Spatiotemporal factors affecting fish harvest and their use in estimating the monthly yield of single otter trawls in Putuo district of Zhoushan, China  

作　　者：王迎宾 郑基 王洋 郑献之 

机构地区：[1]School of Fisheries of Zhejiang Ocean University

出　　处：《Chinese Journal of Oceanology and Limnology》2012年第4期580-586,共7页中国海洋湖沼学报（英文版）

基　　金：Supported by the National Natural Science Foundation for Young Scientists of China (No. 40801225);the Natural Science Foundation of Zhejiang Province (No. Y3090038)

摘　　要：We used generalized additive models (GAM) to analyze the relationship between spatiotemporal factors and catch, and to estimate the monthly marine fishery yield of single otter trawls in Putuo district of Zhoushan, China. We used logbooks from five commercial fishing boats and data in government's monthly statistical reports. We developed two GAM models: one included temporal variables (month and hauling time) and spatial variables (longitude and latitude), and another included just two variables, month and the number of fishing boats. Our results suggest that temporal factors explained more of the variability in catch than spatial factors. Furthermore, month explained the majority of variation in catch. Change in spatial distribution of fleet had a temporal component as the boats fished within a relatively small area within the same month, but the area varied among months. The number of boats fishing in each month also explained a large proportion of the variation in catch. Engine power had no effect on catch. The pseudo-coefficients (PCf) of the two GAMs were 0.13 and 0.29 respectively, indicating the both had good fits. The model yielded estimates that were very similar to those in the governmental reports between January to September, with relative estimate errors (REE) of <18%. However, the yields in October and November were significantly underestimated, with REEs of 36% and 27%, respectively.We used generalized additive models （GAM） to analyze the relationship between spatiotemporal factors and catch, and to estimate the monthly marine fishery yield of single otter trawls in Putuo district of Zhoushan, China. We used logbooks from five commercial fishing boats and data in government＇s monthly statistical reports. We developed two GAM models： one included temporal variables （month and hauling time） and spatial variables （longitude and latitude）, and another included just two variables, month and the number of fishing boats. Our results suggest that temporal factors explained more of the variability in catch than spatial factors. Furthermore, month explained the majority of variation in catch. Change in spatial distribution of fleet had a temporal component as the boats fished within a relatively small area within the same month, but the area varied among months. The number of boats fishing in each month also explained a large proportion of the variation in catch. Engine power had no effect on catch. The pseudo-coefficients （PCf） of the two GAMs were 0.13 and 0.29 respectively, indicating the both had good fits. The model yielded estimates that were very similar to those in the governmental reports between January to September, with relative estimate errors （REE） of 〈18%. However, the yields in October and November were significantly underestimated, with REEs of 36% and 27%, respectively.

关 键 词：generalized additive model （GAM） estimate of catch single otter trawl Zhoushan 

分 类 号：F326.4[经济管理—产业经济] F224