An Analysis of the Commercial Lobster (Homorus omericonus) 

 Fishery Along the Coast of Maine, 

 August 1966 Through December 1970 1 



By 

 JAMES C. THOMAS 2 



ABSTRACT 



We have used some life history information and detailed catch and effort data 

 from probability sampling of the commercial catch of lobsters to estimate a biological 

 minimum size of 89-mm (3'/2 inches) carapace length for maximum sustainable yield. 

 In view of this recommendation, the maximum size regulation of 127-mm (5 inches) 

 carapace length is unnecessary. 



INTRODUCTION 



A review of the publications concerning the 

 lobster fishery along the coast of Maine reveals 

 that limited funds have prevented any sustained 

 collection of detailed catch (numbers, pounds, 

 value; individual lengths, weights; percentages 

 of females, shedders, culls) and effort (traps, 

 trap-hauls, trap-haul-set-over-days, man-days 

 and hours, boat-days and hours) data from this 

 commercial fishery. The relatively new Federal- 

 State aid program has enabled us not only to 

 accomplish these prerequisites but also to 

 sample as many sizes as possible of the natural 

 population of lobsters within the limitations 

 of several types of gear. In addition, this funding 

 has enabled us to collect other biological in- 

 formation on lobsters that might have manage- 

 ment implications, such as (1) size ranges of 

 berried females and (2) relationship of premolt 

 and postmolt sizes. 



1 This study was conducted in cooperation with the 

 Department of Commerce, National Marine Fisheries 

 Service, under Commercial Fisheries Research and 

 Development Act, Project 3-14-R. 



2 State of Maine Department of Sea and Shore Fish- 

 eries, Fisheries Research Station, West Boothbay Har- 

 bor, ME 04575. 



From this combination of information, we 

 have made a first approximation of population 

 parameters that are necessary to make manage- 

 ment recommendations in accordance with 

 some theories in population dynamics. Budget- 

 ary limitations still prevent a complete study 

 of all the relationships usually analyzed in a 

 comprehensive investigation, for example, par- 

 ent-progeny or stock-recruitment relationships. 



To make the best use of appropriated funds, 

 we used probability rather than intuitive samp- 

 ling of the commercial catch. In this way, it 

 is possible for this and future surveys to be 

 more efficient in terms of determining the 

 sample sizes within a prescribed degree of 

 accuracy in each of the described catch and 

 effort categories. 



Some Aspects of the History of the 

 Commercial Lobster Fishery 



Before undertaking the stated objectives, 

 we examined the possible effects that regula- 

 tions had on the historical catch and effort 

 information. One way of evaluating these rela- 

 tionships is to juxtapose the regulations on 

 the compiled catch in pounds and number of 



