CE0918 Irish Groundfish Survey Leg 2

This survey was conducted on board the RV Celtic Explorer in 2009 by the Marine Institute (MI) as part of the annual groundfish survey to determine the distribution and Abundance of commercial fish around Ireland. The Irish Groundfish Survey (igFs) forms part of the International Bottom Trawl Survey (IBTS) programme, an international survey effort coordinated by the International Council of the Exploration of the Sea (ICES). Each year the survey, taking place in Autumn/Winter, collects demersal trawls and ancillary data in Irish waters to produce relative Abundance Indices for fisheries management. In particular the survey provides an index of the share of young fish in the stock, which in turn gives an indication of its spawning success. The igFs contribute to Ireland’s international obligation to supply scientific data that support the implementation of the Common Fisheries Policy (CFP). This survey is a series of demersal sampling trawls at pre-defineds stations. The 2009 survey took place over 3 legs. Leg 1 focused on the northerly ICES Area and took place in late September and early October, while Leg 2 in the western and southern areas was carried out during November/December. In order to make data as comparable as possible, each survey operates under a set of agreed standard protocols. Each tow is 30 min long and takes place during daylight hours at 3.5-4 Knots. Net geometry and ground contact is monitored and logged. All fish and commercial Shellfish are sorted to species level prior to taking lengths and other biological measurements such as age, sex and Maturity. The primary purpose of the Irish Groundfish Survey is to Develop estimates of Juvenile abundances for important commercial fish species. Measurements of the Abundance of Juvenile fish are a critical measure of the health of a stock, serving as an annual indication of recruitment (the number of newly spawned fish which enter the population each year) success or failure. Most importantly, they allow Forecasting of future commercial Abundance. In addition, the Irish Groundfish Survey provided data on the distribution and biology of commercial and non-commercial species of ecological interest, as well as as Hydrographic and environmental observations.本调查于2009年由爱尔兰海洋研究所（Marine Institute, MI）在“凯尔特探险家号”（RV Celtic Explorer）科考船上开展，作为年度底层鱼类调查项目的一部分，旨在探明爱尔兰周边海域商业鱼类的分布与丰度情况。 爱尔兰底层鱼类调查（Irish Groundfish Survey, igFS）是国际底拖网调查（International Bottom Trawl Survey, IBTS）计划的组成部分，该国际调查项目由国际海洋考察理事会（International Council for the Exploration of the Sea, ICES）统筹协调。 该调查于每年秋冬两季开展，在爱尔兰海域采集底栖拖网采样数据及配套辅助数据，以生成用于渔业管理的相对丰度指数。尤为重要的是，本调查可生成种群内幼鱼占比指数，以此反映种群的产卵繁殖成效。 爱尔兰底层鱼类调查（igFS）履行了爱尔兰的国际义务，为共同渔业政策（Common Fisheries Policy, CFP）的实施提供科学数据支撑。本调查通过在预设站位开展系列底栖采样拖网作业完成。 2009年的调查共分为3个航次段：第1航次段聚焦国际海洋考察理事会（ICES）北部海域，于9月末至10月初开展；第2航次段覆盖西部与南部海域，于11月至12月间实施。 为确保数据具备尽可能高的可比性，所有调查均遵循一套统一约定的标准作业规程。每次拖网作业时长为30分钟，于日间开展，航速保持在3.5至4节。 拖网网具结构及网具与海底的接触状态均会被监测并记录。所有鱼类及商业性水生无脊椎动物均会按物种分类，随后测量其体长，并开展年龄、性别与成熟度等其他生物学指标测定。 爱尔兰底层鱼类调查的核心目标是估算重要商业鱼类的幼体丰度。幼鱼丰度的测定是评估种群健康状况的关键指标，可每年反映种群补充量（即每年新孵化并加入种群的幼鱼数量）的成败情况。最为关键的是，该数据可用于预测未来商业鱼类的丰度水平。 此外，本调查还采集了具有生态价值的商业与非商业物种的分布及生物学数据，同时开展了水文与环境观测。