Abstract

Fish select habitat based on many abiotic and biotic factors, with some species having narrow habitat requirements due to morphological traits. Fish of the genus Ammodytes (sand lance) are small schooling pelagic forage fish that lack a swim bladder and burrow into sandy substrate when not actively feeding to avoid predation and reduce energy expenditure. Sand lance species in the Pacific and Northeast Atlantic show diel shifts in feeding in the water column and burrowing, but diel patterns for species in the Northwest Atlantic remain unclear. The objectives of this study were to investigate sand lance habitat characteristics and diel behaviour during July–August 2013–2021 on the northeast Newfoundland coast. Integrating underwater camera surveys, sediment grabs, and hydroacoustics, sand lance were found associated with fine sediment (0.5–4 mm) that were < 11˚C (typically ~ 2˚C). Acoustic sand lance biomass in the water column tended to decline between the morning (09:00 Newfoundland Daylight Time, NDT) and late evening (23:00 NDT), while fish densities in sediment grabs peaked during the evening (~ 19:00 NDT) when buried fish more commonly had non-empty stomachs. Findings suggest that sand lance primarily fed in the water column during the day and burrowed in the evening once stomachs were full. Diel patterns were size-dependent, with a higher proportion of larger sand lance (≥ 150 mm) caught in sediments throughout the night, when smaller sand lance (< 150 mm) were absent from sediments. Overall, sand lance species in the Northwest Atlantic appear to exhibit similar habitat requirements and diel patterns to those in other regions.

中文翻译：

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纽芬兰沿海沙矛（Ammodytes spp）的栖息地特征和昼夜模式

摘要

鱼类根据许多非生物和生物因素选择栖息地，某些物种由于形态特征而对栖息地要求狭窄。沙矛鱼属小型鱼群，没有鱼鳔，在不积极进食时会钻入沙底以避免捕食并减少能量消耗。太平洋和东北大西洋的沙矛物种在水体中摄食和穴居方面表现出昼夜变化，但西北大西洋物种的昼夜模式仍不清楚。本研究的目的是调查 2013 年 7 月至 2021 年 8 月期间纽芬兰东北部海岸的沙矛栖息地特征和昼夜行为。综合水下摄像机调查、沉积物抓取和水声学，发现沙枪与 < 11°C（通常约为 2°C）的细沉积物（0.5–4 毫米）有关。水体中的声学沙枪生物量在早上（09:00 纽芬兰夏令时间，NDT）和深夜（23:00 NDT）之间趋于下降，而沉积物中的鱼类密度在晚上（~ 19:00 NDT）达到峰值）当埋藏的鱼更常见时胃不空。研究结果表明，沙矛鱼白天主要在水体中进食，晚上胃吃饱后就会挖洞。昼夜模式取决于尺寸，当沉积物中不存在较小的沙枪（< 150 毫米）时，整个晚上沉积物中捕获的较大沙枪（≥ 150 毫米）的比例较高。总体而言，西北大西洋的沙矛物种似乎表现出与其他地区相似的栖息地要求和昼夜模式。