DTU Aqua, National Institute of Aquatic Resources, North Sea Science Park, Hirtshals, Denmark.
SINTEF, Fisheries and Aquaculture, Fishing Gear Technology, North Sea Science Park, Hirtshals, Denmark.
PLoS One. 2014 Feb 20;9(2):e88819. doi: 10.1371/journal.pone.0088819. eCollection 2014.
During the fishing process, fish react to a trawl with a series of behaviours that often are species and size specific. Thus, a thorough understanding of fish behaviour in relation to fishing gear and a scientific understanding of the ability of different gear designs to utilize or stimulate various behavioural patterns during the catching process are essential for developing more efficient, selective, and environmentally friendly trawls. Although many behavioural studies using optical and acoustic observation systems have been conducted, harsh observation conditions on the fishing grounds often hamper the ability to directly observe fish behaviour in relation to fishing gear. As an alternative to optical and acoustic methods, we developed and applied a new mathematical model to catch data to extract detailed and quantitative information about species- and size-dependent escape behaviour in towed fishing gear such as trawls. We used catch comparison data collected with a twin trawl setup; the only difference between the two trawls was that a 12 m long upper section was replaced with 800 mm diamond meshes in one of them. We investigated the length-based escape behaviour of cod (Gadus morhua), haddock (Melanogrammus aeglefinus), saithe (Pollachius virens), witch flounder (Glyptocephalus cynoglossus), and lemon sole (Microstomus kitt) and quantified the extent to which behavioural responses set limits for the large mesh panel's selective efficiency. Around 85% of saithe, 80% of haddock, 44% of witch flounder, 55% of lemon sole, and 55% of cod (below 68 cm) contacted the large mesh panel and escaped. We also demonstrated the need to account for potential selectivity in the trawl body, as it can bias the assessment of length-based escape behaviour. Our indirect assessment of fish behaviour was in agreement with the direct observations made for the same species in a similar section of the trawl body reported in the literature.
在捕捞过程中，鱼类对拖网会产生一系列反应，这些反应通常具有物种和大小特异性。因此，深入了解鱼类与渔具之间的行为关系，以及科学理解不同渔具设计在捕捞过程中利用或激发各种行为模式的能力，对于开发更高效、更具选择性和更环保的拖网至关重要。尽管已经进行了许多使用光学和声学观测系统的行为研究，但在渔业水域恶劣的观测条件往往会阻碍直接观察鱼类与渔具之间的行为的能力。作为光学和声学方法的替代方法，我们开发并应用了一种新的数学模型来分析渔获数据，以提取有关拖网等拖曳渔具中与物种和大小相关的逃逸行为的详细和定量信息。我们使用双拖网设置收集的渔获比较数据；两个拖网之间的唯一区别是，一个拖网的上部分 12 米长的部分被 800 毫米的菱形网片代替。我们研究了鳕鱼（Gadus morhua）、黑线鳕（Melanogrammus aeglefinus）、拟庸鲽（Pollachius virens）、鲽鱼（Glyptocephalus cynoglossus）和黄盖鲽（Microstomus kitt）的基于长度的逃逸行为，并量化了行为反应对大网板选择性效率的限制程度。大约 85%的拟庸鲽、80%的黑线鳕、44%的鲽鱼、55%的黄盖鲽和 55%的鳕鱼（小于 68 厘米）接触到大网板并逃脱。我们还证明了需要考虑拖网体的潜在选择性，因为它可能会影响对基于长度的逃逸行为的评估。我们对鱼类行为的间接评估与文献中报道的同一物种在拖网体类似部分的直接观察结果一致。
