ALMQ Data Analysis Final Report
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Box 25125, Halifax, Nova Scotia B3M 4H4 Telephone: (902) 876-1160 Fax: (902) 876-1320 www.fsrs.ns.ca Final Report Prepared for: Fishermen and Scientists Research Society Contract: FSRS2012-022 ATLANTIC LOBSTER MOULT & QUALITY PROJECT Data analysis and descriptive statistics September 22, 2013 www.lobstermoult.ca ALMQ data analysis Final Report Table of Content Report Contribution 3 Executive Summary 4 Project Background and Introduction 6 Materials and Methods 8 Site Selection 8 Sampling Procedure 8 Data Analysis 8 Moult Timing Definitions 10 Results 12 Descriptive Statistics 12 Moult Timing Based on Brix Index Value 15 Moult Timing Based on Moult Stage Proportion 18 Moult Timing Based on Shell Hardness 19 Comparison of Moult Timing Classification Methods 19 Graphical Comparison of Moult Timing Classification Methods 20 Interpretation 23 Acknowledgement 27 References 28 Appendices 31 2 ALMQ data analysis Final Report Report Contribution Primary authour Jean Lavallée Principal Consultant Aquatic Science & Health Services 465 University Avenue, PO Box 21116 Charlottetown, PE C1A 9H6 902.628.7981 [email protected] Other report resource Tim Burnley Melanie Burton Owner Field Biologist Eastern Epidemiological Services Aquatic Science & Health Services 23 Karen Drive 465 University Avenue, PO Box 21116 Cornwall, PE C0A 1H8 Charlottetown, PE C1A 9H6 902.626.8118 902.940.3788 [email protected] [email protected] John Tremblay Shannon Scott-Tibbetts Research Scientist & Head, Lobster Unit Research Biologist Population Ecology Division Fishermen and Scientists Research Society Fisheries and Oceans PO Box 25125 Bedford Institute of Oceanography Halifax, NS B3M 4H4 1 Challenger Drive 902.461.8119 Dartmouth, NS B2Y 4A2 [email protected] 902.426.3926 [email protected] Angelica Silva Douglas Pezzack Research Scientist Biologist Coastal Ecosystem Science Division Population Ecology Division Fisheries and Oceans Fisheries and Oceans Bedford Institute of Oceanography Bedford Institute of Oceanography 1 Challenger Drive 1 Challenger Drive Dartmouth, NS B2Y 4A2 Dartmouth, NS B2Y 4A2 902.426.6525 902.426.2099 [email protected] [email protected] 3 ALMQ data analysis Final Report Executive Summary Background Since the early 2000's, there has been a significant increase in the proportion of soft shelled lobsters caught in Southwest Nova Scotia, especially at the first few weeks of the commercial fishing season in late November-early December, which has resulted in severe economic hardship for both fishers and processors. The Atlantic Lobster Moult & Quality monitoring project began in 2004 at the request of harvesters and processors, as a collaborative effort to better understand the variation in their catch quality and all information collected for this project is available on the Internet (www.lobstermoult.ca). Lobster shell hardness (and implications for quality) is directly related to moult timing. Understanding the extent of the occurrence of different lobster quality is vital to the sustainability and health of the Canadian lobster industry. Data from 2004 to 2012 generated from this project were analysed to generate descriptive statistics. Methodology Whenever possible, lobsters from various sites were sampled every second week inside and outside the commercial fishing season. Lobsters were sexed, measured, checked for liveliness/vigour, damage, shell hardness, sampled for hemolymph protein levels and for pre- moult stage assessment. In total, 117,571 lobsters were sampled between 2004 and 2012 through 981 different sampling events in 15 different locations in LFAs 33, 34 and 35. Descriptive statistics were generated for lobster gender and size by location and year. Only the sites with sufficient data to allow for proper data analysis were further investigated and these include: Jacquard’s Ridge, Lobster Bay, Port Latour Inside, Yarmouth Inside, and Yarmouth Outside. Additionally, data collected in 2004 were insufficient to allow for valid year-to-year comparisons and therefore, weren’t included in the in-depth analysis. Interest in the identification of moult timing among the five sampling locations over the eight year study period (2005 - 2012), resulted in the evaluation of potential dataset variables that could be used to identify moult timing. The lobster variables protein blood levels (Brix), moult stage, moult stage group, and shell hardness were evaluated for potential use in identifying moult timing. Summary of results The extensive dataset on moult indicators collected from 2005-2012 was analyzed to assess differences in moult timing. Three different methods of assessing moult timing were used: hemolymph protein levels (Brix index), shell hardness and pleopods staging for premoult assessment. The agreement among those methods was only fair at the most, which may result from the semi-objective nature of some of these methods. Moulting appears to occur at different times in different areas. Areas further from shore appeared to have later moulting periods compared to areas closer to shore. There were differences in moult timing between males and females, and lobsters of different sizes; larger lobsters moulting first. 4 ALMQ data analysis Final Report There was an overall tendency for the moult to become progressively earlier from 2005 to 2011; however, this was not uniform across all sites. Moulting appears to have been later in 2012, even though this was an exceptionally warm year. Additionally, 2012 appeared to have had more moulting activity as indicated by the presence of more soft-shelled lobsters. Recommendations Sampling methodology for this project should be reviewed after consideration of the program goals. Possible expansion of the sampling program to extend throughout the entire study period to ensure that peak moulting is captured among all locations. Expansion could include greater frequency of sampling over entire study periods (e.g., weekly sampling), using the current sampling procedure. A cost benefit analysis of the current sampling strategy vs. alternatives should be evaluated with the program goals in mind. The choice of the proper variable for the determination of moult timing needs to be further evaluated with respect to choices in cut-points (protein levels), and the repeatability and reproducibility of the other more subjective moult scoring variables (shell hardness, premoult staging). Further work with Gaussian curve fitting methodologies may provide alternatives to expanding or modifying the current sampling program and provide a greater accuracy in determination of moult timing. Water temperature data and other environmental parameters should be incorporated in the sampling program and in further data analysis. This could allow for the establishment of correlations between these parameters and moult timing. The incorporation of ocean forecasting models should also be considered to generate long-term moult timing predictions. These novel prediction models could have fishery management applications with lower post- harvest product downgrading and greater economic return to the industry. Among other things, the following options could be considered: dynamic fishing season opening/closing dates, sub- area and smaller scale management, at-sea management procedures, and establishment of grading/quality standards with corresponding labeling on Canadian lobster harvests. This document represents the Final Report on the data analysis and descriptive statistics for the ATLANTIC LOBSTER MOULT & QUALITY PROJECT. This was completed in fulfillment of Contract # FSRS2012-022 between the Fishermen & Scientist Research Society (Halifax, NS) and Aquatic Science & Health Services (Charlottetown, PE). 5 ALMQ data analysis Final Report Project Background and Introduction Since the early 2000's, there has been a significant increase in the proportion of soft shelled lobsters caught in Southwest Nova Scotia (SWNS), especially at the first few weeks of the commercial fishing season in late November-early December. Anecdotal reports have estimated the proportion of soft shell lobsters to have increased from traditionally 5-10% to over 30-40% in recent years. These soft shelled lobsters often have low meat yield and poor survivability during holding and transportation. This has resulted in severe economic hardship for both fishers and processors. It is crucial to understand the extent of the occurrence of lower quality lobster in terms of shell hardness to ensure the lobster fishery in SWNS remains sustainable and healthy. The Atlantic Lobster Moult & Quality (ALMQ) monitoring project began in 2004 at the request of harvesters and processors, as a collaborative effort to better understand the variation in their catch quality. The information collected for this project is available on the Internet and allows users to look at lobster sex, size, hemolymph protein levels, moult stage and shell hardness by sampling location or dates (www.lobstermoult.ca). The ALMQ project provided a new focus and resource to the lobster fishery by building on knowledge and capacity developed during previous years of research. The accumulated data could be used to build predictive models for landed lobster quality. Funding was initially provided by Fisheries and Oceans Canada in 2004 to the Fishermen & Scientists Research Society (FSRS) with additional financial support from the Province of Nova Scotia. In 2005, the AVC Lobster Science Centre at the University of Prince Edward Island