2009 UPDATE ON CANADA S BLUEFIN TUNA FISHERIES

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1 SCRS/9/162 Collect. Vol. Sci. Pap. ICCAT, 65(3): () 9 UPDATE ON CANADA S BLUEFIN TUNA FISHERIES Stacey D. Paul, Sean C. Smith and John D. Neilson 1 SUMMARY This document provides a brief update on information from the Canadian bluefin tuna fisheries in 8 and 9, including anecdotal reports from the fishery, recent size composition information, and updated nominal catch rates. In general, the Canadian fleets are reporting the strongest fisheries in recent memory. Catch rates in the southern Gulf of St. Lawrence are now at the highest level observed in the time series. The size composition of the catch has been increasing since 5. Catch rates and size composition have also increased in the southwestern Nova Scotia fishery from 7 to 8, but the information from the fishery is affected by market conditions, and fine-scale fleet distributions. RÉSUMÉ Ce document fournit une brève mise à jour de l'information des pêcheries canadiennes de thon rouge en 8 et 9, et inclut des rapports anecdotiques provenant de la pêcherie, des informations récentes sur la composition par taille et des taux de capture nominale mis à jour. En général, les flottilles canadiennes déclarent les pêcheries les plus importantes ayant été connues. Les taux de capture dans le Golfe du Saint-Laurent méridional se situent actuellement à leur niveau le plus élevé observé dans la série temporelle. La composition par taille de la capture a augmenté depuis 5. Les taux de capture et la composition par taille ont également augmenté dans la pêcherie du sud-ouest de la Nouvelle-Écosse de 7 à 8, mais les informations de la pêcherie sont altérées par les conditions du marché et par les distributions de la flottille à échelle fine. RESUMEN Este documento proporciona una breve actualización de la información de las pesquerías canadienses de atún rojo en 8 y 9, e incluye informes anecdóticos de la pesquería, información sobre la composición por tallas reciente y una actualización de las tasas de captura nominal.en general, las flotas canadienses están comunicando las pesquerías más potentes de las que se recuerdan en los últimos tiempos. Las tasas de captura en el Golfo de San Lorenzo meridional se sitúan actualmente en el nivel más elevado observado en la serie temporal. La composición por talla de la captura se ha incrementado desde 5. Las tasas de captura y las composiciones por talla también se han incrementado en la pesquería de Nueva Escocia suroccidental desde 7 a 8, pero la información de la pesquería se ve afectada por las condiciones del mercado y por la distribución de la flota en una escala más fina. KEYWORDS Tuna fisheries catch rates, size composition 1 Fisheries and Oceans Canada, St. Andrews Biological Station, 531 Brandy Cove Road, St. Andrews, New Brunswick E5B 2L9 Canada. Stacey.Paul@dfo-mpo.gc.ca 858

2 1. Introduction This document provides a brief update on information from the Canadian bluefin tuna fisheries in 8 and 9, including anecdotal reports from the fishery, recent size composition information, and updated nominal catch rates. 2. Description of the fisheries An informal and small-scale telephone survey of key contacts in the Canadian fishing industry was conducted in mid-september, 9. Industry representatives were contacted representing fleets operating off southwest Nova Scotia, the southern Gulf of St. Lawrence and southern Grand Banks of Newfoundland. Respondents were asked to comment on recent fishery performance, including spatial distribution, catch rates, and composition in 8 and 9. In 8, fishermen reported a broad range of fish sizes in waters off southwestern Nova Scotia. Later in the summer, there were reports of many small bluefin near the surface, averaging approximately 6-7 kg. Fishermen suggested that the overall size of fish in the Gulf of St. Lawrence was up in 8 and this is reflected in DFO s own data (see Figures 1, 2). Overall, the condition of the fish was unchanged in 8 but the prices were down due to market conditions and the number of fish entering the market at one time. Fishermen suggested that the spatial distribution of bluefin tuna in Canadian waters has increased. The trend of a broad range of sizes in the Canadian catch continued during the 9 season. Also, the spatial distribution of the fishery continued to be broad compared with the recent past, with catches being made in the western Gulf of St. Lawrence. Additionally, bluefin tuna were foraging on German Bank in the lower Bay of Fundy in September, where they have not been noted for many years. In 9, management disallowed transfer of quotas among fleets, which has impacted the fleet behaviour. There are increasing anecdotal reports of bycatch problems in fisheries where such incidents are unexpected (groundfish handline, groundfish longline and herring purse seine). In general, the Canadian fleets are reporting the strongest fisheries in recent memory. 3. Trends in size composition In Canada, submission of log records for the bluefin tuna fishery was initially done on a voluntary basis, although since 1994 it has been mandatory. While log record coverage has varied over the years, it has been assumed that what is available is representative of the fishery. The Canadian Atlantic statistical systems provide real time monitoring of catch and effort for all fishing trips. Since 1996, this system has applied to all fleets and included monitoring of all trips even when no fish were caught. At the completion of each fishing trip, independent and certified Dockside Monitors must be present for off-loading, and log record data must be submitted by each fisherman to the Monitoring Company that inputs the data into a central computer system. The computerized log records provide detailed information on catch (number and weight of tuna), size (individual weight and length), effort (hours fished), date, gear characteristics, home port (fleet) and catch location (latitude and longitude). Ideally, this ensures % coverage of properly completed log records and individual fish sizes. In actuality, 97% of individual bluefin landed in 8 had associated size information. In the southern Gulf of St. Lawrence rod and reel fishery, the median weight of the catch has declined since, accompanied by an increase in the range of weights caught in that fishery (Figure 1). There is evidence that the decline in the median round weight ceased in 5, and the medians have increased in the past three years. In the Southwest Nova Scotia rod and reel fishery, the median round weight of the fish has declined from 1996 to 2. Since 2, the median size of the landings has been variable but generally increasing. Length-frequency information for the Gulf of St. Lawrence rod and reel fishery is shown in Figure 2. The length composition information reflects the trends in median weight described earlier, in general. In there was a greater proportion of the catch in the + cm length classes, compared with 2 to 6. The + cm size class has been increasing in 7 and 8. The ages (from the Turner and Restrepo (1994) growth model) represented in the catch are generally from ages to. 859

3 4. Catch and effort data As completed by Neilson et al. 9, two separate standardized indices were developed based on (1) the spatial distribution of catches, (2) differences in the size of fish captured, and (3) patterns of nominal CPUE: Gulf of St. Lawrence tended line/rod and reel (1981-5), and Southwest Nova Scotia tended line/harpoon/rod and reel (=Hell Hole plus Bay of Fundy, ). These two series encompass the overall size/age range of tuna captured in the Canadian fishery and represent about 8% of the Canadian landings. Logbook data were edited and condensed to the trip level to provide total number of fish and total number of hours fished per trip by area, fleet, month and gear type. Catch per hour was the unit measure of effort selected for all fisheries used in the nominal series. This measure is most appropriate when effective fishing time during a day is generally limited to a period of time influenced by the tidal cycle and when trips occur over more than one day. Nominal CPUE was calculated as the number of tuna captured per trip divided by total hours fished per trip, and scaled by a factor of. The Gulf of St. Lawrence nominal index was based on catch and effort data for vessels with + trips per year and included observations for 28 years (1981-8), three months (August, September, October), two fleets (Prince Edward Island and Gulf Nova Scotia) and two gear types (tended line, rod and reel) (n= 79,525 trips). The + trip threshold restricts the analysis to full time, experienced fishermen that fish the main months of the fishery (August-October). The Southwest Nova Scotia nominal index was based on catch and effort data aggregated by trip. The data set included observations for 21 years (1988-8), two areas (Hell Hole, Bay of Fundy), five fleet sectors (Nova Scotia, Prince Edward Island, Quebec, Gulf Nova Scotia, Gulf New Brunswick), three gear types (rod and reel, tended line, harpoon), and three months (August, September, October) (n=,326 trips). 5. Discussion Concerning trends in the size of the fish caught in Canadian fisheries, industry has stressed that the size of fish landed reflects, in part, market demand and small scale changes in the fishery spatial distribution (Neilson et al. 9). This appears particularly to be the case off southwestern Nova Scotia, where the size composition of the catch can vary substantially from year to year. In contrast, the size composition in the southern Gulf of St. Lawrence varies in a more gradual fashion from year to year. In recent years (from 5 to 8), the trend is towards a larger average size. The 8 western Atlantic Bluefin Executive Summary noted the increasing trend in the southern Gulf of St. Lawrence, and commented that the high catch rates observed in Figure 3 could be supported by a single or a limited number of strong year-classes. However, Figure 2 suggests that the current high catch rates are sustained by at least five year-classes. The catch rates in the southern Gulf of St. Lawrence are now at the highest observed in the series, which commenced in The catch rates off Southwestern Nova Scotia have also increased, but this series is considered to be less indicative of abundance due to fishermen making strategic decisions on when to fish (Neilson et al. 9). Both catch rate series reflect nominal data, and have not been standardized. However, the effects of standardization have tended to be minor in previous analyses (see, for example, Neilson and Smith, 8), and have not significantly impacted the overall trend of the series. Literature cited Neilson, J.D., Smith, S.C., Ortiz, M.A., and Lester, B. 9, Indices of stock status obtained from the Canadian bluefin tuna fishery, 8. Collect. Vol. Sci. Pap. ICCAT, 64(2): Turner, S.C., and Restrepo, V.R. 1994, A review of the growth rate of west Atlantic bluefin tuna, Thunnus thynnus, estimated from marked and recaptured fish. Collect. Vol. Sci. Pap. ICCAT, 42(1):

4 6 SWNS Tended Line Fishery August & September n= Gulf of St. Lawrence Rod & Reel Fishery August & September n= Figure 1. Trends in median weight (upper and lower edges of the box represent 75 and 25 th percentiles of the data in each year, and the upper and lower whiskers signify the 95 and 5 th percentiles, respectively) shown by gear and area for bluefin tuna captured in Canadian fisheries. SWNS = southwest Nova Scotia. 861

5 Figure 2. Length-frequency distribution of the landings of bluefin tuna in the southern Gulf of St. Lawrence. For reference, the lengths at age predicted by Turner and Restrepo (1994) growth model are shown for selected ages X Data 6 Age Curved Fork Length (cm)

6 a) PRELIMINARY Canadian Bluefin tuna CPUE GSL 7 nominal CPUE (fish per hours) PRELIMINARY Canadian Bluefin tuna CPUE SWNS b).6 nominal CPUE (fish per hours) Figure 3. Nominal catch rates (fish per hours) for Canadian bluefin tuna in a) Gulf of St. Lawrence and b) southwest Nova Scotia. 863