CSAS
SCCS
Canadian Science Advisory Secretariat
Secrétariat canadien de consultation scientifique
Research Document 2002/015
Document de recherche 2002/015
Not to be cited without permission of the authors *
Ne pas citer sans autorisation des auteurs *
Assessment of the scallop stock in Scallop Production Area 1 in the Bay of Fundy for 2001
Évaluation du stock de pétoncle de la zone de production du pétoncle 1 (baie de Fundy) en 2001
Dale Roddick
Invertebrate Fisheries Division Science Branch Department of Fisheries and Oceans P.O. Box 1006 Dartmouth, Nova Scotia
* This series documents the scientific basis for the evaluation of fisheries resources in Canada. As such, it addresses the issues of the day in the time frames required and the documents it contains are not intended as definitive statements on the subjects addressed but rather as progress reports on ongoing investigations.
* La présente série documente les bases scientifiques des évaluations des ressources halieutiques du Canada. Elle traite des problèmes courants selon les échéanciers dictés. Les documents qu’elle contient ne doivent pas être considérés comme des énoncés définitifs sur les sujets traités, mais plutôt comme des rapports d’étape sur les études en cours.
Research documents are produced in the official language in which they are provided to the Secretariat.
Les documents de recherche sont publiés dans la langue officielle utilisée dans le manuscrit envoyé au Secrétariat.
This document is available on the Internet at: Ce document est disponible sur l’Internet à: http://www.dfo-mpo.gc.ca/csas/ ISSN 1480-4883 © Her Majesty the Queen in Right of Canada, 2002 © Sa majesté la Reine, Chef du Canada, 2002
Abstract Starting on 1 January 1997, the Bay of Fundy scallop fishery was divided into Scallop Production Areas (SPA’s) for management considerations. This move was made in response to declining catches and concerns over the long term viability of the scallop fishery. SPA 1 is the largest SPA in the Bay of Fundy, and is accessible, at least in part, to all Bay of Fundy scallop license holders. This assessment examines survey data, logbook data, and port sampling data. Survey biomass estimates and commercial catch rates declined from the historic peak in 1988/89, to the lowest levels in either time series in 1997. Since that time they have improved, and there is a large recruitment pulse in the Digby area entering the fishery. This pulse is not evident in the Cape Spencer or Upper Bay areas of SPA 1. In the Cape Spencer area the population has started to decline as the moderate year class that recruited to the fishery in 2000 is fished down. In the Upper Bay area the strong year class that recruited to the fishery in 2001 will be followed by two weaker year classes. The large recruitment pulse in the 8-16 mile area off Digby is not available to all fleet sectors, complicating setting a single quota for SPA 1. Preliminary work with a biomass dynamic model indicates that the 8-16 mile area off Digby can sustain a sizable increase to the TAC. Under an assumption that natural mortality in 2002 will be similar to that of 2001, an increase to the 500-600 t range would still not exceed F0.1 Résumé Depuis le 1er janvier 1997, on gère la pêche du pétoncle de la baie de Fundy au moyen de zones de production du pétoncle (ZPP). Cette mesure a été prise en réaction à la baisse des captures et aux inquiétudes concernant la viabilité à long terme de cette pêche. La ZPP 1 est la plus grande de la baie de Fundy et est accessible, du moins en partie, à tous les détenteurs de permis de pêche du pétoncle de la baie de Fundy. La présente évaluation porte sur les données des relevés, des registres de bord et des échantillonnages aux ports. Les biomasses estimées par relevés et les taux de capture de la pêche commerciale ont diminué, passant de leur maximum historique en 1988-1989 à la plus faible valeur de leur série chronologique respective en 1997. Depuis, ces chiffres se sont améliorés, et la région de Digby connaît une forte vague de recrutement de pétoncles, qui ne semble pas s’étendre aux secteurs de Cape Spencer et du fond de la baie, dans la ZPP 1. La population du secteur de Cape Spencer diminue à mesure que l’on pêche la classe d’âge d’importance moyenne recrutée en 2000. Dans le secteur du fond de la baie, la forte classe d’âge recrutée en 2000 sera suivie par deux classes d’âge plus faibles. Les pétoncles de la forte vague de recrutement observée dans le secteur situé de 8 à 16 milles au large de Digby ne sont pas accessibles à tous les secteurs de la flottille, ce qui complique l’établissement d’un quota unique pour la ZPP 1. Les résultats préliminaires obtenus au moyen d’un modèle dynamique de la biomasse indiquent que ce secteur situé au large de Digby peut soutenir une hausse marquée du TAC. Si l’on suppose que la mortalité naturelle en 2002 sera semblable à celle de 2001, une augmentation du TAC à 500-600 tonnes ne dépasserait pas la valeur F0,1.
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Introduction Commercial scallop fishing in the Bay of Fundy was first reported by W.F. Ganong in 1889 (Ganong 1889), who reported that about 200 bushels originating from Maces Bay and L’Etang Harbour were sold annually in Saint John. In the 1920’s, a commercial fishery started in Annapolis Basin N.S., where Lescarbot had first reported scallops in 1609 (Lescarbot, 1609). This fishery quickly moved out into the productive grounds off Digby, Nova Scotia, and now occurs throughout the Bay of Fundy and the inshore and offshore waters around Nova Scotia. Scallop fishing regulations were first initiated in 1918 with licenses, a minimum size and closed seasons. These types of regulations are still in use for this fishery. Special regulations for specific areas within the Bay of Fundy date back to 1939 when a restriction on gear width was introduced specifically for Grand Manan waters. On the Nova Scotia side, a special zone was created off Digby in 1952, with a closed season from May 1 to September 30 to provide an area close to port for the winter fishery. This area has evolved into what is currently managed as Scallop Production Area 4. The Bay of Fundy scallop fishery became a limited entry fishery in 1972. Over time the scallop fleet still grew as more Bay of Fundy scallop licences were issued, and new licence categories for the inshore New Brunswick and Upper Bay areas were created. In 1986 an accord was reached between the scallop fleets, separating the offshore and Bay of Fundy fleets and creating the Mid Bay line for inshore New Brunswick based vessels. In 1987 an effort to cancel “inactive” inshore licences had limited success. On January 1, 1997, in response to declining catches and concerns over the long term viability of the fishery, the Bay of Fundy was divided into Scallop Production Areas (SPA’s) for better management (Figure 1). Total Allowable Catches (TAC’s) were introduced at this time, with sharing formulas to divide the TAC between the scallop fleets for areas where more than one fleet fished. Scallop Production Area 1 in the Bay of Fundy is a large area encompassing several different fishing grounds, and is accessible by three different scallop license categories (Table 1). Full Bay scallop licenses are able to fish scallops anywhere in the Bay of Fundy and are usually held by larger vessels (>25.5 Gross Tons). Mid Bay license holders can fish for scallops on the northern side of the Mid Bay line (Figure 1), and Upper Bay license holders east of the Upper Bay line.
These last two categories of licenses are typically held by smaller multi-
purpose vessels that fish local waters.
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Scallop fishing regulations in 2001 consisted of: Limited entry. Restrictions on gear type - no offshore or green sweep drags. Maximum width of gear - 5.5 m Minimum ring size - 82 mm. Meat count (minimum average meat weight) - 45/500g. Minimum shell size - 95 mm. Total Allowable Catches, either as individual vessel quotas in the Full Bay Fleet or an overall allowable catch for the Mid and Upper Bay fleets. Hail out upon leaving port and Hail in 2 hours before landing. Dockside monitoring of catches. Required to keep a Logbook (Scallop Monitoring Document) reporting location catch and effort. Special seasons, i.e. for a 2-mile conservation zone along the New Brunswick coast, 1mile closure along the Digby Neck. In 2001 there was also a closure of SPA 1 from the SPA 4 line out to 12 miles from shore to protect an area with a high density of juveniles until October 15. Landings in SPA 1 have increased from the low of 130 t in 1997, and for 2001 were 387 t in total (285 t for the Full Bay vessels, 59 t for the Mid Bay vessels and 43 t for the Upper Bay vessels). This was an 11 % increase in landings over 2000, and almost three times that of 1997. A portion of SPA 1 outside SPA 4, which contained large numbers of juvenile scallops, was closed until October 15. The main concentration of scallops in SPA 1 is an area that runs between Centerville and Hampton on the Nova Scotia side, over towards Cape Spencer on the New Brunswick side. This area is divided into SPA’s 1 and 4, and by the Mid Bay line (Figure 1). The largest portion is on the Nova Scotia side of the Mid Bay line, and is accessible only to the Full Bay fleet, while that on the New Brunswick side is accessible to both the Mid and Full Bay fleets. There are several smaller grounds further up the Bay, including those fished by the Upper Bay fleet. There is no survey covering the entire SPA 1, but there are productive portions that have had multiple surveys. The SPA boundaries cut through an area that has a long time series of annual surveys (Figure 2). Although the survey areas are not an exact match to the new SPA boundaries, it was felt that the match was close enough that it would be better to retain the consistency of the surveys than to alter their format. Surveys used in this assessment are: 1) the annual surveys in the “2-16 mile” section from Sandy Cove to Hampton, excluding Area 4; 2) several older surveys, and recent annual ones covering the section from 16 miles going towards Cape Spencer, New Brunswick; and 3) recent surveys that were carried out in the Upper Bay.
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Data Availability: Research surveys There have been annual surveys of the Digby portion of SPA 1 since 1981 (Kenchington et al. 1995). The Cape Spencer grounds were first surveyed in 1987, (Chandler et al., 1989) during a survey of the Northern side and Upper Bay area. Robinson and Chandler (1990) and Robinson et al. (1992) conducted surveys covering the Cape Spencer area in 1989, 1990 and 1991. Annual surveys of the Cape Spencer area were initiated with grid surveys in 1996 and 1997, in conjunction with the stratified random surveys of the 2-16 mile Digby area. The design was changed to a random survey in 1998. The Upper Bay area was surveyed in 1986-87 (Chandler et al., 1989), and in conjunction with studies on the effects of opening the Peticodiac River causeway in 1998 (Kenchington et al., 1998) and twice in 1999. It was surveyed with Industry cooperation in 2000, and as part of the regular Bay of Fundy surveys in 2001. Logbooks Logbooks were required for vessels >25 gross tonnes (G.T.) starting in 1973. In 1979 the requirement was changed to vessels > 25.5 G.T. or > 14 m Length Over All (LOA). These requirements covered most of the Full Bay license holders but few of the Mid Bay or Upper Bay licenses, although some of these vessels submitted logbooks.
In the Full Bay Fleet, the
percentage of active licenses that submitted logs has varied from 11 to 100%. The Mid Bay and Upper Bay license holders agreed to complete logbooks on a voluntary basis in 1996 and logbooks became mandatory for these fleets in 1997. The logbook database has been moved to an Oracle system and there was additional editing done during this transition. In addition, the assignment of historical landings to the current SPA boundaries was redone (Smith and Lundy, 2002). In 2001 the quota season for the Full Bay fleet was changed from the calendar year to one starting October 1, and running to September 30 the following year. This was done to bring it in line with their traditional fishing season in SPA 4. The quota season for the Mid and Upper Bay fleet remains on a calendar year. For this analysis of SPA 1 all data is analyzed on a calendar year basis Port sampling Port samples have been collected from the Full Bay Fleet landing in Nova Scotia since 1983, first on a voluntary basis, and since 2000 as part of the dockside monitoring program, but there had been no port sampling program covering the Mid Bay or Upper Bay Fleets in SPA 1.
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There are occasional Mid Bay port samples from an industry program targeted at SPA 6, and in October of 1999, a port sampling program was initiated in conjunction with an extension of the allowable catch limit for the Mid and Upper Bay fleets. Most of the samples from this program came from the Upper Bay area, while most of the available Full Bay samples come from the 216 mile Digby Area. Methods Survey Methods The survey analysis was divided into separate areas. The first was the area 2-16 miles off the Nova Scotia shore from Sandy Cove to Hampton, excluding SPA 4, for which a time series of surveys exists. Annual surveys of this area have been conducted since 1981, but the station allocation scheme and area covered has changed during this period.
For a full
description of these changes see Kenchington et al. (1995). For this reason, the 1991 to 2001 surveys, which are of a consistent area and with the most consistent design, will be the main ones used for this analysis, with the older surveys used to look at longer-term trends. The survey area is now split between SPA 1, and SPA 4, which extends out to 8 miles from Sandy Cove to Parkers Cove (Figure 1). The SPA 1 survey in this area was therefore broken down into two sections, the 8-16 mile area from Sandy Cove to Hampton, and a 2-8 mile area above SPA 4 (Figure 2). Tows of approximately 8 minutes duration were carried out at each randomly assigned station with a set of 4 Digby buckets (0.762 meters wide, 76 mm rings with rubber washers), 2 lined and 2 unlined. The catch of scallops in the lined (38 mm diagonal mesh liner) was used to estimate the catch of scallops