INCIDENCE OF CULL LOBSTERS, HOMARUS AMERICANUS, IN 

 COMMERCIAL AND RESEARCH CATCHES OFF THE MAINE COAST^ 



Jay S. Krouse^ 



ABSTRACT 



Data obtained by port sampling the Maine commercial lobster catch (1968-74) and the natural lobster 

 population near Boothbay Harbor, Maine, with research gear (1969-74) indicate that 6.5% of the 

 commercially harvested lobsters have lost at least one claw while 21.0% of the lobsters (all sizes) in the 

 natural population have missing and/or regenerating claws. An assessment of variations in cull 

 frequencies associated with different seasons, fishing localities, and lobster size distributions suggests a 

 direct relationship between fishing intensity and the incidence of culls. This information further 

 supports Krouse and Thomas' recommendation that all lobster traps be equipped with an escape vent 

 thus minimizing fishermen's needless handling of excessive numbers of sublegal-sized lobsters. 



Over the years the occurrence of American lobster, 

 Homarus americantis, with a missing and /or 

 regenerating cheHped in the commercial landings 

 has undoubtedly resulted in a significant financial 

 loss to the fishing industry due to the culls' reduced 

 weight and marketability (retail price of culls is 

 less per pound). Scarratt (1973) reported that 

 commercially caught lobsters from ports off Nova 

 Scotia and Prince Edward Island had incidences of 

 missing claws ranging from 5 to 19%. Although 

 claw loss could not be attributed to a single factor, 

 causes related to fishing such as rough handling by 

 fishermen and movement of traps over the seabed 

 were cited. Recognizing the importance of this 

 situation, I have analyzed cull data provided by the 

 Maine Department of Marine Resources Lobster 

 Research Program's research catches (Krouse 

 1973) and sampling of the commercial catch 

 (Thomas 1973). In this paper I attempt to assess 

 the magnitude of the cull problem along the Maine 

 coast, some of its causes, and a possible solution to 

 diminish the number of culls. 



METHODS 



From June 1969 through December 1974, the 

 occurrence of lobsters with missing and/or regen- 

 erating claw(s) in daily catches of research gear 



'This study was conducted in cooperation with the U.S. 

 Department of Commerce, National Marine Fisheries Service, 

 under Public Law 88-309, as amended. Commercial Fisheries 

 Research and Development Act, Project 3-153-R. 



^Maine Department of Marine Resources, West Boothbay 

 Harbor, ME 04575. 



was noted. Carapace length in millimeters, weight 

 in grams, and sex were recorded for each lobster. 

 Wire lobster traps (2.54 x 2.54 cm mesh) were 

 fished throughout the 6-yr period, whereas 

 modified wooden traps with plastic escape vents of 

 3.81, 4.13, and 4.45 cm were not used until July 

 1972. Most experimental fishing was conducted in 

 the vicinity of Capitol, Squirrel, and Damariscove 

 islands in the Boothbav region of Maine (Figure 



1). 



Information pertaining to the frequency of culls 

 in the Maine commercial catch from 1968 through 

 1974 was obtained from the probability sampling 

 program described by Thomas (1973). 



A length-weight relationship was calculated for 

 297 lobster's with a regenerating claw and for 225 

 lobsters with a missing claw collected near Booth- 

 bay Harbor, 1972-73. All lobster culls used in this 

 determination had one normal sized claw. The 

 regression of weight on carapace length for these 

 two cull categories was fitted by the method of 

 least squares using the logarithmic transforma- 

 tion logio W = logio a + b logio L. 



RESULTS AND DISCUSSION 



Seasonal and Size Variation in • 

 Cull Frequency 



From the research catches I have calculated the 

 percentage of culls by month and 5-mm size groups 

 for 1969 through 1974 (Tables 1, 2). Fluctuations in 

 the monthly percentages of culls seem to follow a 

 seasonal pattern, i.e., the number of culls peaked 



Manuscript accepted May 1976. 



FISHERY BULLETIN: VOL. 74, NO. 4, 1976. 



719 



