DEEP DEMERSAL FISH ASSEMBLAGE STRUCTURE IN THE PORCUPINE SEABIGHT (EASTERN NORTH-ATLANTIC) - SLOPE SAMPLING BY 3 DIFFERENT TRAWLS COMPARED

被引:132
作者
MERRETT, NR
GORDON, JDM
STEHMANN, M
HAEDRICH, RL
机构
[1] INST OCEANOG SCI,DEACON LAB,GODALMING GU8 5UB,SURREY,ENGLAND
[2] DUNSTAFFNAGE MARINE RES LAB,OBAN PA34 4AD,ARGYLL,SCOTLAND
[3] ZOOL MUSEUM,ICHTHYOL INST SEEFISCHEREI,W-2000 HAMBURG 13,GERMANY
[4] MEM UNIV NEWFOUNDLAND,CTR OCEAN SCI,ST JOHNS A1B 3X9,NEWFOUNDLAND,CANADA
关键词
D O I
10.1017/S0025315400051638
中图分类号
Q17 [水生生物学];
学科分类号
071004 ;
摘要
The demersal ichthyofauna of the continental slope of the Porcupine Seabight, eastern North Atlantic, was studied from 144 samples taken by three different types of otter trawl. At least 118 species from 43 families were represented among some 54,000 specimens collected from 247 to 2172 m soundings. Collectively, the catches were dominated in species richness by the Macrouridae, Alepocephalidae and Squalidae and in abundance by the Synaphobranchidae, Macrouridae and Moridae. Separately, relative abundance of species was more similar between the two larger trawls, setting their catches apart from the smaller net. Gear selectivity evidently accounted for this variation, which was examined by an index we developed and call species fidility. This accounts for patterns of continuous faunal change with increased sounding concomitant with variance in species adult size and mobility. In pursuance of a more accurate representation of relative biomass and abundance than achieved hitherto, the best estimate, within the limitations imposed by the sampling gears and regime, was derived from a combination of the mean values per 200- m stratum of the two large trawls with the addition of those of the eel, Synaphobranchus kaupi, from the small gear. Tentative comparisons between these results and those from elsewhere suggest that the Porcupine Seabight is generally lower in biomass and similar or lower in abundance. It was concluded that an accurate indication of ichthyofaunal structure with increased sounding can only be achieved through a detailed knowledge of the size structure of each species over its entire sounding range synthesized from a multi-trawl investigation via analyses of species fidelity.
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页码:329 / 358
页数:30
相关论文
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