Reproduction of European eel (Anguilla anguilla) in aquaculture systems has become a focus research area due to severe decline of natural stocks, and increasing interest to breed eels for a self-sustained aquaculture. Despite over hundred years of research there are still large parts of its life cycle and biology that are unknown. Viable embryos and larvae are some of the key issues for rearing European eel in captivity where scarce knowledge of abiotic factors and adequate culture conditions remain a problem. Knowledge on the effect of water temperature is important to improve larval rearing and aquaculture systems, since thermal tolerance and optimal temperature is closely related to growth rate, development and survival. The aim of the present study was to investigate muscle growth and development in yolk-sac larvae of European eel, and how embryonic incubation temperatures affected survival rate, morphological development and muscle growth. European eel eggs and larvae were therefore incubated at 16, 20 and 24° C. The previous small scale incubation experiment showed that time until hatching was clearly related to temperature, and provide information about the actual time and day degrees required for embryonic development from fertilization to hatching, similar to those temperatures found in the spawning-area. Incubation at 24° C had a negative effect on survival rates of newly hatched larvae, indicating that this temperature is suboptimal for egg incubation. The present study demonstrated that muscle morphology, rate of development and onset of muscle differentiation follow a unique pattern, indicating that yolk-sac larvae of eels prepare for a somewhat different developmental strategy, i.e. leptocephalus phase. Larval muscle growth occurred by hyperplasia and hypertrophy, and the somatic length growth was poorly correlated to muscle growth in the initial yolk-sac stage.

Salmon lice (Lepeophtheirus salmonis) have been an increasing problem for the Norwegian aquaculture industry in recent years, and several chemicals have been used by the industry to get rid of the louse. However, resistance and reduced sensitivity towards a large quantity of these has resulted in a blooming interest for the use of wrasse as a biological method of sea louse control. The ballan wrasse (Labrus bergylta) is considered the most promising species for aquaculture, but problems with poor survival, growth and skeletal deformities suggest that a suboptimal first feeding practice may be used. At present, commercial farmers first feed the ballan wrasse larvae on enriched rotifers from 4 to approximately 30 dph, followed by Artemia sp. until weaning on formulated feed is successful. Copepods are considered the natural prey of most marine fish larvae, and usually a greater larval growth, survival and development are observed when they are used as first feed instead of rotifers. This has been attributed to the copepods high fraction of essential fatty acids in their polar lipid fraction, in addition to their great amounts of protein and free amino acids. The present study was conducted to evaluate the effect of using intensively reared copepods (Acartia tonsa naupliii) as early live feed for the ballan wrasse larvae on the larval growth and survival, and early organ growth and development, compared to using rotifers (Brachionus ibericus). Four different feeding regimes were used, varying in the live feed provided during the first 30 days. Larvae from the “Copepod”-treatment were fed exclusively with A. tonsa during this period. Larvae from the “Cop7”-treatment were fed A. tonsa from 4 to 10 dph, with a transition to enriched rotifers. Fish larvae from the “RotMG”-treatment were fed enriched rotifers the whole period, while the “RotChl”-treatment had a diet consisting of unenriched rotifers. All treatments had a transition to Artemia from 24-30 dph, and were weaned to formulated feed from 40-50 dph. Results from the present study indicated that intensively reared A. tonsa was more suitable as early live feed for ballan wrasse larvae compared to enriched or unenriched rotifers. Increased growth rates were obtained while feeding the larvae with copepods, and it resulted in larvae with significantly higher dry weight at the end of the experimental period (61 dph). No difference in larval growth was observed when feeding with enriched or unenriched rotifers, however larvae fed unenriched rotifers had a significantly lower survival than larvae from all other treatments. Higher organ volume growth rates were observed when copepods were used as feed, and the organ volumes were found to relate to the larval standard length. At 21 dph, the Copepod larvae had a significantly higher proportion of musculature than larvae from the other treatments, and the intestine appeared to be more developed and mature.

Biofouling is the one of the main problems in marine finfish aquaculture. Biofouling occludes the nets and incurs major costs to fish farmers in the form of copper containing anti fouling paints used on the net surfaces, cleaning and changing of nets. Copper containing anti fouling paints is the major protective method in use by the fish farmers, but given the toxicity of the copper towards the marine invertebrates and its ability to accumulate in the food chain, it may face a ban in marine aquaculture. So, there is a need to develop better anti fouling methods which will be as effective as copper, have least impact on the environment and cost effective to use. To design these, better understanding of the process of biofouling is needed. There is little data available about the biofouling in marine aquaculture.In this regard, I studied biofouling in a marine cage aquaculture farm (ACE/Tristeinen), located in mid-Norwegian coastal waters. In this study, knot less nylon net panels and Micanti net panels were used to compare different aspects of biofouling and to test the effectiveness of the Micanti nets. Zooplankton samples were collected and analyzed with a focus on the larval stages of the fouling organisms, to relate the plakntonic stages of the foulers in the zooplankton sample to the foulers present on the net panels. Sea lice larval stages presence in the zooplankton samples was also detected to study the movement of sea lice larval stages.Analysis of the net panels and zooplankton samples together showed a trend between the larvae of foulers found in the zooplankton samples and foulers present on the net panels. On net panels hydroids, mussels, algae, amphipods and nudibranchs accounted for the major proportion of the fouling. On nylon net panels hydroids were more compared to mussels and on Micanti net panels mussels were more compared to hydroids. Nets occlusion and net fouling wet weight was slightly less on the micanti net panels compared to nylon net panels. Few sea lice, Lepeophtheirus salmonis larval stages were found in the zooplankton samples. Micanti did not work as expected, as it having problems with strength, length and density of the fibers flocked on the net. Improving these would help to improve the functionality of the Micanti nets as a better non-toxic antifouling technology.

Copepods play a key role in the marine ecosystem where they form a vital trophodynamic link between primary and tertiary producers, and are the dominant prey of many marine fishes during their larval stage. Because of their naturally high nutritional quality, copepods are excellent alternatives to traditional live feed organisms for intensive marine fish production. For aquaculturists, it is important to have continuous access to live feed organisms when rearing altricial fish larvae. Cold stored subitaneous copepod eggs are highly relevant as inoculum for culturing live food.In the present study, the effects of light, salinity and short-term elevations in temperature on the 48-h hatching success (HS, %) of cold stored (2 °C) A. tonsa eggs were evaluated. A light experiment exposed the eggs to three different environments with respect to light for a period of up to 7.5 months; one treatment exposed the eggs to an artificial light source, the second treatment had eggs stored in complete darkness, and the third treatment had eggs stored under the storage conditions applied at NTNU Sealab (SSC-treatment). A salinity experiment stored eggs in seawater of four different salinities (34, 50, 75 and 100 ‰) for a period of up to 7.5 months to evaluate if this was beneficial for long-term cold storage of A. tonsa eggs. A short-term temperature elevation experiment was conducted in order to simulate shipping conditions with insufficient cooling for consignments of A. tonsa eggs. Cold stored eggs were exposed to temperatures elevated to 9 and 17 °C for 12 and 24 hours, with and without oxygen present in the storage media, whereupon they were put back in cold storage for a period of one week before determining the HS.The results for the light experiment showed that light had a profound negative effect on the HS of the cold stored A. tonsa eggs. No hatching was observed for eggs that were stored under constant light after 3 months of cold storage. Eggs stored in darkness showed a significantly higher HS at the final sampling of month 7.5 compared to the SSC treatment, and less dispersion in HS between the replicates throughout the experiment. The salinity experiment showed that the eggs could be stored in seawater with a salinity of 50 ‰ for up to 3 months with a high HS, whereas storage in seawater of 75 and 100 ‰ showed a low HS for most samplings and thus proved as a poor cold storage media. The short-term elevation in temperature experiment showed that the HS was significantly affected by the oxygen concentration in the seawater upon a cold storage period of 3 weeks, and that short-term elevations in temperature, up to 17 °C for a duration of 24 hours, did not significantly affect the HS when hatched one week after the onset of incubation. The viability of the hatched nauplii post temperature exposures was assessed in a feeding incidence experiment. It showed that neither of the conducted temperature elevations utterly inhibited the nauplii from feeding.

Intensive salmonid cage culture releases nutrients and organic matter that lead eutrophication of coastal waters. Integrated multi-trophic aquaculture (IMTA) is receiving great attention as a means of reducing organic/inorganic nutrient loads to the environment and increasing productivity by rearing viable secondary organisms. In this study blue mussels (Mytilus edulis) were cultured close to a salmon (Salmo salar) cage farm at Tristen, Bjugn in Sør Trøndelag, Central Norway from June 2010 to February 2011. 3 experimental stations at the fish farming area and 2 reference stations (1.8 and 3.6 km away from the fish farm, respectively) were positioned to test if the integrated mussel culture reduces the environmental impact from salmon cage culture.Highest water temperature recorded was 14.3 °C in July. Water temperature was above 10 °C until middle of October and the lowest was 3.1 °C in winter. Total particulate matter (TPM) and chlorophyll a contents varied 6.3 – 10.5 mg L-1 and 0.1 - 2.5 µg L-1, respectively. The mussel (n=450) length increased from 31.1±0.04 mm (standard length±SE) to 41.5±0.17 mm. The mussel growth was high in summer (June – September) and was close to zero in the winter (October – February). Multiple regression analysis showed that water temperature was the prime factor affecting condition index (CI) (meat dry weight/shell dry weight) and specific growth rate (SGR) of mussel. No differences were found in the environmental variables and food availabilities among the stations. Significantly higher CIs at the experimental stations (station 1, 2 and 3) than at the reference stations were caused by utilization of fish farm discharges by the mussels. Fatty acids 18:1 (n-9), 18:2 (n-6) and 20:5 (n-3) signatures and the ratio of n-3 to n-6 in the digestive gland tissue of mussels collected in February support the findings. SGR in shell length was highest at reference station 5 (0.29 % day-1 in summer and 0.02 % day-1 in winter). This result might be caused by slow current speed at the station.It is concluded that, mussels may play an important role reducing environmental impact from salmon farm and it gives a possibility to integrating mussels on the salmon cage culture.

Ballan wrasse (Labrus bergylta) is a new species in aquaculture, the newly initiated intensive production is a response to the increasing demands for wrasse as cleaner fish in salmon and trout farming. The dietary requirements of the ballan wrasse larvae are largely unknown. The nutritional quality of the live feed commonly used in the farming of marine larvae today, rotifers and Artemia sp., may be suboptimal to the dietary need of developing ballan wrasse larvae, and contribute to the problems with growth, survival and skeletal anomalies currently observed in the rearing of this species. Copepods are the natural feed for pelagic marine larvae. To use intensively cultivated copepod nauplii in the farming of marine species, either as a supplement to, or instead of rotifers or Artemia sp., have lead to improved growth and normal development, earlier onset of ossification, and less skeletal anomalies. The aim of this study was to examine the effects of four different feeding regimes from 4 to 30 days post hatch (dph), on larval growth, development and quality. The larvae in the Copepod and Cop7 treatments were fed cultivated copepod nauplii of the species Acartia tonsa from 4 to 30 dph, and from 4 to 10 dph, respectively. The larvae in the RotMG and RotChl treatments were fed enriched and unenriched rotifers (Brachionus ibericus Cayman), respectively. All groups were fed Artemia fransiscana nauplii from 24 to 51 dph, and formulated feed from 40 to 61 dph. The experiment was terminated on 61 dph. Growth and survival was recorded, and the quality difference between the larvae from the different treatments was assessed through several quality parameters; observations of larval behaviour, response to handling stress, bone ossification, and skeletal anomalies.The larvae fed copepods instead of rotifers showed better growth and stress tolerance, were more effective predators, showed earlier onset of ossification of the axial and fin ray skeleton, and had significantly less skeletal anomalies per larvae compared to the larvae fed rotifers, when the most common anomaly (twisted arches) was excluded. Larval size was consistently more related to degree of ossification than age. Growth was the parameter most notably affected by the diet, and significant differences in dry weight, standard length and myotome height was found already on 8 dph.

Diatom contamination is a problem in the early cultivation stages of Saccharina latissima. Macro- and microalgae compete for the same abiotic resources, and diatoms may overgrow and eliminate seedlings of S. latissima if introduced to the macroalgae cultivation system. Germanium dioxide (GeO2), which blocks the cell division in diatoms, has been used as a diatom controller in the growth medium in cultivation of macroalgae. However, the chemical is very expensive and it has been suggested that the chemical inhibit growth of S. latissima seedlings. In the present study, it was desirable to establish a sori disinfection method for large-scale cultivation systems that eliminate diatoms prior to S. latissima spore release. It that was called for a purely chemical disinfection method as mechanical removal of contamination is labour-intensive and costly. Five chemicals, including 130 different trials, were tested on diatoms in free suspension. Acetic acid, sodium hypochlorite and ethanol eliminated diatom growth independent of concentration, exposure time and exposure temperature. Formaldehyde and Lugol’s solution revealed surviving diatoms in the weaker treatments. GeO2 eliminated growth of Chaetoceros muelleri and Skeletonema costatum, but monocultures of Phaeodactylum tricornutum were found at both concentrations (0.1mL L-1 and 0.5mL L-1) eleven days after inoculation. Acetic acid, Lugol’s solution and sodium hypochlorite were tested as sori disinfectants, and GeO2 was used as a negative control for diatom growth. Acetic acid treatments were lethal to both diatoms and S. latissima spores, and GeO2 treatments appeared to have negative influence on fertility and growth of young seedlings of S. latissima. Disinfection with 600ppm sodium hypochlorite or 2% Lugol’s solution, with an exposure time of 2 minutes and exposure temperature of 10°C, followed by two rinsing baths of sterile seawater, gave total elimination of diatoms. No notable effects on spore release, sporophyte growth or early development of young seedling were seen. This implies that disinfection of sori can be done safely by use of these treatments, without concern about reduced quality or quantity of cultivated seaweeds. Sori disinfection was done on disks cut from ripe sori in a disinfecting bath, and no mechanical removal of sori contamination was performed. Sodium hypochlorite was suggested as a new sori disinfectant based on an apparently good safety margin between lethal doses to diatoms and a harmful dose for S. latissima. The chemical also appears to be a widespread disinfectant in aquaculture systems, and can easily be neutralized with thiosulphate.

Sea lice have been causing problems in Norwegian salmon farming industry for decades; increasing mortality and reducing the welfare of farmed and wild fish. Various chemical agents have been used to combat sea lice, but increased tolerance and resistance have shifted the focus more onto biological combatants in the form of cleaner wrasse. The ballan wrasse (Labrus bergylta) is the most promising species for aquaculture, but problems with poor larval growth and survival suggests that the feeding practices in use today remain suboptimal.At present, the feeding regimes consist of enriched rotifers, followed by Artemia sp. and weaning onto formulated feed. However, the nutritional profile of copepods is known to be highly beneficial for marine fish larvae, and increased larval growth, survival and development have been reported when copepods are administered as live feed. In the present study the fish larvae were fed intensively cultivated copepod nauplii (Acartia tonsa) in order to evaluate the effects on somatic growth, survival and muscle development, compared to when being fed rotifers (Brachionus ibericus). Four different feeding regimes were used; the Copepod treatment received copepod nauplii 4-30 dph, while larvae from the Cop7 treatment received copepod nauplii 4-10 dph, followed by short-term enriched rotifers (11-30 dph). Larvae from the treatments RotMG and RotChl were given short-term enriched and cultivated rotifers respectively, 4-30 dph. Larvae from all treatments went through a transition phase onto Artemia sp. 24-30 dph, and were weaned onto formulated feed 40-50 dph. The larval somatic growth and survival were studied from start to end (2-61 dph), while muscle development was studied until 21 dph, in order to address the direct effects of copepod nauplii vs. rotifers. The results in the present study revealed that larvae fed copepod nauplii achieved higher growth rates initially, and greater dry weight already at 8 dph (also at the end of the experiment) compared to larvae fed rotifers. From 4-21 dph the increase in muscle mass was significantly larger in larvae from the Copepod treatment; accounted for by higher hyperplastic and hypertropic growth. The number of red and white fibres, size of deep white fibres, and total muscle area was found to correlate strongly with larval standard length.

The experiment was carried out from 23rd Junuary to 24th March 2011 at Sealab. Atlantic cod larvae were reared with water from three different systems: flow-though, maturated water and recirculation water. The water, larvae and feed specimens will be sampled from those three systems for microbial analysis by PCR-DGGE (denaturing gradient gel electrophoresis) and sequencing of bands. DNA will be extracted from water, feed and larvae, and used as template in PCR to amplify 16S rRNA encoding genes of bacteria. Subsequently, the PCR products will be separated by DGGE. The phylogenetic affiliation of the predominant community members, as represented in the DGGE band pattern, will be excised, re-amplified and sequences, and used for taxonomic assignment of the bacteria. Analyses of similarity (ANOSIM) with Bray-Curtis dissimilarity will be used to compare microbial community composition in three systems as well as microbiota of gut larvae.

Good nutritional quality is a key for a successful Atlantic cod (Gadus morhua) juvenile producer. Copepods are the natural prey for marine fish larvae, and its nutritional composition is believed to be optimal for the marine fish larvae. Despite the suitability for copepods in cod cultivation, only a few hatcheries have used this technique. When cultivating cod larvae and copepods intensively they can be produced in larger quantities and year-round, compared to the seasonal extensive cultivation. Intensive produced copepods have yet to be used in large-scale cod hatcheries. It has several times been documented that nutrition is important for survival, growth and the general quality of cod larvae. Even though these variables are something many farmers of juvenile cod (Gadus morhua) are struggling with, there has still not been developed any standard evaluation of quality. Codeggs were divided and after hatching given 4 different feeding regimes (3-28 dph). One was fed the copepod Acartia tonsa, a second fed the rotifer Brachionus ibericus enriched, a third fed Brachionus ibericus unenriched and a last with a mixture of copepods (7 days) and enriched rotifers. This was done to better see the effect of copepod feeding compared to the rotifer effect, and if there could be some benefits from only feeding with copepods for a small period. All treatments were fed Artemia sp. (20-40 dph) and dry feed (36-60 dph). In addition to growth and survival, the quality of the fish larvae was assessed. This was done by using the following quality parameters: Larval feeding activity, resistance to handling stress, skeletal deformations and shape variation.The study showed a clear trend where the larvae fed mostly copepods were the most successful in terms of growth, survival and quality, followed by those fed copepods for 7 days, and enriched and unenriched rotifers at the end. These results clearly showed that intensively cultivated copepods successfully could be used during intensive cod cultivation. All quality parameters gave results and combined gave a broad picture of the general quality of the cod larvae.