FISHERY BULLETIN: VOL. 77, NO, 4 



Narragansett Bay and Rhode Island Sound. Five 

 trap styles, representing the most commonly used 

 trap tjT)es in this area, were selected for use in the 

 study. Each fisherman was given traps of one type 

 only. 



Seven of the fishermen were provided with 

 equal numbers of vented and nonvented traps to 

 be arranged in trawls (strings) of alternating 

 vented and control traps. The escape panels were 

 constructed of 6061 gage aluminum with a 42 mm 

 X 152 mm opening placed in the parlor section of 

 the trap. Single parlor traps were equipped with 

 one vent placed vertically in the end section of the 

 parlor. Double parlor traps were equipped with 

 two vents positioned horizontally in the sides of 

 each parlor section. 



To determine the efficiency of vented traps when 

 compared with traps having equivalent lath spac- 

 ing and to evaluate the effects of vent orientation 

 (horizontal vs. vertical) on escapement, one of the 

 fishermen was given traps with the following 

 characteristics: 



1) control traps (mean lath spacing 31 mm, SD = 



6 mm), 



2) traps with horizontal vents (42 mm x 152 mm), 



3) traps with vertical vents (42 mm x 152 mm), 



4) traps with one vertical lath space opened to 42 



mm, 



5) traps with horizontal vents (44.5 mm x 152 



mm), 



6) traps with vertical vents (44.5 mm x 152 mm), 



and 



7) traps with one vertical lath space opened to 



44.5 mm. 



Each trap type was represented once in each trawl 

 and trap order was randomized both within and 

 between trawls. 



The fishermen provided with experimental gear 

 recorded the number of legal and sublegal lobster 

 per trap haul. Additional information on fishing 

 location, depth, bottom type, and soak time (set 

 over days) was also recorded. Periodic sampling 

 trips were made by personnel of the Rhode Island 

 Division of Fish and Wildlife, Marine Fisheries 

 Section. While on board commercial lobster boats, 

 we recorded the number of legal and sublegal lob- 

 ster per trap haul; physical condition including 

 molt status, appendage loss, and the presence of an 

 external egg mass on females; and carapace length 

 (measured from the posterodorsal edge of the eye 

 socket to the posterior margin of the carapace). 



RESULTS AND DISCUSSION 

 Catch Per Unit Effort 



Catch per trap haul (CTH) and CTH weighted 

 by immersion time (CTHSOD) were examined for 

 the seven fishermen provided with unmodified 

 control traps and traps equipped with rectangular 

 (42 X 152 mm) escape vents. A total of 18,984 

 lobster were obtained in 7,002 trap hauls of the 

 experimental gear. The overall catch of sublegal- 

 sized lobster was reduced by 79% in vented traps. 

 Dramatic reductions in the sublegal catch were 

 evident for each individual fisherman with one 

 exception (Table 1). The ratio of sublegal to legal 

 lobster was 1.375:1 in vented gear and 2.746:1 in 

 control traps, again indicating the efficiency of 

 vented traps in releasing sublegal lobster (Table 

 1). The overall mean CTH for sublegal lobster was 

 1.299 and 2.330 in vented and control traps, re- 

 spectively (Table 2). These results support the 

 findings of Krouse and Thomas (1975), Krouse 

 (1978), Pecci et al. (1978), and Fair and Estrella 

 (see footnote 2) in establishing the effectiveness of 

 employing vented gear. 



Table l. — Number of legal (378 mm CD, sublegal and percentage of legal American lobster; ratio of sublegal to legal lobst«r (S/L); and 

 the number of trap hauls (TH) in vented and nonvented gear for individual fisherman Numbers in parentheses are totals adjusted to 

 retain equal sample sizes. Chi-square contingency table analyses ( x ,^) tested the hypothesis that the catch of legal and sublegal lobster 

 is independent of trap type. 



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