不同离岸距离的养殖海区对海带养殖性状及苗绳老化的影响

Effects of Cultivation Area of Different Offshore Distances on the Agronomic Traits and Breeding Rope Aging of Saccharina japonica

关键词:  海带  离岸距离  养殖绳性能  捻距  脱苗率

Key words:  Saccharina japonica  Offshore distance  Breeding rope performance  Pitch of twist  Seedling drop rate

摘要:

本研究选取不同离岸距离的养殖海区(由远到近分别为高区、中区、低区)，研究不同海区环境对3个海带(Saccharina japonica)品种/品系(“寻山2号”、“寻山3号”和“205”)的生长性状，如长度、宽度、厚度、鲜重和干重的影响，结合不同捻距(80.8、65.6、61.1、53.4和48.3 mm)的养殖苗绳，分析了影响海带脱苗率的主要因素，同时，对比研究了不同海区和苗绳捻距对养殖苗绳力学性能和老化程度的影响。结果显示，对于相同海带品种/品系，其长度、宽度和厚度性状在不同海区表现不同，海带“寻山2号”和海带“寻山3号”在高区具有更优良的经济性状。不同品种海带的鲜重和干重均呈现为在高区较大、中区次之、低区最低，但离岸养殖对不同品种鲜重与干重的提升作用不同。无论养殖前后，特制养殖苗绳的断裂强力均显著高于传统养殖苗绳(P<0.05)，养殖使用1年后，特制养殖苗绳的强力保持率为93.8%，而传统养殖苗绳仅为63.6%。捻距为61.1 mm的苗绳脱苗率较低，捻距过大(80.8 mm)或过小(≤53.4 mm)的苗绳脱苗率均显著增大。高区养殖的苗绳分子链氧化更剧烈，老化程度更高。本研究表明，离岸式养殖对不同海带品种/品系产量均有提升作用，但不同品种对不同离岸距离，尤其是离岸深水区的适应性不同；通过控制苗绳捻距可有效降低海带脱苗率；离岸水域环境下进行海带养殖，选择耐老化、捻距为61.1 mm的特制苗绳可适当延长使用时间并降低脱苗率。本研究结果对推动我国离岸式海带养殖产业发展具有指导作用。

Abstract:

The trend towards kelp Saccharina japonica cultivation in offshore areas is becoming increasingly obvious, but there is no relevant research report on the influence of different offshore distances on the agronomic traits of kelp aquaculture. The factors influencing the growth (length, width, thickness, fresh weight, and dry weight) of kelp and the seedling drop rate were explored for different kelp cultivars ("Xunshan No.2", "Xunshan No.3", kelp "205"), offshore sea areas (from far to near, defined as offshore, middle area and inshore), and pitches of twist kelp breeding rope (80.8 mm, 65.6 mm, 61.1 mm, 53.4 mm, 48.3 mm); the mechanical properties and aging degree of the breeding rope were also investigated. The results showed that: for the same kelp cultivar in different sea areas, the length, width, and thickness properties of the blade were different. The cultivars "Xunshan 2" and "Xunshan 3" showed better economic traits in the offshore area. The fresh and dry weights of the different cultivars were higher in the offshore area, followed by the middle area, and were lowest in the inshore area; however, offshore cultivation had different effects on the fresh and dry weight enhancement of the different cultivars. Whether before or after use, the breaking strength of the special breeding rope was significantly higher than that of the traditional breeding rope (P<0.05). After using a year, the strength retention rate of the special breeding rope was 93.8%, whereas that of the traditional breeding rope was only 63.6%. The seedling drop rate of the breeding ropes with a twist pitch of approximately 61.1 mm was the lowest, and the seedling drop rate significantly increased if the pitch of twist of the breeding ropes was too large (80.8 mm) or too small (≤53.4 mm). The molecular chain of the breeding rope used in the offshore was oxidized more severely, and the degree of aging was higher. The above results showed that offshore aquaculture can improve the yield of different kelp cultivars, but different cultivars have different adaptabilities to different offshore distances; and controlling the pitch of twist of the culture rope can effectively reduce the kelp seedling drop rate. For kelp culture under offshore sea conditions, a special rope with aging resistance and a twist pitch of approximately 61.1 mm can prolong the use time and reduce the rate of seedling drop. The results of this study can guide the development of the offshore kelp culture industry.