Inshore Gulf of Maine Jonah Crab (Cancer Borealis)

Fisheries Pêches and Oceans et Océans DFO Science Maritimes Region Stock Status Report C3-66(2000)

Inshore Gulf of Maine Jonah Crab (Cancer borealis) Summary Background • Jonah crab landings in the exploratory The Jonah crab, Cancer borealis, is found from Nova fishery in LFA 34 peaked at 146 t in Scotia to South Carolina and in the Bermudas at 1997. Preliminary landings in 1999 were depths ranging from intertidal to 800 m. In the waters off Nova Scotia the crabs are found primarily 119 t. Based on logbook analysis, annual at depths of 50-300 m and temperatures of 8-14°C. average catch rate ranged between 4.1 The Jonah crab's substrate of preference ranges from and 4.8 kg. per trap haul (kg/th) from rocky off the coast of Maine to sand and clay off 1996 to 1998 and increased to 6.3 (kg/th) Chesapeake Bay. during the 1999 season. • As with lobsters, the female broods her eggs on the Reported landings of Jonah crab under swimmerets under the abdomen. The larvae develop the bycatch provision in the inshore through several plankton stages in the water column lobster fishery surpass those of these before settling to the bottom. Most male Jonah crabs new exploratory fisheries. Removals are physiologically mature at 90-100 mm carapace through this bycatch are considered to be width (CW) and most females mature at 85 mm CW. Maximum carapace width for males is approximately underestimated. Until the quantity of 180 mm with a weight of 0.9 kg. Females usually do Jonah crab removals by the lobster not exceed 150 mm (CW) and 0.5 kg in weight. fishery is evaluated, biological sustainability of the directed fishery Inshore Gulf of Maine exploratory rock and Jonah cannot be evaluated. crab fisheries were initiated in southwest New Brunswick (Lobster Fishing Areas, LFA’s 36 & 38) • Jonah crab landings in LFA 38, after the in 1995 and in southwest Nova Scotia (LFA's’34 & addition of four more permits in 1998, 35) in 1996. Two Developing Species Advisory increased to 61 t. Preliminary landings, Boards (DSAB’s) were created to manage these new in 1999 were 51 t. Based on logbook crab fisheries as well as other developing fisheries. One was initiated in southwest New Brunswick in analysis, annual catch rates ranged 1995 and the other in southwest Nova Scotia in 1996. between 4.8 and 6.5 kg/th from 1995 to The crab permits were distributed by Lobster Fishing 1999. Areas (LFA’s).

March 2000 Maritimes Region Inshore Gulf of Maine Jonah Crab

• Although no commercial concentration open all year. For participants to retain their of Jonah crab was found in LFA 35, exploratory fishing permits, they were preliminary exploratory fishing results required to complete 15 fishing trips and had (up to 0.7 kg/th) in the southwestern part to land at least 30 % of the average landings of LFA 36 shows some potential. (in weight) of all fishers within a given year • Based on at sea sampling of trap for their respective LFA. contents, monthly mean size of males and females were larger in LFA 34 The exploratory Jonah crab fishery, in compared to LFA 38. This is due to operation since 1995, has located two different trap types and smaller commercial concentrations. One is located minimum legal size in LFA 38. in LFA 34, off southwestern Nova Scotia in • Lobster by-catch in the inshore Jonah the midshore (yearly catch rates of 4.1 to 6.3 crab fishery was negligible. kg/th), and the other is located in LFA 38 off southern Grand Manan (yearly catch rates of The Fishery 4.8 to 6.5 kg/th). Jonah crab were found in the southwestern New Brunswick (LFA 36) but due the low yearly catch rates there (0.3 Evolving from two separate Developing to 0.7 kg/th), have not yet been proven Species Advisory Boards (DSAB’s), the commercially viable. present management regime has various regulations. Presently, in LFA 34 and 35 Distribution of Jonah crab fishing locations as reported participants are allowed to land Jonah crab in fishers’ logbooks only. The minimum size limit for male Jonah crab was set at 130 mm CW. Modified lobster traps were permitted to be used as well as conical crab traps, with a trap limit of 375. Traps were to include a minimum of two escape gaps of a minimum diameter of 79 mm (3.125 inches). They were only allowed to begin fishing for crab one week after the closer of the spring lobster fishing season, and had to remove their traps one week before the opening of the fall lobster fishing season. In order for participants to retain their exploratory permits, they had to land and sell a minimum of 10,000 kg of Jonah crab. Resource Status In LFA’s 36 & 38, exploratory crab permit There are no fishery-independent surveys holders were allowed to land rock and Jonah for this species, and this assessment is based crab. The minimum size limit for male on catch rates and size composition data Jonah was set at 121 mm CW. The trap limit from the commercial catch. Traps are highly was set at 200 in LFA 36 and 300 in LFA selective, and crustacean catchability is 38. Only conical traps were allowed, and affected by a variety of factors. The catch were required to have a minimum of two rate data have not been standardized for circular openings of 63.5 mm (2 ½”) in fisher, trap type, area and season, and diameter. Also the crab fishing season is standardization would be difficult because

2 Maritimes Region Inshore Gulf of Maine Jonah Crab the important variables are available for only average rates varied between 4.8 and 6.5 a small subset of the data. Some of the kg/th. Monthly catch rates varied between variation in the catch rate and size months and did not follow any trend. composition probably results from factors other than the abundance of Jonah crab. Yearly average catch rates were similar in both LFA’s despite the fact that different Jonah crabs were found in commercial trap types were used. Low concentrations of concentration in only two areas; a midshore Jonah crabs were also found in LFA 35 area in LFA 34 (4.0 to 6.3 kg/th) and off (Annapolis Basin) (0.05 to 0.09 kg/th) and southern Grand Manan in LFA 38 (4.8 to 6.5 LFA 36, off Campobello (0.3 to 0.7 kg/th). kg/th). In LFA’s 34 and 38, most of the Jonah Crab Catch Rate and Effort (LFA 34, 1996-99) fishing took place between June and the end 12 12000 (TH) 10 of October even though the crab season was 10000 (Kg/TH) 8 Hauls

open all year in LFA 38. Hauls 8000 p p 6 6000 er Tra

4000 4 p .

In LFA 34, between 2 & 8 crab fishers have g No. of Tra been fishing for Jonah crab since 1996. 2000 2 K 0 0 Jonah crab landings obtained from logbooks Jul-96 Jul-97 Jul-98 Jul-99 Oct-96 Oct-97 Oct-98 Oct-99 Jun-96 Jun-97 Jun-98 Jun-99 Sep-96 Sep-97 Sep-98 Sep-99 Aug-96 Aug-97 Aug-98 peaked in 1997 at 146 t. However, the 1999 Aug-99 landings of 119 t are not complete due to Monthly Periods missing logbooks. From 1996 to 1998 yearly Jonah Crab Catch Rate and Effort (LFA 38, 1995-99) average catch rates have varied between 4.1 12 5000 (TH) and 4.8 kg/th and during the 1999 season the 10 4000 (Kg/TH)

8 Hauls Hauls

yearly average catch rate increased to 6.3 p

p 3000 6 kg/th. Monthly average catch rates showed 2000 4 er Tra p . an increasing trend in CPUE between 1000 g

No. of Tra 2 K months from July to September of each year. 0 0 Jul-95 Jul-96 Jul-97 Jul-98 Jul-99

Jonah crab 1995 1996 1997 1998 1999 Oct-95 Oct-96 Oct-97 Oct-98 Oct-99 Sep-95 Sep-96 Sep-97 Sep-98 Sep-99 Aug-95 Aug-96 Aug-97 Aug-98 Aug-99 LFA 34 Trap Hauls 4079 36598 13035 18966 (Midshore) Landings (t) 19 146 54 119 Monthly Peri ods Mean CPUE 4.8 4.0 4.1 6.3 No. of Logbooks 2 8 6 5 By-catch (t) ** ** ** 289 152 LFA 35 Trap Hauls 3010 4165 2550 Landings (t) 0.2 0.2 0.2 At-sea sampling provides detailed Mean CPUE 0.07 0.05 0.09 No. of Logbooks 3 4 2 information on crab size structure in the By-catch (t) ** ** 0 LFA 36 Trap Hauls 1359 3422 3210 traps. All crabs retained in individual trap Landings (t) 0.04 1.8 2.3 Mean CPUE 0.03 0.5 0.7 hauls are measured (carapace width, CW in No. of Logbooks 4 6 5 By-catch (t) ** 0 0 mm), and examined to determine species, LFA 38 Trap Hauls 3875 3875 5125 12760 8939 sex, molt condition and egg development Landings (t) 21 25 27 61 51 Mean CPUE 5.3 6.5 5.3 4.8 5.7 stage for berried crabs. As the exploratory No. of Logbooks 1 1 1 5 4 By-catch (t) ** ** ** 27 86 rock/Jonah crab fisheries were evolving in ** Unknown the various LFA’s, emphasis was placed in In LFA 38, only one Jonah crab fisher was sampling a series of representative ports in active between 1995 and 1997. In 1998 and areas and at time periods when high fishing 1999, five and four logbooks were received activity occurred. respectively. Landings remained between 20 and 27 t until 1997. During 1998, landings All the sampling was done during July, increased to 61 t and preliminary landings in August and September. In some instances, 1999 were 51 t. Since 1995, yearly catch when several samples that were taken during

3 Maritimes Region Inshore Gulf of Maine Jonah Crab the same month in the same location, the from 127-136 mm CW. The lower mean size samples were combined into one monthly of 127 mm CW observed in July 1995 was sample. taken at the infancy stage of this exploratory crab fishery. The mean size of females Sea samples obtained from LFA 34 in the varied between 111 and 116 mm CW. Over midshore area during August and October the five years of sampling an average of 5% 1998 and August 1999 yielded mean sizes of females were berried. for males ranging from 139-142 mm CW. LFA 38, July 1995, Jonah Crab The mean size of females varied between 50 Legal Size 121 & 125 mm CW. The percentage of 40 females captured that were berried was less Males 30 Females N = 282 than one percent. N = 90 Mean = 127 mm CW Mean = 111 mm CW SD = 16.1 20 LFA 34, August 1998, Jonah Crab SD= 9.1 42 % < 121 mm CW 57 % < 130 mm CW

120 No. of Jonah Crabs 10 Legal size Males 100 N = 2265 0 Mean = 142 mm CW 80 SD = 10.4 80 90 100 110 120 130 140 150 160 170 180 190 Females Carapace Width (mm) 9 % < 130 mm CW 60 N = 154 Mean = 125 mm CW 40 SD = 6.4 LFA 38, August 1995, Jonah Crab

No. of Jonah Crabs 20 50 Legal Size Males 0 s 40 Females 80 90 100 110 120 130 140 150 160 170 180 190 N = 739 N = 139 Mean = 135 mm CW 30 Carapace Width (mm) Mean = 113 mm CW SD = 13.7 SD = 9.3 16% < 121 mm CW 20 33% < 130 mm CW LFA 34, October 1998, Jonah Crab

No. of Jonah Crab 10 120 Males N = 1055 0 100 Legal size Mean = 141 mm CW 80 90 100 110 120 130 140 150 160 170 180 190 SD = 10.2 80 Carapace Width (mm) 14 % < 130 mm CW Females 60 N = 221 LFA 38, September 1996, Jonah Crab Mean = 123 mm CW 40 SD = 6.6 50 Legal Size No. of Jonah Crabs 20 Males 40 Females N = 838 0 N = 227 Mean = 136 mm CW 30 80 90 100 110 120 130 140 150 160 170 180 190 Mean = 116 mm CW SD = 12.5 SD = 7.2 13 % < 121 mm CW Carapace Width (mm) 20 33 % < 130 mm CW

LFA 34, August 1999, Jonah Crab No. of Jonah Crabs 10 120 0 Legal size 100 Males 80 90 100 110 120 130 140 150 160 170 180 190 N = 1159 Carapace Width (mm) 80 Females Mean = 139 mm CW N = 616 SD = 12.1 60 Mean = 121 mm CW 19 % < 130 mm CW LFA 38, September 1997, Jonah Crab SD = 8.0 50 40 Legal Size Males No. of Jonah Crabs 20 40 Females N = 497 N = 318 Mean = 130 mm CW 0 30 Mean = 115 mm CW SD = 13.3 SD = 7.7 80 90 100 110 120 130 140 150 160 170 180 190 24 % < 121 mm CW 50 % < 130 mm CW Carapace Width (mm) 20

No. of Jonah Crabs 10

In LFA 38, samples obtained between July 0 and September 1995 and August 1999 80 90 100 110 120 130 140 150 160 170 180 190 indicated a mean size for males ranging Carapace Width (mm)

4 Maritimes Region Inshore Gulf of Maine Jonah Crab

LFA 38, August 1998, Jonah Crab Sources of Uncertainty

50 Legal Size Females Males 40 N = 223 N = 1079 Total removals of Jonah crab in the Gulf of Mean = 114 mm CW Mean = 131 mm CW 30 SD = 7.7 SD = 11.3 Maine are not known because the bycatch of 20 % < 121 mm CW 48 % < 130 mm CW Jonah crab by the lobster fishery is not well 20 documented. Anecdotal evidence indicates

No. of Jonah Crabs 10 few Jonah crab are retained by lobster

0 fishers in some areas (e.g. LFA’s 35 & 36) 80 90 100 110 120 130 140 150 160 170 180 190 but in other areas lobster traps are set Carapace Width (mm) specifically for Jonah crab to be used as bait LFA 38, August 1999, Jonah Crab or sold. Reported landings in LFA’s 34 and 50 Legal size 38 have shown that bycatch of Jonah crabs 40 surpassed landings from the directed fishery Females Males N = 603 30 N = 195 in 1999, and could increase or decrease in Mean = 116 mm CW Mean= 131 mm CW SD = 6.2 SD = 12.1 response to economic factors. 20 22 % < 121 mm CW 48 % < 130 mm CW 10 No. of Jonah Crabs Outlook 0 80 90 100 110 120 130 140 150 160 170 180 190 Carapace Width (mm) There is still some room for limited expansion in unexplored areas in LFA 34 & 38. One reason, for the larger mean size of However in the Bay of Fundy (LFA 35 & 36) males and females in LFA 34 compared to it is unlikely that any further commercial LFA 38, is that the minimum size limit in concentrations of Jonah crab can be found. LFA 34 is 130 mm CW compared to 121 The current level of effort does not appear to mm CW for LFA 38. Regulation in gear be having any obvious impact on the resource design (larger size of escape vents in LFA such as a reduction in average catch size or 34) was set to select the size of crab reduction in catch rates. The economic targeted. In LFA 34, the percentage of crabs feasibility of this fishery is marginal and very below the legal size limit of 130 mm CW dependent on the value and the demand for varied between 9 and 19% compared to 33- the product. 57 % in LFA 38. Removals of Jonah crab by the lobster fishery Lobster bycatch has been a management as a bycatch, are currently underestimated and concern since the introduction of the under no limitation. Reported landing exploratory crab fishery. However, statistics shows that Jonah crab landings as a restrictions on the type of traps used and bycatch to the lobster fishery have surpassed limitations on the size and shape of the the directed fishery in 1999. Until the quantity entrances, seem to have reduced the of Jonah crab removals by the lobster fishery incidence of lobster bycatch. Yearly average has been further evaluated, biological number of lobsters per trap haul varied sustainability of the directed fishery cannot be between 0.0 and 0.01 in LFA 34 and evaluated. between 0.0 and 0.04 in LFA 38. The by-catch of lobsters does not seem to be a problem for the Jonah crab fishery.

5 Maritimes Region Inshore Gulf of Maine Jonah Crab

Management Considerations References

Jonah crabs are fished by a directed fishery Robichaud, D. A. and P Lawton, 2000. and as a bycatch in the lobster fishery. The Exploratory Fisheries for Rock Crab, potential effort by the lobster fishery is far Cancer irroratus, and Jonah Crab greater than the current directed fishery. Cancer borealis, in Canadian Lobster Removals by the lobster fishery are a Fishing Areas 34, 35, 36 & 38. DFO fundamental piece of missing information Can. Stock Assess. Sec. Res. Doc. needed for the assessment of Jonah crab 2000/051. stock(s). Until the quantity of Jonah crab removals by the lobster fishery is evaluated This report is available from the: and controlled, biological sustainability of the directed fishery cannot be evaluated. The Maritimes Provinces bycatch issues should be look at on an LFA Regional Advisory Process by LFA basis since in some LFA’s these Department of Fisheries and Oceans issues could be more easily resolved than in P.O. Box 1006, Stn. B203 others. Lobster fishermen should be Dartmouth, Nova Scotia encouraged to report their bycatch whether it Canada B2Y 4A2 is used directly as bait or sold. Phone number: 902-426-7070 e-mail address: [email protected] As far as the directed fishery is concerned, management provisions should remain Internet address: www.dfo-mpo.gc.ca/csas flexible to reflect the developing nature of the ISSN: 1480-4913 fishery. La version française est disponible à For more Information l’adresse ci-dessus.

Contact: David Robichaud or Peter Lawton Fisheries & Oceans Biological Station 531 Brandy Cove Rd. Correct citation for this publication St. Andrews N.B. E5B 2L9 DFO, 2000. Inshore Gulf of Maine Jonah (Cancer borealis). DFO Science Stock Tel: (506) 529-8854 Status Report C3-66(2000). Fax: (506) 529-5862 E-Mail: [email protected] Or [email protected]

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