BG-NL-05-03 April 6, 2005 2005 Crab Stock Assessment A Regional Assessment Meeting (RAP) was held in St. John’s March 1 – 5 2005 to review the status of Newfoundland and Labrador snow crab. Participants at the meeting included fisheries scientists and fisheries managers from DFO Newfoundland and Labrador Region, representatives of the Fisheries Resource Conservation Council (FRCC), Newfoundland and Labrador Department of Fisheries and Aquaculture, aboriginal representatives, fish harvesters, industry and academia. Overview Resource status was evaluated based on trends in fishery catch per unit of effort (CPUE), exploitable biomass, recruitment prospects, and mortality. Data were derived from fall multi-species bottom trawl surveys in Divisions 2J3KLNO, inshore trap surveys in Divisions 3KL, fishery data from logbooks, and observer catch-effort data, as well as biological sampling data from multiple sources. A decline in the Newfoundland and Labrador snow crab resource is evident in some divisions. Commercial CPUE in Division 2J and Subdivision 3Ps has declined steadily over 6 years to very low levels. The fall multi-species surveys in Divisions 2J3KLNO indicate a decline in exploitable biomass since 1998. Recruitment declined from 1996-2002 and has since remained at a low level. Exploitation rate indices are near their highest levels within each of Divisions 2J3KL. However comparisons cannot be made across divisions due to unquantified effects of spatial variation in substrate type on catchability of crabs by the survey trawl. The percentage of crabs discarded in the fishery, which is used as an index of handling mortality, is near its highest level in Divisions 2J3KPs but near its lowest level in Divisions 3LNO. Resource status could not be evaluated in Division 4R and Subdivision 3Pn due to inadequate data. The percentage of mature females carrying full clutches of viable eggs has remained high throughout the time series, despite reduced abundance of legal sized adults. Handling mortality on undersized males may adversely affect insemination of females, especially when abundance of larger adults is low. There has been a broadly distributed incidence of bitter crab disease during 1996-2004. This disease, which is fatal to crabs, occurs in new-shelled crab of both sexes and appears to be acquired during molting. Prevalence increases with size within new-shelled adolescent (i.e., non-terminally-molted) males. It is uncommon in Divisions 3NOP4R and has been most prevalent in Division 3K. Prevalence has recently increased, particularly in Division 3L. Gillnet fisheries for groundfish impose an unquantified fishing mortality on snow crab. Snow crab and shrimp fisheries occur on common grounds in Divisions 2J3K, but the mortality on snow crab due to shrimp trawling remains unknown. An area of the Hawke Channel has been closed to all fisheries except snow crab during 2002-2004. It would be premature to draw any conclusions regarding the impact of this closure on the snow crab resource. The abundance of predatory groundfish species has remained low since the early 1990’s but the implications for mortality are unknown. Cannibalism is known to occur but there are no data on spatial or annual variation in its prevalence. The following are excerpts from the 2005 Science Advisory Report, which is available http://www.dfo-mpo.gc.ca/CSAS/Csas/English/Status/SAR-AS_2005_e.htm Division 2J Landings declined by 65% from 5400t in 1999 to 1900t in 2004 (due to reductions in TAC) while effort increased by 42%. The exploitable biomass index decreased steadily, by 94%, from 1998-2002 and has remained low during 2002-2004. Commercial CPUE has declined steadily by 77% since 1998 to a record low level in 2004. The fall survey and observer pre-recruit indices agree that recruitment appears promising in the short term. The survey data indicate an increase in abundance of sub-legal sized males that will begin to achieve legal size in 2005, as new-shelled immediate pre-recruits, and will recruit to the fishery as older-shelled crabs predominately in 2006-2007. Longer-term recruitment prospects are unknown. The effects of maintaining the current catch level on the exploitation rate are unknown. Continued exploitation in the short term would likely impose a very high mortality on immediate pre-recruits that would seriously impair recovery of the exploitable biomass. Division 3K Landings declined by 29% from 21,400 t in 1999 to 15,300 t in 2000 and 2001 due to a reduction in TAC imposed in those years. Landings increased to 16,500 t in 2002-2004 due to an increase in TAC. Effort decreased during 1999-2001, then increased by 17% to 2003, and further increased by 37% in 2004. The exploitable biomass index, as determined from fall multi-species surveys, declined by 68% during 2001-2003 and remained low in 2004. The offshore commercial CPUE decreased 32% from 1998-2001, remained at this relatively low level until 2003, and decreased sharply in 2004. Inshore commercial CPUE has declined since 2001 to about the long-term average. Longer-term recruitment prospects are unknown. The exploitation rate index increased steadily from 1997 to 2000 and changed little to 2003, before increasing sharply in 2004. The percentage of the total catch discarded in the fishery increased from 1999-2001 and remained relatively high, at about 30%, during 2001-2003. It then increased to about 40%, implying relatively high handling mortality on small and new-shelled pre-recruits during the fishery in 2004. Fishery-induced mortality is expected to remain high in 2005 if the recent catch level is maintained and current fishing practices persist. Division 3L Landings increased by 16% from 22,600 t in 2000 to 26,200 t in 2003, and decreased to 25,800 t in 2004 due to changes in TAC. Meanwhile effort has increased by 75% since 2000. The fall survey pre-recruit index has been low since 1997. The observer discard pre-recruit index has declined since 1997. Recruitment is expected to remain relatively low in the short term. Longer-term recruitment prospects are unknown. The exploitation rate index increased from 1996-2000 and remained high thereafter. The percentage of the total catch discarded decreased sharply in 1998 and continued to decline gradually until 2004, implying reduced handling mortality on pre-recruits. The effect on exploitation rate of maintaining the current catch level remains unclear because trends in the exploitable biomass index and CPUE do not agree. Divisions 3NO The fishery has been concentrated along the shelf edge. Landings increased sharply in 1999 and averaged 5200 t over the past six years. Because estimates of the exploitable biomass index have wide margins of error, no inferences about biomass trends can be made from these data. CPUE has remained high in recent years relative to other areas, but decreased by 26% between 2002 and 2004. Wide margins of error introduce uncertainty in interpreting the fall multi-species survey pre-recruit index. However, biological data from the survey, as well as data from at-sea observers, indicate that recruitment is expected to remain relatively low in the short term. Longer-term recruitment prospects are unknown. The effects of maintaining the current catch level on the exploitation rate are unknown. Subdivision 3Ps Landings decreased by 38% from 7600 t in 2002 to 4700 t in 2004, due to reductions in TAC. Effort increased by 64% from 2001-2003 before decreasing by 10% in 2004. The observer discard pre-recruit index has changed little over the past six years (1999-2004). Recruitment is expected to change little in the short term. The percentage of the total catch discarded in the fishery decreased from 46% in 2003 to 34% in 2004 implying reduced handling mortality on pre-recruits during the 2004 fishery. Assuming that recent CPUE reflects low exploitable biomass, exploitation rate and pre-recruit mortality will likely remain high if the current catch level is maintained. Division 4R and Subdivision 3Pn Landings increased by 88% from 930t to 1750 t between 1997 and 2002 due to increases in TAC. Landings then dropped by 17% to 1450 t in 2004. The TAC was not fully taken in the past two years. Effort increased steadily until 2001, decreased in 2002, and increased in 2003-2004. There are insufficient fishery independent data from this area. It is not possible to infer trends in exploitable biomass from commercial CPUE data because of recent changes in the spatial distribution of fishing effort. CPUE is consistently low relative to other divisions. The observer data for this area are insufficient to estimate a reliable pre-recruit index or infer levels of handling mortality.

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