Science Advisory Report  2010/017

Assessment of Scallops (Placopecten magellanicus) in Scallop Production Areas 1 to 6 in the Bay of Fundy

Summary

General

• Biomass estimates for recent years from the 2009 versions of the population model were lower than estimated in previous years. It appears that this occurred because decreases in survey estimates from 2008 to 2009 were greater than the models can account for based on the reported catch and estimated natural mortality. A complete investigation of the models and the data inputs will need to be conducted before the next full assessment.
• Some observer coverage was funded by DFO’s Species at Risk Program between August 2008-March 2009 for investigation of bycatch. No information from this program was available in time to be included in this assessment.

SPA 1A

• Landings were 267 t for the Full Bay Fleet during the 2008/2009 fishing year against a quota of 265 t.  An interim TAC of 100 t was set for the 2009/2010 season based on the 2008 assessment advice. The average commercial catch rate in 2008/2009 changed little from that in 2007/2008 and was above the long-term median.
• Since the above average 1998 year-class recruited to the fishery in this area, recruitment has been lower and the abundance of commercial size scallops has been fished down.  Recruitment is expected to be at very low levels for at least the next two years.
• Survey indices for abundance and biomass of commercial size scallops in 2009 declined from 2008 estimates by 23 and 28%, respectively.
• Population biomass, estimated to be 1,299 t (meats) in 2009, was close to the estimate for 2008 (1,307 t) and close to the median biomass of 1,295 t.
• Catches of less than 350 t for 2009/2010 should result in an increase in biomass for 2010. However, the model has a tendency to overestimate the abundance of commercial size scallop, and catches approaching this value may actually result in a decrease in biomass in 2010.  

SPA 1B

• The total landings of all fleets in 2009/2009 were 388.7 t against a TAC of 385 t.
• Commercial catch rates for the Full Bay and Mid Bay fleets in 2009 changed little from 2008 in SFA 28B and SFA 28C, while Upper Bay and Full Bay fleet catch rates declined by 25 to 30%, respectively, in SFA 28D.
• The 2009 survey mean number and biomass per tow for commercial size scallops indicated declines for all areas from 2008, except for the Outer stratum of SFA 28D and Scots Bay.  While most declines in biomass and numbers were on the order of 12 to 20%, survey mean number and biomass decreased by close to 50% in the Advocate stratum.
• Population biomass, estimated to be 1,703 t (meats) in 2009, has decreased from the estimate for 2008 (1,818 t) but is still above the median biomass of 1,672 t.
• Catches for 2009/2010 of 430 t or less should not result in a decline in biomass for 2010. However, the model has a tendency to overestimate the abundance of commercial size scallop, and catches approaching this value may actually result in a decrease in biomass in 2010.

SPA 2

• This area is considered to be marginal habitat for scallops and is not monitored regularly. SPA 2 was last assessed in 2006 (DFO 2007).

SPA 3

• Total landings for the 2008/2009 fishing year were 62 t against a TAC of 60 t. An interim TAC of 50 t was set for October of the 2009/2010 fishing season.
• Commercial catch rates have been stable and close to the median over the time series since 2007 while effort has been declining. However, fishing activity has been concentrated on the eastern nearshore areas, and the catch rates may not reflect conditions in SPA 3 as a whole.
• Survey estimates of mean numbers per tow of commercial size scallops have been declining since 2004 while mean biomass per tow has declined since 2007. This decline has occurred despite decreasing fishing effort and is evident in both fished areas and areas not fished since 2006. Recruitment is expected to be low for at least the next two years.
• Commercial catch rates have been stable over the last three years for current catch levels but may only reflect stock status in the eastern nearshore areas of SPA 3. The survey data has indicated declining trends even the areas that are not being fished. More work is required to reconcile these different trends.

SPA 4

• Total landings in 2008/2009 were 98.6 t against a TAC of 100 t. An interim TAC of 100 t was set for the 2009/2010 season based on last year’s assessment.
• Commercial catch rates declined after the above average 1998 year-class recruited to the fishery but have been either relatively stable or slightly increasing since 2005/2006. The 2008/2009 catch rate is equal to the long-term median.
• Overall, the survey indices indicate that the population has been stable from 2006 to 2008 with low levels of recruitment, pre-recruits, and clappers. Survey estimates of commercial size mean numbers per tow and biomass per tow declined by 21 and 27%, respectively, in 2009. Given the trends in the pre-recruit estimates, low levels of recruitment will probably continue for the next two years.
• Population biomass, estimated to be 722 t (meats) in 2009, has increased over the estimate for 2008 (680 t) and is below the long-term median biomass of 787 t.
• The current interim TAC of 100 t for 2009/2010 is predicted to result in a decrease in the biomass of commercial size scallops for 2010. Similar to the other areas, the population model tends to overestimate biomass when projecting to the next year, though to a lesser degree. The actual decline in biomass in 2010 may be greater than predicted at this time.

SPA 5

• Landings in 2009 were 5.7 t against a TAC of 10 t.
• Commercial catch rates in 2009 decreased from 2008 and were below to the long-term median levels.
• The annual survey was discontinued as of 2009 in this SPA at the request of industry.
• The average catch of 9 t over the period 1997-2008 (excluding the high catch in 2004) have not led to marked increases or decreases in CPUE over that time, which would suggest a relatively stable population size at this level of harvest.

SPA 6

• Landings in 2009 were 90 t against a TAC of 140 t.
• Both catch and catch rates for Full Bay and Mid Bay fleets have been relatively stable over the last five years.
• Pre-recruits (40–64 mm) continue to be found in high concentrations around Campobello Island, south of the Wolves in SPA 6A, Duck Island Sound and, south of Grand Manan in SPA 6B. The main concentration of recruits (65–79 mm) coincided with the distribution of pre-recruits in the 2008 survey, being mainly found around Campobello and Duck Island Sound.
• Survey mean catch per tow for commercial size scallops has increased in all subareas of SPA 6 in 2009, although the increase in 6C may be partly due to limiting the survey to the areas around Campobello Island.
• Recent levels of catch do not appear to have resulted in a decrease in the abundance of scallops in the SPA 6 area as a whole.

Rationale for Assessment

As part of the Regional Science Advisory Process, a meeting was held 9 November 2009 at the Bedford Institute of Oceanography in Dartmouth, N.S., to review the 2009 scallop fishery and assess the status of the scallop stocks in Scallop Production Areas 1 to 6 in the Bay of Fundy, as well as to provide the scientific advice for the 2010 fishery.

The Bay of Fundy scallop fisheries have a long and well documented history of peer reviewed assessments and the assessment approach has been accepted in previous advisory meetings. The focus of this year’s assessment was on the assessment results and projections.

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