Several species of wrasse (Labridae) are used as cleaner fish to remove salmon lice from farmed Atlantic salmon. We estimated the fishery and use of wrasse in Hardangerfjord. The estimated numbers of labrids used on salmon and rainbow trout farms varied between 86,000 and 251,000 from 2002Á2006, but increased to as much as 1.1 million in 2009 and 2010. A total of 93,500 kg (around 1.54 million) labrids were reported landed during 2000Á2010. Corkwing wrasse (Symphodus melops) was by far the most important wrasse species: 52% by weight and 56% by number. Ballan wrasse (Labrus bergylta) made up 34% by weight but only 14% by number (due to its larger size). The relative proportion of species between the different sampling locations in the fjord was significantly different, as was the condition factor of some species. Goldsinny wrasse (Ctenolabrus rupestris) had the slowest growth of the labrids in this study, and did not reach the minimum commercial catch size (11 cm) before they were 4Á5 years old. Very few goldsinny caught were over that size. Corkwing reach commercial size in 1Á2 years. The results of this study indicate that wrasse should be protected during the spawning season. Species such as goldsinny grow so slowly that they will most likely be collected several times in heavily fished areas but discarded because they are smaller than the minimum allowable size. This could be avoided through the use of modified traps with escape routes for undersized fish. This study represents a first step towards establishing a knowledge-based management plan for the wrasse fishery.
Abstract. The ongoing warming and acidification of the world's oceans are expected to influence the marine ecosystems, including benthic marine resources. Ocean acidification may especially have an impact on calcifying organisms, and the European lobster (Homarus gammarus) is among those species at risk. A project was initiated in 2011 aiming to investigate long-term effects of ocean acidification on the early life-cycle of lobster under two temperatures. Larvae were exposed to pCO 2 levels of ambient water (water intake at 90 m depth), medium 750 (pH = 7.79) and high 1200 µatm pCO 2 (pH = 7.62) at temperatures 10 and 18 • C. The water parameters in ambient water did not stay stable and were very low towards the end of the experiment in the larval phase at 10 • C,with pH between 7.83 and 7.90. At 18 • , pH in ambient treatment was even lower, between 7.76 and 7.83, i.e. close to medium pCO 2 treatment. Long-term exposure lasted 5 months. At 18 • C the development from stage 1 to 4 lasted 14 to 16 days, as predicted under optimal water conditions. Growth was very slow at 10 • C and resulted in three larvae reaching stage 4 in high pCO 2 treatment only.There were no clear effects of pCO 2 treatment, on either carapace length or dry weight. However, deformities were observed in both larvae and juveniles. The proportion of larvae with deformities increased with increasing pCO 2 exposure, independent of temperature. In the medium treatment about 23 % were deformed, and in the high treatment about 43 % were deformed. None of the larvae exposed to water of pH > 7.9 developed deformities. Curled carapace was the most common deformity found in larvae raised in medium pCO 2 treatment, irrespective of temperature, but damages in the tail fan occurred in addition to a bent rostrum. Curled carapace was the only deformity found in high pCO 2 treatment at both temperatures. Occurrence of deformities after five months of exposure was 33 and 44 % in juveniles raised in ambient and low pCO 2 levels, respectively, and 21 % in juveniles exposed to high pCO 2 . Deformed claws were most often found in ambient and medium treatment (56 %), followed by stiff/twisted walking legs (39 %) and puffy carapace (39 %). In comparison, at high pCO 2 levels 71 % of the deformed juveniles had developed a puffy carapace. Overall, about half of the deformed juveniles from the ambient and medium pCO 2 treatment displayed two or three different abnormalities; 70 % had multiple deformities in the high pCO 2 treatment. Some of the deformities in the juveniles may affect respiration (carapace), the ability to find food, or sexual partners (walking legs, claw and antenna), and ability to swim (tail-fan damages).
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