KROUSE: INCIDENCE OF CULL LOBSTERS IN CATCHES 



Table 5-Comparison of the incidence of lobster culls in catches of wire and wood traps for various areas near Boothbay 



Harbor, Maine, 1969-74. 



correlation between fishing intensity and in- 

 cidence of culls; however, this does not preclude 

 other factors such as predation, intraspecific 

 competition, molting difficulties, and storm relat- 

 ed damages. 



Loss of Value of Catch Due to Culls 



At the beginning of this paper I mentioned that 

 culls have perennially detracted from the landed 

 value of the lobster catch. To assess this situation, 

 the regressions of weight for lobsters with missing 

 and regenerating claws on carapace length for 

 sublegal- and legal-sized lobsters were calculated. 

 These curves were then compared to the length- 

 weight relationship for noncull lobsters (Krouse 

 1973) (Figure 3). These comparisons reveal that 

 noncull lobsters are about 14 to 20% heavier than 

 those lobsters with regenerating and missing 

 claws. Knowing these weight differentials and 

 that about 6.5% of the lobsters in the commercial 

 catch are missing at least one claw (Table 4) and 

 that at least an equal percentage (6.5) of lobsters 

 must have regenerating claws, the cull loss to the 

 fishery can now be quantified. From the 1974 

 Maine Landings which reported a lobster catch of 

 16,457,666 pounds valued at $23,212,808, 1 estimat- 

 ed that the annual catch without any culls could 

 have been increased by about 363,700 pounds 

 (2.2%), adding $512,800 to the landed value. Un- 

 fortunately, there probably is no way to eliminate 

 culls completely; however, proper size escape vents 

 in all traps would be beneficial in effecting a 

 marked reduction in the incidence of culls (Krouse 

 and Thomas 1975). This reduction in culls would be 

 the result of decidedly fewer numbers of sub- 

 legal-sized lobsters being handled by fishermen as 

 indicated by the conspicuous disparity between 

 the size composition of research catches with wire 

 and vented wooden traps (Figure 2). Even if the 

 cull loss could be lessened by only 25%, the industry 



40 



50 



60 70 



CARAPACE LENGTH, MM 



Figure 3.-Comparison of the calculated length-weight relation- 

 ships for lobsters with regenerating, missing, and normal claws 

 (noncull). The regression equations are: 1) regenerating claws: 

 logio ^= -2.99-h2.91 logio L; 2) missing claws: log,o 

 W = -3.03 + 2.92 logio L; and 3) noncull: logio W' = -2.91-1-2.90 

 logic L- 



would still realize an annual increase of about 

 $128,000. 



ACKNOWLEDGMENTS 



I am grateful to the summer aides who assisted 

 in the collection of field data. Thanks are due to 

 David A. Libby for his help with data complila- 

 tions and figure drafting. I also extend my ap- 



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