Garcia Elena Guijarro
Marine Research Institute, 101 Reykjavík, Iceland.
Adv Mar Biol. 2007;52:147-266. doi: 10.1016/S0065-2881(06)52002-4.
This chapter describes the development and current situation of the offshore shrimp fisheries in Iceland, Greenland, Svalbard, Jan Mayen and the Norwegian Barents Sea area, with information on the biology of Pandalus borealis and its relation to the environment. Some additional information about the inshore shrimp fisheries of Iceland and Greenland of relevance to this study is also included. The Icelandic offshore shrimp fishery started in 1975 and has formed between 68% and 94% of the annual catch of shrimp since 1984. Landings peaked at 66,000 tons in 1997. The offshore fleet increased threefold from 1983 to 1987, and catch per unit of effort doubled. The first signs of overfishing were detected in 1987, when the first total allowable catch (TAC) was set, and catches decreased during the next few years despite the discovery of new fishing grounds. Good recruitment allowed catches to rise steadily from 1990 to 1996. However, catches and stock index have decreased markedly since then, with a minimum catch for the period 1998-2003 of 21,500 tons in 2000. It has been suggested that predation by cod is an important factor affecting shrimp stock size, but mortality from predation is slightly lower than fishing mortality, so that the impact of fishing cannot be disregarded. The Greenland offshore shrimp fishery is one of the largest in the North Atlantic and it generates 90% of the export value of the country. The fishery started in 1970 in West Greenland with landings of 1200 tons, but since 1974 it has formed between 59% and 89% of the annual shrimp catch. In 2004, landings reached 113,000 tons and the fishable stock was estimated at 300,000 tons. The significant spatial expansion of the fishery from the original fishing grounds off the Disko Island area to all of the West coast south of 75 degrees N and the fleet improvement over the past three decades have made possible this spectacular growth. Other fishing grounds off the East coast have been fished since 1978, mostly by foreign vessels. Catches in this area oscillated between 5000 and 15,000 tons during the period 1980-2004. The main problem of the shrimp fishery in Greenland is its overlapping with nursery areas of redfish, Greenland halibut, cod and other groundfish species, some of which show declining trends of biomass and abundance. This led to the implementation in 2000 of sorting grids and laws that forbid fishing when the bycatch exceeds legal limits. However, it is likely that ecological processes only partially understood, such as the trophic web and hydrography of the area, greatly influence the stock abundance of the demersal community. The offshore Norwegian fishery started in 1973. The main fishing grounds are off Svalbard and in the Barents Sea. Catches at Jan Mayen have never exceeded 5% of the total annual catch of northern shrimp. Large fluctuations in catches and stock size are the main characteristic of this fishery. Stock size seems to be largely dependent on the annual hydrographic variability in the area and trends in abundance of predator species, especially cod. However, shrimp mortality due to predation has been estimated to be the same as fishing mortality, and therefore fishing probably accounts for part of the observed variability in stock size. Large populations of juvenile cod, haddock, redfish and Greenland halibut are often found on the shrimp fishing grounds. The implementation of sorting grids in 1991 and a bio-economical model in 1993 to estimate allowable maximum catches of the commercial bycatch species have not solved the bycatch problem. All the commercial fish species present on the shrimp grounds are currently below safe biological limits. This is the only fishery within the studied area that is not regulated by means of a TAC system.
本章介绍了冰岛、格陵兰、斯瓦尔巴群岛、扬马延岛和挪威巴伦支海地区近海虾类渔业的发展及现状,并提供了北方长额虾的生物学信息及其与环境的关系。还纳入了一些与本研究相关的冰岛和格陵兰近岸虾类渔业的补充信息。冰岛近海虾类渔业始于1975年,自1984年以来占虾类年捕捞量的68%至94%。1997年上岸量达到峰值6.6万吨。近海捕捞船队从1983年到1987年增加了两倍,单位捕捞努力量的渔获量翻了一番。1987年首次发现过度捕捞的迹象,当时设定了首个总可捕量(TAC),尽管发现了新渔场,但在接下来的几年里捕捞量仍有所下降。良好的补充量使捕捞量从1990年到1996年稳步上升。然而,从那时起,捕捞量和种群指数显著下降,2000年19至2003年期间的最低捕捞量为2.15万吨。有人认为鳕鱼的捕食是影响虾类种群规模的一个重要因素,但捕食造成的死亡率略低于捕捞死亡率,因此捕捞的影响不可忽视。格陵兰近海虾类渔业是北大西洋最大的渔业之一,占该国出口值的90%。该渔业始于1970年的西格陵兰,上岸量为1200吨,但自1974年以来占虾类年捕捞量的59%至89%。2004年,上岸量达到11.3万吨,可捕捞种群估计为30万吨。渔业从迪斯科岛地区附近的原始渔场大幅扩展到北纬75度以南的整个西海岸,以及过去三十年船队的改进,使得这种显著增长成为可能。自1978年以来,东海岸的其他渔场也被开发,主要是外国船只捕捞。1980年至2004年期间,该地区的捕捞量在5000吨至1.5万吨之间波动。格陵兰虾类渔业的主要问题是它与红鱼、格陵兰庸鲽、鳕鱼和其他底栖鱼类的育苗区重叠,其中一些种群的生物量和丰度呈下降趋势。这导致在2000年实施了分拣格栅和法律,禁止在兼捕超过法定限额时捕鱼。然而,该地区的营养网和水文等可能仅被部分理解的生态过程,很可能对底栖生物群落的种群丰度有很大影响。挪威近海渔业始于1973年。主要渔场在斯瓦尔巴群岛附近和巴伦支海。扬马延岛的捕捞量从未超过北方虾类年总捕捞量的5%。捕捞量和种群规模的大幅波动是该渔业的主要特征。种群规模似乎在很大程度上取决于该地区每年的水文变化以及捕食者物种(尤其是鳕鱼)的丰度趋势。然而,据估计,捕食造成的虾类死亡率与捕捞死亡率相同,因此捕捞可能是观察到的种群规模变化的部分原因。在虾类渔场经常发现大量幼鳕鱼、黑线鳕、红鱼和格陵兰庸鲽。1991年实施了分拣格栅,1993年采用了生物经济模型来估计商业兼捕物种的最大可捕量,但仍未解决兼捕问题。虾类渔场目前所有商业鱼类种群都低于安全生物学极限。这是研究区域内唯一不受总可捕量制度监管的渔业。