Research TAC Set Aside Scallop Exemption Program for 2008
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NOAA Grant Number: NA11NMF4540019 (DMR#4312) Grantee: Maine Department of Marine Resources (ME DMR) Project Title: An Assessment of Sea Scallop Distribution and Abundance in Federal and Adjacent State Waters of the Gulf of Maine Project Code: 11-SCA-04 Amount of Grant: 77,135 lbs. of scallops from any open area or open access area Start Date: 03/01/2011 Period Covered by Report: 03/01/2011 – 3/31/2015 Executive Summary The sea scallop fishery in the Northern Gulf of Maine (NGOM) occurs in federal waters and is managed by the New England Fishery Management Council. The NGOM resource and associated fishery are at times locally important but amount to a small portion of the total stock and landings. The fishery is managed by total allowable catch (TAC) independently of the rest of the EEZ sea scallop stock. The NGOM fishery does not use biological reference points as targets or thresholds. A cooperative survey was carried out by the Maine Department of Marine Resources (DMR) and the University of Maine in May-June 2012. Survey results indicate that the biomass (by meat weight) of NGOM sea scallops targeted by the fishery (102+ mm or 4+ in shell height) was approximately 164 MT (90% confidence interval of 74-279 MT) in 2012. Landings during 2009-12 amounted to approximately 7 MT. Based on these biomass estimates the exploitation rate in weight (landings/stock biomass, assuming harvested scallops greater than 102 mm shell height and a survey dredge efficiency of 43.6%) during 2012 was 2.1% with a 90% confidence interval from 1.3% to 4.7%. The previous survey in 2009 noted a large year class of 10-50 mm scallops on Platts Bank; this year class was still evident in 2012 and had grown to approximately 65-90 mm. Maine state waters were surveyed in 2012-14. In 2013 Cobscook Bay had the highest amount of harvestable (> 4 in. shell height) biomass (452.2 + 27.2 thsd. lbs.) ever observed from the survey with a large amount of it present in South Bay. The highest density of harvestable scallops was in Whiting Bay/Dennys Bay. Highest densities of both seed (0.101 per m²) and sublegals (0.333 per m²) were in Johnson Bay. A sea scallop survey was carried out in April 2014 in management zone 2 (eastern Maine coast between W. Quoddy Head and upper Penobscot Bay). The survey was directed into the seven (7) rotational areas scheduled to be open to fishing in the 2014-15 season. A total of 139 tows were completed on the survey. Harvestable (> 4 in. shell height) scallop density was significantly higher in the Bold Coast rotational area in 2014 than in the adjacent open area in 2013. Sublegal (2.5-3.9 in. shell height) density also was greater than in the adjacent open area in 2013. Seed (<2.5 in. shell height) density remained at a relatively high level, comparable to 2013. Density of harvestable scallops was higher in the Little Kennebec/Englishman Bay rotational area in 2014 than in the adjacent open area in 2013. Seed and sublegal densities were less than in 2013 however. This area contained mostly harvestable scallops. The five other (Addison, Frenchmans Bay, Swan’s Island, Isle au Haut Bay, upper Penobscot Bay) rotational areas had poor scallop abundance. The highest density of harvestables was in Isle au Haut Bay but this was only in a limited part of the survey area. Purpose The major objective of the project was to develop a survey program to assess scallop distribution and abundance in federal waters of the Northern Gulf of Maine (NGOM) Scallop Management Area (as defined in Amendment 11 to the Atlantic Sea Scallop Fishery Management Plan) and to estimate a biologically sustainable TAC for the stock. A dredge-based survey of the scallop resource in the federal portion of the NGOM was conducted by Maine DMR in collaboration with the commercial fishing industry and the University of Maine in May-June 2012 to provide information upon which management actions such as a TAC could be based. The scope of work of this project was extended into dredge-based surveys of state NGOM waters along eastern Maine and in Cobscook Bay during 2012-14. Approach A.) Northern Gulf of Maine (federal waters) survey Vessel and gear F/V Foxy Lady II, a 45 ft. side-rigged scallop vessel based in Stonington, ME, served as the platform for the entire survey. The vessel and captain were well-experienced, having conducted several scallop surveys with DMR since 2002. The 2012 NGOM survey was conducted from the ports of Gloucester (MA) and Portland, Stonington, Southwest Harbor and Bucks Harbor (ME). The survey gear was a 7 ft. wide New Bedford-style chain sweep dredge with 2 inch rings, 1¾ inch head bale, 3½ inch twine top and 10 inch pressure plate and equipped with rock chains (Fig. 1). The dredge was not lined. The dredge frame and clubstick were fabricated by Blue Fleet Welding (New Bedford, MA) and the ring bag was constructed by Pacheco Gear (E. Freetown, MA). Final assembly of the dredge and installation of the twine top was by Capt. Wally Gray (Stonington, ME) in 2009. The survey dredge was of a configuration largely consistent with that used in 2002-08 inshore Gulf of Maine surveys (Kelly 2009; Schick and Feindel 2005), with the exception of a slightly larger pressure plate for towing in deeper water and smaller rings to allow better retention of small scallops. The gear was of a size which would allow it to be used in both nearshore and offshore parts of the Gulf of Maine, would facilitate sufficient bottom coverage and allow it to be transported over ground to various sampling locations throughout the region. 2 Figure 1. View of survey dredge constructed in 2009. Survey design The NGOM management area is bounded by Cape Ann, Massachusetts in the west and the Canadian border in the east (Fig. 2). Prior to 2009 when the first survey was conducted, the NGOM had limited fishery dependent and no recent fishery-independent data available to help design the survey. Scallops are not found uniformly throughout this region so sampling efforts were focused on a subset of areas in the NGOM. To determine this subset, fishing locations from National Marine Fisheries Service vessel trip reports (VTRs) from 2000 to 2008 were reviewed as well as three historical surveys of the region from the 1970s and 1980s (Spencer 1974; Serchuk 1983; Serchuk and Wigley 1984). In addition to the information available, two fishermen with a history of scalloping in the Gulf of Maine were interviewed to help identify current and historical fishing grounds. These sources of information were used qualitatively to determine the five sampling areas: Machias-Seal Island (MSI), Mount Desert Rock (MDR), Platts Bank (PB), Northeast of Cape Ann (NCA) and Northern Stellwagen Bank (NSB; Fig. 2). To increase sampling precision, the two western strata off the Massachusetts coast (where most fishing occurs), NCA and NSB, were further divided into substrata of expected high, medium and low scallop density. Dredge tow stations were selected from a grid overlying each stratum. The dimensions of each grid unit were 1 km2. Each survey followed a two-stage random stratified design 3 in the NCA and NSB strata. Station allocation in the first stage was based on fishing intensity from 2000-2008 vessel trip report (VTR) data and the size of each substratum. Forty stations in each stratum were assigned to the first stage and distributed among substrata according to the formula: Eqn. 1 where Ns (rounded) is the number of stations to be sampled in substratum , is the median function, is the VTR landings from 2000 to 2008 for substratum and is the area of substratum . VTR data is assumed to be a proxy for scallop density and so was used to help allocate survey sample size. Such commercial data have also been used in the design of Canadian scallop surveys (Robert and Jamieson 1986; Serchuk and Wigley 1986). Area size was included in the weighting to ensure sufficient effort in the larger substrata. Figure 2. The NGOM and the 5 strata selected for the survey, with substrata of differing expected scallop density appearing in the western areas inset. MSI: Machias-Seal Island; MDR: Mount Desert Rock; PB: Platts Bank; NCA: Northeast of Cape Ann; NSB: Northern Stellwagen Bank. In the NCA and NSB strata, which were further divided into substrata, a two-stage survey was employed. The approach taken by Francis (1984) was used to allocate tows to the second survey stage. His formula to assign one additional station among strata is: 4 Eqn. 2 where is the assumed reduction in variance from adding a single station to a particular substratum , is the area, is the mean catch rate (when squared, a proxy for the variance suggested by Francis (1984)) and is the number of additional stations. Twenty stations were available for the second stage and were apportioned among the substrata. They were assigned one-by-one (by repeated use of Eqn. 2) according to whichever substratum would gain the most in terms of reduced variance from receiving one additional station. As such, the assignment of the th station can be written: Eqn. 3 A single stage design was used for the remaining three strata in the eastern GOM. In 2012 206 stations were sampled with a target tow duration of 5 minutes and about 540 m although fixed gear (lobster traps, gillnets) in some locations forced shorter tows. B.) State waters surveys The 2012-14 surveys were conducted aboard two commercial scallop vessels each deploying the standardized survey drag.