

 mortality (< 10% annually, Thomas 1973) were probably the most 

 important sources of error. 



The effect of size on catchability was examined by compar- 

 ing the mean carapace length of lobsters recaptured at each 

 release site with those tagged lobsters not recaptured before 

 October 1977 (Table 3). The /-test (P>0.05) revealed no 

 significant difference between the mean sizes of those lobsters 

 caught with those still at large. Similarly, the chi-square test 

 indicated no statistical differences (P>0.05) between sex 

 ratios of lobsters returned to those liberated (Table 4). 





Kennebunkport Boothbay Harbor 

 CL (mm) SE CL (mm) SE 



Jonesport 



Tagged 

 lobsters 



CL (mm) SE 



Recaptured 

 Not recaptured 



86.5 ±0.14 87.5 ±0.21 



86.6 ±0.24 87.0 ±0.29 



87.4 ±0.19 

 87.8 ±0.40 



Table 4. — Comparison of the sex ratios of tagged American lobsters released 

 with those recaptured at each release area, 1975-77. Chi-square values indicating 

 no significant difference between sex ratios of lobsters released to those recap- 

 tured are denoted by NS. 





Kennebunkport 

 Ratio 

 6 9 (6:9) 



Boothbay Harbor 



Ratio 



rf 9 (rf:9) 



Jonesport 



Tagged 

 lobsters 



Ratio 

 rf 9 (6:9) 



Recaptured 

 Released 



316 400 0.79:1 



415 542 0.77:1 



0.07NS 



314 320 0.98:1 

 456 486 0.94:1 



0.1 5NS 



359 478 0.75:1 



439 544 0.81:1 



0.05NS 



Although the above analysis indicates that there probably 

 was no difference in the catchability of legal-sized lobsters by 

 size and sex, plots of the percentages of lobsters not recaptured 

 against carapace length show that 4-9% fewer 81 than 82 mm CL 

 lobsters were returned (Fig. 3). This disparity might appear to 

 be due to gear selectivity, but is in fact unlikely since previous 

 studies (Krouse 1973; Krouse and Thomas 1975) show that 

 lobsters become fully vulnerable to conventional lobster pots 

 at about 75 mm CL. Actually this lower than expected catch of 

 small legal lobsters is due to the Maine fishermen's method of 

 measurement and interpretation of what lobsters are legal to 

 keep. The minimum legal size is 81 mm (3-3/16 in) CL in 

 Maine; but the minimum size retained in practice is closer to 

 82-83 mm. This conclusion is further supported by length fre- 

 quencies of Maine commercial lobster catches compiled by 

 Thomas (1973) which showed marked deficiencies of the 81 

 mm group; in fact, even the 82 through 84 mm sizes were less 

 numerous than expected. 



A KENNEBUNKPORT 

 O BOOTHBAY HARBOR 

 D JONESPORT 



60 65 90 9S 100 



CARAPACE LENGTH (mm) 



Figure 3. — Size distributions of tagged American lobsters still at large after 

 September 1977 (about 28 mo since release) at each tagging area. 



Growth 



From July 1975 through May 1977, only 66 (3.0%) lobsters of 

 2,188 returns had molted prior to recapture. This extremely 



